0001060955-23-000027 | 6-K | XBRL Viewer

Intangible assets (Tables)

6 Months Ended

Jun. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Finite-Lived Intangible Assets

Intangible assets are amortized on a straight-line basis over the expected useful life, as set forth in the table below:


			Estimated Useful Life
Customer relationships			23 years
Order backlog			3 years
Trade names			3 years
Patient database			7 years
Technology assets			5 years

Intangible assets, net consisted of the following:


	Six Months Ended		Year Ended
	June 30, 2023		December 31, 2022
Cost	(in thousands)
Customer relationships	$	4,077,225	$	4,076,435
Order backlog	537,182		536,934
Trade names & brands	204,636		204,621
Patient database	170,342		170,238
Technology assets	121,110		120,984



Total cost	5,110,495		5,109,212
Accumulated amortization	(1,060,702)		(830,553)

Net book value	$	4,049,793	$	4,278,659

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 270,176	$ 288,768
Available for sale investments	1,653	1,713
Accounts receivable, net of allowance for credit losses	1,759,111	1,731,388
Unbilled revenue	985,034	957,655
Other receivables	129,101	63,658
Prepayments and other current assets	152,774	137,094
Income taxes receivable	70,021	48,790
Total current assets	3,367,870	3,229,066
Non-current assets:
Property, plant and equipment, net	346,521	350,320
Goodwill	8,993,583	8,971,670
Intangible assets	4,049,793	4,278,659
Operating right-of-use assets	144,514	153,832
Other receivables	64,140	70,790
Income taxes receivable	25,169	21,380
Deferred tax asset	80,772	76,930
Equity method investments	0	0
Investments in equity- long term	35,298	32,631
Total Assets	17,107,660	17,185,278
Current Liabilities:
Accounts payable	46,920	81,194
Unearned revenue	1,573,311	1,507,449
Other liabilities	994,883	1,005,025
Income taxes payable	39,885	41,783
Current bank credit lines and loan facilities	105,150	55,150
Total current liabilities	2,760,149	2,690,601
Non-current liabilities:
Non-current bank credit lines and loan facilities	4,206,936	4,599,037
Lease liabilities	129,079	131,644
Non-current other liabilities	39,438	38,260
Non-current income taxes payable	241,410	239,188
Deferred tax liability	934,208	988,585
Commitments and contingencies	0	0
Total Liabilities	8,311,220	8,687,315
Shareholders' Equity:
Ordinary shares, par value 6 euro cents per share; 100,000,000 shares authorized, 81,928,422 shares issued and outstanding at June 30, 2023 and 81,723,555 shares issued and outstanding at December 31, 2022	6,676	6,649
Additional paid-in capital	6,891,494	6,840,306
Other undenominated capital	1,162	1,162
Accumulated other comprehensive loss	(156,528)	(171,538)
Retained earnings	2,053,636	1,821,384
Total Shareholders' Equity	8,796,440	8,497,963
Total Liabilities and Shareholders' Equity	$ 17,107,660	$ 17,185,278

Cover	6 Months Ended
Cover	Jun. 30, 2023
Cover [Abstract]
Document Type	6-K
Document Fiscal Year Focus	2023
Entity Registrant Name	ICON plc
Amendment Flag	false
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001060955
Current Fiscal Year End Date	--12-31
Document Period End Date	Jun. 30, 2023

Restructuring - Summary of Details of Movement in Restructuring Charges (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Restructuring Reserve [Roll Forward]
Opening provision	$ 6,022	$ 10,311
Additional provisions	39,338	4,364
Utilization	(10,188)	(8,653)
Ending provision	$ 35,172	$ 6,022

Summary of significant accounting policies

6 Months Ended

Jun. 30, 2023

Accounting Policies [Abstract]

Summary of significant accounting policies

Revenue recognition

The Company earns revenues by providing a number of different services to its customers. These services, which are integral elements of the clinical development process, include clinical trials management, consulting, contract staffing, data services and laboratory services. These services, which are described below, can be purchased collectively or individually as part of a clinical trial contract. There is not significant variability in how economic factors affect these services. Contracts range in duration from a number of months to several years.

ASC 606 requires application of five steps: (1) identify the contract(s) with a customer; (2) identify the performance obligation in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when (or as) the entity satisfies the performance obligation(s), which have been applied to revenue recognized from each service described below.

Clinical trial service revenue

A clinical trial service is a single performance obligation satisfied over time, i.e. the full-service obligation in respect of a clinical trial (including those services performed by investigators and other parties) is considered a single performance obligation. Promises offered to the customer are not distinct within the context of the contract. ICON is the contract principal in respect of both direct services and in the use of third parties (principally investigator services) that support the clinical research projects. The transaction price is determined by reference to the contract or change order value (total service revenue and pass-through/ reimbursable expenses) adjusted to reflect a realizable contract value. Revenue is recognized over time as the single performance obligation is satisfied. The progress towards completion for clinical service contracts is measured based on an input measure being total project costs incurred (inclusive of pass-through/ reimbursable expenses) at each reporting period as a percentage of forecasted total project costs.

Laboratory services revenue

Revenue is recognized when, or as, obligations under the terms of a contract are satisfied, which occurs when control of the products or services are transferred to the customer. Revenue for laboratory services is measured as the amount of consideration we expect to receive in exchange for transferring products or services. Where contracts with customers contain multiple performance obligations, the transaction price is allocated to each performance obligation based on the estimated relative selling price of the promised good or service. Service revenue is recognized over time as the services are delivered to the customer based on the extent of progress towards completion of the performance obligation. The determination of the methodology to measure progress requires judgment and is based on the nature of services provided. This requires an assessment of the transfer of value to the customer. The right to invoice measure of progress is generally related to rate per unit contracts, as the extent of progress towards completion is measured based on discrete service or time-based increments, such as samples tested or labor hours incurred. Revenue is recorded in the amount invoiced since that amount corresponds to the value of the Company's performance and the transfer of value to the customer.

Contracting services revenue

The Company has availed of the practical expedient which results in recognition of revenue on a right to invoice basis. Application of the practical expedient reflects the right to consideration from the customer in an amount that corresponds directly with the value to the customer of the performance completion to date. This reflects hours performed by contract staff.

Consulting services revenue

Our consulting services contracts represent a single performance obligation satisfied over time. The transaction price is determined by reference to contract or change order value. Revenue is recognized over time as the performance obligation is satisfied. The progress towards completion for consulting contracts is measured based on total project inputs (time) at each reporting period as a percentage of forecasted total project inputs.

Data services revenue

The Company provides data reports and analytics to customers based on agreed-upon specifications, including the timing of delivery, which is typically either weekly, monthly, or quarterly. If a customer requests more than one type of data report or series of data reports within a contract, each distinct type of data report is a separate performance obligation. The contracts provide for the Company to be compensated for the value of each deliverable. The transaction price is determined using list prices, discount agreements, if any, and negotiations with the customers, and generally includes any out-of-pocket expenses. Typically, the Company bills in advance of services being provided with the amount being recorded as unearned revenue.

When multiple performance obligations exist, the transaction price is allocated to performance obligations on a relative standalone selling price basis. In cases where the Company contracts to provide a series of data reports, or in some cases data, the Company recognizes revenue over time using the “units delivered” output method as the data or reports are delivered. Expense reimbursements are recorded to revenue as the expenses are incurred as they relate directly to the services performed.

Certain arrangements include upfront customization or consultative services for customers. These arrangements often include payments based on the achievement of certain contractual milestones. Under these arrangements, the Company contracts with a customer to carry out a specific study, ultimately resulting in delivery of a custom report or data product. These arrangements are a single performance obligation given the integrated nature of the service being provided. The Company typically recognizes revenue under these contracts over time, using an output-based measure, generally time elapsed, to measure progress and transfer of control of the performance obligation to the customer. Expense reimbursements are recorded to revenue as the expenses are incurred as they relate directly to the service performed.

The Company enters into contracts with some of its larger data suppliers that involve non-monetary terms. The Company issues purchase credits to be used toward the data supplier's purchase of the Company's services based on the fair value of the data obtained. In exchange, the Company receives monetary discounts on the data received from the data suppliers. The fair value of the revenue earned from the customer purchases is recognized as services are delivered as described above. At the end of the contract year, any unused customer purchase credits may be forfeited or carried over to the next contract year based on the terms of the data supplier contract.

Commissions

Incremental costs of obtaining a contract are recognized as an asset on the Consolidated Balance Sheet in respect of those contracts that exceed one year. Where commission costs relate to contracts that are less than one year, the practical expedient is applied as the amortization period of the asset which would arise on deferral would be one year or less.

Business Combinations

The cost of a business combination is measured as the aggregate of the fair value of assets received, liabilities assumed and equity instruments issued in exchange for control. The Company records and allocates to its reporting units the excess of the cost over the fair value of the net assets acquired, known as goodwill. Where a business combination agreement provides for an adjustment to the cost of the acquisition which is contingent upon future events, the amount of the estimated adjustment is recognized at the acquisition date at the fair value of the contingent consideration. Any changes to this estimate outside the measurement period will depend on the classification of the contingent consideration. If the contingent consideration is classified as equity it shall not be re-measured and the settlement shall be accounted for within equity. If the contingent consideration is classified as a liability any adjustments will be accounted for through the Consolidated Statement of Operations or Other Comprehensive Income depending on whether the liability is considered a financial instrument.

The assets, liabilities and contingent liabilities of businesses acquired are measured at their fair values at the date of acquisition. In the case of a business combination which is completed in stages, the fair values of the identifiable assets, liabilities and contingent liabilities are determined at the date of each exchange transaction. When the initial accounting for a business combination is determined provisionally, any subsequent adjustments to the provisional values allocated to the identifiable assets, liabilities and contingent liabilities are made within twelve months of the acquisition date and presented as adjustments to goodwill in the reporting period in which the adjustments are determined.

The Company allocates a share of net income to the noncontrolling interest holders based on percentage ownership.

Intangible Assets

Intangible assets are measured at their fair value when acquired and amortized on the straight line basis over their respective useful lives. The Company has no indefinite life intangibles other than goodwill. The Company evaluates its intangibles for impairment when indicators of impairment exist.

Intangible assets are amortized on a straight-line basis over the expected useful life, as set forth in the table below:


			Estimated Useful Life
Customer relationships			23 years
Order backlog			3 years
Trade names			3 years
Patient database			7 years
Technology assets			5 years

The Company periodically assesses the useful lives of intangible assets to evaluate whether what was established at acquisition continues to be appropriate.

Income taxes

The Company applies the asset and liability method of accounting for income taxes. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amount of existing assets and liabilities and their respective tax bases and for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Deferred tax assets are reduced by a valuation allowance to the amount that is more likely than not to be realized. The Company recognizes the effect of income tax positions only if those positions will more likely than not be sustained. Recognized income tax positions are measured at the largest amount of tax benefit that is greater than 50 percent likely of being realized upon settlement. Interest and penalties related to income taxes are included in income tax expense and classified with the related liability on the Consolidated Balance Sheet. The Company accounts for the impact of GILTI (“global intangible low-taxed income”) in the period it arises and has therefore not provided for deferred taxes in respect of this item.

Bank credit lines and loan facilities - Narrative (Details) - USD ($) $ in Thousands			1 Months Ended		6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Apr. 30, 2023	Jan. 31, 2023	Jun. 30, 2023	Jun. 30, 2022	May 02, 2023	Jan. 13, 2023	Dec. 31, 2022	Jul. 01, 2021
Debt Instrument [Line Items]
Drawdown of bank credit lines and loan facilities					$ 230,000	$ 25,000
Long-term debt at fair value	$ 4,310,100				$ 4,310,100
Senior secured credit facility and senior secured notes \| Senior Secured Term Loan
Debt Instrument [Line Items]
Debt discount paid										$ 27,600
Senior Secured Term Loan \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	0.50%
Senior Secured Term Loan \| SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	2.25%
Senior Secured Term Loan \| Senior Secured Term Loan
Debt Instrument [Line Items]
Debt instrument, principal amount										$ 5,515,000
Debt instrument, interest rate	7.41%				7.41%				7.09%	1.00%
Repayments of senior debt	$ 150,000	$ 250,000
Interest paid	74,000	75,300
Payments of debt restructuring costs	1,200	$ 2,200
Senior Secured Revolving Loan Facility \| Base rate \| Variable rate component one
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)					0.60%
Senior Secured Revolving Loan Facility \| Base rate \| Maximum \| Variable rate component one
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)					1.00%
Senior Secured Revolving Loan Facility \| Base rate \| Minimum \| Variable rate component one
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)					0.25%
Senior Secured Revolving Loan Facility \| SOFR \| Variable rate component two
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)					1.60%
Senior Secured Revolving Loan Facility \| SOFR \| Maximum \| Variable rate component two
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)					2.00%
Senior Secured Revolving Loan Facility \| SOFR \| Minimum \| Variable rate component two
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)					1.25%
Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility
Debt Instrument [Line Items]
Repayments of senior debt	$ 80,000
Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility
Debt Instrument [Line Items]
Debt instrument, maximum borrowing capacity							$ 500,000			$ 300,000
Debt instrument, interest rate	6.51%	6.17%	6.25%		6.51%
Drawdown of bank credit lines and loan facilities		$ 80,000	$ 50,000	$ 100,000
Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate				5.89%
Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility \| Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate								5.80%
Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility \| SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	1.25%	1.25%	1.25%	1.25%
Senior Secured Notes \| Senior Secured Notes
Debt Instrument [Line Items]
Debt instrument, principal amount										$ 500,000
Debt instrument, interest rate	2.88%				2.88%				2.88%	2.875%

Fair value measurements

6 Months Ended

Jun. 30, 2023

Fair Value Disclosures [Abstract]

Fair value measurements

The Company records certain assets and liabilities at fair value. Fair value is defined as the price that would be received to sell an asset, or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. A three-level fair value hierarchy that prioritizes the inputs used to measure fair value is described below. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows:

•Level 1 — Quoted prices in active markets for identical assets or liabilities.

•Level 2 — Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data.

•Level 3 — Unobservable inputs that are supported by little or no market activity. This includes certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs.

The carrying amounts of financial instruments, including cash and cash equivalents, accounts receivable, unbilled services, contract assets, accounts payable and unearned revenue approximate fair value due to the short maturities of these instruments.

As of June 30, 2023, the fair value of the major classes of the Company's assets and liabilities measured at fair value on a recurring basis were as follows (in thousands):


	Level 1		Level 2		Level 3		Investments Measured at Net Asset Value		Total
	(in thousands)
Assets:
Available for sale securities (short-term) (a)	1,653		—		—		—		1,653
Available for sale investments (long-term) (b)	—		—		—		35,298		35,298
Derivative instruments (c)	—		7,433		—		—		7,433
Total assets	$	1,653	$	7,433	$	—	$	35,298	$	44,384

Liabilities:
Derivative instruments (c)	—		—		—		—		—
Total liabilities	$	—	$	—	$	—	$	—	$	—

As of December 31, 2022, the fair value of the major classes of the Company's assets and liabilities measured at fair value on a recurring basis were as follows (in thousands):


	Level 1		Level 2		Level 3		Investments Measured at Net Asset Value		Total
	(in thousands)
Assets:
Available for sale securities (short-term) (a)	1,713		—		—		—		1,713
Available for sale investments (long-term) (b)	—		—		—		32,631		32,631
Derivative instruments (c)	—		12		—		—		12
Total assets	$	1,713	$	12	$	—	$	32,631	$	34,356

Liabilities:
Derivative instruments (c)	—		3,670		—		—		3,670
Total liabilities	$	—	$	3,670	$	—	$	—	$	3,670

(a) Represents the fair value of investments in highly liquid investments with maturities of greater than three months and a minimum "A-" rated fixed term deposits and are based on quoted market prices.

(b) To determine the classification of its interests in long-term investments, the Company considered the nature of its investment, the extent of influence over operating and financial decisions and the availability of readily determinable fair values. The Company determined that the interests in funds meet the definition of equity securities without readily determinable fair values, which qualify for the Net Asset Value (NAV) practical expedient in ASC 820 'Fair value measurements and disclosures'. Any increases or decreases in fair value are recognized in net income in the period.

(c) Represents the fair value of interest rate cap and interest rate swap agreements. The fair value of the agreements are the estimated amount that the Company would receive or pay to terminate such agreements, taking into account market interest rates and the remaining time to maturities or using market inputs with mid-market pricing as a practical expedient for bid-ask spread.

Non-recurring Fair Value Measurements

Certain assets and liabilities are carried on the accompanying Condensed Consolidated Balance Sheet at cost and are not re-measured to fair value on a recurring basis. These assets include finite-lived intangible assets that are tested for

impairment when a triggering event occurs and goodwill that is tested for impairment annually or when a triggering event occurs. As of June 30, 2023, assets carried on the balance sheet at cost and not re-measured to fair value on a recurring basis totaled approximately $13,043.4 million and are identified as Level 3 assets. These assets are comprised of goodwill of $8,993.6 million and net identifiable intangible assets of $4,049.8 million. The estimated fair value of the Company’s debt was $4,310.1 million at June 30, 2023. The fair values of the Senior Secured Credit Facilities and Senior Secured Notes were determined based on Level 2 inputs, which are based on rates at which the debt is traded among financial institutions. The fair value of the senior secured revolving loan facility is recorded as its carrying value, due to the short term duration.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Bank credit lines and loan facilities - Schedule of Outstanding Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Apr. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jul. 01, 2021
Debt Instrument [Line Items]
Total debt	$ 4,351,213			$ 4,701,213
Less current portion of long-term debt	(105,150)			(55,150)
Total long-term debt	4,246,063			4,646,063
Less debt issuance costs and debt discount	(39,127)			(47,026)
Total long-term debt, net	$ 4,206,936			$ 4,599,037
Senior Secured Term Loan \| Senior Secured Term Loan
Debt Instrument [Line Items]
Debt instrument, interest rate	7.41%			7.09%	1.00%
Total debt	$ 3,801,213			$ 4,201,213
Senior Secured Notes \| Senior Secured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	2.88%			2.88%	2.875%
Total debt	$ 500,000			$ 500,000
Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility \| Senior Secured Revolving Loan Facility
Debt Instrument [Line Items]
Debt instrument, interest rate	6.51%	6.25%	6.17%
Line of credit facility, interest rate at period end	6.51%
Total debt	$ 50,000			$ 0

Net income per ordinary share - Schedule of Reconciliation of Net Income Attributable to the Group (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Net income per Ordinary Share attributable to the Group:
Basic (in USD per share)	$ 1.41	$ 1.42	$ 2.84	$ 2.80
Diluted (in USD per share)	$ 1.40	$ 1.41	$ 2.81	$ 2.76

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482635/260-10-55-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (e)(4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-7

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-60B

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-4

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482662/260-10-50-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-10

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(25))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(27))
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-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

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-Topic 944
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-Paragraph 1
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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

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+ Details

Net income per ordinary share - Schedule of Reconciliation of Number of Shares Used in Computation of Basic and Diluted Net Income Per Ordinary Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Weighted average number of ordinary shares outstanding for basic net income per ordinary share (in shares)	81,999,746	81,398,071	81,892,662	81,430,507
Effect of dilutive share options and other awards outstanding under share based compensation programs (in shares)	628,187	914,875	724,729	1,032,335
Weighted average number of ordinary shares outstanding for diluted net income per ordinary share (in shares)	82,627,933	82,312,946	82,617,391	82,462,842

Business Segment and Geographical Information - Schedule of Distribution of Depreciation and Amortization by Geographical Area (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Long-lived assets	$ 491,035	$ 504,152
Ireland
Segment Reporting Information [Line Items]
Long-lived assets	148,242	143,025
Rest of Europe
Segment Reporting Information [Line Items]
Long-lived assets	95,048	99,721
U.S.
Segment Reporting Information [Line Items]
Long-lived assets	195,407	213,311
Rest of World
Segment Reporting Information [Line Items]
Long-lived assets	$ 52,338	$ 48,095

Share-based awards - Summary of Stock Option Activity (Details) - Employee Stock Option			6 Months Ended
	Jun. 30, 2023 $ / shares shares	Dec. 31, 2022 $ / shares shares	Jun. 30, 2023 $ / shares shares
Options Outstanding Number of Shares
Outstanding at beginning of period (in shares) \| shares			1,378,119
Granted (in shares) \| shares			82,472
Exercised (in shares) \| shares			(229,953)
Canceled/expired (in shares) \| shares			(6,885)
Outstanding at end of period (in shares) \| shares	1,223,753	1,378,119	1,223,753
Exercisable at end of period (in shares) \| shares	952,614		952,614
Weighted Average Exercise Price
Outstanding at beginning of period (in USD per share) \| $ / shares			$ 119.86
Granted (in USD per share) \| $ / shares			232.48
Exercised (in USD per share) \| $ / shares			87.69
Canceled/expired (in USD per share) \| $ / shares			116.33
Outstanding at end of period (in USD per share) \| $ / shares	$ 133.51	$ 119.86	133.51
Exercisable at end of period (in USD per share) \| $ / shares	$ 113.27		$ 113.27
Weighted Average Remaining Contractual Life
Weighted average contractual term of options outstanding	4 years 8 months 1 day	4 years 8 months 8 days
Weighted average contractual term of options exercisable	4 years 2 months 12 days

Bank credit lines and loan facilities (Tables)

6 Months Ended

Jun. 30, 2023

Debt Disclosure [Abstract]

Schedule of Outstanding Debt

The Company had the following debt outstanding as of June 30, 2023 and December 31, 2022:


					Principal amount
	Interest rate as of		Interest rate as of		June 30,		December 31,
(in thousands)	June 30, 2023		December 31, 2022		2023		2022		Maturity Date
Credit Facilities:
Senior Secured Term Loan	7.41	%	7.09	%	$	3,801,213	$	4,201,213	July 2028
Senior Secured Notes	2.88	%	2.88	%	$	500,000	$	500,000	July 2026
Senior Secured Revolving Loan Facility	6.51	%	—		50,000		—		July 2023




Total debt					4,351,213		4,701,213

Less current portion of long-term debt					(105,150)		(55,150)
Total long-term debt					4,246,063		4,646,063
Less debt issuance costs and debt discount					(39,127)		(47,026)
Total long-term debt, net					$	4,206,936	$	4,599,037

Schedule of Contractual Maturities of Debt

As of June 30, 2023, the contractual maturities of the Company's debt obligations were as follows:


Contractual maturities of long-term debt:	(in thousands)
2023 (remaining)	$	77,575
2024	55,150
2025	55,150
2026	55,150
2027 and thereafter	4,108,188
Total	$	4,351,213

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows from operating activities:
Net income	$ 232,252	$ 227,704
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	290,185	285,424
Impairment of long lived assets	8,613	20,749
Reduction in carrying value of operating right-of-use assets	23,607	23,570
Loss on equity method investments	383	1,641
Acquisition-related gain	(6,160)	0
Charge on cash flow hedge	3,646	0
Amortization of financing costs and debt discount	7,899	9,188
Stock compensation expense	31,357	38,186
Deferred taxes	(59,177)	(75,265)
Foreign exchange movements	(3,345)	(37,421)
Other non-cash items	18,202	9,159
Changes in operating assets and liabilities:
Accounts receivable	(40,675)	(41,032)
Unbilled revenue	(27,210)	(33,187)
Unearned revenue	65,266	(176,904)
Other net assets	(165,462)	157,154
Net cash provided by operating activities	379,381	408,966
Cash flows from investing activities:
Purchase of property, plant and equipment	(58,880)	(47,840)
Purchase of subsidiary undertakings	(5,100)	0
Sale of available for sale investments	482	0
Purchase of available for sale investments	(422)	0
Purchase of investments in equity - long term	(4,733)	(799)
Net cash used in investing activities	(68,653)	(48,639)
Cash flows from financing activities:
Drawdown of bank credit lines and loan facilities	230,000	25,000
Repayment of bank credit lines and loan facilities	(580,000)	(425,000)
Proceeds from exercise of equity compensation	20,177	15,140
Share issue costs	(9)	(3)
Repurchase of ordinary shares	0	(99,983)
Share repurchase costs	0	(17)
Net cash used in financing activities	(329,832)	(484,863)
Effect of exchange rate movements on cash	512	(12,759)
Net decrease in cash and cash equivalents	(18,592)	(137,295)
Cash and cash equivalents at beginning of period	288,768	752,213
Cash and cash equivalents at end of period	$ 270,176	$ 614,918

Fair value measurements - Measurement of Fair Value of Major Asset and Liability classed (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities (short-term)	$ 1,653	$ 1,713
Available for sale investments (long-term)	35,298	32,631
Total assets	44,384	34,356
Total liabilities	0	3,670
Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	7,433	12
Derivative instruments	0	3,670
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities (short-term)	1,653	1,713
Available for sale investments (long-term)	0	0
Total assets	1,653	1,713
Total liabilities	0	0
Level 1 \| Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	0	0
Derivative instruments	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities (short-term)	0	0
Available for sale investments (long-term)	0	0
Total assets	7,433	12
Total liabilities	0	3,670
Level 2 \| Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	7,433	12
Derivative instruments	0	3,670
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities (short-term)	0	0
Available for sale investments (long-term)	0	0
Total assets	0	0
Total liabilities	0	0
Level 3 \| Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	0	0
Derivative instruments	0	0
Investments Measured at Net Asset Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities (short-term)	0	0
Available for sale investments (long-term)	35,298	32,631
Total assets	35,298	32,631
Total liabilities	0	0
Investments Measured at Net Asset Value \| Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	0	0
Derivative instruments	$ 0	$ 0

Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Revenue (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue	$ 2,020,251	$ 1,935,193	$ 3,998,829	$ 3,836,957
Clients 1-5
Disaggregation of Revenue [Line Items]
Revenue	529,792	525,938	1,092,220	1,065,641
Clients 6-10
Disaggregation of Revenue [Line Items]
Revenue	284,382	260,689	563,908	553,350
Clients 11-25
Disaggregation of Revenue [Line Items]
Revenue	420,880	368,675	829,047	726,985
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 785,197	$ 779,891	$ 1,513,654	$ 1,490,981

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Derivatives - Effect of Derivative Financial Instruments on Statement of Financial Position (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other receivables
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities
Interest Rate Caps \| Total derivatives designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	$ 4,461,000	$ 12,000
Derivative liability	0	3,363,000
Notional	1,900,606,000	2,100,606,000
Interest Rate Swap \| Total derivatives designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	2,972,000	0
Derivative liability	0	307,000
Notional	1,100,606,000	1,100,606,000
Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	7,433,000	12,000
Derivative liability	0	3,670,000
Notional	3,001,212,000	3,201,212,000
Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments \| Level 2
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	7,433,000	12,000
Derivative liability	$ 0	$ 3,670,000

Goodwill (Tables)

6 Months Ended

Jun. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill


	Six Months Ended		Year Ended
	June 30, 2023		December 31, 2022
	(in thousands)
Opening balance	$	8,971,670	$	9,037,931
Current period acquisition	13,379		—
Prior period acquisition	—		(35,692)
Foreign exchange movement	8,534		(30,569)

Closing balance	$	8,993,583	$	8,971,670

- Definition

Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 24
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482548/350-20-55-24

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+ Details

Fair Value Measures and Disclosures (Tables)

6 Months Ended

Jun. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value, Liabilities Measured on Recurring Basis

As of June 30, 2023, the fair value of the major classes of the Company's assets and liabilities measured at fair value on a recurring basis were as follows (in thousands):


	Level 1		Level 2		Level 3		Investments Measured at Net Asset Value		Total
	(in thousands)
Assets:
Available for sale securities (short-term) (a)	1,653		—		—		—		1,653
Available for sale investments (long-term) (b)	—		—		—		35,298		35,298
Derivative instruments (c)	—		7,433		—		—		7,433
Total assets	$	1,653	$	7,433	$	—	$	35,298	$	44,384

Liabilities:
Derivative instruments (c)	—		—		—		—		—
Total liabilities	$	—	$	—	$	—	$	—	$	—

As of December 31, 2022, the fair value of the major classes of the Company's assets and liabilities measured at fair value on a recurring basis were as follows (in thousands):


	Level 1		Level 2		Level 3		Investments Measured at Net Asset Value		Total
	(in thousands)
Assets:
Available for sale securities (short-term) (a)	1,713		—		—		—		1,713
Available for sale investments (long-term) (b)	—		—		—		32,631		32,631
Derivative instruments (c)	—		12		—		—		12
Total assets	$	1,713	$	12	$	—	$	32,631	$	34,356

Liabilities:
Derivative instruments (c)	—		3,670		—		—		3,670
Total liabilities	$	—	$	3,670	$	—	$	—	$	3,670

Fair Value, Assets Measured on Recurring Basis

As of June 30, 2023, the fair value of the major classes of the Company's assets and liabilities measured at fair value on a recurring basis were as follows (in thousands):


	Level 1		Level 2		Level 3		Investments Measured at Net Asset Value		Total
	(in thousands)
Assets:
Available for sale securities (short-term) (a)	1,653		—		—		—		1,653
Available for sale investments (long-term) (b)	—		—		—		35,298		35,298
Derivative instruments (c)	—		7,433		—		—		7,433
Total assets	$	1,653	$	7,433	$	—	$	35,298	$	44,384

Liabilities:
Derivative instruments (c)	—		—		—		—		—
Total liabilities	$	—	$	—	$	—	$	—	$	—

As of December 31, 2022, the fair value of the major classes of the Company's assets and liabilities measured at fair value on a recurring basis were as follows (in thousands):


	Level 1		Level 2		Level 3		Investments Measured at Net Asset Value		Total
	(in thousands)
Assets:
Available for sale securities (short-term) (a)	1,713		—		—		—		1,713
Available for sale investments (long-term) (b)	—		—		—		32,631		32,631
Derivative instruments (c)	—		12		—		—		12
Total assets	$	1,713	$	12	$	—	$	32,631	$	34,356

Liabilities:
Derivative instruments (c)	—		3,670		—		—		3,670
Total liabilities	$	—	$	3,670	$	—	$	—	$	3,670

CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Ordinary shares	Additional Paid-in Capital	Other Undenominated Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2021		81,554,683
Beginning balance at Dec. 31, 2021	$ 8,066,827	$ 6,640	$ 6,733,910	$ 1,134	$ (90,937)	$ 1,416,080
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	111,970					111,970
Exercise of share options (in shares)		84,090
Exercise of share options	7,497	$ 6	7,491
Issue of restricted share units / performance share units (in shares)		74,769
Issue of restricted share units / performance share units	4	$ 4
Non-cash stock compensation expense	18,840		18,840
Share issuance costs	(3)		(3)
Share repurchase program (in shares)		420,530
Share repurchase program	(99,983)	$ (28)		28		(99,983)
Share repurchase costs	17					17
Other comprehensive loss, net of tax	(35,818)				(35,818)
Ending balance (in shares) at Mar. 31, 2022		81,293,012
Ending balance at Mar. 31, 2022	8,069,317	$ 6,622	6,760,238	1,162	(126,755)	1,428,050
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	115,734					115,734
Exercise of share options (in shares)		75,671
Exercise of share options	7,653	$ 4	7,649
Issue of restricted share units / performance share units (in shares)		157,924
Issue of restricted share units / performance share units	11	$ 11
Non-cash stock compensation expense	19,478		19,478
Other comprehensive loss, net of tax	(66,180)				(66,180)
Ending balance (in shares) at Jun. 30, 2022		81,526,607
Ending balance at Jun. 30, 2022	$ 8,146,013	$ 6,637	6,787,365	1,162	(192,935)	1,543,784
Beginning balance (in shares) at Dec. 31, 2022	81,723,555	81,723,555
Beginning balance at Dec. 31, 2022	$ 8,497,963	$ 6,649	6,840,306	1,162	(171,538)	1,821,384
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	116,654					116,654
Exercise of share options (in shares)		136,649
Exercise of share options	12,936	$ 9	12,927
Issue of restricted share units / performance share units (in shares)		68,218
Issue of restricted share units / performance share units	4	$ 4
Non-cash stock compensation expense	14,658		14,658
Share issuance costs	(4)		(4)
Other comprehensive loss, net of tax	11,642				11,642
Ending balance (in shares) at Mar. 31, 2023		81,928,422
Ending balance at Mar. 31, 2023	$ 8,653,853	$ 6,662	6,867,887	1,162	(159,896)	1,938,038
Beginning balance (in shares) at Dec. 31, 2022	81,723,555	81,723,555
Beginning balance at Dec. 31, 2022	$ 8,497,963	$ 6,649	6,840,306	1,162	(171,538)	1,821,384
Ending balance (in shares) at Jun. 30, 2023	82,151,049	82,151,049
Ending balance at Jun. 30, 2023	$ 8,796,440	$ 6,676	6,891,494	1,162	(156,528)	2,053,636
Beginning balance (in shares) at Mar. 31, 2023		81,928,422
Beginning balance at Mar. 31, 2023	8,653,853	$ 6,662	6,867,887	1,162	(159,896)	1,938,038
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	115,598					115,598
Exercise of share options (in shares)		93,304
Exercise of share options	7,229	$ 6	7,223
Issue of restricted share units / performance share units (in shares)		129,323
Issue of restricted share units / performance share units	8	$ 8
Non-cash stock compensation expense	16,389		16,389
Share issuance costs	(5)		(5)
Other comprehensive loss, net of tax	$ 3,368				3,368
Ending balance (in shares) at Jun. 30, 2023	82,151,049	82,151,049
Ending balance at Jun. 30, 2023	$ 8,796,440	$ 6,676	$ 6,891,494	$ 1,162	$ (156,528)	$ 2,053,636

Goodwill

6 Months Ended

Jun. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill


	Six Months Ended		Year Ended
	June 30, 2023		December 31, 2022
	(in thousands)
Opening balance	$	8,971,670	$	9,037,931
Current period acquisition	13,379		—
Prior period acquisition	—		(35,692)
Foreign exchange movement	8,534		(30,569)

Closing balance	$	8,993,583	$	8,971,670

On April 20, 2023, the Company completed the purchase of the majority investor's 51% majority voting share capital of Oncacare Limited ("Oncacare"), such that Oncacare and its subsidiaries became wholly-owned subsidiaries of the ICON Group. The Oncacare acquisition resulted in goodwill of $13.4 million and also gave rise to an acquisition-related gain of $6.2 million.

There were no impairment charges for the six months ended June 30, 2023 or for the year ended December 31, 2022.

Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities) (Tables)

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

Schedule of accounts receivables and unbilled revenue, and unbilled services and unearned revenue

Accounts receivables and unbilled revenue are as follows:


	June 30, 2023		December 31, 2022
	(in thousands)
Contract assets:
Billed services (accounts receivable)	$	1,788,140	$	1,751,950
Unbilled services (unbilled revenue)	985,034		957,655
Accounts receivable and unbilled revenue, gross	2,773,174		2,709,605
Allowance for credit losses	(29,029)		(20,562)
Accounts receivable and unbilled revenue, net	$	2,744,145	$	2,689,043

Unbilled services and unearned revenue or payments on account (contract assets and liabilities) were as follows:


(in thousands, except percentages)	June 30, 2023		December 31, 2022		$ Change		% Change

Unbilled services (unbilled revenue)	$	985,034	$	957,655	$	27,379	2.9	%
Unearned revenue (payments on account)	(1,573,311)		(1,507,449)		(65,862)		4.4	%
Net balance	$	(588,277)	$	(549,794)	$	(38,483)	7.0	%

Business Segment and Geographical Information - Narrative (Details)	6 Months Ended
	Jun. 30, 2023 segment
Segment Reporting [Abstract]
Number of operating segments	1

Goodwill - Schedule of Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Goodwill [Roll Forward]
Opening balance	$ 8,971,670	$ 9,037,931
Current period acquisition	13,379	0
Prior period acquisition	0	(35,692)
Foreign exchange movement	8,534	(30,569)
Closing balance	$ 8,993,583	$ 8,971,670

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References + Details

Operating leases - Schedule of Operating Lease Maturity (Details) $ in Thousands	Jun. 30, 2023 USD ($)
Leases [Abstract]
Year 1	$ 44,466
Year 2	33,902
Year 3	26,909
Year 4	22,801
Year 5	16,924
Thereafter	38,952
Total future minimum lease payments	183,954
Lease imputed interest	(14,729)
Total	$ 169,225

Restructuring

6 Months Ended

Jun. 30, 2023

Restructuring and Related Activities [Abstract]

Restructuring

In the six months ended June 30, 2023, a restructuring charge of $45.4 million was recorded in the Condensed Consolidated Statement of Operations under a restructuring plan adopted following a review of operations. The restructuring plan reflected a workforce reduction of $34.1 million and an office consolidation program to optimize the Company's office footprint of $11.3 million.


	Six Months Ended
	June 30, 2023		June 30, 2022
	(in thousands)
Restructuring charges	$	45,390	$	26,693
Net charge	$	45,390	$	26,693

At June 30, 2023, a total liability of $35.2 million was recorded on the Consolidated Balance Sheet relating to restructuring activities. The total liability included $29.4 million of personnel related liabilities as a result of the workforce reduction; all of which have been classified as short-term. The total liability also included $5.8 million of facilities related liabilities of which $3.2 million is included within other liabilities and $2.6 million is included within non-current other liabilities.


	Six Months Ended		Year ended
	June 30, 2023		December 31, 2022
	(in thousands)

Opening provision	$	6,022	$	10,311
Additional provisions	39,338		4,364
Utilization	(10,188)		(8,653)
Ending provision	$	35,172	$	6,022

Operating leases - Schedule of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Leases [Abstract]
Operating lease costs	$ 12,818	$ 13,548	$ 25,689	$ 28,812
Income from sub-leases	(283)	(303)	(561)	(630)
Net operating lease costs	$ 12,535	$ 13,245	$ 25,128	$ 28,182

Share capital	6 Months Ended
Share capital	Jun. 30, 2023
Equity [Abstract]
Share capital	Share capital The Company can acquire up to 10% of its outstanding ordinary shares (by way of redemption), in accordance with Irish law and the Company’s constitutional documents through open market share acquisitions. On February 18, 2022, the Company commenced a share buyback program which was fully complete at March 31, 2022. Under this buyback program, 420,530 ordinary shares were redeemed by the Company for total consideration of $100.0 million. The buyback program gives a broker authority to acquire the Company’s ordinary shares from time to time on the open market in accordance with agreed terms and limitations. All ordinary shares that were redeemed under the buyback program were canceled in accordance with the Constitution of the Company and the nominal value of these shares transferred to other undenominated capital reserve as required under Irish Company Law.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Subparagraph (b)
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Income taxes - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Liability for unrecognized tax benefit	$ 249.6	$ 240.2
Items generating unrecognized tax benefits	220.4	217.6
Interest and related penalties	$ 29.2	$ 22.6

Intangible assets (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Total cost	$ 5,110,495	$ 5,109,212
Accumulated amortization	(1,060,702)	(830,553)
Net book value	4,049,793	4,278,659
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total cost	4,077,225	4,076,435
Order backlog
Finite-Lived Intangible Assets [Line Items]
Total cost	537,182	536,934
Trade names & brands
Finite-Lived Intangible Assets [Line Items]
Total cost	204,636	204,621
Patient database
Finite-Lived Intangible Assets [Line Items]
Total cost	170,342	170,238
Technology assets
Finite-Lived Intangible Assets [Line Items]
Total cost	$ 121,110	$ 120,984

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement [Abstract]
Revenue	$ 2,020,251	$ 1,935,193	$ 3,998,829	$ 3,836,957
Costs and expenses:
Direct costs (excluding depreciation and amortization)	1,429,540	1,392,062	2,825,086	2,770,529
Selling, general and administrative expense	187,806	189,953	387,812	385,214
Depreciation and amortization	145,059	144,019	290,185	285,424
Transaction and integration-related expenses	12,701	8,884	24,083	20,969
Restructuring	35,661	22,486	45,390	26,693
Total costs and expenses	1,810,767	1,757,404	3,572,556	3,488,829
Income from operations	209,484	177,789	426,273	348,128
Interest income	949	166	2,021	293
Interest expense	(85,206)	(47,111)	(171,757)	(91,536)
Income before provision for income taxes	125,227	130,844	256,537	256,885
Provision for income taxes	(9,629)	(14,254)	(23,902)	(27,540)
Income before share of earnings from equity method investments	115,598	116,590	232,635	229,345
Share of losses in equity method investments	0	(856)	(383)	(1,641)
Net income attributable to the Group	$ 115,598	$ 115,734	$ 232,252	$ 227,704
Net income per Ordinary Share attributable to the Group (note 13):
Basic (in USD per share)	$ 1.41	$ 1.42	$ 2.84	$ 2.80
Diluted (in USD per share)	$ 1.40	$ 1.41	$ 2.81	$ 2.76
Weighted average number of Ordinary Shares outstanding (note 13):
Basic (in shares)	81,999,746	81,398,071	81,892,662	81,430,507
Diluted (in shares)	82,627,933	82,312,946	82,617,391	82,462,842

Share capital (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
Share capital (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Mar. 31, 2022	Jun. 30, 2023
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, value of shares repurchased		$ 99,983
Buyback Program
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, number of shares repurchased (in shares)	420,530
Share repurchase program, value of shares repurchased	$ 100,000
Buyback Program \| Maximum
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, authorized percentage			10.00%

Basis of presentation	6 Months Ended
Basis of presentation	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	Basis of presentation These condensed consolidated financial statements which have been prepared in accordance with United States Generally Accepted Accounting Principles (“US GAAP”) have not been audited. The condensed consolidated financial statements reflect all adjustments, which are, in the opinion of management, necessary to present a fair statement of the operating results and financial position for the periods presented. The preparation of the condensed consolidated financial statements in conformity with US GAAP requires management to make estimates and assumptions that affect reported amounts and disclosures in the condensed consolidated financial statements. Actual results could differ from those estimates. The condensed consolidated financial statements should be read in conjunction with the accounting policies and notes to the consolidated financial statements included in ICON’s Form 20-F for the year ended December 31, 2022 (see note 2 - Summary of significant accounting policies). Operating results for the six months ended June 30, 2023 are not necessarily indicative of the results that may be expected for the fiscal period ending December 31, 2023.

Income taxes (Tables)

6 Months Ended

Jun. 30, 2023

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense

Income taxes recognized during the three and six months ended June 30, 2023 and June 30, 2022, comprise:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)
Provision for income taxes	$	9,629	$	14,254	$	23,902	$	27,540

Revenue

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

Revenue

Revenue disaggregated by customer concentration is as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)



Clients 1-5	$	529,792	$	525,938	$	1,092,220	$	1,065,641
Clients 6-10	$	284,382	$	260,689	$	563,908	$	553,350
Clients 11-25	$	420,880	$	368,675	$	829,047	$	726,985
Other	$	785,197	$	779,891	$	1,513,654	$	1,490,981

Total	$	2,020,251	$	1,935,193	$	3,998,829	$	3,836,957

There was no revenue from individual customers greater than 10% of consolidated revenue in the respective periods.

Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities)

Accounts receivables and unbilled revenue are as follows:


	June 30, 2023		December 31, 2022
	(in thousands)
Contract assets:
Billed services (accounts receivable)	$	1,788,140	$	1,751,950
Unbilled services (unbilled revenue)	985,034		957,655
Accounts receivable and unbilled revenue, gross	2,773,174		2,709,605
Allowance for credit losses	(29,029)		(20,562)
Accounts receivable and unbilled revenue, net	$	2,744,145	$	2,689,043

Unbilled services and unearned revenue or payments on account (contract assets and liabilities) were as follows:


(in thousands, except percentages)	June 30, 2023		December 31, 2022		$ Change		% Change

Unbilled services (unbilled revenue)	$	985,034	$	957,655	$	27,379	2.9	%
Unearned revenue (payments on account)	(1,573,311)		(1,507,449)		(65,862)		4.4	%
Net balance	$	(588,277)	$	(549,794)	$	(38,483)	7.0	%

Timing may differ between the satisfaction of performance obligations and the invoicing and collection of amounts related to our contracts with customers. We record assets for amounts related to performance obligations that are satisfied but not yet billed and/or collected. These assets are recorded as unbilled services and therefore contract assets rather than accounts receivables when receipt of the consideration is conditional on something other than the passage of time. Liabilities are recorded for amounts that are collected in advance of the satisfaction of performance obligations or billed in advance of the revenue being earned.

Unbilled services/revenue balances arise where invoicing or billing is based on the timing of agreed milestones related to service contracts for clinical research. Contractual billing arrangements in respect of certain reimbursable expenses (principally investigators) require billing by the investigator to the Company prior to billing by the Company to the customer. As there is no contractual right to set-off between unbilled services (contract assets) and unearned revenue (contract liabilities), each are separately presented gross on the Condensed Consolidated Balance Sheet.

Unbilled services as at June 30, 2023 increased by $27.4 million compared to December 31, 2022. Unearned revenue increased by $65.9 million over the same period resulting in a decrease of $38.5 million in the net balance of unbilled services and unearned revenue or payments on account between December 31, 2022 and June 30, 2023. These fluctuations are primarily due to timing of payments and invoicing related to the Group's clinical trial management contracts. Billings and payments are established by contractual provisions including predetermined payment schedules which may or may not correspond to the timing of the transfer of control of the Company's services under the contract. Unbilled services arise from long-term contracts when a cost-based input method of revenue recognition is applied and revenue recognized exceeds the amount billed to the customer.

As of June 30, 2023 approximately $13.9 billion (June 30, 2022: $13.9 billion) of revenue is expected to be recognized in the future in respect of unsatisfied performance obligations. The Company expects to recognize revenue on approximately 51% of the unsatisfied performance obligations over the next 12 months, with the remainder recognized thereafter over the duration of the customer contracts.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-10

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-15

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

Summary of significant accounting policies (Tables)

6 Months Ended

Jun. 30, 2023

Accounting Policies [Abstract]

Schedule of Finite-Lived Intangible Assets

Intangible assets are amortized on a straight-line basis over the expected useful life, as set forth in the table below:


			Estimated Useful Life
Customer relationships			23 years
Order backlog			3 years
Trade names			3 years
Patient database			7 years
Technology assets			5 years

Intangible assets, net consisted of the following:


	Six Months Ended		Year Ended
	June 30, 2023		December 31, 2022
Cost	(in thousands)
Customer relationships	$	4,077,225	$	4,076,435
Order backlog	537,182		536,934
Trade names & brands	204,636		204,621
Patient database	170,342		170,238
Technology assets	121,110		120,984



Total cost	5,110,495		5,109,212
Accumulated amortization	(1,060,702)		(830,553)

Net book value	$	4,049,793	$	4,278,659

Operating leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Lessee, Lease, Description [Line Items]
Total lease cost	$ 12,535	$ 13,245	$ 25,128	$ 28,182
Right-of-use assets obtained in exchange for lease obligations	$ 10,200	$ 29,000	$ 22,500	$ 35,800
Weighted average remaining lease term	7 years 3 days		7 years 3 days
Weighted average discount rate	2.66%		2.66%
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other Liabilities	Other Liabilities	Other Liabilities	Other Liabilities
Other liabilities
Lessee, Lease, Description [Line Items]
Operating lease liabilities	$ 40,100	$ 47,000	$ 40,100	$ 47,000
Selling, general and administration costs
Lessee, Lease, Description [Line Items]
Total lease cost			19,300	27,100
Direct costs
Lessee, Lease, Description [Line Items]
Total lease cost			$ 5,800	$ 1,100

Bank credit lines and loan facilities

6 Months Ended

Jun. 30, 2023

Debt Disclosure [Abstract]

Bank credit lines and loan facilities

The Company had the following debt outstanding as of June 30, 2023 and December 31, 2022:


					Principal amount
	Interest rate as of		Interest rate as of		June 30,		December 31,
(in thousands)	June 30, 2023		December 31, 2022		2023		2022		Maturity Date
Credit Facilities:
Senior Secured Term Loan	7.41	%	7.09	%	$	3,801,213	$	4,201,213	July 2028
Senior Secured Notes	2.88	%	2.88	%	$	500,000	$	500,000	July 2026
Senior Secured Revolving Loan Facility	6.51	%	—		50,000		—		July 2023




Total debt					4,351,213		4,701,213

Less current portion of long-term debt					(105,150)		(55,150)
Total long-term debt					4,246,063		4,646,063
Less debt issuance costs and debt discount					(39,127)		(47,026)
Total long-term debt, net					$	4,206,936	$	4,599,037

The Company paid a $27.6 million debt discount in connection with the Senior Secured Credit Facility and Senior Secured Notes on July 1, 2021.

As of June 30, 2023, the contractual maturities of the Company's debt obligations were as follows:


Contractual maturities of long-term debt:	(in thousands)
2023 (remaining)	$	77,575
2024	55,150
2025	55,150
2026	55,150
2027 and thereafter	4,108,188
Total	$	4,351,213

The Company's primary financing arrangements are its senior secured credit facilities (the "Senior Secured Credit Facilities"), which consists of a senior secured term loan and a revolving credit facility, and the senior secured notes (the "Senior Secured Notes").

Senior Secured Credit Facilities

On July 1, 2021, the Company completed the acquisition of PRA Health Sciences, Inc. ("PRA") by means of a merger whereby Indigo Merger Sub, Inc., a Delaware corporation and subsidiary of ICON, merged with and into PRA, the parent of the PRA Health Sciences ("the Merger"). In conjunction with the completion of the Merger, on July 1, 2021, ICON entered into a credit agreement providing for a senior secured term loan facility of $5,515 million and a senior secured revolving loan facility in an initial aggregate principal amount of $300 million (the "Senior Secured Credit Facilities"). On May 2, 2023, the Company agreed with its lenders to increase the aggregate principal amount of the senior secured revolving loan facility from $300 million to $500 million.

Borrowings under the senior secured term loan facility amortize in equal quarterly installments in an amount equal to 1.00% per annum of the principal amount, with the remaining balance due at final maturity. The interest rate margin applicable to borrowings under the senior secured term loan facility is USD Term SOFR and a Term SOFR Adjustment depending on the interest period chosen plus an applicable margin which is dependent on the Company's net leverage ratio. At June 30, 2023, the applicable margin is 2.25%. The senior secured term loan facility is subject to a floor of 0.50%.

The interest rate margin applicable to borrowings under the revolving loan facility will be, at the option of the borrower, either (i) the applicable base rate plus an applicable margin of 1.00%, 0.60% or 0.25% based on ICON’s current corporate family rating assigned by S&P of BB- (or lower), BB or BB+ (or higher), respectively, or (ii) Term SOFR plus a Term SOFR Adjustment on the interest period chosen plus an applicable margin of 2.00%, 1.60% or 1.25% based on ICON’s current corporate family rating assigned by S&P of BB- (or lower), BB or BB+ (or higher), respectively. In addition, lenders under the revolving loan facility are entitled to commitment fees as a percentage of the applicable margin at the time of drawing and utilization fees dependent on the proportion of the facility drawn.

In January 2023, $100.0 million of the senior secured revolving loan facility was drawn down, in the aggregate, at interest rates of 5.89% and 5.80%, representing one month SOFR plus a margin of 1.25%. This was repaid in full in March 2023. On March 31, 2023, $80.0 million of the senior secured revolving loan facility was drawn down at an interest rate of 6.17%, representing one month SOFR plus a margin of 1.25%. In April 2023, the Company drew down $50.0 million of the senior secured revolving loan facility at an interest rate of 6.25%, representing one month SOFR plus a margin of 1.25%. The Company repaid $80.0 million of the senior secured revolving loan facility on June 30, 2023. As at June 30, 2023, interest on the senior secured revolving loan facility is at 6.51% following facility renewal, representing one month SOFR plus a margin of 1.25%.

The Borrowers’ (as defined in the Senior Secured Credit Facility) obligations under the Senior Secured Credit Facilities are guaranteed by ICON and the subsidiary guarantors. The Senior Secured Credit Facilities are secured by a lien on substantially all of ICON’s, the Borrowers’ and each of the subsidiary guarantor’s assets (subject to certain exceptions), and the Senior Secured Credit Facilities have a first-priority lien on such assets, which will rank pari passu with the lien securing the Senior Secured Notes, subject to other permitted liens. The Company is permitted to make prepayments on the senior secured term loan without penalty.

On March 31, 2023 the Company repaid $250.0 million of the senior secured term loan facility and made a quarterly

interest payment of $75.3 million. This repayment resulted in an additional charge associated with previously capitalized fees of

$2.2 million.

On June 30, 2023 the Company repaid $150.0 million of the senior secured term loan facility and made a quarterly interest payment of $74.0 million. This repayment resulted in an additional charge associated with previously capitalized fees of $1.2 million.

Senior Secured Notes

In addition to the Senior Secured Credit Facilities, on July 1, 2021, a subsidiary of the Company issued $500 million in aggregate principal amount of 2.875% senior secured notes due 2026 (the "Senior Secured Notes") in a private offering (the “Offering”). The Senior Secured Notes will mature on July 15, 2026.

Fair Value of Debt

The estimated fair value of the Company’s debt was $4,310.1 million at June 30, 2023. The fair values of the Senior Secured Credit Facilities and Senior Secured Notes were determined based on Level 2 inputs, which are based on rates at which the debt is traded among financial institutions. The fair value of the senior secured revolving loan facility is recorded as its carrying value due to the short term duration.

Intangible assets

6 Months Ended

Jun. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets

Intangible assets, net consisted of the following:


	Six Months Ended		Year Ended
	June 30, 2023		December 31, 2022
Cost	(in thousands)
Customer relationships	$	4,077,225	$	4,076,435
Order backlog	537,182		536,934
Trade names & brands	204,636		204,621
Patient database	170,342		170,238
Technology assets	121,110		120,984



Total cost	5,110,495		5,109,212
Accumulated amortization	(1,060,702)		(830,553)

Net book value	$	4,049,793	$	4,278,659

The identifiable intangible assets are amortized over their estimated useful lives.

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - € / shares	Jun. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Ordinary shares, par value (in EUR cents per share)	€ 0.06	€ 0.06
Ordinary shares, shares authorized (in shares)	100,000,000	100,000,000
Ordinary shares, shares issued (in shares)	82,151,049	81,723,555
Ordinary shares, shares outstanding (in shares)	82,151,049	81,723,555

Business Segment and Geographical Information

6 Months Ended

Jun. 30, 2023

Segment Reporting [Abstract]

Business Segment and Geographical Information

The Company is a clinical research organization ("CRO"), providing outsourced development services on a global basis to the pharmaceutical, biotechnology and medical device industries. It specializes in the strategic development, management and analysis of programs that support all stages of the clinical development process - from compound selection to Phase I-IV clinical studies. The Company has the expertise and capability to conduct clinical trials in most major therapeutic areas on a global basis and has the operational flexibility to provide development services on a stand-alone basis or as part of an integrated "full-service" solution. The Company has expanded through internal growth, together with a number of strategic acquisitions to enhance its expertise and capabilities in certain areas of the clinical development process.

The Company determines and presents operating segments based on the information that is internally provided to the chief operating decision maker, the (‘CODM’) in accordance with ASC 280 'Segment Reporting'. The Company determined that the CODM was comprised of the Chief Executive Officer and the Chief Financial Officer.

The Company operates as one reporting segment, which is the provision of outsourced development services on a global basis to the pharmaceutical, biotechnology and medical devices industries.

Revenues are allocated to individual entities based on where the work is performed in accordance with the Company's global transfer pricing model. Revenues and income from operations in Ireland are a function of our global contracting model and the Group’s transfer pricing model.

ICON Ireland (Ireland Segment) acts as the Group entrepreneur under the Company’s global transfer pricing model given its role in the development and management of the Group, its ownership of key intellectual property and customer relationships, its key role in the mitigation of risks faced by the Group and its responsibility for maintaining the Company’s global network. ICON Ireland enters into the majority of the Company’s customer contracts.

ICON Ireland remunerates other operating entities in the Group on the basis of a guaranteed cost plus mark-up for the services they perform in each of their local territories. The cost plus mark-up for each ICON entity is established to ensure that each of ICON Ireland and the ICON entities that are involved in the conduct of services for customers, earn an appropriate arms-length return having regard to the assets owned, risks borne and functions performed by each entity from these intercompany transactions. The cost plus mark-up policy is reviewed annually to ensure that it is market appropriate. The integration of entities acquired through the Merger into this global network and global transfer pricing model remains ongoing.

The geographic split of revenue disclosed for each region outside Ireland is the cost plus revenue attributable to these entities. The residual revenues of the Group, once each ICON entity has been paid its respective intercompany service fee, generally fall to be retained by ICON Ireland. As such, revenues and income from operations in Ireland are a function of this global transfer pricing model and comprise revenues of the Group after deducting the cost plus revenues attributable to the activities performed outside Ireland.

The geographical distribution of the Company’s segment measures for the three and six months ended June 30, 2023 and June 30, 2022 and at June 30, 2023 and December 31, 2022 is as follows:

a) The distribution of revenue by geographical area was as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)
Ireland	$	593,407	$	500,972	$	1,105,241	$	868,330
Rest of Europe	373,810		428,393		788,033		884,458
U.S.	848,019		894,016		1,692,423		1,864,645
Rest of World	205,015		111,812		413,132		219,524

Total	$	2,020,251	$	1,935,193	$	3,998,829	$	3,836,957

b) The distribution of income from operations by geographical area was as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)
Ireland *	$	125,896	$	55,544	$	177,223	$	65,418
Rest of Europe	22,489		59,173		82,255		118,682
U.S.	55,744		53,321		143,833		113,789
Rest of World	5,355		9,751		22,962		50,239

Total	$	209,484	$	177,789	$	426,273	$	348,128

* Includes the full amount of the amortization charge associated with the intangible asset acquired in the Merger.

c) The distribution of long-lived assets (property, plant and equipment and operating right-of-use assets), net, by geographical area was as follows:


	June 30, 2023		December 31, 2022
	(in thousands)
Ireland	$	148,242	$	143,025
Rest of Europe	95,048		99,721
U.S.	195,407		213,311
Rest of World	52,338		48,095

Total	$	491,035	$	504,152

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//280/tableOfContent

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-26

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-34

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

+ Details

Business Segment and Geographical Information - Schedule of Distribution of Revenue by Geographical Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Revenue	$ 2,020,251	$ 1,935,193	$ 3,998,829	$ 3,836,957
Ireland
Segment Reporting Information [Line Items]
Revenue	593,407	500,972	1,105,241	868,330
Rest of Europe
Segment Reporting Information [Line Items]
Revenue	373,810	428,393	788,033	884,458
U.S.
Segment Reporting Information [Line Items]
Revenue	848,019	894,016	1,692,423	1,864,645
Rest of World
Segment Reporting Information [Line Items]
Revenue	$ 205,015	$ 111,812	$ 413,132	$ 219,524

- Definition

+ References

+ Details

Share-based awards - Schedule of Non-cash Stock Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	$ 16,598	$ 19,283	$ 31,357	$ 38,186
Direct costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	6,420	5,833	12,088	10,832
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	$ 10,178	$ 13,450	$ 19,269	$ 27,354

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
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-Subparagraph (c)(1)(i)
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-Topic 718
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Topic 718
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-Topic 718
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-Topic 718
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-Topic 718
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Summary of significant accounting policies - Estimated Useful Lives of Intangible Assets (Details)	Jun. 30, 2023
Customer relationships
Indefinite-Lived Intangible Assets [Line Items]
Estimated Useful Life	23 years
Order backlog
Indefinite-Lived Intangible Assets [Line Items]
Estimated Useful Life	3 years
Trade names
Indefinite-Lived Intangible Assets [Line Items]
Estimated Useful Life	3 years
Patient database
Indefinite-Lived Intangible Assets [Line Items]
Estimated Useful Life	7 years
Technology assets
Indefinite-Lived Intangible Assets [Line Items]
Estimated Useful Life	5 years

Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities)

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities)

Revenue

Revenue disaggregated by customer concentration is as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)



Clients 1-5	$	529,792	$	525,938	$	1,092,220	$	1,065,641
Clients 6-10	$	284,382	$	260,689	$	563,908	$	553,350
Clients 11-25	$	420,880	$	368,675	$	829,047	$	726,985
Other	$	785,197	$	779,891	$	1,513,654	$	1,490,981

Total	$	2,020,251	$	1,935,193	$	3,998,829	$	3,836,957

There was no revenue from individual customers greater than 10% of consolidated revenue in the respective periods.

Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities)

Accounts receivables and unbilled revenue are as follows:


	June 30, 2023		December 31, 2022
	(in thousands)
Contract assets:
Billed services (accounts receivable)	$	1,788,140	$	1,751,950
Unbilled services (unbilled revenue)	985,034		957,655
Accounts receivable and unbilled revenue, gross	2,773,174		2,709,605
Allowance for credit losses	(29,029)		(20,562)
Accounts receivable and unbilled revenue, net	$	2,744,145	$	2,689,043

Unbilled services and unearned revenue or payments on account (contract assets and liabilities) were as follows:


(in thousands, except percentages)	June 30, 2023		December 31, 2022		$ Change		% Change

Unbilled services (unbilled revenue)	$	985,034	$	957,655	$	27,379	2.9	%
Unearned revenue (payments on account)	(1,573,311)		(1,507,449)		(65,862)		4.4	%
Net balance	$	(588,277)	$	(549,794)	$	(38,483)	7.0	%

- Definition

+ References

+ Details

Income taxes

6 Months Ended

Jun. 30, 2023

Income Tax Disclosure [Abstract]

Income taxes

Income taxes recognized during the three and six months ended June 30, 2023 and June 30, 2022, comprise:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)
Provision for income taxes	$	9,629	$	14,254	$	23,902	$	27,540

As at June 30, 2023 the Company maintains a $249.6 million liability (December 31, 2022: $240.2 million) for unrecognized tax benefit, which is comprised of $220.4 million (December 31, 2022: $217.6 million) related to items generating unrecognized tax benefits and $29.2 million (December 31, 2022: $22.6 million) for interest and penalties related to such items. The Company recognizes interest accrued on unrecognized tax benefits as an additional income tax expense.

The Company has analyzed the filing positions in all of the significant federal, state and foreign jurisdictions where it is required to file income tax returns, as well as open tax years in these jurisdictions. The only periods subject to audit by the major tax jurisdictions where the Company does business are the 2016 through 2022 tax years. During such audits, local tax authorities may challenge the positions taken by us in our tax returns.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
-Section S99
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Summary of significant accounting policies (Policies)

6 Months Ended

Jun. 30, 2023

Accounting Policies [Abstract]

Revenue recognition

Clinical trial service revenue

Laboratory services revenue

Contracting services revenue

Consulting services revenue

Data services revenue

Commissions

Business Combinations

The Company allocates a share of net income to the noncontrolling interest holders based on percentage ownership.

Intangible Assets

Intangible assets are amortized on a straight-line basis over the expected useful life, as set forth in the table below:


			Estimated Useful Life
Customer relationships			23 years
Order backlog			3 years
Trade names			3 years
Patient database			7 years
Technology assets			5 years

The Company periodically assesses the useful lives of intangible assets to evaluate whether what was established at acquisition continues to be appropriate.

Income taxes

- Definition

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

+ References + Details

- Definition

Disclosure of accounting policy for revenue from contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-19

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147479806/606-10-50-18

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-18

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
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-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-20

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-20

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-20

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-20

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (e)
-SubTopic 10
-Topic 235
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483426/235-10-50-4

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

Share-based awards

6 Months Ended

Jun. 30, 2023

Share-Based Payment Arrangement [Abstract]

Share-based awards

Share Options

The following table summarizes option activity for the six months ended June 30, 2023:


	Options Outstanding Number of Shares	Weighted Average Exercise Price		Weighted Average Grant Date Fair Value	Weighted Average Remaining Contractual Life
Outstanding at December 31, 2022	1,378,119	$	119.86		4.69

Granted	82,472	$	232.48
Exercised	(229,953)	$	87.69
Canceled/expired	(6,885)	$	116.33

Outstanding at June 30, 2023	1,223,753	$	133.51		4.67

Exercisable at June 30, 2023	952,614	$	113.27		4.20

The Company issues ordinary shares for all options exercised. The total amount of fully vested share options which remained outstanding at June 30, 2023 was 952,614. Fully vested share options at June 30, 2023 have an average remaining contractual term of 4.20 years and an average exercise price of $113.27.

Fair value of Stock Options Assumptions

The weighted average fair value of options granted during the six months ended June 30, 2023 and June 30, 2022 was calculated using the Black-Scholes option pricing model. The weighted average grant date fair values and assumptions used were as follows:


	Six Months Ended
	June 30, 2023			June 30, 2022
Weighted average grant date fair value	$	85.12		$	68.40
Assumptions:
Expected volatility	33		%	31		%
Dividend yield	—		%	—		%
Risk-free interest rate	3.98		%	1.85		%
Expected life	5 years			5 years

Expected volatility is based on the historical volatility of our common stock over a period equal to the expected term of the options; the expected life represents the weighted average period of time that options granted are expected to be outstanding given consideration to vesting schedules and our historical experience of past vesting and termination patterns. The risk-free rate is based on the U.S. government zero-coupon bonds yield curve in effect at time of the grant for periods corresponding with the expected life of the option.

Restricted Share Units and Performance Share Units

On April 23, 2013 the Company adopted the 2013 Employees Restricted Share Unit and Performance Share Unit Plan (the "2013 RSU Plan") pursuant to which the Compensation and Organization Committee of the Company's Board of Directors may select any employee, or any Director holding a salaried office or employment with the Company, or a Subsidiary to receive an award under the plan. On May 11, 2015 the 2013 RSU Plan was amended and restated in order to increase the number of shares that can be issued under the RSU Plan by 2.5 million shares. Accordingly, an aggregate of 4.1 million ordinary shares have been reserved for issuance under the 2013 RSU Plan. The shares are awarded at par value and vest over a service period. Awards under the 2013 RSU Plan may be settled in cash or shares at the option of the Company. No awards may be granted under the 2013 RSU Plan after May 11, 2025.

On April 30 2019, the Company approved the 2019 Consultants and Directors Restricted Share Unit Plan (the “2019 Consultants RSU Plan”), which was effective as of May 16, 2019, pursuant to which the Compensation and Organization Committee of the Company’s Board of Directors may select any consultant, adviser or non-executive Director retained by the Company, or a Subsidiary to receive an award under the plan. 250,000 ordinary shares have been reserved for issuance under the 2019 Consultants RSU Plan. The awards are at par value and vest over a service period. Awards granted to non-executive directors during 2020, 2021 and 2022 vest in twelve months.

The Company has awarded RSUs and PSUs to certain key individuals of the Group. The following table summarizes RSU and PSU activity for the six months ended June 30, 2023:


	PSU Outstanding Number of Shares	PSU Weighted Average Grant Date Fair Value		RSU Outstanding Number of Shares	RSU Weighted Average Grant Date Fair Value
Outstanding at December 31, 2022	152,420	$	192.29	582,612	$	207.73

Granted	60,374	$	232.51	294,683	$	217.52
Shares vested	(47,026)	$	159.57	(150,515)	$	187.96
Forfeited	—	$	—	(31,396)	$	209.13

Outstanding at June 30, 2023	165,768	$	216.22	695,384	$	216.09

The fair value of PSUs vested for the six months ended June 30, 2023 totaled $7.5 million (full year 2022: $6.5 million).

The fair value of RSUs vested for the six months ended June 30, 2023 totaled $28.3 million (full year 2022: $34.1 million).

The PSUs vest based on service and specified EPS targets over the periods 2021 - 2023, 2022 - 2024, and 2023 - 2025. Depending on the amount of EPS from 2021 to 2025, up to an additional 82,884 PSUs may also be granted.

Non-cash stock compensation expense

Non-cash stock compensation expense for the three and six months ended June 30, 2023 and June 30, 2022 has been allocated as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)
Direct costs	$	6,420	$	5,833	$	12,088	$	10,832
Selling, general and administrative	$	10,178	$	13,450	$	19,269	$	27,354

Total	$	16,598	$	19,283	$	31,357	$	38,186

Share-based awards (Tables)

6 Months Ended

Jun. 30, 2023

Share-Based Payment Arrangement [Abstract]

Summary of stock option activity

The following table summarizes option activity for the six months ended June 30, 2023:


	Options Outstanding Number of Shares	Weighted Average Exercise Price		Weighted Average Grant Date Fair Value	Weighted Average Remaining Contractual Life
Outstanding at December 31, 2022	1,378,119	$	119.86		4.69

Granted	82,472	$	232.48
Exercised	(229,953)	$	87.69
Canceled/expired	(6,885)	$	116.33

Outstanding at June 30, 2023	1,223,753	$	133.51		4.67

Exercisable at June 30, 2023	952,614	$	113.27		4.20

Schedule of weighted average fair values and assumptions used

The weighted average grant date fair values and assumptions used were as follows:


	Six Months Ended
	June 30, 2023			June 30, 2022
Weighted average grant date fair value	$	85.12		$	68.40
Assumptions:
Expected volatility	33		%	31		%
Dividend yield	—		%	—		%
Risk-free interest rate	3.98		%	1.85		%
Expected life	5 years			5 years

Summary of RSU and PSU activity

The following table summarizes RSU and PSU activity for the six months ended June 30, 2023:


	PSU Outstanding Number of Shares	PSU Weighted Average Grant Date Fair Value		RSU Outstanding Number of Shares	RSU Weighted Average Grant Date Fair Value
Outstanding at December 31, 2022	152,420	$	192.29	582,612	$	207.73

Granted	60,374	$	232.51	294,683	$	217.52
Shares vested	(47,026)	$	159.57	(150,515)	$	187.96
Forfeited	—	$	—	(31,396)	$	209.13

Outstanding at June 30, 2023	165,768	$	216.22	695,384	$	216.09

Schedule of non-cash stock compensation expense

Non-cash stock compensation expense for the three and six months ended June 30, 2023 and June 30, 2022 has been allocated as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)
Direct costs	$	6,420	$	5,833	$	12,088	$	10,832
Selling, general and administrative	$	10,178	$	13,450	$	19,269	$	27,354

Total	$	16,598	$	19,283	$	31,357	$	38,186

Restructuring (Tables)

6 Months Ended

Jun. 30, 2023

Restructuring and Related Activities [Abstract]

Summary of Restructuring Charges


	Six Months Ended
	June 30, 2023		June 30, 2022
	(in thousands)
Restructuring charges	$	45,390	$	26,693
Net charge	$	45,390	$	26,693

Summary of details of movement in restructuring charges


	Six Months Ended		Year ended
	June 30, 2023		December 31, 2022
	(in thousands)

Opening provision	$	6,022	$	10,311
Additional provisions	39,338		4,364
Utilization	(10,188)		(8,653)
Ending provision	$	35,172	$	6,022

Net income per ordinary share (Tables)

6 Months Ended

Jun. 30, 2023

Earnings Per Share [Abstract]

Schedule of reconciliation of number of shares used in computation of basic and diluted net income per ordinary share

The reconciliation of the number of shares used in the computation of basic and diluted net income per ordinary share is as follows:


	Three Months Ended		Six Months Ended
	June 30, 2023	June 30, 2022	June 30, 2023	June 30, 2022
Weighted average number of ordinary shares outstanding for basic net income per ordinary share	81,999,746	81,398,071	81,892,662	81,430,507
Effect of dilutive share options and other awards outstanding under share based compensation programs	628,187	914,875	724,729	1,032,335
Weighted average number of ordinary shares outstanding for diluted net income per ordinary share	82,627,933	82,312,946	82,617,391	82,462,842


	Three Months Ended		Six Months Ended
	June 30, 2023	June 30, 2022	June 30, 2023	June 30, 2022
Net income per Ordinary Share attributable to the Group:
Basic	1.41	1.42	2.84	2.80
Diluted	1.40	1.41	2.81	2.76

Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities) - Schedule of Accounts Receivables and Unbilled Revenue (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Contract Assets [Abstract]
Billed services (accounts receivable)	$ 1,788,140	$ 1,751,950
Unbilled services (unbilled revenue)	985,034	957,655
Accounts receivable and unbilled revenue, gross	2,773,174	2,709,605
Allowance for credit losses	(29,029)	(20,562)
Accounts receivable and unbilled revenue, net	$ 2,744,145	$ 2,689,043

Derivatives

6 Months Ended

Jun. 30, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivatives

On November 29, 2022, the Company entered into two interest rate cap agreements ("2022 Caps") with an initial total notional value of $2,101 million to limit its exposure to changes in the variable interest rate on its Senior Secured Credit Facilities. Interest on the 2022 Caps began accruing on December 30, 2022 and the interest rate cap expires on December 31, 2024. The Company pays a fixed rate of 0.42% and receives a variable rate equal to the amount that the three-month SOFR rate exceeds 4.75%.

On November 29, 2022, the Company entered into an interest rate swap agreement ("2022 Swap") with an initial notional value of $1,101 million to limit its exposure to changes in the variable interest rate on its Senior Secured Credit Facilities. Interest on the 2022 Swaps begins accruing on December 31, 2024 and the interest rate swap expires on December 31, 2026. The Company pays a fixed rate of 3.4% and receives a variable rate of interest equal to the three-month SOFR on the 2022 Swap.

The fair value of the Company’s derivative financial instruments, on a gross basis, and the line items on the accompanying consolidated balance sheets to which they were recorded are summarized in the following table:


		June 30, 2023			December 31, 2022
		Asset	Liability	Notional	Asset	Liability	Notional
		(in thousands)			(in thousands)
Derivatives designated as hedging instruments:

Interest Rate Caps	Other Current Liabilities, Other Assets and Liabilities	$4,461	$—	$1,900,606	$12	$3,363	$2,100,606
Interest Rate Swap	Other Assets and Liabilities	$2,972	$—	$1,100,606	$—	$307	$1,100,606

Total derivatives designated as hedging instruments		$7,433	$—	$3,001,212	$12	$3,670	$3,201,212

During the next 12 months, the Company estimates that an additional $1.2 million will be reflected as interest income in the consolidated statements.

The Company recognized $14.9 million of a gain within other comprehensive income ("OCI") for the three months ended June 30, 2023 (June 30, 2022: $nil) after a reclassification of $1.4 million of a loss from OCI to the income statement (June 30, 2022: $nil). The Company recognized $10.1 million of a net gain within OCI for the six months ended June 30, 2023 (June 30, 2022: $nil) after a reclassification of $3.6 million of a loss from OCI to the income statement (June 30, 2022: $nil).

Share-based awards - Schedule of Weighted Average Fair Values and Assumptions Used (Details) - Employee Stock Option - $ / shares	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value	$ 85.12	$ 68.40
Assumptions:
Expected volatility	33.00%	31.00%
Dividend yield	0.00%	0.00%
Risk-free interest rate	3.98%	1.85%
Expected life	5 years	5 years

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Derivatives - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
Derivatives - Narrative (Details) $ in Thousands	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Nov. 29, 2022 USD ($) instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$ (1,200)		$ (1,200)
Other comprehensive income (loss), cash flow hedge, gain (loss), before reclassification and tax	14,900	$ 0	(10,100)	$ 0
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, before tax	$ 1,400	$ 0	$ 3,600	$ 0
Interest Rate Caps \| Total derivatives designated as hedging instruments
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of interest rate derivatives held \| instrument					2
Derivative, notional amount					$ 2,101,000
Derivative, fixed interest rate					0.42%
Interest Rate Caps \| Total derivatives designated as hedging instruments \| SOFR
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, variable interest rate, reference rate in excess of					4.75%
Interest Rate Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount					$ 1,101,000
Derivative, fixed interest rate					3.40%

Fair value measurements - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 44,384	$ 34,356
Long-term debt at fair value	4,310,100
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	$ 0
Level 3 \| Fair value, nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	13,043,400
Goodwill at fair value	8,993,600
Net intangible assets at fair value	$ 4,049,800

Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities) - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Increase in unbilled services (unbilled revenue)	$ 27,379
Decrease in unearned revenue (payments on account)	65,862
Increase in net balance	(38,483)
Revenue, remaining performance obligation	$ 13,900,000	$ 13,900,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation percentage	51.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period	12 months

Income taxes - Components of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 9,629	$ 14,254	$ 23,902	$ 27,540

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Operating leases (Tables)

6 Months Ended

Jun. 30, 2023

Leases [Abstract]

Schedule of Lease Costs

Lease costs recorded under operating leases for the six months ended June 30, 2023 and June 30, 2022 were as follows:


	Three Months Ended		Six Months Ended
	June 30, 2023	June 30, 2022	June 30, 2023		June 30, 2022
	(in thousands)		(in thousands)
Operating lease costs	12,818	13,548	$	25,689	$	28,812
Income from sub-leases	(283)	(303)	(561)		(630)
Net operating lease costs	12,535	13,245	$	25,128	$	28,182

Schedule of Operating Lease Maturity

Future minimum lease payments under non-cancelable leases as of June 30, 2023 were as follows:


	Minimum rental payments
(in thousands)	June 30, 2023
Year 1	$	44,466
Year 2	33,902
Year 3	26,909
Year 4	22,801
Year 5	16,924
Thereafter	38,952
Total future minimum lease payments	183,954
Lease imputed interest	(14,729)
Total	$	169,225

Share-based awards - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions			6 Months Ended	12 Months Ended	50 Months Ended
	Jun. 30, 2023	May 11, 2015	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2023	May 16, 2019
Employee Stock Option
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Number of shares exercisable (in shares)	952,614		952,614		952,614
Weighted average contractual term of options exercisable	4 years 2 months 12 days
Weighted average exercise price of options exercisble (USD per share)	$ 113.27		$ 113.27		$ 113.27
Consultants Restricted Stock Units 2019
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Ordinary shares which have been reserved for issuance (in shares)						250,000
Consultants Restricted Stock Units 2019 \| Non-executive directors
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Shares vesting period					12 months
Restricted stock units 2013
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Ordinary shares which have been reserved for issuance (in shares)		2,500,000
Ordinary shares which have been reserved for issuance (in shares)		4,100,000
Performance Share Unit (PSUs)
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Fair value of stock units vested			$ 7.5	$ 6.5
Restricted Stock Units (RSUs)
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Fair value of stock units vested			$ 28.3	$ 34.1
PSUs based on service and EPS targets \| Maximum
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Stock units to be granted (in shares)	82,884		82,884		82,884

Subsequent events	6 Months Ended
Subsequent events	Jun. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent eventsThe Company has evaluated subsequent events from the balance sheet date through to the date at which the financial statements were available to be issued. The Company has determined that there are no items to disclose.

Restructuring - Summary of Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Restructuring and Related Activities [Abstract]
Restructuring charges	$ 35,661	$ 22,486	$ 45,390	$ 26,693

Bank credit lines and loan facilities - Schedule of Contractual Maturities of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
2023 (remaining)	$ 77,575
2024	55,150
2025	55,150
2026	55,150
2027 and thereafter	4,108,188
Total debt	$ 4,351,213	$ 4,701,213

Business Segment and Geographical Information - Schedule of Distribution of Income from Operations by Geographical Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Income from operations	$ 209,484	$ 177,789	$ 426,273	$ 348,128
Ireland
Segment Reporting Information [Line Items]
Income from operations	125,896	55,544	177,223	65,418
Rest of Europe
Segment Reporting Information [Line Items]
Income from operations	22,489	59,173	82,255	118,682
U.S.
Segment Reporting Information [Line Items]
Income from operations	55,744	53,321	143,833	113,789
Rest of World
Segment Reporting Information [Line Items]
Income from operations	$ 5,355	$ 9,751	$ 22,962	$ 50,239

Share-based awards - Summary of RSU and PSU Activity (Details)	6 Months Ended
	Jun. 30, 2023 $ / shares shares
Performance Share Unit (PSUs)
Outstanding Number of Shares
Outstanding at beginning of period (in shares) \| shares	152,420
Granted (in shares) \| shares	60,374
Shares vested (in shares) \| shares	(47,026)
Forfeited (in shares) \| shares	0
Outstanding at end of period (in shares) \| shares	165,768
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in USD per share) \| $ / shares	$ 192.29
Granted (in USD per share) \| $ / shares	232.51
Shares vested (in USD per share) \| $ / shares	159.57
Forfeited (in USD per share) \| $ / shares	0
Outstanding at end of period (in USD per share) \| $ / shares	$ 216.22
Restricted Stock Units (RSUs)
Outstanding Number of Shares
Outstanding at beginning of period (in shares) \| shares	582,612
Granted (in shares) \| shares	294,683
Shares vested (in shares) \| shares	(150,515)
Forfeited (in shares) \| shares	(31,396)
Outstanding at end of period (in shares) \| shares	695,384
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in USD per share) \| $ / shares	$ 207.73
Granted (in USD per share) \| $ / shares	217.52
Shares vested (in USD per share) \| $ / shares	187.96
Forfeited (in USD per share) \| $ / shares	209.13
Outstanding at end of period (in USD per share) \| $ / shares	$ 216.09

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Comprehensive income (net of tax):
Net income attributable to the Group	$ 115,598	$ 115,734	$ 232,252	$ 227,704
Currency translation adjustment	(10,638)	(66,180)	4,862	(101,998)
Gain on cash flow hedge	14,006	0	10,148	0
Total comprehensive income attributable to the Group	$ 118,966	$ 49,554	$ 247,262	$ 125,706

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

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-URI https://asc.fasb.org//1943274/2147481175/810-10-55-4K

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-2

Reference 38: http://www.xbrl.org/2003/role/disclosureRef
-Topic 810
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481203/810-10-50-1A

Reference 39: http://www.xbrl.org/2003/role/disclosureRef
-Topic 810
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481203/810-10-50-1A

+ Details

Operating leases

6 Months Ended

Jun. 30, 2023

Leases [Abstract]

Operating leases

Lease costs recorded under operating leases for the six months ended June 30, 2023 and June 30, 2022 were as follows:


	Three Months Ended		Six Months Ended
	June 30, 2023	June 30, 2022	June 30, 2023		June 30, 2022
	(in thousands)		(in thousands)
Operating lease costs	12,818	13,548	$	25,689	$	28,812
Income from sub-leases	(283)	(303)	(561)		(630)
Net operating lease costs	12,535	13,245	$	25,128	$	28,182

Of the total cost of $25.1 million incurred in the six months ended June 30, 2023 (June 30, 2022: $28.2 million), $19.3 million (June 30, 2022: $27.1 million) is recorded within selling, general and administration costs and $5.8 million (June 30, 2022: $1.1 million) is recorded within direct costs.

During the six months ended June 30, 2023 and June 30, 2022, costs incurred by the Group related to variable lease payments was de minimis.

Right-of-use assets obtained, in exchange for lease obligations during the three months ended June 30, 2023, totaled $10.2 million (June 30, 2022: $29.0 million). Right-of-use assets obtained, in exchange for lease obligations during the six months ended June 30, 2023, totaled $22.5 million (June 30, 2022: $35.8 million).

The weighted average remaining lease term and weighted-average discount rate at June 30, 2023 were 7.01 years and 2.66%, respectively.

Future minimum lease payments under non-cancelable leases as of June 30, 2023 were as follows:


	Minimum rental payments
(in thousands)	June 30, 2023
Year 1	$	44,466
Year 2	33,902
Year 3	26,909
Year 4	22,801
Year 5	16,924
Thereafter	38,952
Total future minimum lease payments	183,954
Lease imputed interest	(14,729)
Total	$	169,225

Operating lease liabilities are presented as current and non-current. Operating lease liabilities of $40.1 million have been included in other liabilities as at June 30, 2023 (June 30, 2022: $47.0 million).

Restructuring - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 35,661	$ 22,486	$ 45,390	$ 26,693
Other Restructuring Costs			11,300
Provision balance	35,172		35,172		$ 6,022	$ 10,311
2021 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Severance Costs			34,100
Personnel related liabilities
Restructuring Cost and Reserve [Line Items]
Provision balance	29,400		29,400
Facility liability
Restructuring Cost and Reserve [Line Items]
Provision balance	5,800		5,800
Other liability \| Other liabilities
Restructuring Cost and Reserve [Line Items]
Provision balance	3,200		3,200
Other liability \| Non-current other liabilities
Restructuring Cost and Reserve [Line Items]
Provision balance	$ 2,600		$ 2,600

Net income per ordinary share

6 Months Ended

Jun. 30, 2023

Earnings Per Share [Abstract]

Net income per ordinary share

Basic net income per ordinary share attributable to the Group has been computed by dividing net income available to ordinary shareholders by the weighted average number of ordinary shares outstanding during the period. Diluted net income per ordinary share is computed by adjusting the weighted average number of ordinary shares outstanding during the period for all potentially dilutive ordinary shares outstanding during the period and adjusting net income for any changes in income or loss that would result from the conversion of such potential ordinary shares. There is no difference in net income used for basic and diluted net income per ordinary share.

The reconciliation of the number of shares used in the computation of basic and diluted net income per ordinary share is as follows:


	Three Months Ended		Six Months Ended
	June 30, 2023	June 30, 2022	June 30, 2023	June 30, 2022
Weighted average number of ordinary shares outstanding for basic net income per ordinary share	81,999,746	81,398,071	81,892,662	81,430,507
Effect of dilutive share options and other awards outstanding under share based compensation programs	628,187	914,875	724,729	1,032,335
Weighted average number of ordinary shares outstanding for diluted net income per ordinary share	82,627,933	82,312,946	82,617,391	82,462,842


	Three Months Ended		Six Months Ended
	June 30, 2023	June 30, 2022	June 30, 2023	June 30, 2022
Net income per Ordinary Share attributable to the Group:
Basic	1.41	1.42	2.84	2.80
Diluted	1.40	1.41	2.81	2.76

Goodwill - Narrative (Details) - USD ($)	6 Months Ended		12 Months Ended
Goodwill - Narrative (Details) - USD ($)	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	Apr. 20, 2023
Acquired Finite-Lived Intangible Assets [Line Items]
Current period acquisition	$ 13,379,000		$ 0
Accumulated impairment loss	0		$ 0
Acquisition-related gain	6,160,000	$ 0
Oncacare
Acquired Finite-Lived Intangible Assets [Line Items]
Percentage of share capital acquired				51.00%
Current period acquisition	$ 13,400,000

Business Segment and Geographical Information (Tables)

6 Months Ended

Jun. 30, 2023

Segment Reporting [Abstract]

Schedule of Distribution of Revenue by Geographical Area

The distribution of revenue by geographical area was as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)
Ireland	$	593,407	$	500,972	$	1,105,241	$	868,330
Rest of Europe	373,810		428,393		788,033		884,458
U.S.	848,019		894,016		1,692,423		1,864,645
Rest of World	205,015		111,812		413,132		219,524

Total	$	2,020,251	$	1,935,193	$	3,998,829	$	3,836,957

Schedule of Distribution of Income from Operations by Geographical Area

The distribution of income from operations by geographical area was as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)
Ireland *	$	125,896	$	55,544	$	177,223	$	65,418
Rest of Europe	22,489		59,173		82,255		118,682
U.S.	55,744		53,321		143,833		113,789
Rest of World	5,355		9,751		22,962		50,239

Total	$	209,484	$	177,789	$	426,273	$	348,128

* Includes the full amount of the amortization charge associated with the intangible asset acquired in the Merger.

Schedule of Distribution of Depreciation and Amortization by Geographical Area

The distribution of long-lived assets (property, plant and equipment and operating right-of-use assets), net, by geographical area was as follows:


	June 30, 2023		December 31, 2022
	(in thousands)
Ireland	$	148,242	$	143,025
Rest of Europe	95,048		99,721
U.S.	195,407		213,311
Rest of World	52,338		48,095

Total	$	491,035	$	504,152

Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities) - Schedule of Unbilled Services and Unearned Revenue or Payments on Account (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Unbilled services (unbilled revenue)	$ 985,034	$ 957,655
Change in unbilled services (unbilled revenue)	$ 27,379
Percentage change in unbilled services (unbilled revenue)	2.90%
Unearned revenue (payments on account)	$ (1,573,311)	(1,507,449)
Change in unearned revenue (payments on account)	$ (65,862)
Percentage change in unearned revenue (payments on account)	4.40%
Net balance	$ (588,277)	$ (549,794)
Change in net balance	$ (38,483)
Percentage change in net balance	7.00%

Derivatives (Tables)

6 Months Ended

Jun. 30, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value


		June 30, 2023			December 31, 2022
		Asset	Liability	Notional	Asset	Liability	Notional
		(in thousands)			(in thousands)
Derivatives designated as hedging instruments:

Interest Rate Caps	Other Current Liabilities, Other Assets and Liabilities	$4,461	$—	$1,900,606	$12	$3,363	$2,100,606
Interest Rate Swap	Other Assets and Liabilities	$2,972	$—	$1,100,606	$—	$307	$1,100,606

Total derivatives designated as hedging instruments		$7,433	$—	$3,001,212	$12	$3,670	$3,201,212

Revenue (Tables)

6 Months Ended

Jun. 30, 2023

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregation of Revenue

Revenue disaggregated by customer concentration is as follows:


	Three Months Ended				Six Months Ended
	June 30, 2023		June 30, 2022		June 30, 2023		June 30, 2022
	(in thousands)				(in thousands)



Clients 1-5	$	529,792	$	525,938	$	1,092,220	$	1,065,641
Clients 6-10	$	284,382	$	260,689	$	563,908	$	553,350
Clients 11-25	$	420,880	$	368,675	$	829,047	$	726,985
Other	$	785,197	$	779,891	$	1,513,654	$	1,490,981

Total	$	2,020,251	$	1,935,193	$	3,998,829	$	3,836,957

There was no revenue from individual customers greater than 10% of consolidated revenue in the respective periods.