0001060955-23-000033 | 6-K | XBRL Viewer

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Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities) - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Increase in unbilled services (unbilled revenue)	$ (15,771)
Decrease in unearned revenue (payments on account)	155,734
Increase in net balance	171,505
Revenue, remaining performance obligation	$ 14,300,000	$ 13,500,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
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

Fair value measurements - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 56,855	$ 34,356
Long-term debt at fair value	4,032,000
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	12,917,600
Goodwill at fair value	8,982,900
Net intangible assets at fair value	$ 3,934,700

Derivatives - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
Derivatives - Narrative (Details) $ in Thousands	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Nov. 29, 2022 USD ($) instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other receivables		Other receivables
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other liabilities		Other liabilities
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$ 2,300		$ 2,300
Gain on cash flow hedge	4,986	$ 0	15,134	$ 0
Other comprehensive income (loss), cash flow hedge, gain (loss), before reclassification and tax	5,000	0	15,100	0
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, before tax	(300)	$ 0	3,300	$ 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%
Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments \| Level 2
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative asset, current	3,800		3,800
Derivative liability, current	3,300		3,300
Derivative asset, noncurrent	9,300		9,300
Derivative liability, noncurrent	400		400
Interest rate cap and interest rate swap \| Total derivatives designated as hedging instruments \| Level 2 \| Other receivables
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative asset, current	$ 10		$ 10

Subsequent events	9 Months Ended
Subsequent events	Sep. 30, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent events On October 2, 2023, the Company acquired 100% of the equity of BioTel Research, LLC which comprised the business formerly known as Philips Pharma Solutions, a leading provider of medical imaging and cardiac safety monitoring services. The initial consideration paid on the closing date of the acquisition was $68.1 million. The 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, other than the items described above, to disclose.

Share-based awards - Schedule of Non-cash Stock Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 16,465	$ 17,517	$ 47,822	$ 55,703
Direct costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	6,637	6,285	18,725	17,117
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 9,828	$ 11,232	$ 29,097	$ 38,586

- 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

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+ Details

Bank credit lines and loan facilities - Schedule of Outstanding Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 29, 2023	Apr. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jul. 01, 2021
Debt Instrument [Line Items]
Total debt	$ 4,076,213				$ 4,701,213
Less current portion of long-term debt	(130,150)				(55,150)
Total long-term debt	3,946,063				4,646,063
Less debt issuance costs and debt discount	(34,541)				(47,026)
Total long-term debt, net	$ 3,911,522				$ 4,599,037
Senior Secured Term Loan \| Senior Secured Term Loan
Debt Instrument [Line Items]
Debt instrument, interest rate	7.75%				7.09%	1.00%
Total debt	$ 3,501,213				$ 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		6.68%	6.25%	6.17%
Line of credit facility, interest rate at period end	6.68%
Total debt	$ 75,000				$ 0

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Comprehensive income (net of tax):
Net income attributable to the Group	$ 163,665	$ 160,154	$ 395,917	$ 387,859
Currency translation adjustment	(38,648)	(98,966)	(33,786)	(200,964)
Gain on cash flow hedge	4,986	0	15,134	0
Total comprehensive income attributable to the Group	$ 130,003	$ 61,188	$ 377,265	$ 186,895

- Definition

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

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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
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+ Details

Intangible assets (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Total cost	$ 5,108,471	$ 5,109,212
Accumulated amortization	(1,173,798)	(830,553)
Net book value	3,934,673	4,278,659
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total cost	4,076,010	4,076,435
Order backlog
Finite-Lived Intangible Assets [Line Items]
Total cost	536,716	536,934
Trade names & brands
Finite-Lived Intangible Assets [Line Items]
Total cost	204,608	204,621
Patient database
Finite-Lived Intangible Assets [Line Items]
Total cost	170,262	170,238
Technology assets
Finite-Lived Intangible Assets [Line Items]
Total cost	$ 120,875	$ 120,984

Income taxes (Tables)

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense

Income taxes recognized during the three and nine months ended September 30, 2023 and September 30, 2022, comprise:


	Three Months Ended				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)
Provision for income taxes	$	18,011	$	21,012	$	41,913	$	48,552

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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	160,154					160,154
Exercise of share options (in shares)		117,140
Exercise of share options	13,831	$ 4	13,827
Issue of restricted share units / performance share units (in shares)		1,532
Issue of restricted share units / performance share units	4	$ 4
Non-cash stock compensation expense	17,686		17,686
Share issuance costs	(1)		(1)
Other comprehensive loss, net of tax	(98,966)				(98,966)
Ending balance (in shares) at Sep. 30, 2022		81,645,279
Ending balance at Sep. 30, 2022	$ 8,238,721	$ 6,645	6,818,877	1,162	(291,901)	1,703,938
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 Sep. 30, 2023	82,326,976	82,326,976
Ending balance at Sep. 30, 2023	$ 8,959,034	$ 6,688	6,924,073	1,162	(190,190)	2,217,301
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
Ending balance at Jun. 30, 2023	8,796,440	$ 6,676	6,891,494	1,162	(156,528)	2,053,636
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	163,665					163,665
Exercise of share options (in shares)		147,661
Exercise of share options	16,337	$ 9	16,328
Issue of restricted share units / performance share units (in shares)		28,266
Issue of restricted share units / performance share units	3	$ 3
Non-cash stock compensation expense	16,256		16,256
Share issuance costs	(5)		(5)
Other comprehensive loss, net of tax	$ (33,662)				(33,662)
Ending balance (in shares) at Sep. 30, 2023	82,326,976	82,326,976
Ending balance at Sep. 30, 2023	$ 8,959,034	$ 6,688	$ 6,924,073	$ 1,162	$ (190,190)	$ 2,217,301

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Revenue	$ 2,055,099	$ 1,942,427	$ 6,053,928	$ 5,779,384
Costs and expenses:
Direct costs (excluding depreciation and amortization)	1,449,136	1,375,837	4,274,222	4,146,366
Selling, general and administrative expense	185,187	166,787	572,999	552,000
Depreciation and amortization	146,032	141,861	436,217	427,285
Transaction and integration-related expenses	10,433	8,001	34,516	28,970
Restructuring	0	6,197	45,390	32,890
Total costs and expenses	1,790,788	1,698,683	5,363,344	5,187,511
Income from operations	264,311	243,744	690,584	591,873
Interest income	1,273	1,434	3,294	1,727
Interest expense	(83,908)	(63,010)	(255,665)	(154,546)
Income before provision for income taxes	181,676	182,168	438,213	439,054
Provision for income taxes	(18,011)	(21,012)	(41,913)	(48,552)
Income before share of earnings from equity method investments	163,665	161,156	396,300	390,502
Share of losses in equity method investments	0	(1,002)	(383)	(2,643)
Net income attributable to the Group	$ 163,665	$ 160,154	$ 395,917	$ 387,859
Net income per Ordinary Share attributable to the Group (note 13):
Basic (in USD per share)	$ 1.99	$ 1.96	$ 4.83	$ 4.76
Diluted (in USD per share)	$ 1.97	$ 1.94	$ 4.79	$ 4.70
Weighted average number of Ordinary Shares outstanding (note 13):
Basic (in shares)	82,215,627	81,582,375	82,001,500	81,481,686
Diluted (in shares)	82,972,888	82,493,211	82,737,073	82,473,521

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net income	$ 395,917	$ 387,859
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	436,217	427,285
Impairment of long lived assets	8,845	27,727
Reduction in carrying value of operating right-of-use assets	33,979	35,238
Loss on equity method investments	383	2,643
Acquisition-related gain	(6,160)	0
Charge on cash flow hedge	3,335	0
Amortization of financing costs and debt discount	12,485	13,544
Stock compensation expense	47,303	55,703
Deferred taxes	(114,487)	(126,620)
Foreign exchange movements	(7,670)	(52,334)
Other non-cash items	21,966	18,595
Changes in operating assets and liabilities:
Accounts receivable	(139,096)	(140,760)
Unbilled revenue	14,370	(221,104)
Unearned revenue	158,269	28,352
Other net assets	(144,760)	166,613
Net cash provided by operating activities	720,896	622,741
Cash flows from investing activities:
Purchase of property, plant and equipment	(87,980)	(85,145)
Purchase of subsidiary undertakings	(5,100)	0
Sale of available for sale investments	1,611	0
Purchase of available for sale investments	(1,852)	0
Purchase of investments in equity - long term	(10,829)	(1,840)
Net cash used in investing activities	(104,150)	(86,985)
Cash flows from financing activities:
Drawdown of bank credit lines and loan facilities	305,000	25,000
Repayment of bank credit lines and loan facilities	(930,000)	(625,000)
Proceeds from exercise of equity compensation	36,517	28,967
Share issue costs	(14)	(3)
Repurchase of ordinary shares	0	(99,983)
Share repurchase costs	0	(17)
Net cash used in financing activities	(588,497)	(671,036)
Effect of exchange rate movements on cash	(3,952)	(7,775)
Net increase (decrease) in cash and cash equivalents	24,297	(143,055)
Cash and cash equivalents at beginning of period	288,768	752,213
Cash and cash equivalents at end of period	$ 313,065	$ 609,158

Share-based awards - Summary of Stock Option Activity (Details) - Employee Stock Option			9 Months Ended
	Sep. 30, 2023 $ / shares shares	Dec. 31, 2022 $ / shares shares	Sep. 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			(377,614)
Canceled/expired (in shares) \| shares			(6,885)
Outstanding at end of period (in shares) \| shares	1,076,092	1,378,119	1,076,092
Exercisable at end of period (in shares) \| shares	804,953		804,953
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			96.67
Canceled/expired (in USD per share) \| $ / shares			116.33
Outstanding at end of period (in USD per share) \| $ / shares	$ 136.65	$ 119.86	136.65
Exercisable at end of period (in USD per share) \| $ / shares	$ 113.75		$ 113.75
Weighted Average Remaining Contractual Life
Weighted average contractual term of options outstanding	4 years 5 months 12 days	4 years 8 months 8 days
Weighted average contractual term of options exercisable	3 years 10 months 28 days

Derivatives - Effect of Derivative Financial Instruments on Statement of Financial Position (Details) - Total derivatives designated as hedging instruments - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Interest Rate Caps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	$ 4,262,000	$ 12,000
Derivative liability	0	3,363,000
Notional	1,750,606,000	2,100,606,000
Interest Rate Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	8,849,000	0
Derivative liability	0	307,000
Notional	1,100,606,000	1,100,606,000
Interest rate cap and interest rate swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	13,111,000	12,000
Derivative liability	0	3,670,000
Notional	2,851,212,000	3,201,212,000
Interest rate cap and interest rate swap \| Level 2
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	13,111,000	12,000
Derivative liability	$ 0	$ 3,670,000

- Definition

Nominal or face amount used to calculate payments on the derivative asset.

+ References + Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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+ Details

Operating leases

9 Months Ended

Sep. 30, 2023

Leases [Abstract]

Operating leases

Lease costs recorded under operating leases for the three and nine months ended September 30, 2023 and September 30, 2022 were as follows:


	Three Months Ended		Nine Months Ended
	September 30, 2023	September 30, 2022	September 30, 2023		September 30, 2022
	(in thousands)		(in thousands)
Operating lease costs	11,850	12,164	$	37,539	$	40,976
Income from sub-leases	(284)	(268)	(845)		(898)
Net operating lease costs	11,566	11,896	$	36,694	$	40,078

Of the total cost of $36.7 million incurred in the nine months ended September 30, 2023 (September 30, 2022: $40.1 million), $28.1 million (September 30, 2022: $38.1 million) is recorded within selling, general and administration costs and $8.6 million (September 30, 2022: $2.0 million) is recorded within direct costs.

During the nine months ended September 30, 2023 and September 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 September 30, 2023, totaled $2.1 million (September 30, 2022: $1.7 million). Right-of-use assets obtained, in exchange for lease obligations during the nine months ended September 30, 2023, totaled $24.6 million (September 30, 2022: $37.6 million).

The weighted average remaining lease term and weighted-average discount rate at September 30, 2023 were 6.75 years and 3.15%, respectively.

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


	Minimum rental payments
(in thousands)	September 30, 2023
Year 1	$	38,084
Year 2	31,545
Year 3	26,709
Year 4	21,934
Year 5	15,039
Thereafter	35,884
Total future minimum lease payments	169,195
Lease imputed interest	(13,883)
Total	$	155,312

Operating lease liabilities are presented as current and non-current. Operating lease liabilities of $33.9 million have been included in other liabilities as at September 30, 2023 (September 30, 2022: $42.2 million).

Goodwill - Narrative (Details) - USD ($)	9 Months Ended		12 Months Ended
Goodwill - Narrative (Details) - USD ($)	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Apr. 20, 2023
Acquired Finite-Lived Intangible Assets [Line Items]
Current period acquisition	$ 13,379,000		$ 0
Acquisition-related gain	6,160,000	$ 0
Accumulated impairment loss	0		$ 0
Oncacare
Acquired Finite-Lived Intangible Assets [Line Items]
Percentage of share capital acquired				51.00%
Current period acquisition	$ 13,400,000

Goodwill

9 Months Ended

Sep. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill


	Nine Months Ended		Year Ended
	September 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	(2,153)		(30,569)

Closing balance	$	8,982,896	$	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 nine months ended September 30, 2023 or for the year ended December 31, 2022.

Intangible assets (Tables)

9 Months Ended

Sep. 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:


	Nine Months Ended		Year Ended
	September 30, 2023		December 31, 2022
Cost	(in thousands)
Customer relationships	$	4,076,010	$	4,076,435
Order backlog	536,716		536,934
Trade names & brands	204,608		204,621
Patient database	170,262		170,238
Technology assets	120,875		120,984



Total cost	5,108,471		5,109,212
Accumulated amortization	(1,173,798)		(830,553)

Net book value	$	3,934,673	$	4,278,659

Business Segment and Geographical Information - Schedule of Distribution of Income from Operations by Geographical Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Income from operations	$ 264,311	$ 243,744	$ 690,584	$ 591,873
Ireland
Segment Reporting Information [Line Items]
Income from operations	121,343	93,640	298,567	159,059
Rest of Europe
Segment Reporting Information [Line Items]
Income from operations	56,705	76,178	138,959	194,860
U.S.
Segment Reporting Information [Line Items]
Income from operations	70,013	63,356	213,846	177,145
Rest of World
Segment Reporting Information [Line Items]
Income from operations	$ 16,250	$ 10,570	$ 39,212	$ 60,809

Share capital (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
Share capital (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Mar. 31, 2022	Sep. 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%

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	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Unbilled services (unbilled revenue)	$ 941,884	$ 957,655
Change in unbilled services (unbilled revenue)	$ (15,771)
Percentage change in unbilled services (unbilled revenue)	(1.60%)
Unearned revenue (payments on account)	$ (1,663,183)	(1,507,449)
Change in unearned revenue (payments on account)	$ (155,734)
Percentage change in unearned revenue (payments on account)	10.30%
Net balance	$ (721,299)	$ (549,794)
Change in net balance	$ 171,505
Percentage change in net balance	31.20%

Cover	9 Months Ended
Cover	Sep. 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	Q3
Entity Central Index Key	0001060955
Current Fiscal Year End Date	--12-31
Document Period End Date	Sep. 30, 2023

Share-based awards - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions			9 Months Ended	12 Months Ended	53 Months Ended
	Sep. 30, 2023	May 11, 2015	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2023	May 16, 2019
Employee Stock Option
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Number of shares exercisable (in shares)	804,953		804,953		804,953
Weighted average contractual term of options exercisable	3 years 10 months 28 days
Weighted average exercise price of options exercisble (USD per share)	$ 113.75		$ 113.75		$ 113.75
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
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
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			$ 33.3	$ 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

Business Segment and Geographical Information - Schedule of Distribution of Revenue by Geographical Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Revenue	$ 2,055,099	$ 1,942,427	$ 6,053,928	$ 5,779,384
Ireland
Segment Reporting Information [Line Items]
Revenue	596,337	526,867	1,701,580	1,395,198
Rest of Europe
Segment Reporting Information [Line Items]
Revenue	384,720	397,538	1,172,752	1,281,996
U.S.
Segment Reporting Information [Line Items]
Revenue	831,789	903,200	2,524,212	2,767,844
Rest of World
Segment Reporting Information [Line Items]
Revenue	$ 242,253	$ 114,822	$ 655,384	$ 334,346

- 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)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479941/924-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 22
-Subparagraph (b)
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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
-Topic 280
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Restructuring - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring	$ 0	$ 6,197	$ 45,390	$ 32,890
Other restructuring costs			11,300
Opening provision	19,620		19,620		$ 6,022	$ 10,311
Personnel related liabilities
Restructuring Cost and Reserve [Line Items]
Opening provision	16,200		16,200
Facility liability
Restructuring Cost and Reserve [Line Items]
Opening provision	3,400		3,400
Other liability \| Other liabilities
Restructuring Cost and Reserve [Line Items]
Opening provision	1,100		1,100
Other liability \| Non-current other liabilities
Restructuring Cost and Reserve [Line Items]
Opening provision	$ 2,300		2,300
2021 restructuring plan
Restructuring Cost and Reserve [Line Items]
Severance costs			$ 34,100

Fair value measurements - Measurement of Fair Value of Major Asset and Liability classed (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale securities (short-term)	$ 1,954	$ 1,713
Available for sale investments (long-term)	41,790	32,631
Total assets	56,855	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	13,111	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)	1,954	1,713
Available for sale investments (long-term)	0	0
Total assets	1,954	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	13,111	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	13,111	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)	41,790	32,631
Total assets	41,790	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

Restructuring (Tables)

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Summary of Restructuring Charges


	Nine Months Ended
	September 30, 2023		September 30, 2022
	(in thousands)
Restructuring charges	$	45,390	$	32,890
Net charge	$	45,390	$	32,890

Summary of details of movement in restructuring charges


	Nine Months Ended		Year ended
	September 30, 2023		December 31, 2022
	(in thousands)

Opening provision	$	6,022	$	10,311
Additional provisions	36,704		4,364
Utilization	(23,106)		(8,653)
Ending provision	$	19,620	$	6,022

Summary of significant accounting policies - Estimated Useful Lives of Intangible Assets (Details)	Sep. 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

Share-based awards (Tables)

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Summary of stock option activity

The following table summarizes option activity for the nine months ended September 30, 2023:


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

Granted	82,472	$	232.48
Exercised	(377,614)	$	96.67
Canceled/expired	(6,885)	$	116.33

Outstanding at September 30, 2023	1,076,092	$	136.65	4.45

Exercisable at September 30, 2023	804,953	$	113.75	3.91

Schedule of weighted average fair values and assumptions used

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


	Nine Months Ended
	September 30, 2023			September 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 nine months ended September 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	306,780	$	218.68
Shares vested	(47,026)	$	159.57	(178,781)	$	186.35
Forfeited	—	$	—	(59,260)	$	211.45

Outstanding at September 30, 2023	165,768	$	216.22	651,351	$	218.41

Schedule of non-cash stock compensation expense

Stock compensation expense for the three and nine months ended September 30, 2023 and September 30, 2022 has been allocated as follows:


	Three Months Ended				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)
Direct costs	$	6,637	$	6,285	$	18,725	$	17,117
Selling, general and administrative	$	9,828	$	11,232	$	29,097	$	38,586

Total	$	16,465	$	17,517	$	47,822	$	55,703

Business Segment and Geographical Information - Schedule of Distribution of Depreciation and Amortization by Geographical Area (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Long-lived assets	$ 474,581	$ 504,152
Ireland
Segment Reporting Information [Line Items]
Long-lived assets	172,016	143,025
Rest of Europe
Segment Reporting Information [Line Items]
Long-lived assets	89,265	99,721
U.S.
Segment Reporting Information [Line Items]
Long-lived assets	165,597	213,311
Rest of World
Segment Reporting Information [Line Items]
Long-lived assets	$ 47,703	$ 48,095

Subsequent events - Narrative (Details) - Philips Pharma Solutions (formerly BioTel Research, LLC) - Subsequent event $ in Millions	Oct. 02, 2023 USD ($)
Business Acquisition [Line Items]
Percentage of share capital acquired	100.00%
Business combination, consideration transferred	$ 68.1

Share capital	9 Months Ended
Share capital	Sep. 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
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-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
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-Name Accounting Standards Codification
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-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
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-Name Accounting Standards Codification
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-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
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-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
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-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
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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
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-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
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-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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-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
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-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
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-Name Accounting Standards Codification
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-Paragraph 14
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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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
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-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Summary of significant accounting policies (Policies)

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

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 the provision of income taxes 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.

- 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
-Paragraph 19
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-19

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-18

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-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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-Section 50
-Paragraph 20
-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
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-Name Accounting Standards Codification
-Section 50
-Paragraph 20
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-URI https://asc.fasb.org//1943274/2147479806/606-10-50-20

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Name Accounting Standards Codification
-Section 50
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
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-Section 50
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-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
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-Topic 235
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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

Income taxes - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Liability for unrecognized tax benefit	$ 251.1	$ 240.2
Items generating unrecognized tax benefits	221.1	217.6
Interest and related penalties	$ 30.0	$ 22.6

Basis of presentation	9 Months Ended
Basis of presentation	Sep. 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 nine months ended September 30, 2023 are not necessarily indicative of the results that may be expected for the fiscal period ending December 31, 2023.

Restructuring - Summary of Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Restructuring and Related Activities [Abstract]
Restructuring	$ 0	$ 6,197	$ 45,390	$ 32,890

Operating leases (Tables)

9 Months Ended

Sep. 30, 2023

Leases [Abstract]

Schedule of Lease Costs

Lease costs recorded under operating leases for the three and nine months ended September 30, 2023 and September 30, 2022 were as follows:


	Three Months Ended		Nine Months Ended
	September 30, 2023	September 30, 2022	September 30, 2023		September 30, 2022
	(in thousands)		(in thousands)
Operating lease costs	11,850	12,164	$	37,539	$	40,976
Income from sub-leases	(284)	(268)	(845)		(898)
Net operating lease costs	11,566	11,896	$	36,694	$	40,078

Schedule of Operating Lease Maturity

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


	Minimum rental payments
(in thousands)	September 30, 2023
Year 1	$	38,084
Year 2	31,545
Year 3	26,709
Year 4	21,934
Year 5	15,039
Thereafter	35,884
Total future minimum lease payments	169,195
Lease imputed interest	(13,883)
Total	$	155,312

Business Segment and Geographical Information (Tables)

9 Months Ended

Sep. 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				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)
Ireland	$	596,337	$	526,867	$	1,701,580	$	1,395,198
Rest of Europe	384,720		397,538		1,172,752		1,281,996
U.S.	831,789		903,200		2,524,212		2,767,844
Rest of World	242,253		114,822		655,384		334,346

Total	$	2,055,099	$	1,942,427	$	6,053,928	$	5,779,384

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				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)
Ireland *	$	121,343	$	93,640	$	298,567	$	159,059
Rest of Europe	56,705		76,178		138,959		194,860
U.S.	70,013		63,356		213,846		177,145
Rest of World	16,250		10,570		39,212		60,809

Total	$	264,311	$	243,744	$	690,584	$	591,873

* 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:


	September 30, 2023		December 31, 2022
	(in thousands)
Ireland	$	172,016	$	143,025
Rest of Europe	89,265		99,721
U.S.	165,597		213,311
Rest of World	47,703		48,095

Total	$	474,581	$	504,152

Fair Value Measures and Disclosures (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value, Liabilities Measured on Recurring Basis

As of September 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)	1,954		—		—		—		1,954
Available for sale investments (long-term) (b)	—		—		—		41,790		41,790
Derivative instruments (c)	—		13,111		—		—		13,111
Total assets	$	1,954	$	13,111	$	—	$	41,790	$	56,855

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.

Fair Value, Assets Measured on Recurring Basis

As of September 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)	1,954		—		—		—		1,954
Available for sale investments (long-term) (b)	—		—		—		41,790		41,790
Derivative instruments (c)	—		13,111		—		—		13,111
Total assets	$	1,954	$	13,111	$	—	$	41,790	$	56,855

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

Restructuring - Summary of Details of Movement in Restructuring Charges (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Restructuring and Related Activities [Abstract]
Opening provision	$ 19,620	$ 6,022
Additional provisions	36,704	4,364
Utilization	(23,106)	(8,653)
Ending provision	$ 6,022	$ 10,311

Summary of significant accounting policies (Tables)

9 Months Ended

Sep. 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:


	Nine Months Ended		Year Ended
	September 30, 2023		December 31, 2022
Cost	(in thousands)
Customer relationships	$	4,076,010	$	4,076,435
Order backlog	536,716		536,934
Trade names & brands	204,608		204,621
Patient database	170,262		170,238
Technology assets	120,875		120,984



Total cost	5,108,471		5,109,212
Accumulated amortization	(1,173,798)		(830,553)

Net book value	$	3,934,673	$	4,278,659

Income taxes

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

Income taxes

Income taxes recognized during the three and nine months ended September 30, 2023 and September 30, 2022, comprise:


	Three Months Ended				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)
Provision for income taxes	$	18,011	$	21,012	$	41,913	$	48,552

As at September 30, 2023 the Company maintains a $251.1 million liability (December 31, 2022: $240.2 million) for unrecognized tax benefit, which is comprised of $221.1 million (December 31, 2022: $217.6 million) related to items generating unrecognized tax benefits and $30.0 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
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

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

+ Details

Net income per ordinary share

9 Months Ended

Sep. 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		Nine Months Ended
	September 30, 2023	September 30, 2022	September 30, 2023	September 30, 2022
Weighted average number of ordinary shares outstanding for basic net income per ordinary share	82,215,627	81,582,375	82,001,500	81,481,686
Effect of dilutive share options and other awards outstanding under share based compensation programs	757,261	910,836	735,573	991,835
Weighted average number of ordinary shares outstanding for diluted net income per ordinary share	82,972,888	82,493,211	82,737,073	82,473,521


	Three Months Ended		Nine Months Ended
	September 30, 2023	September 30, 2022	September 30, 2023	September 30, 2022
Net income per Ordinary Share attributable to the Group:
Basic	1.99	1.96	4.83	4.76
Diluted	1.97	1.94	4.79	4.70

Operating leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lessee, Lease, Description [Line Items]
Total lease cost	$ 11,566	$ 11,896	$ 36,694	$ 40,078
Right-of-use assets obtained in exchange for lease obligations	$ 2,100	$ 1,700	$ 24,600	$ 37,600
Weighted average remaining lease term	6 years 9 months		6 years 9 months
Weighted average discount rate	3.15%		3.15%
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	$ 33,900	$ 42,200	$ 33,900	$ 42,200
Selling, general and administration costs
Lessee, Lease, Description [Line Items]
Total lease cost			28,100	38,100
Direct costs
Lessee, Lease, Description [Line Items]
Total lease cost			$ 8,600	$ 2,000

Summary of significant accounting policies

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Summary of significant accounting policies

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

Income taxes - Components of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 18,011	$ 21,012	$ 41,913	$ 48,552

- Definition

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

+ References + Details

Restructuring

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Restructuring

In the nine months ended September 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.


	Nine Months Ended
	September 30, 2023		September 30, 2022
	(in thousands)
Restructuring charges	$	45,390	$	32,890
Net charge	$	45,390	$	32,890

At September 30, 2023, a total liability of $19.6 million was recorded on the Consolidated Balance Sheet relating to restructuring activities. The total liability included $16.2 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 $3.4 million of facilities related liabilities of which $1.1 million is included within other liabilities and $2.3 million is included within non-current other liabilities.


	Nine Months Ended		Year ended
	September 30, 2023		December 31, 2022
	(in thousands)

Opening provision	$	6,022	$	10,311
Additional provisions	36,704		4,364
Utilization	(23,106)		(8,653)
Ending provision	$	19,620	$	6,022

Share-based awards - Schedule of Weighted Average Fair Values and Assumptions Used (Details) - Employee Stock Option - $ / shares	9 Months Ended
	Sep. 30, 2023	Sep. 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

9 Months Ended

Sep. 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 caps 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 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 Swap begins accruing on December 31, 2024 and the interest rate swap expires on September 30, 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, are summarized in the following table:


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

Interest Rate Caps	$4,262	$—	$1,750,606	$12	$3,363	$2,100,606
Interest Rate Swap	$8,849	$—	$1,100,606	$—	$307	$1,100,606

Total derivatives designated as hedging instruments	$13,111	$—	$2,851,212	$12	$3,670	$3,201,212

As of September 30, 2023, the Company recognized a current derivative asset of $3.8 million within other receivables (December 31, 2022, current derivative asset of $0.01 million recognized within other receivables and a current derivative liability of $3.3 million recognized within other liabilities). A further $9.3 million non-current derivative asset was recognized within non-current other receivables (December 31,2022, non-current derivative liability of $0.4 million recognized within non-current other liabilities).

During the next 12 months, the Company estimates that an additional $2.3 million will be reflected as interest income in the consolidated statements.

The Company recognized $5.0 million of a gain within other comprehensive income ("OCI") for the three months ended September 30, 2023 (September 30, 2022: $nil) after a reclassification of $0.3 million from OCI to the income statement (September 30, 2022: $nil). The Company recognized $15.1 million of a net gain within OCI for the nine months ended September 30, 2023 (September 30, 2022: $nil) after a reclassification of $3.3 million from OCI to the income statement (September 30, 2022: $nil).

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

9 Months Ended

Sep. 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:


	September 30, 2023		December 31, 2022
	(in thousands)
Contract assets:
Billed services (accounts receivable)	$	1,883,296	$	1,751,950
Unbilled services (unbilled revenue)	941,884		957,655
Accounts receivable and unbilled revenue, gross	2,825,180		2,709,605
Allowance for credit losses	(32,934)		(20,562)
Accounts receivable and unbilled revenue, net	$	2,792,246	$	2,689,043

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


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

Unbilled services (unbilled revenue)	$	941,884	$	957,655	$	(15,771)	(1.6)	%
Unearned revenue (payments on account)	(1,663,183)		(1,507,449)		(155,734)		10.3	%
Net balance	$	(721,299)	$	(549,794)	$	(171,505)	31.2	%

Operating leases - Schedule of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Leases [Abstract]
Operating lease costs	$ 11,850	$ 12,164	$ 37,539	$ 40,976
Income from sub-leases	(284)	(268)	(845)	(898)
Net operating lease costs	$ 11,566	$ 11,896	$ 36,694	$ 40,078

Intangible assets

9 Months Ended

Sep. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets

Intangible assets, net consisted of the following:


	Nine Months Ended		Year Ended
	September 30, 2023		December 31, 2022
Cost	(in thousands)
Customer relationships	$	4,076,010	$	4,076,435
Order backlog	536,716		536,934
Trade names & brands	204,608		204,621
Patient database	170,262		170,238
Technology assets	120,875		120,984



Total cost	5,108,471		5,109,212
Accumulated amortization	(1,173,798)		(830,553)

Net book value	$	3,934,673	$	4,278,659

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

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 313,065	$ 288,768
Available for sale investments	1,954	1,713
Accounts receivable, net of allowance for credit losses	1,850,362	1,731,388
Unbilled revenue	941,884	957,655
Other receivables	121,687	63,658
Prepayments and other current assets	150,193	137,094
Income taxes receivable	42,039	48,790
Total current assets	3,421,184	3,229,066
Non-current assets:
Property, plant and equipment, net	342,262	350,320
Goodwill	8,982,896	8,971,670
Intangible assets	3,934,673	4,278,659
Operating right-of-use assets	132,319	153,832
Other receivables	52,797	70,790
Income taxes receivable	40,481	21,380
Deferred tax asset	83,095	76,930
Investments in equity- long term	41,790	32,631
Total Assets	17,031,497	17,185,278
Current Liabilities:
Accounts payable	87,317	81,194
Unearned revenue	1,663,183	1,507,449
Other liabilities	948,829	1,005,025
Income taxes payable	41,518	41,783
Current bank credit lines and loan facilities	130,150	55,150
Total current liabilities	2,870,997	2,690,601
Non-current liabilities:
Non-current bank credit lines and loan facilities	3,911,522	4,599,037
Lease liabilities	121,424	131,644
Non-current other liabilities	41,661	38,260
Non-current income taxes payable	242,972	239,188
Deferred tax liability	883,887	988,585
Commitments and contingencies	0	0
Total Liabilities	8,072,463	8,687,315
Shareholders' Equity:
Ordinary shares, par value 6 euro cents per share; 100,000,000 shares authorized, 82,326,976 shares issued and outstanding at September 30, 2023 and 81,723,555 shares issued and outstanding at December 31, 2022	6,688	6,649
Additional paid-in capital	6,924,073	6,840,306
Other undenominated capital	1,162	1,162
Accumulated other comprehensive loss	(190,190)	(171,538)
Retained earnings	2,217,301	1,821,384
Total Shareholders' Equity	8,959,034	8,497,963
Total Liabilities and Shareholders' Equity	$ 17,031,497	$ 17,185,278

Business Segment and Geographical Information

9 Months Ended

Sep. 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 nine months ended September 30, 2023 and September 30, 2022 and at September 30, 2023 and December 31, 2022 is as follows:

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


	Three Months Ended				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)
Ireland	$	596,337	$	526,867	$	1,701,580	$	1,395,198
Rest of Europe	384,720		397,538		1,172,752		1,281,996
U.S.	831,789		903,200		2,524,212		2,767,844
Rest of World	242,253		114,822		655,384		334,346

Total	$	2,055,099	$	1,942,427	$	6,053,928	$	5,779,384

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


	Three Months Ended				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)
Ireland *	$	121,343	$	93,640	$	298,567	$	159,059
Rest of Europe	56,705		76,178		138,959		194,860
U.S.	70,013		63,356		213,846		177,145
Rest of World	16,250		10,570		39,212		60,809

Total	$	264,311	$	243,744	$	690,584	$	591,873

* 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:


	September 30, 2023		December 31, 2022
	(in thousands)
Ireland	$	172,016	$	143,025
Rest of Europe	89,265		99,721
U.S.	165,597		213,311
Rest of World	47,703		48,095

Total	$	474,581	$	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
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-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
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 280
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-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

+ Details

Derivatives (Tables)

9 Months Ended

Sep. 30, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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

The fair value of the Company’s derivative financial instruments, on a gross basis, are summarized in the following table:


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

Interest Rate Caps	$4,262	$—	$1,750,606	$12	$3,363	$2,100,606
Interest Rate Swap	$8,849	$—	$1,100,606	$—	$307	$1,100,606

Total derivatives designated as hedging instruments	$13,111	$—	$2,851,212	$12	$3,670	$3,201,212

Net income per ordinary share (Tables)

9 Months Ended

Sep. 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		Nine Months Ended
	September 30, 2023	September 30, 2022	September 30, 2023	September 30, 2022
Weighted average number of ordinary shares outstanding for basic net income per ordinary share	82,215,627	81,582,375	82,001,500	81,481,686
Effect of dilutive share options and other awards outstanding under share based compensation programs	757,261	910,836	735,573	991,835
Weighted average number of ordinary shares outstanding for diluted net income per ordinary share	82,972,888	82,493,211	82,737,073	82,473,521


	Three Months Ended		Nine Months Ended
	September 30, 2023	September 30, 2022	September 30, 2023	September 30, 2022
Net income per Ordinary Share attributable to the Group:
Basic	1.99	1.96	4.83	4.76
Diluted	1.97	1.94	4.79	4.70

Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Revenue (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue	$ 2,055,099	$ 1,942,427	$ 6,053,928	$ 5,779,384
Clients 1-5
Disaggregation of Revenue [Line Items]
Revenue	527,345	539,907	1,615,713	1,595,007
Clients 6-10
Disaggregation of Revenue [Line Items]
Revenue	302,407	270,073	868,753	831,660
Clients 11-25
Disaggregation of Revenue [Line Items]
Revenue	448,428	405,171	1,267,750	1,100,118
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 776,919	$ 727,276	$ 2,301,712	$ 2,252,599

- 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

+ References

+ Details

Revenue

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

Revenue

Revenue disaggregated by customer concentration is as follows:


	Three Months Ended				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)



Clients 1-5	$	527,345	$	539,907	$	1,615,713	$	1,595,007
Clients 6-10	$	302,407	$	270,073	$	868,753	$	831,660
Clients 11-25	$	448,428	$	405,171	$	1,267,750	$	1,100,118
Other	$	776,919	$	727,276	$	2,301,712	$	2,252,599

Total	$	2,055,099	$	1,942,427	$	6,053,928	$	5,779,384

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:


	September 30, 2023		December 31, 2022
	(in thousands)
Contract assets:
Billed services (accounts receivable)	$	1,883,296	$	1,751,950
Unbilled services (unbilled revenue)	941,884		957,655
Accounts receivable and unbilled revenue, gross	2,825,180		2,709,605
Allowance for credit losses	(32,934)		(20,562)
Accounts receivable and unbilled revenue, net	$	2,792,246	$	2,689,043

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


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

Unbilled services (unbilled revenue)	$	941,884	$	957,655	$	(15,771)	(1.6)	%
Unearned revenue (payments on account)	(1,663,183)		(1,507,449)		(155,734)		10.3	%
Net balance	$	(721,299)	$	(549,794)	$	(171,505)	31.2	%

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 September 30, 2023 decreased by $15.8 million compared to December 31, 2022. Unearned revenue increased by $155.7 million over the same period resulting in an increase of $171.5 million in the net balance of unbilled services and unearned revenue or payments on account between December 31, 2022 and September 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 September 30, 2023 approximately $14.3 billion (September 30, 2022: $13.5 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
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-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
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-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
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-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
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-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
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-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
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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

Fair value measurements

9 Months Ended

Sep. 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 September 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)	1,954		—		—		—		1,954
Available for sale investments (long-term) (b)	—		—		—		41,790		41,790
Derivative instruments (c)	—		13,111		—		—		13,111
Total assets	$	1,954	$	13,111	$	—	$	41,790	$	56,855

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

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 September 30, 2023, assets carried on the balance sheet at cost and not re-measured to fair value on a recurring basis totaled approximately $12,917.6 million and are identified as Level 3 assets. These assets are comprised of goodwill of $8,982.9 million and net identifiable intangible assets of $3,934.7 million.

The estimated fair value of the Company’s debt was $4,032.0 million at September 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 (Tables)

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Schedule of Outstanding Debt

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


					Principal amount
	Interest rate as of		Interest rate as of		September 30,		December 31,
(in thousands)	September 30, 2023		December 31, 2022		2023		2022		Maturity Date
Credit Facilities:
Senior Secured Term Loan	7.75	%	7.09	%	$	3,501,213	$	4,201,213	July 2028
Senior Secured Notes	2.88	%	2.88	%	500,000		500,000		July 2026
Senior Secured Revolving Loan Facility	6.68	%	—		75,000		—		October 2023




Total debt					4,076,213		4,701,213

Less current portion of long-term debt					(130,150)		(55,150)
Total long-term debt					3,946,063		4,646,063
Less debt issuance costs and debt discount					(34,541)		(47,026)
Total long-term debt, net					$	3,911,522	$	4,599,037

Schedule of Contractual Maturities of Debt

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


Contractual maturities of long-term debt:	(in thousands)
2023 (remaining)	$	88,788
2024	55,150
2025	55,150
2026	555,150
2027 and thereafter	3,321,975
Total	$	4,076,213

Bank credit lines and loan facilities - Schedule of Contractual Maturities of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
2023 (remaining)	$ 88,788
2024	55,150
2025	55,150
2026	555,150
2027 and thereafter	3,321,975
Total debt	$ 4,076,213	$ 4,701,213

Goodwill (Tables)

9 Months Ended

Sep. 30, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill


	Nine Months Ended		Year Ended
	September 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	(2,153)		(30,569)

Closing balance	$	8,982,896	$	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

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
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-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
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-Paragraph 1
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-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
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-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

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Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
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-Section 50
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-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 350
-SubTopic 20
-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1

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-Topic 350
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147482573/350-20-50-1A

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-Topic 350
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-2

+ 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		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Weighted average number of ordinary shares outstanding for basic net income per ordinary share (in shares)	82,215,627	81,582,375	82,001,500	81,481,686
Effect of dilutive share options and other awards outstanding under share based compensation programs (in shares)	757,261	910,836	735,573	991,835
Weighted average number of ordinary shares outstanding for diluted net income per ordinary share (in shares)	82,972,888	82,493,211	82,737,073	82,473,521

Revenue (Tables)

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregation of Revenue

Revenue disaggregated by customer concentration is as follows:


	Three Months Ended				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)



Clients 1-5	$	527,345	$	539,907	$	1,615,713	$	1,595,007
Clients 6-10	$	302,407	$	270,073	$	868,753	$	831,660
Clients 11-25	$	448,428	$	405,171	$	1,267,750	$	1,100,118
Other	$	776,919	$	727,276	$	2,301,712	$	2,252,599

Total	$	2,055,099	$	1,942,427	$	6,053,928	$	5,779,384

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

Business Segment and Geographical Information - Narrative (Details)	9 Months Ended
	Sep. 30, 2023 segment
Segment Reporting [Abstract]
Number of operating segments	1

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

9 Months Ended

Sep. 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				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)



Clients 1-5	$	527,345	$	539,907	$	1,615,713	$	1,595,007
Clients 6-10	$	302,407	$	270,073	$	868,753	$	831,660
Clients 11-25	$	448,428	$	405,171	$	1,267,750	$	1,100,118
Other	$	776,919	$	727,276	$	2,301,712	$	2,252,599

Total	$	2,055,099	$	1,942,427	$	6,053,928	$	5,779,384

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:


	September 30, 2023		December 31, 2022
	(in thousands)
Contract assets:
Billed services (accounts receivable)	$	1,883,296	$	1,751,950
Unbilled services (unbilled revenue)	941,884		957,655
Accounts receivable and unbilled revenue, gross	2,825,180		2,709,605
Allowance for credit losses	(32,934)		(20,562)
Accounts receivable and unbilled revenue, net	$	2,792,246	$	2,689,043

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


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

Unbilled services (unbilled revenue)	$	941,884	$	957,655	$	(15,771)	(1.6)	%
Unearned revenue (payments on account)	(1,663,183)		(1,507,449)		(155,734)		10.3	%
Net balance	$	(721,299)	$	(549,794)	$	(171,505)	31.2	%

- Definition

+ References

+ Details

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	Sep. 30, 2023	Dec. 31, 2022
Contract Assets [Abstract]
Billed services (accounts receivable)	$ 1,883,296	$ 1,751,950
Unbilled services (unbilled revenue)	941,884	957,655
Accounts receivable and unbilled revenue, gross	2,825,180	2,709,605
Allowance for credit losses	(32,934)	(20,562)
Accounts receivable and unbilled revenue, net	$ 2,792,246	$ 2,689,043

Operating leases - Schedule of Operating Lease Maturity (Details) $ in Thousands	Sep. 30, 2023 USD ($)
Leases [Abstract]
Year 1	$ 38,084
Year 2	31,545
Year 3	26,709
Year 4	21,934
Year 5	15,039
Thereafter	35,884
Total future minimum lease payments	169,195
Lease imputed interest	(13,883)
Total	$ 155,312

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - € / shares	Sep. 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)	82,326,976	81,723,555
Ordinary shares, shares outstanding (in shares)	82,326,976	81,723,555

Goodwill - Schedule of Goodwill (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 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	(2,153)	(30,569)
Closing balance	$ 8,982,896	$ 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

Bank credit lines and loan facilities - Narrative (Details) - USD ($) $ in Thousands					1 Months Ended		9 Months Ended
	Sep. 29, 2023	Aug. 17, 2023	Jun. 30, 2023	Mar. 31, 2023	Apr. 30, 2023	Jan. 31, 2023	Sep. 30, 2023	Sep. 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							$ 305,000	$ 25,000
Long-term debt at fair value							$ 4,032,000
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							7.75%				7.09%	1.00%
Repayments of senior debt	$ 300,000		$ 150,000	$ 250,000
Interest paid	74,500		74,000	75,300
Payments of debt restructuring costs	$ 2,500		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		$ 50,000	$ 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	6.68%			6.17%	6.25%
Drawdown of bank credit lines and loan facilities	$ 75,000			$ 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%	2.875%

Share-based awards

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Share-based awards

Share Options

The following table summarizes option activity for the nine months ended September 30, 2023:


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

Granted	82,472	$	232.48
Exercised	(377,614)	$	96.67
Canceled/expired	(6,885)	$	116.33

Outstanding at September 30, 2023	1,076,092	$	136.65	4.45

Exercisable at September 30, 2023	804,953	$	113.75	3.91

The Company issues ordinary shares for all options exercised. The total amount of fully vested share options which remained outstanding at September 30, 2023 was 804,953. Fully vested share options at September 30, 2023 have an average remaining contractual term of 3.91 years and an average exercise price of $113.75.

Fair value of Stock Options Assumptions

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


	Nine Months Ended
	September 30, 2023			September 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 2013 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 nine months ended September 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	306,780	$	218.68
Shares vested	(47,026)	$	159.57	(178,781)	$	186.35
Forfeited	—	$	—	(59,260)	$	211.45

Outstanding at September 30, 2023	165,768	$	216.22	651,351	$	218.41

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

The fair value of RSUs vested for the nine months ended September 30, 2023 totaled $33.3 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.

Stock compensation expense

Stock compensation expense for the three and nine months ended September 30, 2023 and September 30, 2022 has been allocated as follows:


	Three Months Ended				Nine Months Ended
	September 30, 2023		September 30, 2022		September 30, 2023		September 30, 2022
	(in thousands)				(in thousands)
Direct costs	$	6,637	$	6,285	$	18,725	$	17,117
Selling, general and administrative	$	9,828	$	11,232	$	29,097	$	38,586

Total	$	16,465	$	17,517	$	47,822	$	55,703

Net income per ordinary share - Schedule of Reconciliation of Net Income Attributable to the Group (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net income per Ordinary Share attributable to the Group:
Basic (in USD per share)	$ 1.99	$ 1.96	$ 4.83	$ 4.76
Diluted (in USD per share)	$ 1.97	$ 1.94	$ 4.79	$ 4.70

- Definition

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

+ References

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- 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

Share-based awards - Summary of RSU and PSU Activity (Details)	9 Months Ended
	Sep. 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	306,780
Shares vested (in shares) \| shares	(178,781)
Forfeited (in shares) \| shares	(59,260)
Outstanding at end of period (in shares) \| shares	651,351
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in USD per share) \| $ / shares	$ 207.73
Granted (in USD per share) \| $ / shares	218.68
Shares vested (in USD per share) \| $ / shares	186.35
Forfeited (in USD per share) \| $ / shares	211.45
Outstanding at end of period (in USD per share) \| $ / shares	$ 218.41

Bank credit lines and loan facilities

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Bank credit lines and loan facilities

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


					Principal amount
	Interest rate as of		Interest rate as of		September 30,		December 31,
(in thousands)	September 30, 2023		December 31, 2022		2023		2022		Maturity Date
Credit Facilities:
Senior Secured Term Loan	7.75	%	7.09	%	$	3,501,213	$	4,201,213	July 2028
Senior Secured Notes	2.88	%	2.88	%	500,000		500,000		July 2026
Senior Secured Revolving Loan Facility	6.68	%	—		75,000		—		October 2023




Total debt					4,076,213		4,701,213

Less current portion of long-term debt					(130,150)		(55,150)
Total long-term debt					3,946,063		4,646,063
Less debt issuance costs and debt discount					(34,541)		(47,026)
Total long-term debt, net					$	3,911,522	$	4,599,037

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


Contractual maturities of long-term debt:	(in thousands)
2023 (remaining)	$	88,788
2024	55,150
2025	55,150
2026	555,150
2027 and thereafter	3,321,975
Total	$	4,076,213

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"). The Company paid a $27.6 million debt discount in connection with the Senior Secured Credit Facility and Senior Secured Notes. 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 September 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 a further $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. The remaining $50.0 million was repaid on August 17, 2023. On September 29, 2023, $75.0 million of the senior secured revolving loan facility was drawn down at an interest rate of 6.68%, 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.

On September 29, 2023, the Company repaid $300.0 million of the senior secured term loan facility and made a quarterly interest payment of $74.5 million. This repayment resulted in an additional charge associated with previously capitalized fees of $2.5 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