Accounts payable Accounts receivable Income taxes payable Non-current income taxes payable Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive income Accumulated Other Comprehensive Income Additional Paid in Capital, Common Stock Additional paid-in capital Additional Paid-in Capital Non-cash stock compensation expense Share issuance costs Share issuance costs Tax benefit on exercise of options Adjustments to reconcile net income to net cash provided by operating activities: Amendment Flag Assets Total Assets Assets [Abstract] ASSETS Total current assets Total current assets Current Assets: Other Assets: Short term investments - available for sale Business Acquisition, Accrued Consideration Payable Accrued consideration relating to the potential additional consideration payable in respect of performance milestones Business Acquisition, Acquiree [Domain] Business Acquisition Potential additional consideration Business Acquisition, Cost of Acquired Entity, Additional Cash Paid Additional amount Company paid on completion of review Cash paid Business Acquisition, Cost of Acquired Entity, Consideration Paid First element of additional consideration paid Accrual in respect performance milestones Cash consideration Business Acquisition [Line Items] Percentage of common stock acquired Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets Intangible assets Purchase price Purchase price Business Acquisition, Purchase Price Allocation, Current Assets, Cash and Cash Equivalents Cash and cash equivalents Other current assets Current liabilities Current liabilities Business Acquisition, Purchase Price Allocation, Goodwill Amount Goodwill Property, plant and equipment Noncurrent capital government grants, which are amortized and recognized in earnings over the grant period. Non-current government grants Cash acquired with subsidiary undertakings Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Cash and cash equivalents at beginning of period Cash and cash equivalents Net (decrease)/increase in cash and cash equivalents Net (decrease)/increase in cash and cash equivalents Central Laboratory Central Laboratory Clinical Research Clinical Research Ordinary shares Ordinary shares, par value Ordinary shares, shares authorized Ordinary shares, shares issued Ordinary shares, shares outstanding Ordinary shares, par value 6 euro cents per share; 100,000,000 shares authorized, 60,496,900 shares issued and outstanding at September 30, 2011 and 60,247,092 shares issued and outstanding at December 31, 2010 Compensation Related Costs Share Based Payments Disclosure [Line Items] Compensation Related Costs Share Based Payments Disclosure [Line Items] Compensation Related Costs Share Based Payments Disclosure [Table] Compensation Related Costs Share Based Payments Disclosure [Table] Total comprehensive income Total comprehensive income Comprehensive Income: Gross revenue Direct costs Reimbursable expenses Reimbursable expenses Costs and expenses: Cost of Sales Total costs and expenses Total costs and expenses Current Fiscal Year End Date Deferred taxes Payments on account Deferred tax asset Non-current deferred tax asset Deferred tax liability Non-current deferred tax liability Deferred Tax Liability Not Recognized [Line Items] Deferred Tax Liability Not Recognized [Table] Depreciation and amortization Derivative Instruments, Gain (Loss) by Income Statement Location Disclosure - Clients Representing Company's Net Revenue [Abstract] Disclosure - Clients Representing Company's Net Revenue [Abstract] Disclosure - Details of the Movement in Restructuring Provisions Recognised [Abstract] Disclosure - Details of the Movement in Restructuring Provisions Recognised [Abstract] Disclosure - Distribution of Depreciation and Amortization by Business Segment [Abstract] Disclosure - Distribution of Depreciation and Amortization by Business Segment [Abstract] Disclosure - Distribution of Depreciation and Amortization by Geographical Area [Abstract] Disclosure - Distribution of Depreciation and Amortization by Geographical Area [Abstract] Disclosure - Distribution of Income from Operations by Geographical Area [Abstract] Disclosure - Distribution of Income from Operations by Geographical Area [Abstract] Disclosure - Distribution of Income from Operations by Segment [Abstract] Disclosure - Distribution of Income from Operations by Segment [Abstract] Disclosure - Distribution of Net Revenue by Business Segment [Abstract] Disclosure - Distribution of Net Revenue by Business Segment [Abstract] Disclosure - Distribution of Net Revenue by Geographical Area [Abstract] Disclosure - Distribution of Net Revenue by Geographical Area [Abstract] Disclosure - Distribution of Property, Plant and Equipment, Net, by Business Segment [Abstract] Disclosure - Distribution of Property, Plant and Equipment, Net, by Business Segment [Abstract] Disclosure - Distribution of Property, Plant and Equipment, Net, by Geographical Area [Abstract] Disclosure - Distribution of Property, Plant and Equipment, Net, by Geographical Area [Abstract] Disclosure - Distribution of Total Assets by Business Segment [Abstract] Disclosure - Distribution of Total Assets by Business Segment [Abstract] Disclosure - Distribution of Total Assets by Geographical Area [Abstract] Disclosure - Distribution of Total Assets by Geographical Area [Abstract] Disclosure - Goodwill [Abstract] Disclosure - Goodwill [Abstract] Disclosure - Goodwill - Additional Information [Abstract] Disclosure - Goodwill - Additional Information [Abstract] Disclosure - Income Tax - Additional Information [Abstract] Disclosure - Income Tax - Additional Information [Abstract] Disclosure - Non-Cash Stock Compensation Expense [Abstract] Disclosure - Non-Cash Stock Compensation Expense [Abstract] Stock Options Disclosure - Reconciliation of the Number of Shares Used in the Computation of Basic and Diluted Net Income Per Ordinary Share [Abstract] Disclosure - Reconciliation of the Number of Shares Used in the Computation of Basic and Diluted Net Income Per Ordinary Share [Abstract] Disclosure - Restricted Share Units (RSUs) Awarded to Certain Key Executives [Abstract] Disclosure - Restricted Share Units (RSUs) Awarded to Certain Key Executives [Abstract] Disclosure - Restructuring Charges [Abstract] Disclosure - Restructuring Charges [Abstract] Disclosure - Restructuring Charges - Additional Information [Abstract] Disclosure - Restructuring Charges - Additional Information [Abstract] Disclosure - Schedule of Movement in Non-Vested Share Options [Abstract] Disclosure - Schedule of Movement in Non-Vested Share Options [Abstract] Disclosure - Schedule of Weighted Average Fair Values and Assumptions Used [Abstract] Disclosure - Schedule of Weighted Average Fair Values and Assumptions Used [Abstract] Disclosure - Segment Information - Additional Information [Abstract] Disclosure - Segment Information - Additional Information [Abstract] Disclosure - Stock Options - Additional Information [Abstract] Disclosure - Stock Options - Additional Information [Abstract] Disclosure - Summarizes the Movement in Non-vested Restricted Share Units [Abstract] Disclosure - Summarizes the Movement in Non-vested Restricted Share Units [Abstract] Disclosure - Summary of Fair Values of the Assets Acquired and the Liabilities Assumed Related to Acquisition of Firecrest [Abstract] Disclosure - Summary of Fair Values of the Assets Acquired and the Liabilities Assumed Related to Acquisition of Firecrest [Abstract] Disclosure - Summary of Fair Values of the Assets Acquired and the Liabilities Assumed Related to Acquisition of Oxford Outcomes [Abstract] Disclosure - Summary of Fair Values of the Assets Acquired and the Liabilities Assumed Related to Acquisition of Oxford Outcomes [Abstract] Disclosure - Summary of Fair Values of the Assets Acquired and the Liabilities Assumed Related to Acquisition of Timaq Medical Imaging [Abstract] Disclosure - Summary of Fair Values of the Assets Acquired and the Liabilities Assumed Related to Acquisition of Timaq Medical Imaging [Abstract] Disclosure - Summary of Stock Option Activity [Abstract] Disclosure - Summary of Stock Option Activity [Abstract] Document - Document and Entity Information [Abstract] Document - Document and Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Year Focus Document Information [Line Items] Document Period End Date Document Type Net income per Ordinary Share: Basic Earnings Per Share, Diluted Diluted Net income per ordinary share Effect of exchange rate movements on cash Employee Individual Employee Non-cash stock compensation expense not yet recognized Unrecognized stock-based compensation expense, weighted average period (years) Employee Stock Plan, 2003 Plan Employee Stock Plan, 2003 Plan Employee Stock Plan, 2008 Plan Employee Stock Plan, 2008 Plan Entities [Table] Entity Central Index Key Entity [Domain] Entity Registrant Name Revenue, Major Customer [Line Items] Equity Component [Domain] Tax benefit from the exercise of share options Finite-Lived Intangible Assets, Net Intangible assets Firecrest Clinical Firecrest Clinical Limited First Quarter 2011 Restructuring Plan Q1 Restructuring Plan Gain (Loss) On Contract Termination And Business Exit Costs Lease termination and exit costs Loss on disposal of property, plant and equipment Loss on disposal of property, plant and equipment Goodwill Closing balance Opening balance Current period acquisitions Good will Acquired Prior Period Prior period acquisitions Goodwill and Intangible Assets Disclosure Goodwill Goodwill [Line Items] Goodwill, Translation Adjustments Foreign exchange movement Group 1 Group 1 Group 2 Group 2 Group 3 Group 3 IRELAND Income before provision for income taxes Income before provision for income taxes Income Loss From Operations Before Restructuring Charges Income from Operations Excluding Restructuring Charges Income Statement [Abstract] Income Statement and Other Comprehensive Income (Loss) Location [Domain] Income Taxes Income taxes receivable Non-current income taxes receivable Provision for income taxes Provision for income taxes Decrease in accounts payable (Increase)/decrease in accounts receivable (Increase)/decrease in accounts receivable Decrease in payments on account Decrease/(increase) in income taxes receivable Decrease/(increase) in income taxes receivable Changes in assets and liabilities: Increase/(decrease) in other current liabilities Increase in other non current assets Increase in other non current assets (Decrease)/increase in other non current liabilities (Increase)/decrease in other receivables (Increase)/decrease in other receivables Increase (Decrease) In Prepaid Expense And Other Current Assets Increase in prepayments and other current assets Increase in prepayments and other current assets Increase in unbilled revenue Increase in unbilled revenue Interest expense Interest expense Interest income Investment Type Investment Type Categorization [Domain] Legal Entity Total Liabilities and Shareholders' Equity Total Liabilities and Shareholders' Equity LIABILITIES AND SHAREHOLDERS' EQUITY Total current liabilities Total current liabilities Current Liabilities: Other Liabilities: Maximum Maximum Percentage Of Outstanding Share Based Payment Award As Percentage Of Shares Outstanding Maximum number of award as percentage of shares outstanding Minimum Net cash provided by financing activities Net cash provided by financing activities Cash flows from financing activities: Net cash (used in)/provided by investing activities Net cash (used in)/provided by investing activities Cash flows from investing activities: Net cash (used in)/provided by operating activities Net cash (used in)/provided by operating activities Cash flows from operating activities: Net income Net income Net Revenue by Business Segment Distribution of Net Revenue by Business Segment Other receivables Notes to Financial Statements [Abstract] Notes to Financial Statements [Abstract] Office Consolidations Office Consolidations Operating Income by Geography Distribution of Income from Operations by Geographical Area Operating Income by Segment Distribution of income From Operations by Business Segment Income from Operations Income from operations Call Options Basis of Presentation Non-current other assets Other Comprehensive Income Foreign Currency Transaction And Translation Adjustment Long Term Funding Tax Tax on currency impact of long term funding Adjustment that results from the process of translating the impact of long-term funding into the functional currency of the reporting entity, net of tax Currency impact of long term funding Currency translation adjustment Unrealized capital gain/(loss) - investments Other liabilities Non-current other liabilities Oxford Outcomes Limited Oxford Outcomes Limited Payment to the former shareholders in respect of certain milestones Payments of Stock Issuance Costs Share issuance costs Purchase of subsidiary undertakings Purchase of subsidiary undertakings Purchase of property, plant and equipment Purchase of property, plant and equipment