ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Total assets Assets Goodwill Goodwill, Beginning Balance Goodwill, Ending Balance Goodwill Deferred income taxes Deferred Tax Assets, Net, Noncurrent Total current assets Assets, Current Accounts receivable, net Accounts receivable, net Accounts Receivable, Net, Current Equipment and leasehold improvements, net Equipment and leasehold improvements, net Total long-lived assets Property, Plant and Equipment, Net LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities and Stockholders' Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Shareholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Total liabilities Liabilities Other noncurrent liabilities Other Liabilities, Noncurrent Total current liabilities Liabilities, Current Deferred revenue Deferred Revenue, Current Accrued expenses and other current liabilities Accrued expenses and other current liabilities Accrued expenses and other current liabilities. Total liabilities and shareholders' equity Liabilities and Stockholders' Equity Retained earnings Retained Earnings (Accumulated Deficit) Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive (loss) income Treasury Stock, Value Treasury stock, at cost - 89,236 and 72,948 ordinary shares in 2012 and 2011, respectively Common Stock, Value, Issued Ordinary Shares - Authorized 700,000 shares; GBP 0.01 par value; 251,690 and 247,640 issued and 162,454 and 174,692 outstanding, in 2012 and 2011, respectively Preferred Stock, Value, Issued Preferred Shares - Authorized 25,000 shares; GBP 0.01 par value; 0 shares issued and outstanding Cash and cash equivalents Cash and cash equivalents at beginning of year Cash and cash equivalents at end of year Cash and Cash Equivalents, at Carrying Value Treasury stock, at cost, ordinary shares Treasury Stock, Shares Common Stock, Shares, Outstanding Ending balance, Shares Beginning balance, Shares Ordinary Shares, outstanding Ordinary Shares, issued Common Stock, Shares, Issued Ordinary Shares, authorized Common Stock, Shares Authorized Ordinary Shares, par value Common Stock, Par or Stated Value Per Share Preferred Shares, outstanding Preferred Stock, Shares Outstanding Preferred Shares, issued Preferred Stock, Shares Issued Preferred Shares, authorized Preferred Stock, Shares Authorized Preferred Shares, par value Preferred Stock, Par or Stated Value Per Share Revenue: Revenue and Customer Information Revenues [Abstract] Operating expenses: Operating Expenses [Abstract] Diluted weighted average number of shares outstanding Denominator for dilutive earnings per share - adjusted weighted average shares and assumed conversions Weighted Average Number of Shares Outstanding, Diluted Basic weighted average number of shares outstanding Denominator for basic earnings per share - weighted average number of shares outstanding Weighted Average Number of Shares Outstanding, Basic Diluted earnings per share Earnings Per Share, Diluted Basic earnings per share Earnings Per Share, Basic Income taxes Income Tax Expense (Benefit) Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Cumulative Effects of Changes in Accounting Principles, Noncontrolling Interest Operating income Operating income Operating Income (Loss) Amortization of purchased intangible assets and other Amortization of Intangible Assets Selling, general and administrative Selling, General and Administrative Expense Consolidated Statements of Cash Flows [Abstract] Cash Flow from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Reconciliation of net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Net changes in operating assets and liabilities, net of amounts acquired: Increase (Decrease) in Operating Capital [Abstract] Cash and Cash Equivalents, Period Increase (Decrease) Net increase (decrease) in cash and cash equivalents Cash Flow from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Supplementary Cash Flow Information Supplemental Cash Flow Information [Abstract] Proceeds from employee stock options exercised Proceeds from Stock Options Exercised Cash Flow from Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Payments for purchase of equipment and leasehold improvements, net Payments to Acquire Property, Plant, and Equipment Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Deferred revenue Increase (Decrease) in Deferred Revenue Excess tax benefit from equity-based compensation Excess Tax Benefit from Share-based Compensation, Operating Activities Deferred income taxes Deferred Deferred Income Tax Expense (Benefit) Equity-based compensation expense Equity-based compensation expense related to employees Share-based Compensation Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Acquisitions Business Combination Disclosure [Text Block] Equipment and Leasehold Improvements, Net Property, Plant and Equipment Disclosure [Text Block] Goodwill and Intangible Assets, Net Goodwill and Intangible Assets Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] Financing Arrangements Debt Disclosure [Text Block] Noncurrent Liabilities And Other [Abstract] Noncurrent liabilities and other Noncurrent liabilities and other. Other Noncurrent Liabilities Other Liabilities Disclosure [Text Block] Contingencies Commitments and Contingencies Disclosure [Text Block] Intangible assets, net Total Finite-Lived Intangible Assets, Net Total shareholders' equity Beginning balance Ending balance Stockholders' Equity Attributable to Parent Accounts payable Accounts Payable, Current Deferred income taxes and taxes payable Deferred income taxes and taxes payable Deferred income taxes and taxes payable includes the current portion of deferred tax liabilities, which result from applying the applicable tax rate to net taxable temporary differences pertaining to each jurisdiction to which the entity is obligated to pay income tax. A current taxable temporary difference is a difference between the tax basis and the carrying amount of a current asset or liability in the financial statements prepared in accordance with generally accepted accounting principles. In a classified statement of financial position, an enterprise shall separate deferred tax liabilities and assets into a current amount and a noncurrent amount. Deferred tax liabilities and assets shall be classified as current or noncurrent based on the classification of the related asset or liability for financial reporting. A deferred tax liability or asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to carry forwards, shall be classified according to the expected reversal date of the temporary difference. In addition, it also includes the carrying value as of the balance sheet date of obligations incurred and payable for statutory income taxes. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer). Net income Net income Net Income (Loss) Attributable to Parent Interest and Income Taxes Paid [Abstract] Interest and Income Taxes Paid Interest and income taxes paid. Cash Paid For [Abstract] Cash paid for: Cash paid for. Interest Interest Paid, Net Income taxes, net of refunds Income Taxes Paid, Net Repurchase of shares Payments for Repurchase of Common Stock Proceeds from sale of short-term interest-bearing investments Proceeds from Sale of Available-for-sale Securities Purchase of short-term interest-bearing investments Payments to Acquire Available-for-sale Securities Accounts payable, accrued expenses and other current liabilities Accounts payable, accrued expenses and accrued personnel The net change during the reporting period in the value of this group of liabilities within the working capital section. Prepaid expenses and other current assets Increase (Decrease) in Prepaid, Deferred Expense and Other Assets Issuance of restricted stock, net of forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Issuance of restricted stock, net of forfeitures, Shares Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Stock Issued During Period, Shares, Stock Options Exercised Number of Option, Exercised Employee stock options exercised, Shares Employee stock options exercised Stock Issued During Period, Value, Stock Options Exercised Comprehensive income Comprehensive Income, Net of Tax, Attributable to Parent Interest and other expense, net Other Income and Other Expense Disclosure [Text Block] Employee Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Earnings Per Share Earnings Per Share [Text Block] Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Selected Quarterly Results of Operations (Unaudited) Quarterly Financial Information [Text Block] Earnings Per Share [Abstract] Consolidated Balance Sheets [Abstract] Ordinary Shares Ordinary Shares [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Treasury Stock Treasury Stock [Member] Accumulated Other Comprehensive Income (Loss) [Member] Accumulated Other Comprehensive (Loss) Income Retained Earnings Retained Earnings [Member] Other noncurrent assets Other noncurrent assets Other Assets, Noncurrent License Revenue License Aggregate license revenue, in the normal course of business, during the period after deducting allowances and discounts. Service Sales Revenue, Services, Net Repurchase of shares Treasury Stock, Value, Acquired, Cost Method Entity Registrant Name Entity Central Index Key Document Type Document Period End Date Amendment Flag Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Statement [Table] Statement [Line Items] Consolidated Statements of Income [Abstract] Cost of service Cost of Services Nonoperating Income (Expense) Interest and other expense, net Total Consolidated Statements of Changes in Shareholders' Equity [Abstract] Statement, Equity Components [Axis] Equity Component [Domain] Parent [Member] Short-term interest-bearing investments Available-for-sale Securities, Debt Securities, Current Change In Accounts Receivable Accounts receivable, net The increase (decrease) during the reporting period in amount due within one year (or one business cycle) from customers for the credit sale of goods and services. Entity Common Stock Shares Outstanding Provision (benefit) for income taxes Income Tax Expense Benefit [Abstract] Employee equity-based compensation pre-tax expense Share Based Compensation [Abstract] Loss (gain) from short-term interest-bearing investments Loss (gain) from short-term interest-bearing investments This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as available-for-sale. Additionally, this item includes losses recognized for other than temporary impairments. Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Comprehensive income: Comprehensive Income, Net of Tax, Attributable to Parent [Abstract] Unrealized Loss Gain On Derivatives Net Of Tax Unrealized (loss) gain on derivatives, net of tax Balance of unrealized (loss) gain from derivative instrument designated and qualifying as the effective portion of cash flow hedges, net of tax effect. Unrealized Loss Gain On Defined Benefit Plan Assets Net Of Tax Unrealized (loss) on defined benefit plan, net of tax Balance of unrealized (loss) gain on defined benefit plan assets, net of tax. Valuation and Qualifying Accounts Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Additional paid-in capital Additional Paid in Capital Research and development Research and Development Expense, Software (Excluding Acquired in Process Cost) Fair Value Measurements Fair Value Measurement Inputs Disclosure [Text Block] Finite-Lived Intangible Assets, Major Class Name [Domain] Less-allowances Allowance for Doubtful Accounts Receivable, Current Accounts receivable, net Accounts Receivable, Net, Current [Abstract] Accounts receivable - billed Accounts Receivable, Gross, Current Equipment and leasehold improvements, gross Property, Plant and Equipment, Gross Less accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Gross Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Components of equipment and leasehold improvements, net Property, Plant and Equipment [Text Block] Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment, Type [Domain] Leaseholds improvements [Member] Leaseholds And Leasehold Improvements [Member] Machinery and Equipment [Member] Computer Equipment [Member] Computer Equipment [Member] Components of equipment and leasehold improvements, net Property, Plant and Equipment, Net, by Type [Abstract] Finite-Lived Intangible Assets by Major Class [Axis] Estimated future amortization expense Finite-Lived Intangible Assets, Future Amortization Expense [Abstract] Details of total goodwill Schedule of Goodwill [Text Block] Core Technology [Member] Core technology [Member] Core technology. Customer Arrangements [Member] Customer arrangements [Member] Customer arrangements. Intellectual Property Rights and Purchased Computer Software [Member] Intellectual property rights and purchased computer software [Member] Intellectual property rights and purchased computer software. Other noncurrent assets Other Assets, Noncurrent Disclosure [Abstract] Amortization Of Intangible Assets [Abstract] Amortization expense on intangible assets Amortization of intangible assets. Depreciation expense Depreciation Impairment of goodwill Goodwill, Impairment Loss Deferred costs Other Deferred Costs, Net Document Fiscal Year Focus Document Fiscal Period Focus Document and Entity Information [Abstract] Document And Entity Information Abstract. Amortization Of Intangible Assets Included In Cost Of Services Cost of service Amortization of intangible assets included in cost of services. Other Assets Miscellaneous Non Current Other Carrying amount as of the balance sheet date of noncurrent assets which have not been itemized or categorized in the footnotes to the financial statements and are a component of Other Assets, Noncurrent (Other Assets Noncurrent). Noncurrent assets are expected to be realized or consumed after one year (or the normal operating cycle, if longer). Furniture, Fixtures and Other [Member] Furniture And Fixtures Member [Member] Other Goodwill, Period Increase (Decrease) Consolidation Consolidation, [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, [Policy Text Block] Investments Investment, [Policy Text Block] Revenue Recognition Revenue Recognition, [Policy Text Block] Derivatives and Hedging Derivatives, [Policy Text Block] Income Taxes Income Tax, [Policy Text Block] Equity-Based Compensation Compensation Related Costs, [Policy Text Block] Earnings Per Share Earnings Per Share, [Policy Text Block] Treasury Stock [Policy Text Block] Treasury Stock Treasury stock. Research and Development Research, Development, and Computer Software, [Policy Text Block] Share Based Compensation Arrangement By Share Based Payment Award Options [Abstract] Summary of option activity Tabular disclosure of the number and weighted-average exercise prices (or conversion ratios) for share options (or share units) that were outstanding at the beginning and end of the year, vested and expected to vest, exercisable or convertible at the end of the year, and the number of share options or share units that were granted, exercised or converted, forfeited, and expired during the year. Number of Options, Outstanding, Beginning Balance Number of Options, Outstanding, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Number of Options, Granted Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period Number of Options, Forfeited Number of Options, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Weighted Average Exercise Price, Outstanding, Beginning Balance Weighted Average Exercise Price, Outstanding, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Weighted Average Exercise Price, Outstanding, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested [Abstract] Summary of Restricted Stock Units activity Disclosure of the number and weighted-average grant date fair value for restricted stock and restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock and restricted stock units that were granted, vested, or forfeited during the year. Number of Restricted Stock, Beginning Balance Number of Restricted Stock, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Number of Restricted Stock, Granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Number of Restricted Stock, Vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Number of Restricted Stock, Forfeited Restricted stock, Weighted Average Grant Date Fair Value, Beginning Balance Restricted stock, Weighted Average Grant Date Fair Value, Ending Balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Restricted stock, Weighted Average Grant Date Fair Value, Granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Restricted stock, Weighted Average Grant Date Fair Value, Vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Available-for-sale Securities [Abstract] Available-for-sale securities: Interest-bearing investments in available-for-sale securities Total income tax benefit recognized for stock-based compensation Employee Service Share-based Compensation, Tax Benefit from Compensation Expense