Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 42,282	$ 22,429	$ 43,333
Adjustments to reconcile net income to net cash provided by operating activities-
Depreciation	25,435	22,428	20,069
Amortization	42,173	19,438	14,325
Amortization of original issue discount	5,206	6,893	8,382
Gain on short-term investments and other	(60)	(129)	(600)
(Gain) loss on repurchase of convertible debt securities		12,714	(1,468)
Loss on foreign currency transactions		14,023
Deferred income taxes	3,977	3,275	18,492
Excess tax benefit of stock-based compensation awards	(828)	(1,147)	(145)
Stock-based employee compensation	12,152	12,338	12,632
Changes in operating assets and liabilities, net of acquired amounts:
Trade accounts and other receivables, net	(31,552)	(4,295)	12,550
Other current and non-current assets	3,210	(509)	(1,053)
Income taxes payable/receivable	7,573	(9,971)	(7,927)
Trade accounts payable and accrued liabilities	(20,074)	22,288	9,311
Deferred revenue	(28,535)	1,534	25,158
Net cash provided by operating activities	60,959	121,309	153,059
Cash flows from investing activities:
Purchases of property and equipment	(22,197)	(14,277)	(40,313)
Purchases of short-term investments	(37,798)	(64,583)	(57,036)
Proceeds from sale/maturity of short-term investments	43,450	81,900	79,700
Net proceeds from foreign currency option		582
Payments for acquisition-related foreign currency transactions		(14,605)
Acquisition of businesses, net of cash acquired		(259,502)	(6,738)
Acquisition of and investments in client contracts	(9,133)	(4,797)	(16,423)
Net cash used in investing activities	(25,678)	(275,282)	(40,810)
Cash flows from financing activities:
Proceeds from issuance of common stock	1,486	1,405	1,477
Repurchase of common stock	(14,365)	(34,030)	(6,562)
Payments on acquired equipment financing	(1,587)	(1,157)	(992)
Proceeds from long-term debt		385,000
Payments on long-term debt	(70,149)	(150,958)	(26,714)
Payments of deferred financing costs	(205)	(14,999)
Excess tax benefit of stock-based compensation awards	828	1,147	145
Net cash provided by (used in) financing activities	(83,992)	186,408	(32,646)
Effect of exchange rate fluctuations on cash	(2,414)	1,934
Net increase (decrease) in cash and cash equivalents	(51,125)	34,369	79,603
Cash and cash equivalents, beginning of period	197,858	163,489	83,886
Cash and cash equivalents, end of period	146,733	197,858	163,489
Supplemental disclosures of cash flow information:
Interest	13,921	4,345	4,715
Income taxes	$ 22,836	$ 17,869	$ 9,463