Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net income	$ 11,806	$ 11,494
Adjustments to reconcile net income to net cash provided by (used in) operating activities-
Depreciation	5,837	6,247
Amortization	10,302	10,146
Amortization of original issue discount	1,203	1,449
Gain on short-term investments and other	(8)	(13)
Deferred income taxes	(3,111)	7,904
Excess tax benefit of stock-based compensation awards	(286)	(814)
Stock-based employee compensation	3,147	3,274
Changes in operating assets and liabilities:
Trade accounts and other receivables, net	13,252	4,085
Other current and non-current assets	(1,152)	(3,229)
Income taxes payable/receivable	14,614	(3,443)
Trade accounts payable and accrued liabilities	(14,045)	(24,301)
Deferred revenue	6,630	(14,688)
Net cash provided by (used in) operating activities	48,189	(1,889)
Cash flows from investing activities:
Purchases of property and equipment	(2,318)	(4,250)
Purchases of short-term investments	(10,142)	(12,680)
Proceeds from sale/maturity of short-term investments	12,100	15,000
Acquisition of and investments in client contracts	(1,693)	(2,383)
Net cash used in investing activities	(2,053)	(4,313)
Cash flows from financing activities:
Proceeds from issuance of common stock	556	335
Repurchase of common stock	(8,078)	(4,027)
Payments on acquired equipment financing	(417)	(427)
Payments on long-term debt	(7,000)	(37,500)
Payments of deferred financing costs		(205)
Excess tax benefit of stock-based compensation awards	286	814
Net cash used in financing activities	(14,653)	(41,010)
Effect of exchange rate fluctuations on cash	192	1,339
Net increase (decrease) in cash and cash equivalents	31,675	(45,873)
Cash and cash equivalents, beginning of period	146,733	197,858
Cash and cash equivalents, end of period	178,408	151,985
Supplemental disclosures of cash flow information:
Interest	4,473	4,581
Income taxes	$ 242	$ 2,453