Condensed Consolidated Statements of Cash Flows - Unaudited (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 26,970	$ 23,676
Adjustments to reconcile net income to net cash provided by operating activities-
Depreciation	9,770	11,711
Amortization	18,757	21,096
Amortization of original issue discount	2,624	2,429
(Gain) loss on short-term investments and other	998	(23)
Deferred income taxes	6,533	(6,342)
Excess tax benefit of stock-based compensation awards	(542)	(288)
Stock-based employee compensation	7,518	6,529
Changes in operating assets and liabilities:
Trade accounts and other receivables, net	7,848	18,117
Other current and non-current assets	(5,833)	(3,951)
Income taxes payable/receivable	(4,178)	1,842
Trade accounts payable and accrued liabilities	(16,763)	(3,196)
Deferred revenue	7,644	13,168
Net cash provided by operating activities	61,346	84,768
Cash flows from investing activities:
Purchases of property and equipment	(11,125)	(13,550)
Purchases of short-term investments	(98,883)	(24,779)
Proceeds from sale/maturity of short-term investments	41,361	16,800
Acquisition of and investments in client contracts	(3,808)	(2,948)
Net cash used in investing activities	(72,455)	(24,477)
Cash flows from financing activities:
Proceeds from issuance of common stock	921	1,007
Repurchase of common stock	(14,883)	(13,541)
Payments on acquired equipment financing	(1,894)	(663)
Payments on long-term debt	(7,500)	(17,000)
Excess tax benefit of stock-based compensation awards	542	288
Net cash used in financing activities	(22,814)	(29,909)
Effect of exchange rate fluctuations on cash	(2,975)	(1,152)
Net increase in cash and cash equivalents	(36,898)	29,230
Cash and cash equivalents, beginning of period	133,747	146,733
Cash and cash equivalents, end of period	96,849	175,963
Net cash paid during the period for-
Interest	4,770	6,738
Income taxes	2,306	23,115
Non-cash financing activity -
Cash dividends payable	$ 5,069