Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows from operating activities:
Net income	$ 9,958	$ 33,003
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	25,798	21,779
Compensation expense associated with stock-based payments	12,906	9,171
Deferred income taxes	(83)	5,025
Excess tax benefit related to stock-based compensation	(1,869)	(1,318)
Other non-cash adjustments, net	924	683
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	49,701	33,258
Prepaid expenses and other current assets	1,178	4,230
Other assets	2,267	1,955
Accounts payable	4,100	(388)
Accrued compensation	(6,976)	(7,115)
Other accrued expenses	2,306	(4,051)
Income taxes payable	19,971	8,719
Deferred revenue	(2,944)	(3,089)
Other liabilities	(3,271)	(1,282)
Net cash provided by operating activities	113,966	100,580
Cash flows from investing activities:
Purchases of property and equipment	(17,314)	(6,831)
Cash paid for acquisitions, net of cash acquired	(89,429)	(981)
Change in restricted cash	(7,903)	874
Purchases of cost method investments	(27,234)
Purchases of investment securities	(5,136)	(132,283)
Sales and maturities of investment securities	63,562	107,246
Notes receivable from a cost method investee		(2,000)
Cash paid for intellectual property	(1,500)
Change in notes receivable	(750)
Net cash used in investing activities	(85,704)	(33,975)
Cash flows from financing activities:
Repayment of loans payable	(238)	(32,339)
Repurchase of common stock	(205,745)	(37,373)
Repayment of capital lease obligations	(69)	(133)
Cash paid for line of credit fees	(500)
Proceeds from the exercise of stock options	24,925	23,297
Excess tax benefit related to stock-based compensation	1,869	1,318
Net cash used in financing activities	(179,758)	(45,230)
Effect of exchange rate changes on cash and cash equivalents	(943)	1,833
Net (decrease) increase in cash and cash equivalents	(152,439)	23,208
Cash and cash equivalents, beginning of period	356,533	292,940
Cash and cash equivalents, end of period	204,094	316,148
Supplemental disclosures of consolidated cash flow information:
Cash paid for interest	1,570	1,715
Cash (received) paid for income taxes	$ (14,261)	$ 2,319