Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Cash flows from operating activities:
Net income	$ 31,424	$ 61,503
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	40,720	32,493
Compensation expense associated with stock-based payments	18,420	15,526
Unrealized foreign currency losses (gains), net	4,022	(196)
Deferred income taxes	(75)	5,237
Excess tax benefit related to stock-based compensation	(2,055)	(2,211)
Other non-cash adjustments, net	1,043	1,011
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	28,204	15,099
Prepaid expenses and other current assets	(2,103)	3,371
Other assets	1,471	1,486
Accounts payable	1,993	1,379
Accrued compensation	(11,849)	(4,135)
Other accrued expenses	(1,608)	(1,952)
Income taxes payable	19,060	(7,208)
Deferred revenue	12,285	3,161
Other liabilities	(3,419)	(1,513)
Net cash provided by operating activities	137,533	123,051
Cash flows from investing activities:
Purchases of property and equipment	(20,959)	(11,265)
Cash paid for acquisitions, net of cash acquired	(89,519)	(57,058)
Cash paid for software rights		(2,229)
Change in restricted cash	(5,871)	767
Purchases of cost method investments	(29,586)
Purchases of investment securities	(8,797)	(216,193)
Sales and maturities of investment securities	81,126	139,322
Notes receivable from a cost method investee		(2,000)
Cash paid for intellectual property	(1,559)
Change in notes receivable	(850)
Net cash used in investing activities	(76,015)	(148,656)
Cash flows from financing activities:
Repayment of loans payable	(375)	(32,466)
Repurchase of common stock	(252,540)	(37,373)
Repayment of capital lease obligations	(191)	(190)
Cash paid for line of credit fees	(500)
Proceeds from the exercise of stock options	29,206	37,271
Excess tax benefit related to stock-based compensation	2,055	2,211
Net cash used in financing activities	(222,345)	(30,547)
Effect of exchange rate changes on cash and cash equivalents	(1,908)	478
Net decrease in cash and cash equivalents	(162,735)	(55,674)
Cash and cash equivalents, beginning of period	356,533	292,940
Cash and cash equivalents, end of period	193,798	237,266
Supplemental disclosures of consolidated cash flow information:
Cash paid for interest	2,348	2,557
Cash (received) paid for income taxes	$ (10,693)	$ 23,540