Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Operating activities:
Net income (loss)	$ 11,963	$ (1,198)
Adjustment to reconcile net income (loss) to cash provided by (used in) operating activities:
Excess tax benefits from exercise or vesting of equity awards	(6,628)	(5,456)
Deferred income taxes	1,092	(2,088)
Depreciation and amortization	12,648	6,968
Stock-based compensation expense	6,722	5,213
Foreign currency transaction loss	624	3,775
Other	528	716
Change in operating assets and liabilities:
Trade accounts receivable	2,264	(20,076)
Income taxes receivable	(12,006)	(6,772)
Other current assets	7,103	4,750
Accounts payable and accrued expenses	(8,983)	4,971
Deferred revenue	8,250	(281)
Other long-term assets and liabilities	(3,930)	(28)
Cash provided by (used in) operating activities	19,647	(9,506)
Investing activities:
Purchase of marketable securities	(49,689)	(67,228)
Matured and called marketable securities	14,738	27,280
Sale of marketable securities	4,048	162,226
Payments for 2010 acquisition, net of cash acquired		(109,228)
Contingent consideration paid for an acquisition in 2008		(250)
Investment in property and equipment	(5,108)	(4,075)
Cash (used in) provided by investing activities	(36,011)	8,725
Financing activities:
Issuance of common stock for share-based compensation plans	2,164	1,546
Excess tax benefits from exercise or vesting of equity awards	6,628	5,456
Dividend payments to shareholders	(3,365)	(3,330)
Common stock repurchases for tax withholdings for net settlement of equity awards	(5,488)	(4,493)
Common stock repurchases under share repurchase programs	(3,460)	(6,098)
Cash used in financing activities	(3,521)	(6,919)
Effect of exchange rate changes on cash and cash equivalents	361	(3,380)
Net decrease in cash and cash equivalents	(19,524)	(11,080)
Cash and cash equivalents, beginning of period	71,127	63,857
Cash and cash equivalents, end of period	$ 51,603	$ 52,777