Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Operating activities:
Net income (loss)	$ 7,004	$ (4,337)
Adjustment to reconcile net income (loss) to cash provided by (used in) operating activities:
Excess tax benefits from exercise or vesting of equity awards	(4,011)	(5,529)
Deferred income taxes	(83)	(321)
Depreciation and amortization	8,228	3,686
Stock-based compensation expense	4,400	3,632
Foreign currency transaction (gain) loss	377	4,011
Other	414	707
Change in operating assets and liabilities:
Trade accounts receivable	(15,790)	(11,756)
Income taxes receivable	(3,703)	(6,651)
Other current assets	5,250	7,046
Accounts payable and accrued expenses	(2,761)	2,970
Deferred revenue	18,395	6,025
Other long-term assets and liabilities	(500)	(5,801)
Cash provided by (used in) operating activities	17,220	(6,318)
Investing activities:
Purchase of marketable securities	(25,361)	(61,156)
Matured and called marketable securities	7,738	26,280
Sale of marketable securities	1,047	162,242
Payments for 2010 acquisition, net of cash acquired		(108,991)
Contingent consideration paid for an acquisition in 2008		(250)
Investment in property and equipment	(3,563)	(3,497)
Cash (used in) provided by investing activities	(20,139)	14,628
Financing activities:
Issuance of common stock for share-based compensation plans	1,707	1,198
Excess tax benefits from exercise or vesting of equity awards	4,011	5,529
Dividend payments to shareholders	(2,238)	(2,216)
Common stock repurchases for tax withholdings for net settlement of equity awards	(3,569)	(4,212)
Common stock repurchases under share repurchase programs	(2,084)	(3,330)
Cash used in financing activities	(2,173)	(3,031)
Effect of exchange rate changes on cash and cash equivalents	948	(6,103)
Net decrease in cash and cash equivalents	(4,144)	(824)
Cash and cash equivalents, beginning of period	71,127	63,857
Cash and cash equivalents, end of period	$ 66,983	$ 63,033