CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities:
Net income	$ 1,790	$ 7,004
Adjustment to reconcile net income to cash provided by operating activities:
Excess tax benefits from exercise or vesting of equity awards	(2,225)	(4,011)
Deferred income taxes	(305)	(83)
Depreciation and amortization	8,635	8,228
Stock-based compensation expense	5,838	4,400
Foreign currency transaction loss	460	377
Other	753	414
Change in operating assets and liabilities:
Trade accounts receivable	5,795	(15,790)
Income taxes receivable and other current assets	(942)	1,547
Accounts payable and accrued expenses	(14,203)	(2,761)
Deferred revenue	2,037	18,395
Other long-term assets and liabilities	4,894	(500)
Cash provided by operating activities	12,527	17,220
Investing activities:
Purchase of marketable securities	(11,760)	(25,361)
Matured and called marketable securities	14,207	7,738
Sale of marketable securities		1,047
Investment in property and equipment	(14,949)	(3,563)
Cash used in investing activities	(12,502)	(20,139)
Financing activities:
Issuance of common stock for share-based compensation plans	707	1,707
Excess tax benefits from exercise or vesting of equity awards	2,225	4,011
Dividend payments to shareholders	(2,272)	(2,238)
Common stock repurchases for tax withholdings for net settlement of equity awards	(2,851)	(3,569)
Common stock repurchases under share repurchase programs	(2,526)	(2,084)
Cash used in financing activities	(4,717)	(2,173)
Effect of exchange rate on cash and cash equivalents	(834)	948
Net decrease in cash and cash equivalents	(5,526)	(4,144)
Cash and cash equivalents, beginning of period	60,353	71,127
Cash and cash equivalents, end of period	$ 54,827	$ 66,983