CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating activities:
Net income	$ 1,459	$ 11,963
Adjustment to reconcile net income to cash provided by operating activities:
Excess tax benefits from exercise or vesting of equity awards	(3,161)	(6,628)
Deferred income taxes	(511)	1,092
Depreciation and amortization	13,986	12,648
Stock-based compensation expense	8,622	6,722
Foreign currency transaction loss	785	624
Other non-cash items	4,604	528
Change in operating assets and liabilities:
Trade accounts receivable	17,769	2,264
Income taxes receivable and other current assets	(1,471)	(4,903)
Accounts payable and accrued expenses	(20,976)	(8,983)
Deferred revenue	2,747	8,250
Other long-term assets and liabilities	5,231	(3,930)
Cash provided by operating activities	29,084	19,647
Investing activities:
Purchase of marketable securities	(13,336)	(49,689)
Matured and called marketable securities	18,465	14,738
Sale of marketable securities		4,048
Investment in property and equipment	(21,875)	(5,108)
Cash used in investing activities	(16,746)	(36,011)
Financing activities:
Issuance of common stock for share-based compensation plans	753	2,164
Excess tax benefits from exercise or vesting of equity awards	3,161	6,628
Dividend payments to shareholders	(3,404)	(3,365)
Common stock repurchases for tax withholdings for net settlement of equity awards	(3,650)	(5,488)
Common stock repurchases under share repurchase programs	(3,910)	(3,460)
Cash used in financing activities	(7,050)	(3,521)
Effect of exchange rate on cash and cash equivalents	596	361
Net increase (decrease) in cash and cash equivalents	5,884	(19,524)
Cash and cash equivalents, beginning of period	60,353	71,127
Cash and cash equivalents, end of period	$ 66,237	$ 51,603