Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Operating activities:
Net income	$ 4,057	$ 4,731
Adjustment to reconcile net income to cash (used in) provided by operating activities:
Excess tax benefits from exercise or vesting of equity awards	(1,622)	(1,077)
Deferred income taxes	214	142
Depreciation and amortization	4,525	4,011
Stock-based compensation expense	2,852	2,535
Foreign currency transaction loss	395	66
Other	382	87
Change in operating assets and liabilities:
Trade accounts receivable	(8,130)	(28,221)
Income taxes receivable and other current assets	(156)	(399)
Accounts payable and accrued expenses	(25,800)	(7,011)
Deferred revenue	4,696	17,223
Other long-term assets and liabilities	813	(202)
Cash used in operating activities	(17,774)	(8,115)
Investing activities:
Purchase of marketable securities	(10,479)	(9,026)
Matured and called marketable securities	6,780	4,738
Investment in property and equipment	(4,267)	(1,090)
Cash used in investing activities	(7,966)	(5,378)
Financing activities:
Issuance of common stock for share-based compensation plans	293	356
Excess tax benefits from exercise or vesting of equity awards	1,622	1,077
Dividend payments to shareholders	(1,132)	(1,118)
Common stock repurchases for tax withholdings for net settlement of equity awards	(2,072)	(1,517)
Common stock repurchases under share repurchase programs	(814)	(1,032)
Cash used in financing activities	(2,103)	(2,234)
Effect of exchange rate on cash and cash equivalents	963	952
Net decrease in cash and cash equivalents	(26,880)	(14,775)
Cash and cash equivalents, beginning of period	60,353	71,127
Cash and cash equivalents, end of period	$ 33,473	$ 56,352