Condensed Consolidated Statements of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Operating activities
Net income	$ 5,287	$ 2,603
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,506	5,311
Stock-based compensation	8,805	8,063
Gain on disposal of property and equipment	(7)	(45)
Share of loss of equity method investee	119
Changes in assets and liabilities:
Accounts receivable	(8,340)	(1,188)
Prepaid expenses and other assets	(32)	(1,052)
Accounts payable	(1,246)	1,235
Accrued compensation	1,081	(29)
Accrued expenses and other liabilities	588	(211)
Deferred revenues	(1,033)	(553)
Net cash provided by operating activities	10,728	14,134
Investing activities
Purchases of property and equipment	(4,541)	(2,809)
Purchases of marketable securities	(89,482)	(60,627)
Maturities of marketable securities	85,972	62,889
Purchase of other investments	(2,300)
Net cash used in investing activities	(10,351)	(547)
Financing activities
Principal payments of notes payable		(182)
Proceeds from issuance of common stock under stock plans	6,721	1,129
Net cash provided by financing activities	6,721	947
Net increase in cash and cash equivalents	7,098	14,534
Cash and cash equivalents at the beginning of the period	31,183	9,082
Cash and cash equivalents at the end of the period	38,281	23,616
Cash paid for interest		12
Cash paid for income taxes	$ 73	$ 587