Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net income	$ 21,323	$ 14,113
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	6,510	3,335
Amortization of intangible assets	1,779	1,898
Net gains from investments	(290)	(648)
Deferred income taxes	(9,851)	5,820
Stock-based compensation	3,921	3,093
Amortization of premium on investments	2,144	2,523
Foreign currency losses	382	1,202
Changes in assets and liabilities, net of acquisitions
Accounts receivable	37,196	31,273
Deferred commissions	4,127	3,193
Prepaid expenses and other current assets	3,929	926
Accounts payable	(318)	(1,732)
Accrued expenses and other liabilities	(4,327)	(3,428)
Deferred revenue	(23,302)	(15,061)
Net cash provided by operating activities	43,223	46,507
Cash flows from investing activities:
Acquisitions		(7,164)
Purchases of property and equipment	(4,845)	(33,194)
Purchases of marketable investments	(85,211)	(81,008)
Proceeds from sales and maturities of marketable investments	73,055	58,888
Change in restricted cash	946	13,272
Other investing activity	66	307
Net cash used in investing activities	(15,989)	(48,899)
Cash flows from financing activities:
Dividends paid on common stock	(9,481)
Repurchases of common stock	(26,187)	(18,405)
Proceeds from issuance of common stock under employee equity incentive plans	8,538	7,017
Excess tax benefits from stock-based compensation	401	432
Payment of deferred acquisition consideration	(864)
Net cash used in financing activities	(27,593)	(10,956)
Effect of exchange rate changes on cash and cash equivalents	212	7
Net decrease in cash and cash equivalents	(147)	(13,341)
Cash and cash equivalents, beginning of period	81,047	86,927
Cash and cash equivalents, end of period	$ 80,900	$ 73,586