Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 7,963	$ 10,950
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	4,662	4,248
Amortization of intangible assets	1,113	1,200
Net (gains) losses from investments	102	(143)
Deferred income taxes	(5,376)	(4,291)
Stock-based compensation	2,728	2,512
Amortization of premium on investments	1,265	1,460
Foreign currency (gains) losses	(34)	239
Changes in assets and liabilities, net of acquisitions
Accounts receivable	34,564	33,661
Deferred commissions	560	2,647
Prepaid expenses and other current assets	4,619	234
Accounts payable	343	(244)
Accrued expenses and other liabilities	(2,323)	(130)
Deferred revenue	(12,955)	(12,944)
Net cash provided by operating activities	37,231	39,399
Cash flows from investing activities:
Purchases of property and equipment	(1,267)	(3,245)
Purchases of marketable investments	(39,636)	(65,713)
Proceeds from sales and maturities of marketable investments	49,143	52,845
Change in restricted cash		946
Other investing activity	248	124
Net cash provided by (used in) investing activities	8,488	(15,043)
Cash flows from financing activities:
Dividends paid on common stock	(6,414)	(6,356)
Repurchases of common stock	(92,083)	(17,052)
Proceeds from issuance of common stock under employee equity incentive plans	10,513	6,634
Excess tax benefits from stock-based compensation	638	332
Payment of deferred acquisition consideration	(900)	(739)
Net cash used in financing activities	(88,246)	(17,181)
Effect of exchange rate changes on cash and cash equivalents	(1,200)	(559)
Net increase (decrease) in cash and cash equivalents	(43,727)	6,616
Cash and cash equivalents, beginning of period	98,810	81,047
Cash and cash equivalents, end of period	$ 55,083	$ 87,663