Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 10,865us-gaap_NetIncomeLoss	$ 13,024us-gaap_NetIncomeLoss	$ 26,296us-gaap_NetIncomeLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	9,325us-gaap_Depreciation	9,268us-gaap_Depreciation	8,921us-gaap_Depreciation
Amortization of intangible assets	2,171us-gaap_AmortizationOfIntangibleAssets	2,230us-gaap_AmortizationOfIntangibleAssets	2,445us-gaap_AmortizationOfIntangibleAssets
Net (gains) losses from investments	288us-gaap_GainLossOnInvestments	2,433us-gaap_GainLossOnInvestments	(94)us-gaap_GainLossOnInvestments
Deferred income taxes	(7,526)us-gaap_DeferredIncomeTaxExpenseBenefit	(4,529)us-gaap_DeferredIncomeTaxExpenseBenefit	(10,967)us-gaap_DeferredIncomeTaxExpenseBenefit
Stock-based compensation	7,444us-gaap_ShareBasedCompensation	6,051us-gaap_ShareBasedCompensation	5,397us-gaap_ShareBasedCompensation
Amortization of premium on investments	1,273	2,261	2,803
Foreign currency losses	141	385	405
Changes in assets and liabilities
Accounts receivable	9,140	(2,930)	6,959
Deferred commissions	(815)	(3,529)	2,607
Prepaid expenses and other current assets	620	607	6,610
Accounts payable	(82)	222	(490)
Accrued expenses and other liabilities	2,171	3,547	549
Deferred revenue	(6,220)	1,673	1,706
Net cash provided by operating activities	28,795	30,713	53,147
Cash flows from investing activities:
Purchases of property and equipment	(1,503)	(3,127)	(5,103)
Purchases of marketable investments	(35,386)	(44,667)	(91,421)
Proceeds from sales and maturities of marketable investments	60,112	105,086	91,335
Change in restricted cash			946
Other investing activity	1,542	264	167
Net cash provided by (used in) investing activities	24,765	57,556	(4,076)
Cash flows from financing activities:
Dividends paid on common stock	(11,962)us-gaap_PaymentsOfDividendsCommonStock	(12,394)us-gaap_PaymentsOfDividendsCommonStock	(12,588)us-gaap_PaymentsOfDividendsCommonStock
Repurchases of common stock	(73,166)	(118,210)	(29,843)
Proceeds from issuance of common stock under employee equity incentive plans	8,969	17,387	11,215
Excess tax benefits from stock-based compensation	244	737	345
Payment of deferred acquisition consideration		(900)	(864)
Net cash used in financing activities	(75,915)	(113,380)	(31,735)
Effect of exchange rate changes on cash and cash equivalents	(2,127)	433	427
Net increase (decrease) in cash and cash equivalents	(24,482)	(24,678)	17,763
Cash and cash equivalents, beginning of year	74,132	98,810	81,047
Cash and cash equivalents, end of year	49,650	74,132	98,810
Supplemental disclosure of cash flow information:
Cash paid for income taxes	$ 14,180us-gaap_IncomeTaxesPaidNet	$ 9,358us-gaap_IncomeTaxesPaidNet	$ 7,102us-gaap_IncomeTaxesPaidNet

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.