Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income	$ 11,996	$ 10,865	$ 13,024
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and asset write-offs	8,350	9,325	9,268
Amortization of intangible assets	891	2,171	2,230
Net losses from investments	18	288	2,433
Deferred income taxes	(985)	(7,526)	(4,529)
Stock-based compensation	8,347	7,444	6,051
Amortization of premium on investments	693	1,273	2,261
Foreign currency losses	38	141	385
Changes in assets and liabilities
Accounts receivable	(718)	9,140	(2,930)
Deferred commissions	225	(815)	(3,529)
Prepaid expenses and other current assets	1,431	620	607
Accounts payable	(357)	(82)	222
Accrued expenses and other liabilities	4,657	2,171	3,547
Deferred revenue	(2,120)	(6,220)	1,673
Net cash provided by operating activities	32,466	28,795	30,713
Cash flows from investing activities:
Purchases of property and equipment	(3,931)	(1,503)	(3,127)
Purchases of marketable investments	(20,587)	(35,386)	(44,667)
Proceeds from sales and maturities of marketable investments	26,960	60,112	105,086
Other investing activity	347	1,542	264
Net cash provided by investing activities	2,789	24,765	57,556
Cash flows from financing activities:
Dividends paid on common stock	(12,179)	(11,962)	(12,394)
Repurchases of common stock	(20,931)	(73,166)	(118,210)
Proceeds from issuance of common stock under employee equity incentive plans	3,347	8,969	17,387
Excess tax benefits from stock-based compensation	51	244	737
Payment of deferred acquisition consideration			(900)
Net cash used in financing activities	(29,712)	(75,915)	(113,380)
Effect of exchange rate changes on cash and cash equivalents	(1,862)	(2,127)	433
Net increase (decrease) in cash and cash equivalents	3,681	(24,482)	(24,678)
Cash and cash equivalents, beginning of year	49,650	74,132	98,810
Cash and cash equivalents, end of year	53,331	49,650	74,132
Supplemental disclosure of cash flow information:
Cash paid for income taxes	$ 6,425	$ 14,180	$ 9,358