Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 15,380	$ 15,140	$ 17,651
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	7,955	6,648	7,812
Amortization of intangible assets	1,162	781	831
Net (gains) losses from investments	(426)	479	805
Deferred income taxes	2,931	6,425	2,602
Stock-based compensation	8,300	8,490	7,976
Amortization of premium (discount) on investments	(68)	207	345
Foreign currency (gains) losses	603	632	(81)
Changes in assets and liabilities, net of businesses acquired
Accounts receivable	2,588	(10,327)	7,963
Deferred commissions	(1,077)	(1,679)	1,477
Prepaid expenses and other current assets	285	(4,146)	861
Accounts payable	172	(1,600)	1,317
Accrued expenses and other liabilities	1,217	7,857	58
Deferred revenue	(604)	8,586	(5,140)
Net cash provided by operating activities	38,418	37,493	44,477
Cash flows from investing activities:
Acquisitions, net of cash acquired	(9,250)
Purchases of property and equipment	(5,049)	(7,861)	(4,140)
Purchases of marketable investments	(41,810)	(31,910)	(36,763)
Proceeds from maturities of marketable investments	63,627	31,913	18,271
Proceeds from sales of marketable investments	32,568	6,545	4,815
Other investing activity		343	(48)
Net cash provided by (used in) investing activities	40,086	(970)	(17,865)
Cash flows from financing activities:
Dividends paid on common stock	(14,502)	(13,631)	(12,987)
Repurchases of common stock	(9,946)	(39,967)	(1,791)
Proceeds from issuance of common stock under employee equity incentive plans	13,020	18,506	16,734
Taxes paid related to net share settlements of stock-based compensation awards	(2,526)	(2,527)	(2,069)
Net cash used in financing activities	(13,954)	(37,619)	(113)
Effect of exchange rate changes on cash and cash equivalents	(4,044)	3,928	(2,872)
Net increase in cash and cash equivalents	60,506	2,832	23,627
Cash and cash equivalents, beginning of year	79,790	76,958	53,331
Cash and cash equivalents, end of year	140,296	79,790	76,958
Supplemental disclosure of cash flow information:
Cash paid for income taxes	$ 4,174	$ 10,443	$ 8,507