Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Foreign Currency Transaction Gain (Loss) Including Derivatives, Before Tax	$ (354)	$ (577)	$ (355)
Revenues
Revenues	321,607	278,889	230,828
Cost of revenues	69,517	66,185	51,580
Gross profit	252,090	212,704	179,248
Operating expenses:
Research and development	68,239	53,255	42,816
Sales and marketing	70,833	70,039	63,855
General and administrative	40,765	39,049	35,334
Total operating expenses	179,837	162,343	142,005
Income from operations	72,253	50,361	37,243
Other income (expense), net:
Interest expense	(106)	(172)	(3)
Interest income	8,443	6,080	2,674
Total other income (expense), net	7,730	5,107	2,135
Income before income taxes	79,983	55,468	39,378
Provision for (benefit from) income taxes	10,647	(1,836)	(1,062)
Net income	$ 69,336	$ 57,304	$ 40,440
Net income per share:
Basic (usd per share)	$ 1.77	$ 1.47	$ 1.08
Diluted (usd per share)	$ 1.68	$ 1.37	$ 1.01
Weighted average shares used in computing net income per share:
Basic (in shares)	39,075	38,876	37,443
Diluted (in shares)	41,345	41,897	40,071