Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Net revenue:
Revenue from Contract with Customer, Including Assessed Tax	$ 162,720		$ 151,493	$ 118,056
Cost of revenue:
Cost of revenue	82,338		65,383	49,921
Gross profit	80,382		86,110	68,135
Operating expenses:
Sales and marketing	58,420		52,070	41,563
Research and development	14,359		12,874	11,232
General and administrative	20,995		14,090	12,943
Lease termination income			(4,000)
Total operating expenses	93,774		75,034	65,738
Income (loss) from operations	(13,392)		11,076	2,397
Interest and other income(expense), net	(123)	[1]	884	323
Income (loss) before income taxes	(13,515)		11,960	2,720
Income tax (benefit) provision	17,255		(18,033)	143
Net income (loss)	$ (30,770)		$ 29,993	$ 2,577
Net loss per share:
Basic (in dollars per share)	$ (2.23)		$ 2.16	$ 0.19
Diluted (in dollars per share)	$ (2.23)		$ 2.04	$ 0.19
Weighted-average number of shares used in per share calculations:
Basic (in shares)	13,771		13,873	13,225
Diluted (in shares)	13,771		14,728	13,753
Product [Member]
Net revenue:
Revenue from Contract with Customer, Including Assessed Tax	$ 142,535		$ 132,660	$ 99,028
Cost of revenue:
Cost of revenue	66,843		56,363	40,149
Operating expenses:
Sales and marketing	58,420
Service [Member]
Net revenue:
Revenue from Contract with Customer, Including Assessed Tax	20,185		18,833	19,028
Cost of revenue:
Cost of revenue	$ 15,495		$ 9,020	$ 9,772

[1] Included in interest and other income, net, is the estimated interest expense for advance payment related to service contracts under the new revenue standard.