Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Revenue mix	$ 40,573,000		$ 38,173,000	$ 117,251,000		$ 103,861,000
Cost of revenue:
Cost of revenue	18,688,000		15,963,000	55,655,000		45,084,000
Gross profit	21,885,000		22,210,000	61,596,000		58,777,000
Operating expenses:
Sales and marketing	14,479,000		13,148,000	43,102,000		36,708,000
Research and development	3,244,000		3,467,000	10,895,000		9,393,000
General and administrative	5,160,000		3,379,000	15,501,000		10,143,000
Lease termination income			(4,000,000)			(4,000,000)
Total operating expenses	22,883,000		15,994,000	69,498,000		52,244,000
Income (loss) from operations	(998,000)		6,216,000	(7,902,000)		6,533,000
Interest and other income, net*	(49,000)	[1]	197,000	(80,000)	[1]	746,000
Income (loss) before income taxes	(1,047,000)		6,413,000	(7,982,000)		7,279,000
Provision (benefit) for income taxes	(174,000)		225,000	(3,505,000)		166,000
Net income (loss)	$ (873,000)		$ 6,188,000	$ (4,477,000)		$ 7,113,000
Net income (loss) per share:
Basic (in dollars per share)	$ (0.06)		$ 0.44	$ (0.33)		$ 0.51
Diluted (in dollars per share)	$ (0.06)		$ 0.42	$ (0.33)		$ 0.48
Weighted-average number of shares used in per share calculations:
Basic (in shares)	13,851		13,973	13,717		13,917
Diluted (in shares)	13,851		14,767	13,717		14,733
Product [Member]
Revenue mix	$ 35,675,000		$ 33,486,000	$ 102,589,000		$ 89,688,000
Cost of revenue:
Cost of revenue	15,909,000		13,859,000	46,876,000		38,843,000
Operating expenses:
Sales and marketing	14,479,000			43,102,000
Service [Member]
Revenue mix	4,898,000		4,687,000	14,662,000		14,173,000
Cost of revenue:
Cost of revenue	$ 2,779,000		$ 2,104,000	$ 8,779,000		$ 6,241,000

[1] Included in interest and other income, net is the estimated interest expense for advance payment related to contract services under the new revenue standard going forward. Adoption of the standard had no impact to total net cash from or used in operating, investing, or financing activities within the Condensed Consolidated Statements of Cash Flows.