Consolidated Statements of Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues, net	$ 99,878	$ 108,530	$ 99,354
Cost of revenues	35,203	40,137	35,614
Gross profit	64,675	68,393	63,740
Operating expenses
Sales and marketing	32,889	45,132	47,716
Research and development	27,841	33,318	28,751
General and administrative	19,890	22,391	21,257
Total operating expenses	80,620	100,841	97,724
Loss from operations	(15,945)	(32,448)	(33,984)
Interest expense, net	(129)	(118)	(177)
Other income (expenses), net	998	222	(466)
Loss before (provision for) benefit from income taxes	(15,076)	(32,344)	(34,627)
(Provision for) benefit from income taxes	(1,404)	(1,005)	1,456
Net loss	(16,480)	(33,349)	(33,171)
Foreign currency translation adjustments	(1,110)	(1,030)	(747)
Comprehensive loss	$ (17,590)	$ (34,379)	$ (33,918)
Net loss per share available to common stockholders, basic and diluted	$ (0.43)	$ (0.91)	$ (0.97)
Weighted-average shares used to compute net loss per share available to common stockholders, basic and diluted	38,318	36,580	34,210
Amortization of intangible assets is allocated as follows (Note 6):
Amortization of intangible assets	$ 3,080	$ 3,134	$ 1,131
Cost of Revenues [Member]
Stock-based compensation is allocated as follows (Note 12):
Allocation of stock-based compensation	1,314	1,171	765
Amortization of intangible assets is allocated as follows (Note 6):
Amortization of intangible assets	1,027	1,033	399
Restructuring related expenses are allocated as follows (Note 4):
Restructuring related expenses	184	173	0
Sales and Marketing [Member]
Stock-based compensation is allocated as follows (Note 12):
Allocation of stock-based compensation	1,281	2,537	1,895
Amortization of intangible assets is allocated as follows (Note 6):
Amortization of intangible assets	934	921	261
Restructuring related expenses are allocated as follows (Note 4):
Restructuring related expenses	348	718	0
Research and Development [Member]
Stock-based compensation is allocated as follows (Note 12):
Allocation of stock-based compensation	4,989	7,518	3,785
Amortization of intangible assets is allocated as follows (Note 6):
Amortization of intangible assets	1,027	1,034	397
Restructuring related expenses are allocated as follows (Note 4):
Restructuring related expenses	44	53	0
General and Administrative [Member]
Stock-based compensation is allocated as follows (Note 12):
Allocation of stock-based compensation	2,711	4,393	2,797
Amortization of intangible assets is allocated as follows (Note 6):
Amortization of intangible assets	92	146	74
Restructuring related expenses are allocated as follows (Note 4):
Restructuring related expenses	$ 20	$ 270	$ 0