Revenue Recognition - Summary of Impact of Adoption of Accounting Standards (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Revenue:
Software	$ 17,440		$ 19,216	$ 52,877	$ 58,118
Professional engineering service	2,213		3,251	8,465	12,526
Total revenue	19,653		22,467	61,342	70,644
Cost of revenue:
Software	13,653		15,281	40,909	47,901
Professional engineering service	1,620		3,509	5,927	10,877
Total cost of revenue	15,273		18,790	46,836	58,778
Gross profit	4,380		3,677	14,506	11,866
Operating expenses:
Selling, general and administrative	5,338		3,283	15,249	9,693
Research and development	1,588		809	4,381	2,024
Total operating expenses	6,926		4,092	19,630	11,717
Income (loss) from operations	(2,546)		(415)	(5,124)	149
Net income (loss)	$ (2,468)		$ (106)	$ (4,826)	$ 209
Basic and diluted loss per share	$ (0.20)			$ (0.38)
Assets:
Contract Assets	$ 697			$ 697
Liabilities:
Deferred revenue - current	2,622			2,622		$ 2,064
Deferred revenue - noncurrent	56			56		1,798
Shareholders' Equity:
Accumulated deficit	(101,044)			(101,044)		$ (96,607)
Topic 606 [Member] | Balances without adoption of Topic 606 [Member]
Revenue:
Software	17,711			51,064
Professional engineering service	2,284			8,213
Total revenue	19,995			59,277
Cost of revenue:
Software	13,653			40,909
Professional engineering service	1,691			5,797
Total cost of revenue	15,344			46,706
Gross profit	4,651			12,571
Operating expenses:
Selling, general and administrative	5,332			15,096
Research and development	1,588			4,381
Total operating expenses	6,920			19,477
Income (loss) from operations	(2,269)			(6,906)
Net income (loss)	$ (2,191)			$ (6,608)
Basic and diluted loss per share	$ (0.17)			$ (0.53)
Assets:
Contract Assets	$ 537			$ 537
Liabilities:
Deferred revenue - current	3,548			3,548
Deferred revenue - noncurrent	752			752
Shareholders' Equity:
Accumulated deficit	(102,826)			(102,826)
Topic 606 [Member] | Effect of Change Higher/(Lower) [Member]
Revenue:
Software	(271)			1,813
Professional engineering service	(71)			252
Total revenue	(342)	$ 2,800		2,065
Cost of revenue:
Professional engineering service	(71)			130
Total cost of revenue	(71)			130
Gross profit	(271)			1,935
Operating expenses:
Selling, general and administrative	6			153
Total operating expenses	6			153
Income (loss) from operations	(277)			1,782
Net income (loss)	$ (277)			$ 1,782
Basic and diluted loss per share	$ (0.03)			$ 0.15
Assets:
Contract Assets	$ 160			$ 160
Liabilities:
Deferred revenue - current	(926)			(926)
Deferred revenue - noncurrent	(696)			(696)
Shareholders' Equity:
Accumulated deficit	$ 1,782			$ 1,782