Revenue Recognition - Summary of Impact of Adoption of Accounting Standards (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Professional engineering service									$ 10,410	$ 15,271
Total revenue	$ 19,469	$ 19,653	$ 18,848	$ 22,841	$ 26,797	$ 22,467	$ 22,738	$ 25,439	80,811	97,441
Cost of revenue:
Professional engineering service									7,365	13,439
Total cost of revenue									62,689	81,621
Gross profit	3,616	4,380	3,873	6,253	3,954	3,677	3,893	4,296	18,122	15,820
Operating expenses:
Selling, general and administrative									20,982	14,119
Research and development									6,561	2,859
Total operating expenses									27,543	16,978
Loss from operations	(4,297)	(2,546)	(2,619)	41	(1,307)	(415)	(85)	649	(9,421)	(1,158)
Other income, net									214	247
Loss before income taxes									(9,207)	(911)
Income tax benefit									149	(141)
Net loss	$ (4,232)	$ (2,468)	$ (2,560)	$ 202	$ (1,261)	$ (106)	$ (185)	$ 500	$ (9,058)	$ (1,052)
Basic loss per share	$ (0.33)	$ (0.20)	$ (0.20)	$ 0.02	$ (0.10)	$ (0.01)	$ (0.02)	$ 0.04	$ (0.72)	$ (0.09)
Diluted loss per share	$ (0.33)	$ (0.20)	$ (0.20)	$ 0.02	$ (0.10)	$ (0.01)	$ (0.02)	$ 0.04	$ (0.72)	$ (0.09)
ASSETS
Contract assets	$ 937								$ 937
Other noncurrent assets	89				$ 53				89	$ 53
Liabilities:
Deferred revenue - current	3,219				2,064				3,219	2,064
Deferred revenue - noncurrent	61				1,798				61	1,798
Shareholders' Equity:
Accumulated deficit	(105,276)				$ (96,607)				(105,276)	(96,607)
Third Party Software [Member]
Revenue:
Software									65,755	80,231
Cost of revenue:
Software									55,161	67,853
Proprietary Software [Member]
Revenue:
Software									4,646	1,939
Cost of revenue:
Software									163	$ 329
Topic 606 [Member] | Balances without adoption of Topic 606 [Member]
Revenue:
Professional engineering service									10,198
Total revenue									78,917
Cost of revenue:
Professional engineering service									7,277
Total cost of revenue									62,601
Gross profit									16,316
Operating expenses:
Selling, general and administrative									20,909
Research and development									6,561
Total operating expenses									27,470
Loss from operations									(11,154)
Other income, net									214
Loss before income taxes									(10,940)
Income tax benefit									149
Net loss									$ (10,791)
Basic loss per share									$ (0.86)
Diluted loss per share									$ (0.86)
ASSETS
Contract assets	753								$ 753
Other noncurrent assets	59								59
Liabilities:
Deferred revenue - current	4,243								4,243
Deferred revenue - noncurrent	556								556
Shareholders' Equity:
Accumulated deficit	(107,009)								(107,009)
Topic 606 [Member] | Effect of change - higher (lower) [Member]
Revenue:
Professional engineering service									212
Total revenue									1,894
Cost of revenue:
Professional engineering service									88
Total cost of revenue									88
Gross profit									1,806
Operating expenses:
Selling, general and administrative									73
Total operating expenses									73
Loss from operations									1,733
Loss before income taxes									1,733
Net loss									$ 1,733
Basic loss per share									$ 0.14
Diluted loss per share									$ 0.14
ASSETS
Contract assets	184								$ 184
Other noncurrent assets	30								30
Liabilities:
Deferred revenue - current	(1,024)								(1,024)
Deferred revenue - noncurrent	(495)								(495)
Shareholders' Equity:
Accumulated deficit	$ 1,733								1,733
Topic 606 [Member] | Third Party Software [Member] | Balances without adoption of Topic 606 [Member]
Revenue:
Software									65,755
Cost of revenue:
Software									55,161
Topic 606 [Member] | Proprietary Software [Member] | Balances without adoption of Topic 606 [Member]
Revenue:
Software									2,964
Cost of revenue:
Software									163
Topic 606 [Member] | Proprietary Software [Member] | Effect of change - higher (lower) [Member]
Revenue:
Software									$ 1,682