Revenue Recognition - Disaggregated Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	$ 19,203	$ 18,848	$ 39,881	$ 41,689
Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	16,992	15,505	33,056	32,302
Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	281	481	2,076	3,135
Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,930	2,862	4,749	6,252
North America [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	18,179	17,728	37,468	39,498
North America [Member] | Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	16,281	14,956	31,400	31,252
North America [Member] | Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	265	473	1,948	3,118
North America [Member] | Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,633	2,299	4,120	5,128
Europe [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	889	814	1,828	1,636
Europe [Member] | Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	702	435	1,295	859
Europe [Member] | Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	5		105
Europe [Member] | Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	182	379	428	777
Asia [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	135	306	585	555
Asia [Member] | Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	9	114	361	191
Asia [Member] | Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	11	8	23	17
Asia [Member] | Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	$ 115	$ 184	$ 201	$ 347