Revenue Recognition - Disaggregated Revenue (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	$ 80,811
Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	70,401
Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	65,755
Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	4,646
Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	10,410
North America [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	76,062
North America [Member] | Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	67,380
North America [Member] | Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	63,430
North America [Member] | Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	3,950
North America [Member] | Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	8,682
Europe [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	3,105
Europe [Member] | Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,914
Europe [Member] | Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,914
Europe [Member] | Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,191
Asia [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,644
Asia [Member] | Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,107
Asia [Member] | Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	411
Asia [Member] | Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	696
Asia [Member] | Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	537
Transferred at a point in time [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	70,165
Transferred at a point in time [Member] | Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	69,304
Transferred at a point in time [Member] | Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	65,608
Transferred at a point in time [Member] | Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	3,696
Transferred at a point in time [Member] | Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	861
Transferred over time [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	10,646
Transferred over time [Member] | Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	1,097
Transferred over time [Member] | Software [Member] | Third Party Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	147
Transferred over time [Member] | Software [Member] | Proprietary Software [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	950
Transferred over time [Member] | Professional Engineering Service [Member]
Disaggregation Of Revenue [Line Items]
Disaggregated revenue	$ 9,549