Revenue Recognition - Estimated Revenue Expected to be Recognized in Future Related to Performance Obligations (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue, expected recognition period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue, expected recognition period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue, expected recognition period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue, expected recognition period	1 year
Software [Member] | Third Party Software [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue expected to be recognized in future	$ 89
Software [Member] | Third Party Software [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue expected to be recognized in future	50
Software [Member] | Third Party Software [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue expected to be recognized in future	14
Software [Member] | Proprietary Software [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue expected to be recognized in future	1,138
Software [Member] | Proprietary Software [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue expected to be recognized in future	1,133
Software [Member] | Proprietary Software [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue expected to be recognized in future	820
Software [Member] | Proprietary Software [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue expected to be recognized in future	114
Professional Engineering Services [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Estimated revenue expected to be recognized in future	$ 230