Basis of Presentation and Summary of Significant Accounting Policies - Summary of Estimated Revenue Expected to be Recognized Over Time Related to Performance Obligations (Detail) $ in Thousands	Mar. 31, 2018 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue remaining performance obligation, remainder of 2018	$ 109,260
Revenue remaining performance obligation, 2019	31,104
Revenue remaining performance obligation, 2020	12,816
Revenue remaining performance obligation, 2021	2,019
Revenue remaining performance obligation, Thereafter	1,194
Performance Obligations Transferred Over Time [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue remaining performance obligation, remainder of 2018	109,260
Revenue remaining performance obligation, 2019	31,104
Revenue remaining performance obligation, 2020	12,816
Revenue remaining performance obligation, 2021	2,019
Revenue remaining performance obligation, Thereafter	$ 1,194