Revenue - Unsatisfied Performance Obligation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-04-01
Revenue From Contract With Customer [Line Items]
Unsatisfied performance obligations, expected to recognize	54.00%
Unsatisfied performance obligations, expected to recognize, period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue From Contract With Customer [Line Items]
Unsatisfied performance obligations, expected to recognize	34.00%
Unsatisfied performance obligations, expected to recognize, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue From Contract With Customer [Line Items]
Unsatisfied performance obligations, expected to recognize	12.00%
Unsatisfied performance obligations, expected to recognize, period	1 year