Revenue Recognition - Summary of RPOs by Segment (Detail) - USD ($) $ in Thousands	Mar. 31, 2018		Jan. 01, 2018
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 3,386,673	[1]	$ 3,673,317
Remaining performance obligations, Percentage	100.00%
AEA [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 969,000
Remaining performance obligations, Percentage	28.00%
MEA [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 2,021,000
Remaining performance obligations, Percentage	60.00%
ASA [Member]
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations, Total	$ 397,000
Remaining performance obligations, Percentage	12.00%

[1] At March 31, 2018, approximately 48% of our RPOs were attributable to Saudi Aramco