Segment Reporting - Information about Revenue by Service Lines and Contract Types (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues	$ 607,818	$ 519,431
Offshore [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues	394,724	354,064
Subsea and Other [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues	213,094	165,367
Fixed-Price [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues	582,592	475,921
Unit-Basis and Other [Member]
Segment Reporting Revenue Reconciling Item [Line Items]
Revenues	$ 25,226	$ 43,510