Segment Reporting - Information about Operations in Different Segments (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Restructuring and integration costs		$ 63		$ 75
Capital expenditures	[1]	24	$ 18	43	$ 81
Amazon Pipe-lay and Construction Vessel [Member]
Segment Reporting Information [Line Items]
Bareboat charter agreement, term					11 years
Liability Associated with Assets [Member]
Segment Reporting Information [Line Items]
Capital expenditures				14	$ 3
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Restructuring and integration costs		63		75
Gain on sale of assets			$ 3		$ 3
Transaction costs		$ 37		$ 40

[1] Liabilities associated with assets acquired during the first six months of 2018 and 2017 were $14 million and $3 million, respectively.