Property, Plant and Equipment - Components of Property, Plant and Equipment (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Pipeline Equipment [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 2,174	$ 1,887
Offshore Drilling Equipment [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	3,310	3,335
Other [Member]
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 873	$ 811