Intangible Assets - Schedule of Project Related Intangibles (Parenthetical) (Detail) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)
Finite Lived Intangible Assets [Line Items]
Other intangibles amortization	$ 10	$ 10
Project Related Intangibles [Member]
Finite Lived Intangible Assets [Line Items]
Other intangibles amortization	12
Amortization expense for intangible assets, remainder of 2018	42	42
Amortization expense for intangible assets, in 2019	27	27
Amortization expense for intangible assets, in 2020	19	19
Amortization expense for intangible assets, in 2021	$ 12	$ 12