Intangible Assets - Schedule of Other Intangible Assets (Parenthetical) (Detail) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)
Finite Lived Intangible Assets [Line Items]
Other intangibles amortization	$ 25	$ 35
Other Intangible Assets [Member]
Finite Lived Intangible Assets [Line Items]
Other intangibles amortization	25	35
Amortization expense for intangible assets, remainder of 2018	24	24
Amortization expense for intangible assets, in 2019	84	84
Amortization expense for intangible assets, in 2020	83	83
Amortization expense for intangible assets, in 2021	78	78
Amortization expense for intangible assets, in 2022	$ 72	$ 72