Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 32	$ 20	$ 3
Estimated amortization expense in 2019	34
Estimated amortization expense in 2020	33
Estimated amortization expense in 2021	32
Estimated amortization expense in 2022	31
Estimated amortization expense in 2023	$ 31