Goodwill and Other Intangible Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Other Intangible Assets
Intangible assets amortization	$ 96	$ 100	$ 76
Indefinite-lived intangible assets	18
Expected amortization expenses related to other intangible assets in 2018	94
Expected amortization expenses related to other intangible assets in 2019	83
Expected amortization expenses related to other intangible assets in 2020	74
Expected amortization expenses related to other intangible assets in 2021	62
Expected amortization expenses related to other intangible assets in 2022	$ 49