Goodwill and Intangible Assets - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Goodwill impairment	$ 160,000,000	$ 46,600,000	$ 0
Amortization of intangible assets	276,000,000	267,000,000	$ 202,000,000
Tradenames
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets other than goodwill	$ 386,000,000	$ 377,000,000