Equity Affiliates - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Dividends received from equity affiliates	$ 20	$ 16	$ 11
Equity method investments	206
Equity method investment carrying amount over the book value	61
Goodwill [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment carrying amount over the book value	53
Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 5
Minimum [Member] | Other Than Goodwill [Member]
Schedule of Equity Method Investments [Line Items]
Estimated useful life	5 years
Maximum [Member] | Other Than Goodwill [Member]
Schedule of Equity Method Investments [Line Items]
Estimated useful life	45 years