Basis of Presentation and Significant Accounting Policies - Accounts Receivable Securitization and Factoring (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Deferred purchase price receivable	$ 52	$ 0
Accounts receivable sold in securitization program	231
Proceeds from accounts receivable securitization program	179
Accounts receivable sold in factoring program	248	119
Proceeds from accounts receivable factoring program	$ 246	$ 119