Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 65	$ 62	$ 64	$ 59
Provision charged to Other general expenses	7	9	19	21
Accounts written off, net of recoveries	(6)	(8)	(17)	(17)
Foreign currency translation and other	1	3	1	3
Balance at end of period	$ 67	$ 66	$ 67	$ 66