Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 59	$ 64	$ 56	$ 58
Provision charged to Other general expenses	5	4	16	15
Accounts written off, net of recoveries	0	(5)	(10)	(11)
Foreign currency translation	(5)	0	(3)	1
Balance at end of period	$ 59	$ 63	$ 59	$ 63