Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 64	$ 65	$ 58	$ 74
Provision charged to Other general expenses	5	1	17	12
Accounts written off, net of recoveries	(4)	(5)	(11)	(27)
Foreign currency translation	0	2	1	4
Balance at end of period	$ 65	$ 63	$ 65	$ 63