Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 61	$ 62	$ 56	$ 58
Provision charged to Other general expenses	5	6	11	11
Accounts written off, net of recoveries	(7)	(4)	(10)	(6)
Foreign currency translation	0	0	2	1
Balance at end of period	$ 59	$ 64	$ 59	$ 64