Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at January 1	$ 56	$ 58
Provision charged to Other general expenses	6	5
Accounts written off, net of recoveries	(3)	(1)
Foreign currency translation	2	0
Balance at March 31	$ 61	$ 62