Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 58	$ 74
Provision charged to Other general expenses	6	8
Accounts written off, net of recoveries	(2)	(9)
Foreign currency translation	0	(3)
Balance at end of period	$ 62	$ 70