Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	$ 65	$ 88	$ 74	$ 90
Provision charged to operations	1	1	12	9
Accounts written off, net of recoveries	(5)	(14)	(27)	(23)
Foreign currency translation	2	4	4	3
Balance at end of period	$ 63	$ 79	$ 63	$ 79