Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 74	$ 90	$ 118
Provision charged to operations	13	12	9
Accounts written off, net of recoveries	(34)	(33)	(38)
Foreign currency translation	5	5	1
Balance at end of year	$ 58	$ 74	$ 90