Supplemental Disclosures (Schedule of Analysis 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	$ 95	$ 98	$ 106
Provision charged to operations	14	20	16
Accounts written-off, net of recoveries	(18)	(17)	(19)
Effect of exchange rate changes and other	(4)	(6)	(5)
Balance at end of year	$ 87	$ 95	$ 98