Supplemental Disclosures (Schedule of Analysis for Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 87	$ 95	$ 98
Provision charged to operations	31	14	20
Accounts written-off, net of recoveries	(20)	(18)	(17)
Effect of exchange rate changes and other	(2)	(4)	(6)
Balance at end of year	$ 96	$ 87	$ 95