Supplemental Disclosures (Schedule of Analysis for Doubtful Accounts) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 98	$ 106	$ 105
Provision charged to operations	20	16	11
Accounts written-off, net of recoveries	(17)	(19)	(12)
Effect of exchange rate changes and other	(6)	(5)	2
Balance at end of year	$ 95	$ 98	$ 106