Noncurrent Other Liabilities (Schedule of Changes in Asset Retirement Obligations) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Liabilities, Noncurrent [Abstract]
Balance at beginning of year		$ 37	$ 47	$ 64
Additions	[1]	0	4	5
Accretion		1	1	2
Payments		(4)	(8)	(23)
Revisions to cash flow estimates	[2]	2	(7)	(2)
Exchange rate changes		0	0	1
Balance at end of year		$ 36	$ 37	$ 47

[1] Primarily relates to sites which management no longer considers to have an indeterminate life.

[2] Primarily relates to revisions to the estimated cost and timing of future obligations.