Restructuring Charges/Other - Components of Restructuring Charges and Other (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Restructuring Cost And Reserve [Line Items]
Restructuring charges		$ 0	$ (3)	$ (1)	[1]	$ 19
Gains on sales of assets		0	(8)	(1)		(47)
Other		0	2	(1)		4
Restructuring charges/other		0	(9)	(3)		(24)
2013 Actions
Restructuring Cost And Reserve [Line Items]
Restructuring charges	[1]	0	(3)	(1)		25
Prior Actions
Restructuring Cost And Reserve [Line Items]
Restructuring charges	[1]	$ 0	$ 0	$ 0		$ (6)

[1] Includes changes in estimates.