Restructuring Charges/Other - Restructuring Reserve (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring And Related Activities [Abstract]
Balance, January 1		$ 57	$ 161	$ 349
Restructuring charges	[1]	14	20	126
Non-cash items	[2]	0	0	(22)
Payments		(39)	(124)	(292)
Balance, December 31		$ 32	$ 57	$ 161

[1] Includes severance and benefits, along with changes in estimates; 2014 and 2013 also include other exit costs and accelerated depreciation.

[2] Reflects charges for impacts of accelerated depreciation and postretirement benefit plans.