Quarterly Financial Data (Unaudited) - Pre-Tax (Charges)/Gains in Earnings from Continuing Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Asset impairment and exit costs	$ (59)	$ (134)	$ (15)	$ (20)	$ (99)	$ (125)	$ (111)	$ (54)	$ (228)	$ (389)	$ (642)
Divestiture-related costs	0	4	(11)	1	(2)	0	0	3
Net gains on divestitures	0	3	41	0					44	0	186
Impact from pension participation changes	(3)	(3)	35	0	(17)	(3)	(409)	0
Impact from the resolution of tax matters	(85)	0	0	0	26	0	(15)	0
Loss related to interest rate swaps	0	(111)	0	0	0	1	(5)	14
Loss on early extinguishment of debt and related expenses					0	0	(140)	0	0	(140)	(11)
Net (loss)/gain on equity method investment transactions	0	0	(25)	23	21	757	0	0	$ (2)	$ 778	$ 40
Pre-tax charges/(gains) in earnings from continuing operations	$ (147)	$ (241)	$ 25	$ 4	$ (71)	$ 630	$ (680)	$ (37)