Accumulated Other Comprehensive Income - Amounts Reclassified (Details) - USD ($) $ in Millions		3 Months Ended						9 Months Ended
		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses		$ (758)			$ (739)			$ (2,143)	$ (2,363)
Interest expense		(261)			(255)			(773)	(858)
Income taxes		(107)			(121)			(281)	(455)
Discontinued operations, net of tax	[1]	2			(857)			(62)	322
NET INCOME (LOSS)		391	$ 312	$ 320	(458)	$ 299	$ 1,369	1,023	1,210
Reclassifications from AOCI | Gains & losses on cash flow hedges
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Income taxes		0			0			0	(1)
NET INCOME (LOSS)		0			2			1	5
Reclassifications from AOCI | Gains & losses on cash flow hedges | Commodity Contracts
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses		0			0			0	1
Reclassifications from AOCI | Gains & losses on cash flow hedges | Long-term debt
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Interest expense		0			2			1	5
Reclassifications from AOCI | Unrealized gains on AFS securities
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Discontinued operations, net of tax		0			0			0	(1)
Reclassifications from AOCI | Net prior service costs
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Other operating expenses		(7)			(15)			(21)	(55)
Income taxes		3			5			6	14
NET INCOME (LOSS)		$ (4)			$ (10)			$ (15)	$ (41)

[1] Net of income tax expense (benefits) of $2 million and $(342) million for the three months ended September 30, 2019 and 2018, respectively, and $46 million and $(1.2) billion for the nine months ended September 30, 2019 and 2018, respectively.