Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss) from continuing and discontinued operations	$ (3,295)	$ 5,948	$ 5,654
Pension and postretirement benefit plans
Net actuarial loss arising during period	(202)	(543)	(1,819)
Prior service credit (cost) arising during period	2,095	(6)	(22)
Amortization of actuarial loss and prior service cost	373	228	344
Other	(51)	(93)	105
Pension and postretirement benefit plans	2,215	(414)	(1,392)
Unrealized loss on available-for-sale securities	0	0	(5)
Change in unrealized cash flow hedging	263	18	(323)
Foreign currency translation adjustments	609	268	(518)
Other comprehensive income (loss), before tax	3,087	(128)	(2,238)
Income tax (expense) benefit related to items of other comprehensive income (loss)	(547)	43	400
Other comprehensive income (loss), net of tax	2,540	(85)	(1,838)
Comprehensive income (loss)	(755)	5,863	3,816
Less: comprehensive income attributable to noncontrolling interest	224	399	355
Comprehensive income (loss) attributable to common shareowners	$ (979)	$ 5,464	$ 3,461