Benefit Plans (Amounts Recorded in Accumulated Other Comprehensive Losses) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net losses	$ (3,443)	$ (5,050)	$ (4,556)
Prior service cost	50	2	5
Net transition obligation	(3)	(3)	(4)
Deferred income taxes	516	798	726
Losses to be amortized	(2,880)	(4,253)	(3,829)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net losses	(2,495)	(4,147)	(3,718)
Prior service cost	71	22	3
Net transition obligation	(3)	(3)	(4)
Deferred income taxes	278	570	520
Losses to be amortized	(2,149)	(3,558)	(3,199)
Postretirement
Defined Benefit Plan Disclosure [Line Items]
Net losses	(64)	(64)	(63)
Prior service cost	1	2	2
Net transition obligation	0	0	0
Deferred income taxes	24	24	24
Losses to be amortized	(39)	(38)	(37)
Postemployment Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Net losses	(884)	(839)	(775)
Prior service cost	(22)	(22)	0
Net transition obligation	0	0	0
Deferred income taxes	214	204	182
Losses to be amortized	$ (692)	$ (657)	$ (593)