Benefit Plans (Amounts Recorded in Accumulated Other Comprehensive Losses) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	$ (2,487)	$ (3,274)
Prior service (cost) credit	305	9
Deferred income taxes	570	845
Amounts recorded in accumulated other comprehensive losses	(1,612)	(2,420)
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	(2,093)	(2,689)
Prior service (cost) credit	(30)	(27)
Deferred income taxes	549	702
Amounts recorded in accumulated other comprehensive losses	(1,574)	(2,014)
Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	(362)	(541)
Prior service (cost) credit	340	41
Deferred income taxes	12	132
Amounts recorded in accumulated other comprehensive losses	(10)	(368)
Postemployment Retirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	(32)	(44)
Prior service (cost) credit	(5)	(5)
Deferred income taxes	9	11
Amounts recorded in accumulated other comprehensive losses	$ (28)	$ (38)