Employee Benefit Plans (Schedule of PRB Amounts Recognized in Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Actuarial (gain) loss arising during the period	$ (3,246)	$ 202	$ 543
Current year prior service cost (credit)	59	(2,095)	6
Amortization of prior service cost	(258)	(373)	$ (228)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial (gain) loss arising during the period	(88)	47
Amortization of actuarial gain	6	12
Current year prior service cost (credit)	0	(7)
Amortization of prior service cost	3	3
Net settlement and curtailment	0	(1)
Other	0	5
Total recognized in other comprehensive (income) loss	(79)	59
Net recognized in net periodic benefit (income) cost and other comprehensive loss	$ (78)	$ 75