Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 291	$ 268	$ 214
Interest cost	50	68	118
Expected return on plan assets	(371)	(353)	(328)
Amortization:
Net losses	314	265	189
Prior service cost	1	1	(1)
Net transition obligation	0	1	0
Settlement and curtailment	5	4	4
Net periodic pension and postretirement costs	290	254	196
Postretirement
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2	2
Interest cost	5	6	7
Expected return on plan assets	0	0	0
Amortization:
Net losses	3	2	0
Prior service cost	0	0	0
Net transition obligation	0	0	0
Settlement and curtailment	0	0	0
Net periodic pension and postretirement costs	$ 10	$ 10	$ 9