Benefit Plans (Projected Benefit Obligations, Plan Assets and Funded Status of Pension Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in plan assets:
Accrued pension costs	$ (200)	$ (551)
Accrued postretirement health care costs	(1,436)	(1,951)
Pension [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	9,465	8,659
Service cost	68	74	$ 70
Interest cost	184	251	306
Benefits paid	(465)	(477)
Actuarial (gains) losses	(523)	970
Plan amendments	8	(12)
Divestiture	(193)	0
Benefit obligation at end of year	8,544	9,465	8,659
Change in plan assets:
Fair value of plan assets at beginning of year	8,911	8,167
Actual return on plan assets	466	1,188
Employer contributions	26	33
Benefits paid	(465)	(477)
Divestiture	(145)	0
Fair value of plan assets at end of year	8,793	8,911	8,167
Funded status at December 31	249	(554)
Other accrued liabilities	(27)	(23)
Accrued pension costs	(200)	(551)
Other assets	476	20
Accrued postretirement health care costs	0	0
Defined benefit plan, amounts for asset (liability) recognized in statement of financial position	249	(554)
Postretirement Benefit Plan [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	2,229	2,091
Service cost	20	16	16
Interest cost	38	59	76
Benefits paid	(104)	(107)
Actuarial (gains) losses	(150)	169
Plan amendments	(345)	1
Divestiture	0	0
Benefit obligation at end of year	1,688	2,229	2,091
Change in plan assets:
Fair value of plan assets at beginning of year	201	213
Actual return on plan assets	21	21
Employer contributions	0	0
Benefits paid	(37)	(33)
Divestiture	0	0
Fair value of plan assets at end of year	185	201	$ 213
Funded status at December 31	(1,503)	(2,028)
Other accrued liabilities	(67)	(77)
Accrued pension costs	0	0
Other assets	0	0
Accrued postretirement health care costs	(1,436)	(1,951)
Defined benefit plan, amounts for asset (liability) recognized in statement of financial position	$ (1,503)	$ (2,028)