Employee Benefit Plans (Net Periodic Benefit Costs and Other Changes Recognized in OCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other changes in plan assets and benefit obligations recognized in OCI:
Total recognized in OCI	$ (328)	$ (181)	$ (30)
Pension Benefits
Net periodic benefit costs [Abstract]
Service costs	215	226	214
Interest costs	342	363	425
Settlement and curtailment costs	(7)	10	0
Expected return on plan assets	(506)	(528)	(489)
Amortization of net actuarial (gains) losses	162	189	201
Amortization of prior service costs (credit)	(12)	(14)	(15)
Total net periodic benefit costs (credit)	194	246	336
Other changes in plan assets and benefit obligations recognized in OCI:
Net actuarial (gains) losses	(166)	(35)	231
Prior service costs (credit)	1	0	3
Amortization of net actuarial (gains) losses	(162)	(189)	(201)
Amortization of prior service (costs) credit	12	14	15
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax	(10)	(10)	0
Total recognized in OCI	(333)	(215)	48
Total recognized in net periodic benefit costs and OCI	(139)	31	384
Pension Benefits | Accumulated Other Comprehensive Income (Loss) Foreign Currency Translation Adjustments
Other changes in plan assets and benefit obligations recognized in OCI:
Total recognized in OCI	(8)	5	0
Other Postretirement Benefits
Net periodic benefit costs [Abstract]
Service costs	4	5	5
Interest costs	37	42	53
Settlement and curtailment costs	1	0	2
Expected return on plan assets	(56)	(62)	(67)
Amortization of net actuarial (gains) losses	(39)	(74)	(48)
Amortization of prior service costs (credit)	0	(3)	(12)
Total net periodic benefit costs (credit)	(53)	(92)	(67)
Other changes in plan assets and benefit obligations recognized in OCI:
Net actuarial (gains) losses	(54)	(42)	(138)
Prior service costs (credit)	(1)	0	0
Amortization of net actuarial (gains) losses	39	74	48
Amortization of prior service (costs) credit	0	3	12
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax	10	0	0
Total recognized in OCI	(6)	35	(78)
Total recognized in net periodic benefit costs and OCI	(59)	(57)	(145)
Other Postretirement Benefits | Accumulated Other Comprehensive Income (Loss) Foreign Currency Translation Adjustments
Other changes in plan assets and benefit obligations recognized in OCI:
Total recognized in OCI	$ 0	$ 0	$ 0