Postretirement Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Amount by which fair value of plan assets exceeds market-related value of plan assets (MRVA)	$ 4,773
Derivative net notional amount for fixed income as percentage of total plan assets	33.40%	8.30%
Derivative net notional amount for global equity, currency overlay and commodities as a percentage of total plan assets	(5.40%)	0.40%
Expense for defined contribution plans	$ 1,268	$ 1,351	$ 1,533
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation (ABO) for all pension plans	74,199	80,694
Company contribution	11	3,013
Defined Benefit Plan, Plan Assets, Amount	$ 67,813	$ 68,696	61,711
Defined benefit plan, actual plan asset allocations	100.00%	100.00%
Pension Plans [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations	61.00%	49.00%
Pension Plans [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations	16.00%	30.00%
Pension Plans [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 10,851	$ 14,978
Pension Plans [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	198	240	472
Pension Plans [Member] | Level 3 [Member] | Debt Securities [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held		2
Pension Plans [Member] | Level 3 [Member] | Debt Securities [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount		2
Pension Plans [Member] | Level 3 [Member] | Debt Securities [Member] | Mortgage backed and asset backed securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	(1)	1
Pension Plans [Member] | Level 3 [Member] | Debt Securities [Member] | Municipal [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held		3
Pension Plans [Member] | Level 3 [Member] | Debt Securities [Member] | Sovereign Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Increase (Decrease) for Actual Return (Loss) on Plan Assets Still Held	(8)	(1)
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 172	160	$ 149
Other Postretirement Benefits Plans [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations	40.00%
Other Postretirement Benefits Plans [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations	60.00%
Non-Cash Contribution [Member]
Defined Benefit Plan Disclosure [Line Items]
Company contribution	$ 3,000	$ 3,000