v3.20.4

Pension And Postretirement Benefits (Change In The Projected Benefit Obligation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Actuarial (gain) loss	$ 4,169	$ 5,171	$ (3,412)
Pension Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	59,873	55,439
Service cost - benefits earned during the period	1,029	1,019	1,116
Interest cost on projected benefit obligation	1,687	1,960	2,092
Amendments	(340)	0
Actuarial (gain) loss	5,054	7,734
Special termination benefits	0	81
Benefits paid	(5,124)	(6,356)
Curtailment	(1)	0
Plan transfers	(20)	(4)
Benefit obligation at end of year	62,158	59,873	55,439
Postretirement Benefits
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of year	16,041	19,378
Service cost - benefits earned during the period	53	71	109
Interest cost on projected benefit obligation	416	675	778
Amendments	(2,655)	(4,590)
Actuarial (gain) loss	1,423	2,050
Special termination benefits	0	0
Benefits paid	(1,370)	(1,543)
Curtailment	0	0
Plan transfers	20	0
Benefit obligation at end of year	$ 13,928	$ 16,041	$ 19,378

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- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of cost recognized for passage of time related to defined benefit plan.

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