Postretirement Benefit Plans - Accumulated Other Comprehensive Income (Loss) Related to Qualified Defined Benefit Pension and Retiree Medical and Life Insurance Plans (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Qualified Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial losses	$ 14,675	$ 21,040
Prior service (credit) cost	(884)	(1,235)
Total	13,791	19,805
Estimated tax	(2,947)	(4,230)
Net amount recognized in accumulated other comprehensive loss	10,844	15,575
Retiree Medical and Life Insurance Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial losses	(554)	(119)
Prior service (credit) cost	36	73
Total	(518)	(46)
Estimated tax	110	9
Net amount recognized in accumulated other comprehensive loss	$ (408)	$ (37)

Accumulated Other Comprehensive Income (Loss), Defined Benefit Plan, Tax

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- Definition

Amount, after tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section 50
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- Definition

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 45
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- Definition

Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (j)
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- Definition

Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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