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Employee Benefit Plans (Fair Values of the Corporation's Qualified Defined Benefit Pension Plan Investments Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Fair value of plan assets in qualified defined benefit pension plan, Excluding assets valued at net asset value	$ 1,569	$ 2,712
Fair value of plan assets in qualified defined benefit pension plan	3,454	3,349
Equity securities | Mutual funds
Fair value of plan assets in qualified defined benefit pension plan		4
Equity securities | Common stock
Fair value of plan assets in qualified defined benefit pension plan		1,266
Debt securities | U.S. Treasury and other U.S. government agency securities
Fair value of plan assets in qualified defined benefit pension plan	599	494
Debt securities | Corporate and municipal bonds and notes
Fair value of plan assets in qualified defined benefit pension plan	893	861
Debt securities | Mortgage-backed secutities
Fair value of plan assets in qualified defined benefit pension plan	27	29
Debt securities | Collective investments funds
Fair value of plan assets in qualified defined benefit pension plan	1,885	637
Private placements | Private placements
Fair value of plan assets in qualified defined benefit pension plan	50	58
Level 1
Fair value of plan assets in qualified defined benefit pension plan, Excluding assets valued at net asset value	595	1,762
Level 1 | Equity securities | Mutual funds
Fair value of plan assets in qualified defined benefit pension plan		4
Level 1 | Equity securities | Common stock
Fair value of plan assets in qualified defined benefit pension plan		1,266
Level 1 | Debt securities | U.S. Treasury and other U.S. government agency securities
Fair value of plan assets in qualified defined benefit pension plan	595	492
Level 1 | Debt securities | Corporate and municipal bonds and notes
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 1 | Debt securities | Mortgage-backed secutities
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 1 | Private placements | Private placements
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 2
Fair value of plan assets in qualified defined benefit pension plan, Excluding assets valued at net asset value	924	892
Level 2 | Equity securities | Mutual funds
Fair value of plan assets in qualified defined benefit pension plan		0
Level 2 | Equity securities | Common stock
Fair value of plan assets in qualified defined benefit pension plan		0
Level 2 | Debt securities | U.S. Treasury and other U.S. government agency securities
Fair value of plan assets in qualified defined benefit pension plan	4	2
Level 2 | Debt securities | Corporate and municipal bonds and notes
Fair value of plan assets in qualified defined benefit pension plan	893	861
Level 2 | Debt securities | Mortgage-backed secutities
Fair value of plan assets in qualified defined benefit pension plan	27	29
Level 2 | Private placements | Private placements
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3
Fair value of plan assets in qualified defined benefit pension plan, Excluding assets valued at net asset value	50	58
Level 3 | Equity securities | Mutual funds
Fair value of plan assets in qualified defined benefit pension plan		0
Level 3 | Equity securities | Common stock
Fair value of plan assets in qualified defined benefit pension plan		0
Level 3 | Debt securities | U.S. Treasury and other U.S. government agency securities
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3 | Debt securities | Corporate and municipal bonds and notes
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3 | Debt securities | Mortgage-backed secutities
Fair value of plan assets in qualified defined benefit pension plan	0	0
Level 3 | Private placements | Private placements
Fair value of plan assets in qualified defined benefit pension plan	$ 50	$ 58

X

- Definition

Total assets at fair value in the fair value hierarchy valued on a nonrecurring basis.

+ References

No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-SubTopic 20
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