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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

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