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Income Taxes And Tax-Related Items Reconciliation of Expected Income Tax Expense at the Federal Statutory Rate to the Corporation's Provision for Income Taxes (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
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Dec. 31, 2021 | Sep. 30, 2021 | Jun. 30, 2021 | Mar. 31, 2021 | Dec. 31, 2020 | [1] | Sep. 30, 2020 | [1] | Jun. 30, 2020 | [1] | Mar. 31, 2020 | [1] | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Income Tax Disclosure [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Tax based on federal statutory rate, amount |  |  |  |  |  |  |  |  | $ 313 | $ 130 |  | $ 323 |
Tax based on federal statutory rate, percent |  |  |  |  |  |  |  |  | 21.00% | 21.00% |  | 21.00% |
State income tax, amount |  |  |  |  |  |  |  |  | $ 35 | $ 18 |  | $ 34 |
State income tax, percent |  |  |  |  |  |  |  |  | 2.40% | 2.90% |  | 2.20% |
Affordable housing and historic credits, amount |  |  |  |  |  |  |  |  | $ (13) | $ (12) |  | $ (11) |
Affordable housing and historic credits, amount, rate |  |  |  |  |  |  |  |  | (0.90%) | (1.90%) |  | (0.70%) |
Bank-owned life insurance, amount |  |  |  |  |  |  |  |  | $ (10) | $ (10) |  | $ (9) |
Bank-owned life insurance, percent |  |  |  |  |  |  |  |  | (0.60%) | (1.60%) |  | (0.60%) |
FDIC insurance expense, amount |  |  |  |  |  |  |  |  | $ 5 | $ 7 |  | $ 5 |
FDIC insurance expense, rate |  |  |  |  |  |  |  |  | 0.30% | 1.10% |  | 0.30% |
Employee Stock Transactions, amount |  |  |  |  |  |  |  |  | $ (3) | $ (1) |  | $ (12) |
Employee Stock Transactions, percent |  |  |  |  |  |  |  |  | (0.20%) | (0.20%) |  | (0.80%) |
Tax-related interest and penalties, amount |  |  |  |  |  |  |  |  | $ 0 | $ (2) |  | $ 2 |
Tax-related interest and penalties, percent |  |  |  |  |  |  |  |  | 0.00% | (0.30%) |  | 0.10% |
Other, amount |  |  |  |  |  |  |  |  | $ (5) | $ (6) |  | $ 4 |
Other, percent |  |  |  |  |  |  |  |  | (0.40%) | (1.00%) |  | 0.30% |
Provision (benefit) for income taxes | $ 61 | $ 70 | $ 93 | $ 98 | $ 65 | $ 50 | $ 28 | $ (19) | $ 322 | $ 124 | [2] | $ 336 | [2]
Provision for income taxes, percent |  |  |  |  |  |  |  |  | 21.60% | 20.00% |  | 21.80% |
[1] | Recast to reflect the retrospective application of the Corporation's election to change the accounting methodology for certain components of defined pension benefit credit. Refer to Note 1 for further information.
[2] | See Defined Benefit Pension and Other Postretirement Costs in Note 1.

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- Definition The tax effects percentage of employee stock option transactions that are recognized differently for financial reporting and tax purposes, occurring during the period and charged or credited directly to shareholders' equity. + References No definition available. + Details
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- Definition The portion of the difference between total income tax expense (benefit) as reported in the Income Statement for the period and the expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to interest on income tax liabilities. + References No definition available. + Details
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