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Employee Benefit Plans (Presentation Of The Fair Value Of Regions' Qualified Defined-Benefit Pension Plans' Financial Assets) (Details) - USD ($) | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 1,936,000,000 | $ 1,970,000,000 | $ 2,554,000,000
Defined Benefit Plan, Common Collective Trust | Fixed Income Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Assets, Fair Value | 111,000,000 | 340,000,000 |
Defined Benefit Plan, Common Collective Trust | International Fund [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Assets, Fair Value | 117,000,000 | 40,000,000 |
Defined Benefit Plan, Common Collective Trust | Equity Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Assets, Fair Value | 119,000,000 | 168,000,000 |
Collective Investment Trust Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Assets, Fair Value | 347,000,000 | 548,000,000 |
Fair Value Measured at Net Asset Value Per Share | Real Estate Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Assets, Fair Value | 144,000,000 | 177,000,000 |
Fair Value Measured at Net Asset Value Per Share | Private Equity Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Assets, Fair Value | 167,000,000 | 172,000,000 |
Estimate of Fair Value [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 1,278,000,000 | 1,073,000,000 |
Estimate of Fair Value [Member] | Cash and Cash Equivalents [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 74,000,000 | 34,000,000 |
Estimate of Fair Value [Member] | Fixed Income Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 969,000,000 | 649,000,000 |
Estimate of Fair Value [Member] | Fixed Income Securities [Member] | US Treasury and Government [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 359,000,000 | 280,000,000 |
Estimate of Fair Value [Member] | Fixed Income Securities [Member] | Federal Agency Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 7,000,000 | 15,000,000 |
Estimate of Fair Value [Member] | Fixed Income Securities [Member] | Corporate Bond Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 603,000,000 | 354,000,000 |
Estimate of Fair Value [Member] | Equity Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 132,000,000 | 265,000,000 |
Estimate of Fair Value [Member] | Equity Securities [Member] | Domestic [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 132,000,000 | 135,000,000 |
Estimate of Fair Value [Member] | Equity Securities [Member] | International [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 130,000,000 |
Estimate of Fair Value [Member] | Mutual Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 103,000,000 | 125,000,000 |
Estimate of Fair Value [Member] | Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 668,000,000 | 704,000,000 |
Estimate of Fair Value [Member] | Level 1 [Member] | Cash and Cash Equivalents [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 74,000,000 | 34,000,000 |
Estimate of Fair Value [Member] | Level 1 [Member] | Fixed Income Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 359,000,000 | 280,000,000 |
Estimate of Fair Value [Member] | Level 1 [Member] | Fixed Income Securities [Member] | US Treasury and Government [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 359,000,000 | 280,000,000 |
Estimate of Fair Value [Member] | Level 1 [Member] | Fixed Income Securities [Member] | Federal Agency Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 1 [Member] | Fixed Income Securities [Member] | Corporate Bond Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 1 [Member] | Equity Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 132,000,000 | 265,000,000 |
Estimate of Fair Value [Member] | Level 1 [Member] | Equity Securities [Member] | Domestic [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 132,000,000 | 135,000,000 |
Estimate of Fair Value [Member] | Level 1 [Member] | Equity Securities [Member] | International [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 130,000,000 |
Estimate of Fair Value [Member] | Level 1 [Member] | Mutual Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 103,000,000 | 125,000,000 |
Estimate of Fair Value [Member] | Level 2 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 610,000,000 | 369,000,000 |
Estimate of Fair Value [Member] | Level 2 [Member] | Cash and Cash Equivalents [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 2 [Member] | Fixed Income Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 610,000,000 | 369,000,000 |
Estimate of Fair Value [Member] | Level 2 [Member] | Fixed Income Securities [Member] | US Treasury and Government [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 2 [Member] | Fixed Income Securities [Member] | Federal Agency Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 7,000,000 | 15,000,000 |
Estimate of Fair Value [Member] | Level 2 [Member] | Fixed Income Securities [Member] | Corporate Bond Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 603,000,000 | 354,000,000 |
Estimate of Fair Value [Member] | Level 2 [Member] | Equity Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 2 [Member] | Equity Securities [Member] | Domestic [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 2 [Member] | Equity Securities [Member] | International [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 2 [Member] | Mutual Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Cash and Cash Equivalents [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Fixed Income Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Fixed Income Securities [Member] | US Treasury and Government [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Fixed Income Securities [Member] | Federal Agency Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Fixed Income Securities [Member] | Corporate Bond Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Equity Securities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Equity Securities [Member] | Domestic [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Equity Securities [Member] | International [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0 |
Estimate of Fair Value [Member] | Level 3 [Member] | Mutual Funds [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 | $ 0 |

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