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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, 2021
Dec. 31, 2020
Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 2,554,000,000 $ 2,469,000,000 $ 2,299,000,000
Collective Investment Trust Funds [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 717,000,000 671,000,000  
Defined Benefit Plan, Common Collective Trust | Fixed Income Funds [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value [1] 468,000,000 408,000,000  
Defined Benefit Plan, Common Collective Trust | International Fund [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value [1] 45,000,000 46,000,000  
Defined Benefit Plan, Common Collective Trust | Equity Funds      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value [1] 204,000,000 217,000,000  
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 [1] 167,000,000 188,000,000  
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 [1] 227,000,000 280,000,000  
Estimate of Fair Value [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 1,443,000,000 1,330,000,000  
Estimate of Fair Value [Member] | Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 116,000,000 50,000,000  
Estimate of Fair Value [Member] | Fixed Income Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 891,000,000 807,000,000  
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 346,000,000 299,000,000  
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 36,000,000 18,000,000  
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 509,000,000 490,000,000  
Estimate of Fair Value [Member] | Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 288,000,000 294,000,000  
Estimate of Fair Value [Member] | Equity Securities [Member] | Domestic [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 146,000,000 130,000,000  
Estimate of Fair Value [Member] | Equity Securities [Member] | International [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 142,000,000 164,000,000  
Estimate of Fair Value [Member] | Mutual Funds [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 148,000,000 179,000,000  
Estimate of Fair Value [Member] | Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 898,000,000 822,000,000  
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 116,000,000 50,000,000  
Estimate of Fair Value [Member] | Level 1 [Member] | Fixed Income Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 346,000,000 299,000,000  
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 346,000,000 299,000,000  
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 288,000,000 294,000,000  
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 146,000,000 130,000,000  
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 142,000,000 164,000,000  
Estimate of Fair Value [Member] | Level 1 [Member] | Mutual Funds [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 148,000,000 179,000,000  
Estimate of Fair Value [Member] | Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 545,000,000 508,000,000  
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 545,000,000 508,000,000  
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 36,000,000 18,000,000  
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 509,000,000 490,000,000  
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] | International [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] | International [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 0 $ 0  
[1] In accordance with accounting guidance, investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient are not required to be classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of amounts reported in the fair value hierarchy to amounts reported on the balance sheet.