v3.25.4
Employee Benefit Plans (Presentation Of The Fair Value Of Regions' Qualified Defined-Benefit Pension Plans' Financial Assets) (Details) - USD ($)
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 1,877,000,000 $ 1,874,000,000 $ 1,936,000,000
Defined Benefit Plan, Common Collective Trust | Fixed Income Funds [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 102,000,000 117,000,000  
Defined Benefit Plan, Common Collective Trust | Equity Funds      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 114,000,000 126,000,000  
Defined Benefit Plan, Common Collective Trust | International Fund [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 93,000,000 120,000,000  
Collective Investment Trust Funds [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 309,000,000 363,000,000  
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 94,000,000 119,000,000  
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 178,000,000 172,000,000  
Estimate of Fair Value [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 1,296,000,000 1,220,000,000  
Estimate of Fair Value [Member] | Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 30,000,000 27,000,000  
Estimate of Fair Value [Member] | Fixed Income Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 1,038,000,000 979,000,000  
Estimate of Fair Value [Member] | Fixed Income Securities [Member] | US Treasury and Government [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 508,000,000 362,000,000  
Estimate of Fair Value [Member] | Fixed Income Securities [Member] | Federal Agency Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 3,000,000 11,000,000  
Estimate of Fair Value [Member] | Fixed Income Securities [Member] | Corporate Bond Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 527,000,000 606,000,000  
Estimate of Fair Value [Member] | Equity Securities [Member] | Domestic [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 128,000,000 124,000,000  
Estimate of Fair Value [Member] | Mutual Funds [Member] | International [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 100,000,000 90,000,000  
Estimate of Fair Value [Member] | Level 1 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 766,000,000 603,000,000  
Estimate of Fair Value [Member] | Level 1 [Member] | Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 30,000,000 27,000,000  
Estimate of Fair Value [Member] | Level 1 [Member] | Fixed Income Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 508,000,000 362,000,000  
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 Assets, Fair Value 508,000,000 362,000,000  
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 Assets, Fair Value 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 Assets, Fair Value 0 0  
Estimate of Fair Value [Member] | Level 1 [Member] | Equity Securities [Member] | Domestic [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 128,000,000 124,000,000  
Estimate of Fair Value [Member] | Level 1 [Member] | Mutual Funds [Member] | International [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 100,000,000 90,000,000  
Estimate of Fair Value [Member] | Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 530,000,000 617,000,000  
Estimate of Fair Value [Member] | Level 2 [Member] | Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 0 0  
Estimate of Fair Value [Member] | Level 2 [Member] | Fixed Income Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 530,000,000 617,000,000  
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 Assets, Fair Value 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 Assets, Fair Value 3,000,000 11,000,000  
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 Assets, Fair Value 527,000,000 606,000,000  
Estimate of Fair Value [Member] | Level 2 [Member] | Equity Securities [Member] | Domestic [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 0 0  
Estimate of Fair Value [Member] | Level 2 [Member] | Mutual Funds [Member] | International [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 0 0  
Estimate of Fair Value [Member] | Level 3 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 0 0  
Estimate of Fair Value [Member] | Level 3 [Member] | Cash and Cash Equivalents [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 0 0  
Estimate of Fair Value [Member] | Level 3 [Member] | Fixed Income Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 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 Assets, Fair Value 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 Assets, Fair Value 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 Assets, Fair Value 0 0  
Estimate of Fair Value [Member] | Level 3 [Member] | Equity Securities [Member] | Domestic [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value 0 0  
Estimate of Fair Value [Member] | Level 3 [Member] | Mutual Funds [Member] | International [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan Assets, Fair Value $ 0 $ 0