v3.20.4
Borrowings (Narrative) (Details)
$ in Millions
12 Months Ended
Dec. 31, 2020
USD ($)
agreement
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Debt Instrument [Line Items]      
Short-term borrowings $ 0 $ 2,050  
Gain (Loss) on Extinguishment of Debt (22) $ (16) $ 0
Total Borrowing Capacity with the FHLB $ 16,200    
Debt, Weighted Average Interest Rate 2.70% 3.40% 3.20%
Proceeds from Issuance of Debt $ 750    
Federal Home Loan Bank Advances [Member]      
Debt Instrument [Line Items]      
FHLB Advances Weighted Average Interest Rate   1.90% 2.60%
Minimum [Member] | Subordinated Debt [Member]      
Debt Instrument [Line Items]      
Debt Instrument, Interest Rate, Stated Percentage 6.45%    
Maximum [Member] | Subordinated Debt [Member]      
Debt Instrument [Line Items]      
Debt Instrument, Interest Rate, Stated Percentage 7.75%    
Parent Company [Member]      
Debt Instrument [Line Items]      
Gain (Loss) on Extinguishment of Debt $ (14) $ (16) $ 0
Parent Company [Member] | Subordinated Debt [Member]      
Debt Instrument [Line Items]      
Proceeds from Issuance of Subordinated Long-term Debt $ 553    
Number Of Issuances Of Debt | agreement 3    
Regions Bank [Member] | Subordinated Debt [Member]      
Debt Instrument [Line Items]      
Proceeds from Issuance of Subordinated Long-term Debt $ 496    
Number Of Issuances Of Debt | agreement 1