v3.26.1
BORROWINGS - Narrative (Details) - USD ($)
3 Months Ended 6 Months Ended
Mar. 31, 2026
Jun. 30, 2026
Dec. 31, 2025
Debt Instrument [Line Items]      
Carrying value of assets pledged as collateral against repurchase agreements   $ 0 $ 40,000,000
Maturity term   60 days  
Fixed-to-Floating Senior Notes Due April 12, 2028 | Senior Notes      
Debt Instrument [Line Items]      
Debt face amount $ 1,000,000,000.0    
Debt stated interest rate 4.623%    
Basis spread on variable rate 0.99%    
Fixed Rate Subordinated Note Due January, 28 2041 | Subordinated Notes      
Debt Instrument [Line Items]      
Debt face amount $ 750,000,000    
Debt stated interest rate 5.605%    
Huntington National Bank Unsecured Notes Maturing March 2033 | Credit Linked Notes      
Debt Instrument [Line Items]      
Debt face amount $ 410,000,000    
Debt stated interest rate 4.55%    
Huntington National Bank Unsecured Notes Maturing March 2033 | Credit Linked Notes | Minimum      
Debt Instrument [Line Items]      
Basis spread on variable rate 1.00%    
Huntington National Bank Unsecured Notes Maturing March 2033 | Credit Linked Notes | Maximum      
Debt Instrument [Line Items]      
Basis spread on variable rate 8.65%    
Huntington National Bank Unsecured Notes Maturing March 2033 | Credit Linked Notes | Weighted average      
Debt Instrument [Line Items]      
Basis spread on variable rate 4.15%    
Huntington National Bank Unsecured Notes Maturing March 2033 | Auto Loan Securitization Trust      
Debt Instrument [Line Items]      
Reference pool $ 3,500,000,000