BORROWINGS - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2026	Sep. 30, 2025	Mar. 31, 2025	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