Quarterly report pursuant to Section 13 or 15(d)

LONG-TERM DEBT (Details)

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LONG-TERM DEBT (Details) - Senior Notes - USD ($)
3 Months Ended
Sep. 30, 2017
Aug. 07, 2017
Mar. 07, 2017
Huntington National Bank Senior Note Due March 2020, 2.97 Percent [Member]      
Debt Instrument [Line Items]      
Debt face amount     $ 700,000,000.0
Debt percent of value     99.994%
Debt stated interest rate     2.375%
Debt Instrument, Redemption Price, Percentage 100.00%    
Huntington National Bank Senior Floating Rate Notes Due March 2020 [Member]      
Debt Instrument [Line Items]      
Debt face amount     $ 300,000,000.0
Debt percent of value     100.00%
Debt Instrument, Description of Variable Rate Basis three month LIBOR    
Debt Instrument, Basis Spread on Variable Rate 51.00%    
Huntington National Bank Senior Note Due August 2022, 2.5 Percent [Member]      
Debt Instrument [Line Items]      
Debt face amount   $ 700,000,000.0  
Debt percent of value   99.762%  
Debt stated interest rate   2.50%