Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details)

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DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details)
 3 Months Ended
Mar. 31, 2017
USD ($)
group
Mar. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
Derivative [Line Items]      
Increase (decrease) to net interest income due to derivative adjustment $ 10,000,000 $ 21,000,000  
Gain (loss) to be reclassified during next 12 months, net (3,000,000)    
Purchase of interest rate caps and derivative financial instruments, notional value 10,725,000,000    
Total notional amount corresponds to trading assets, fair value 1,000,000    
Notional amount corresponds to trading liabilities, fair value (less than) 2,000,000    
Credit risks from interest rate swaps used for trading purposes $ 171,000,000   $ 196,000,000
Number of primary groups | group 2    
Aggregate credit risk, net of collateral $ 27,000,000   26,000,000
Investment securities and cash collateral pledged by Huntington 140,000,000    
Investment securities and cash collateral pledged to Huntington 78,000,000    
Swap      
Derivative [Line Items]      
Derivative Liability 6,000,000    
Derivative used in trading activity      
Derivative [Line Items]      
Net derivative asset (liability) 81,000,000   80,000,000
Derivative financial instruments used by Huntington on behalf of customers including offsetting derivatives, notional value 21,000,000,000   21,000,000,000
Derivative used in Mortgage Banking Activities      
Derivative [Line Items]      
Purchase of interest rate caps and derivative financial instruments, notional value 200,000,000   300,000,000
Gains (losses) related to derivative instruments Included in total MSR (1,000,000) $ 12,000,000  
Net derivative asset (liability) 6,261,000   16,295,000
Share Swap Economic Hedge      
Derivative [Line Items]      
Purchase of interest rate caps and derivative financial instruments, notional value     20,000,000
Derivative, Fair Value, Net 10,000,000    
Other Credit Derivatives      
Derivative [Line Items]      
Derivative Asset, Notional Amount 596,000,000   $ 582,000,000
Deposits      
Derivative [Line Items]      
Purchase of interest rate caps and derivative financial instruments, notional value 0    
Fair Value Hedging      
Derivative [Line Items]      
Purchase of interest rate caps and derivative financial instruments, notional value 8,175,000,000    
Fair Value Hedging | Deposits      
Derivative [Line Items]      
Purchase of interest rate caps and derivative financial instruments, notional value 0    
Cash Flow Hedging      
Derivative [Line Items]      
Purchase of interest rate caps and derivative financial instruments, notional value 2,550,000,000    
Cash Flow Hedging | Deposits      
Derivative [Line Items]      
Purchase of interest rate caps and derivative financial instruments, notional value $ 0