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 9 Months Ended
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
group
Sep. 30, 2016
USD ($)
Sep. 29, 2017
USD ($)
Jun. 30, 2017
USD ($)
Dec. 31, 2016
USD ($)
Jun. 30, 2016
USD ($)
Derivative [Line Items]                
Increase (decrease) to net interest income due to derivative adjustment $ 3,000,000 $ 18,000,000 $ 20,000,000 $ 58,000,000        
Derivative Liability 59,124,000   59,124,000       $ 98,286,000  
Gain (loss) to be reclassified during next 12 months, net (1,000,000)   (1,000,000)          
Purchase of interest rate caps and derivative financial instruments, notional value 9,700,000,000   9,700,000,000       10,800,000,000  
Total notional amount corresponds to trading assets, fair value 1,000,000   1,000,000          
Notional amount corresponds to trading liabilities, fair value (less than) 2,000,000   2,000,000          
Credit risks from interest rate swaps used for trading purposes 156,000,000   $ 156,000,000       196,000,000  
Number of primary groups | group     2          
Aggregate credit risk, net of collateral 30,000,000   $ 30,000,000       26,000,000  
Investment securities and cash collateral pledged by Huntington 144,000,000   144,000,000          
Investment securities and cash collateral pledged to Huntington 78,000,000   78,000,000          
Swap                
Derivative [Line Items]                
Derivative Liability 5,000,000   5,000,000          
Derivative used in trading activity                
Derivative [Line Items]                
Net derivative asset (liability) 84,000,000   84,000,000       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       21,000,000,000  
Derivative used in Mortgage Banking Activities                
Derivative [Line Items]                
Purchase of interest rate caps and derivative financial instruments, notional value 188,000,000   188,000,000       300,000,000  
Gains (losses) related to derivative instruments Included in total MSR 1,000,000 $ (1,000,000) 1,000,000 $ 17,000,000        
Share Swap Economic Hedge                
Derivative [Line Items]                
Purchase of interest rate caps and derivative financial instruments, notional value 39,000,000   39,000,000   $ 31,000,000 $ 8,000,000   $ 20,000,000
Derivative, Fair Value, Net 1,000,000   1,000,000          
Fair Value Hedging                
Derivative [Line Items]                
Purchase of interest rate caps and derivative financial instruments, notional value 8,375,000,000   8,375,000,000       7,475,000,000  
Cash Flow Hedging                
Derivative [Line Items]                
Purchase of interest rate caps and derivative financial instruments, notional value $ 1,325,000,000   $ 1,325,000,000       $ 3,325,000,000