Derivative Financial Instruments (Details Textuals) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Derivative Financial Instruments (Textuals) [Abstract]
Credit risks from interest rate swaps used for trading purposes	$ 330,900,000	$ 357,700,000	$ 330,900,000	$ 357,700,000	$ 263,000,000
Additional Derivative Financial Instruments (Textuals) [Abstract]
Aggregate credit risk, net of collateral	38,000,000		38,000,000		39,900,000
Investment securities and cash collateral pledged by Huntington	199,000,000		199,000,000
Investment securities and cash collateral pledged to Huntington	141,700,000		141,700,000
Additional collateral to be provided in case of credit downgrades	3,400,000		3,400,000
Increase (decrease) to net interest income due to derivative adjustment	27,400,000	43,900,000	89,300,000	150,300,000
Expected after-tax unrealized gains on cash flow hedging derivatives reclassified to earnings	35,100,000		35,100,000
Interest Rate Cap [Member]
Derivative Financial Instruments (Textuals) [Abstract]
Purchase of interest rate caps and derivative financial instruments, notional value	900,000,000		900,000,000
Interest rate caps sold, value	900,000,000		900,000,000
Swap [Member]
Derivative Financial Instruments (Textuals) [Abstract]
Total derivative liabilities	900,000		900,000
Derivative used in trading activity [Member]
Derivative Financial Instruments (Textuals) [Abstract]
Net derivative liability	54,300,000	38,800,000	54,300,000	38,800,000	46,300,000
Derivative financial instruments used by Huntington on behalf of customers including offsetting derivatives, notional value	10,700,000,000	9,400,000,000	10,700,000,000	9,400,000,000	9,800,000,000
Derivative used in Mortgage Banking Activities [Member]
Derivative Financial Instruments (Textuals) [Abstract]
Net derivative liability	(2,870,000)	5,742,000	(2,870,000)	5,742,000	21,158,000
Purchase of interest rate caps and derivative financial instruments, notional value	1,400,000,000	2,800,000,000	1,400,000,000	2,800,000,000	2,600,000,000
Total notional amount corresponds to trading assets, fair value	13,200,000		13,200,000
Total notional amount corresponds to trading liabilities, fair value	700,000		700,000
MSR hedging gains (losses)	30,300,000	24,300,000	39,100,000	82,500,000
Gains (losses) related to derivative instruments Included in total MSR	30,200,000	24,200,000	39,200,000	81,900,000
Total derivative liabilities	$ 11,967,000	$ 6,983,000	$ 11,967,000	$ 6,983,000	$ 2,328,000