Derivatives and Hedging Activities (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Derivatives and Hedging Activities (Additional Textual) [Abstract]
Derivative assets after effects of bilateral collateral and master netting agreements	$ 180
Derivative liabilities after effects of bilateral collateral and master netting agreements	63
Derivative assets not designated as hedging instruments after effects of bilateral collateral and master netting agreements, and a reserve for potential future losses	650
Derivative liabilities not designated as hedging instruments after effects of bilateral collateral and master netting agreements, and a reserve for potential future losses	817
Amount of debt being hedged under foreign currency exchange risk	0
Reclassification of net losses on derivative instruments from AOCI	19
Length of time hedged in cash flow hedge	Next twelve months
Reclassification of net gains related to terminated cash flow hedges from AOCI to income	12
Maximum length of time over which forecasted transactions are hedged, years	16 years
Cash collateral netted against derivative assets	450	486	264
Cash collateral netted against derivative liabilities	2	11	10
Gross exposure on derivatives, after taking into account the effects of bilateral collateral and master netting agreements	915
Net exposure on derivatives, after taking into account, the effects of bilateral collateral and master netting agreements	223
Additional collateral held in the form of securities	199
Net exposure on derivatives to broker-dealers and banks, after the application of master netting agreements and collateral	24
Default reserve associated with the uncollateralized contracts	22	22
Gross exposure on derivatives, after taking into account the effects of master netting agreements	674
Net exposure on derivatives with clients, after the application of master netting agreements, collateral and the related reserve	607
Payments to terminate contracts	13
Key Bank [Member]
Derivatives and Hedging Activities (Textual) [Abstract]
Net liability position total	626
Derivative assets included in net liability position	532
Derivative liabilities included in net liability position	1,200
Cash and securities collateral posted	626
Key Corp [Member]
Derivatives and Hedging Activities (Textual) [Abstract]
Net liability position total	5
Derivative assets included in net liability position	7
Derivative liabilities included in net liability position	12
Cash and securities collateral posted	$ 5