Derivatives and Hedging Activities (Details Textual) (USD $)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Derivatives and Hedging Activities (Textual) [Abstract]
Net liability position total	$ 217,000,000	$ 250,000,000	$ 250,000,000
Cash and securities collateral posted	70,000,000	64,000,000	33,000,000
Derivatives and Hedging Activities (Additional Textual) [Abstract]
Derivative assets after effects of bilateral collateral and master netting agreements	183,000,000
Derivative liabilities after effects of bilateral collateral and master netting agreements	61,000,000
Derivative assets not designated as hedging instruments after effects of bilateral collateral and master netting agreements, and a reserve for potential future losses	635,000,000
Derivative liabilities not designated as hedging instruments after effects of bilateral collateral and master netting agreements, and a reserve for potential future losses	824,000,000
Amount of debt being hedged under foreign currency exchange risk	0
Reclassification of net losses on derivative instruments from AOCI	5,000,000
Length of time hedged in cash flow hedge	12 months
Reclassification of net gains related to terminated cash flow hedges from AOCI to income	11,000,000
Maximum length of time over which forecasted transactions are hedged, years	17 years
Other comprehensive income unrealized loss on derivatives arising during period net of tax	6,000,000
Cash collateral netted against derivative assets	513,000,000	486,000,000	354,000,000
Cash collateral netted against derivative liabilities	11,000,000	11,000,000	19,000,000
Gross exposure on derivatives, after taking into account the effects of bilateral collateral and master netting agreements	1,000,000,000
Net exposure on derivatives, after taking into account, the effects of bilateral collateral and master netting agreements	244,000,000
Additional collateral held in the form of securities	231,000,000
Net exposure on derivatives to broker-dealers and banks, after the application of master netting agreements and collateral	13,000,000
Default reserve associated with the uncollateralized contracts	24,000,000	22,000,000
Gross exposure on derivatives, after taking into account the effects of master netting agreements	625,000,000
Net exposure on derivatives with clients, after the application of master netting agreements, collateral and the related reserve	574,000,000
Key Bank [Member]
Derivatives and Hedging Activities (Textual) [Abstract]
Net liability position total	589,000,000
Derivative assets included in net liability position	542,000,000
Derivative liabilities included in net liability position	1,100,000,000
Cash and securities collateral posted	537,000,000
Payments to terminate contracts	18,000,000
Key Corp [Member]
Derivatives and Hedging Activities (Textual) [Abstract]
Net liability position total	29,000,000
Derivative assets included in net liability position	0
Derivative liabilities included in net liability position	29,000,000
Cash and securities collateral posted	29,000,000
Payments to terminate contracts	3,000,000
Additional collateral amount	$ 3,000,000