Consolidated Statements of Income (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements of Income [Abstract]
Net tax effect on loss from discontinued operations	$ (26)	$ (14)	$ (28)

Net tax effect on income (loss) from discontinued operations.

No definition available.

Name:	key_NetTaxEffectOnIncomeLossFromDiscontinuedOperations
Namespace Prefix:	key_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration