Asset Quality (Details 9) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Changes in the liability for credit losses on lending-related commitments
Beginning Balance	$ 69	$ 119	$ 73	$ 121
Provision (credit) for losses on lending-related commitments	(12)	(10)	(16)	(12)
Ending Balance	$ 57	$ 109	$ 57	$ 109

Name:

key_ChangesInLiabilityForCreditLossesOnLendingRelatedCommitmentAbstract

Namespace Prefix:

key

Data Type:

xbrli:stringItemType

Balance Type:

na

Period Type:

duration