No definition available.

Name:	key_CompliancePeriodOfProperty
Namespace Prefix:	key_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Expiration of guarantees.

No definition available.

Name:	key_ExpirationOfGuarantees
Namespace Prefix:	key_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	key_GuaranteesAbstract
Namespace Prefix:	key_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	key_ReturnGuaranteeAgreementAbstract
Namespace Prefix:	key_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph c

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Indicates, if estimable, (as a percentage) the approximate extent to which the proceeds from liquidation of any assets held either as collateral or by third parties would be expected to cover the maximum potential amount of future payments under the guarantee or each group of similar guarantees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

Name:	us-gaap_GuaranteeObligationsLiquidationProceedsPercentage
Namespace Prefix:	us-gaap_
Data Type:	us-types:percentItemType
Balance Type:	na
Period Type:	duration

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph b