Maximum exposure to loss unconsolidated VIE unamortized investments.

No definition available.

Name:	key_MaximumExposureToLossUnconsolidatedVieUnamortizedInvestments
Namespace Prefix:	key_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Definition

Variable interest entity maximum exposure to loss recapture tax credits claim.

+ References

No definition available.

+ Details

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

- Definition

Variable interest entity settlement value of third party interests.

+ References

No definition available.

+ Details

Name:	key_VariableInterestEntitySettlementValueOfThirdPartyInterests
Namespace Prefix:	key_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Variable interest entity settlement value of third party interests including reserves.

+ References

No definition available.

+ Details

Name:	key_VariableInterestEntitySettlementValueOfThirdPartyInterestsIncludingReserves
Namespace Prefix:	key_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Total assets of operating partnerships that are held by the consolidated guaranteed funds.

+ References

No definition available.

+ Details

Name:	key_VariableInterestEntityUnconsolidatedOperatingPartnershipsAssets
Namespace Prefix:	key_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 16

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4568740-111683

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

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph A3

-Appendix A

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 55

-Paragraph 4I

-URI http://asc.fasb.org/extlink&oid=18733213&loc=SL4590271-111686

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4568447-111683

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 25

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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

- Definition

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5710-111685

+ Details

Name:	us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph a

-URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5728-111685

+ Details

Name:	us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Variable Interest Entities (Details Textual) (USD $) In Millions, unless otherwise specified																	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Jun. 30, 2012 Retained Earnings [Member]	Dec. 31, 2011 Retained Earnings [Member]	Sep. 30, 2011 Retained Earnings [Member]	Jun. 30, 2011 Retained Earnings [Member]	Dec. 31, 2010 Retained Earnings [Member]	Jan. 01, 2010 Retained Earnings [Member]	Jun. 30, 2012 LIHTC funds [Member]	Jun. 30, 2012 LIHTC funds [Member] Maximum [Member]	Jun. 30, 2012 LIHTC funds [Member] Minimum [Member]	Jun. 30, 2012 LIHTC funds [Member] Investments [Member]	Sep. 30, 2011 LIHTC funds [Member] Retained Earnings [Member]	Dec. 31, 2010 LIHTC funds [Member] Retained Earnings [Member]	Jun. 30, 2012 Education Loan Securitization Trusts [Member]	Jun. 30, 2012 LIHTC investments [Member]
Variable Interest Entities (Textual) [Abstract]
Loan securitization trust VIEs										$ 91			$ 52			$ 2,611
Maximum exposure to Loss, Unconsolidated VIE																	399
Variable Interest Entity, Carrying Amount of Assets, Unconsolidated VIE										119							1,012
Settlement value of third party interest, approximately											21	12
Settlement value of third party interest, reserves										84
Cumulative effect adjustment to beginning balance of Retained Earnings	10,176	9,922	9,737	6,595	6,246	45	5,926	5,557	45					45	45
Recapture tax claims																	95
Additional Investments in Unconsolidated LIHTC Operating Partnerships Held By Consolidated LIHTC																	$ 987