Assets value of unconsolidated variable interest entities.

No definition available.

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- Definition

Maximum exposure to loss unconsolidated VIE unamortized investments.

+ References

No definition available.

+ Details

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Balance Type:	credit
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- Definition

Number of outstanding securitization trusts.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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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

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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

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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
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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- 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

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Variable Interest Entities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified					9 Months Ended
	Dec. 31, 2009 Segment, Discontinued Operations [Member] Trust	Sep. 30, 2013 LIHTC Funds [Member]	Sep. 30, 2013 LIHTC Funds [Member] Minimum [Member]	Sep. 30, 2013 LIHTC Funds [Member] Maximum [Member]	Sep. 30, 2013 LIHTC Investments [Member]	Sep. 30, 2013 Investments [Member] LIHTC Funds [Member]
Variable Interest Entity [Line Items]
Loan securitization trust VIEs		$ 24				$ 14
Settlement value of third-party interests, approximately			0	16
Settlement value of third-party interests, reserves		27
Number of outstanding securitization trusts	10
Variable Interest Entity, Carrying Amount of Assets, Unconsolidated VIE		97			762
Assets of unconsolidated LIHTC operating partnerships					762
Maximum exposure to loss, unconsolidated VIE					353
Recapture tax claim					100
Additional investments in unconsolidated LIHTC operating partnerships held by consolidated LIHTC					$ 773