XML 78 R88.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Securities - Additional Information (Details) | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($) loan position | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Debt Securities, Available-for-sale [Line Items] |  |  |
Impairment recognized in earnings | $ 0 | $ 0 | $ 0
Loans pledged as collateral | $ 8,000,000,000.0 |  |
Collateralized Mortgage Obligations [Member] |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Number of fixed rate collateralized mortgage obligations | loan | 240 |  |
Weighted average maturity collateralized mortgage life | 3 years 9 months 14 days |  |
Collateralized Mortgage Obligations [Member] |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Gross unrealized losses | $ 71,000,000 | 373,000,000 |
Residential Mortgage Backed Securities [Member] | Other Mortgage-Backed Securities [Member] |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Gross unrealized losses | $ 4,000,000 | 36,000,000 |
Securities in unrealized loss positions, number of positions | position | 186 |  |
Weighted average maturity mortgage backed securities | 3 years 7 months 2 days |  |
Commercial Mortgage Backed Securities [Member] |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Gross unrealized losses |  | $ 132,000,000 |
Commercial Mortgage Backed Securities [Member] | Other Mortgage-Backed Securities [Member] |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |
Gross unrealized losses | $ 40,000,000 |  |
Securities in unrealized loss positions, number of positions | position | 27 |  |
Weighted average maturity mortgage backed securities | 4 years 3 months |  |

X
- Definition Number of fixed-rate collateralized mortgage obligations. + References No definition available. + Details
Name: | key_NumberOfFixedRateCollateralizedMortgageObligations
Namespace Prefix: | key_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average maturity mortgage backed securities in years. + References No definition available. + Details
Name: | key_WeightedAverageMaturityCollateralizedMortgageLife
Namespace Prefix: | key_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted Average Maturity Mortgage Backed Securities + References No definition available. + Details
Name: | key_WeightedAverageMaturityMortgageBackedSecurities
Namespace Prefix: | key_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922888-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922888-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5086-111524 + Details
Name: | us-gaap_LoansPledgedAsCollateral
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of other-than-temporary impairment (OTTI) on investment in debt security, recognized in earnings. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 8A -URI http://asc.fasb.org/extlink&oid=118954083&loc=SL6284422-111562 + Details
Name: | us-gaap_OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CollateralizedMortgageObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=us-gaap_MortgageBackedSecuritiesOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |