XML 226 R152.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Employee Benefits - Fair Values of Postretirement Plan Assets by Asset Category (Details) - Other Postretirement Benefit Plans - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 40 | $ 40 | $ 57
Fair Value, Inputs, Level 1, 2 and 3 | Equity — U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 24 | 24 |
Fair Value, Inputs, Level 1, 2 and 3 | Equity — International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 7 | 7 |
Fair Value, Inputs, Level 1, 2 and 3 | Fixed income — U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 8 | 8 |
Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 39 | 39 |
Level 1 | Equity — U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 24 | 24 |
Level 1 | Equity — International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 7 | 7 |
Level 1 | Fixed income — U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 8 | 8 |
Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Level 2 | Equity — U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Level 2 | Equity — International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Level 2 | Fixed income — U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Level 3 | Equity — U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Level 3 | Equity — International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Level 3 | Fixed income — U.S. |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | 0 | 0 |
Measured at NAV | Other assets (measured at NAV) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets | $ 1 | $ 1 |

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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel12And3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=key_DefinedBenefitPlanMutualFundsEquityUSMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=key_DefinedBenefitPlanMutualFundsEquityNonUSMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=key_DefinedBenefitPlanMutualFundsFixedIncomeUSMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=key_DefinedBenefitPlanOtherAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |