XML 168 R141.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Derivatives - Gains/(Losses) on Derivatives Associated with Interest Rate Risk Management Activities (Details) - Hedging Instruments And Hedged Items - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Customer Interest Rate Contracts Hedging | Customer interest rate contracts |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gains/(losses) related to interest rate derivatives | $ (268) | $ 357 | $ 92
Customer Interest Rate Contracts Hedging | Offsetting upstream interest rate contracts |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gains/(losses) related to interest rate derivatives | 268 | (357) | (92)
Debt Hedging | Interest rate contracts |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gains/(losses) related to interest rate derivatives | 0 | 2 | 13
Debt Hedging | Term Borrowings |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gains/(losses) related to term borrowings | $ 0 | $ (2) | $ (13)

X
- Definition Gain Loss Related To Changes In Fair Value Of Term Borrowings Due To Interest Rate Risk + References No definition available. + Details
Name: | fhn_GainLossRelatedToChangesInFairValueOfTermBorrowingsDueToInterestRateRisk
Namespace Prefix: | fhn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Gains Losses Related To Interest Rate Derivatives + References No definition available. + Details
Name: | fhn_GainsLossesRelatedToInterestRateDerivatives
Namespace Prefix: | fhn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_DerivativeInstrumentsGainLossLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=fhn_CustomerInterestRateContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=fhn_OffsettingUpstreamInterestRateContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_LongTermDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |