XML 106 R91.htm IDEA: XBRL DOCUMENT
v3.20.2

Variable Interest Entities - Summary of the Impact of Qualifying LIHTC Investments (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Low income housing tax credits |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |
Amortization of qualifying LIHTC investments | $ 8,273 | $ 4,436 | $ 19,586 | $ 12,721
Affordable Housing Tax Credits And Other Tax Benefits | (6,738) | (3,607) | (16,094) | (10,758)
Other tax benefits related to qualifying LIHTC investments |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |
Affordable Housing Tax Credits And Other Tax Benefits | $ (3,034) | $ (1,751) | $ (8,172) | $ (4,970)

X
- Definition Amount of affordable housing tax credits and other tax benefits recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 740 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=116633289&loc=SL49122993-202985 + Details
Name: | us-gaap_AffordableHousingTaxCreditsAndOtherTaxBenefitsAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of amortization expense of investment in qualified affordable housing projects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 740 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=116633289&loc=SL49122993-202985 + Details
Name: | us-gaap_AmortizationMethodQualifiedAffordableHousingProjectInvestmentsAmortization
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_VariableInterestEntityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=fhn_LowIncomeHousingTaxCreditsMemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=fhn_OtherTaxBenefitsRelatedToQualifyingLihtcInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |