XML 66 R52.htm IDEA: XBRL DOCUMENT
v3.22.2.2

Allowance for Credit Losses - Narrative (Details) - USD ($) $ in Millions | Sep. 30, 2022 | Jun. 30, 2022 | Dec. 31, 2021 | Sep. 30, 2021 | Jun. 30, 2021 | Dec. 31, 2020
--- | --- | --- | --- | --- | --- | ---
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for loan and lease losses (less than) | $ 664 | $ 624 | $ 670 | $ 734 | $ 815 | $ 963
COVID-19 Deferrals |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Allowance for loan and lease losses (less than) | $ 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_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 45 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446 + Details
Name: | us-gaap_FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_UnusualOrInfrequentItemAxis=fhn_COVID19DeferralsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |