XML 146 R119.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Retirement Plans and Other Employee Benefits - Schedule of Assumptions Used in the Defined Benefit Plans (Details) | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Qualified pension |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan assumptions used calculating benefit obligation, discount rate | 2.95% | 2.63% | 3.31%
Defined benefit plan assumptions used calculating net periodic benefit cost, discount rate | 2.64% | 3.31% | 4.43%
Nonqualified pension |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan assumptions used calculating benefit obligation, discount rate | 2.65% | 2.24% | 3.08%
Defined benefit plan assumptions used calculating net periodic benefit cost, discount rate | 2.24% | 3.08% | 4.26%
Other nonqualified pension |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan assumptions used calculating benefit obligation, discount rate | 1.99% | 1.41% | 2.57%
Defined benefit plan assumptions used calculating net periodic benefit cost, discount rate | 1.41% | 2.57% | 3.83%
Postretirement benefits | Minimum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan assumptions used calculating benefit obligation, discount rate | 2.43% | 1.92% | 2.85%
Defined benefit plan assumptions used calculating net periodic benefit cost, discount rate | 1.93% | 2.87% | 4.04%
Postretirement benefits | Maximum |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan assumptions used calculating benefit obligation, discount rate | 3.07% | 2.81% | 3.44%
Defined benefit plan assumptions used calculating net periodic benefit cost, discount rate | 2.81% | 3.44% | 4.56%
Qualified pension/ postretirement benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan assumptions used calculating net periodic benefit cost, expected long-term rate of return on plan assets | 2.30% | 3.45% | 4.80%
Postretirement benefit (retirees post January 1, 1993) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan assumptions used calculating net periodic benefit cost, expected long-term rate of return on plan assets | 5.80% | 6.40% | 6.85%
Postretirement benefit (retirees prior to January 1, 1993) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan assumptions used calculating net periodic benefit cost, expected long-term rate of return on plan assets | 1.00% | 0.90% | 0.05%

X
- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2919-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=us-gaap_QualifiedPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=us-gaap_NonqualifiedPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=fhn_OtherNonqualifiedPensionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=us-gaap_PostretirementBenefitCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=fhn_QualifiedPensionPostRetirementBenefitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=fhn_PostretirementBenefitPostJanuaryOneNineteenNinetyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTaxStatusAxis=fhn_PostretirementBenefitPriorToJanuaryOneNineteenNinetyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |