Mortgage Banking Activity - Residential Mortgage Loans (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Loans Receivable Held-for-sale, Net, Reconciliation to Cash Flow [Roll Forward]
Beginning Balance	$ 1,172
Ending Balance	590	$ 1,172
First Horizon Bank
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	39
Mortgage loans
Loans Receivable Held-for-sale, Net, Reconciliation to Cash Flow [Roll Forward]
Beginning Balance	250	409	$ 4
Acquired	0	0	320
Originations and purchases	1,275	2,836	2,499
Sales, net of gains	(1,481)	(3,025)	(2,405)
Mortgage loans transferred from (to) held for investment	0	30	(9)
Ending Balance	$ 44	$ 250	$ 409

Financing Receivable Held-for-sale, Reconciliation to Cash Flow, Acquired

No definition available.

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- Definition

Financing Receivable Held-for-sale, Reconciliation to Cash Flow, Mortgage Loans Transferred to (from) Held-For-Investment

+ References

No definition available.

+ Details

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- Definition

Financing Receivable Held-for-sale, Reconciliation to Cash Flow, Originations and Purchases

+ References

No definition available.

+ Details

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- 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.

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- Definition

Amount of gain (loss) on sale of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 5
-URI https://asc.fasb.org/extlink&oid=121570589&loc=d3e107425-111719

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- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7)
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

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- Definition

Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124265262&loc=d3e48678-111004

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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