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Allowance for Credit Losses - Rollforward of Allowance for Credit Losses (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | $ 963 | $ 200 | $ 180 |
Charge-offs | (59) | (156) | (59) |
Recoveries | 57 | 36 | 32 |
Initial allowance on loans purchased with credit deterioration |  | 287 |  |
Provision for credit losses | (310) | 503 | 45 |
Ending balance | 670 | 963 | $ 200 | $ 180
Accounting Standards Update [Extensible List] |  |  | Accounting Standards Update 2016-13 [Member] | Accounting Standards Update 2016-02 [Member]
Loans and leases | 54,859 | 58,232 |  |
Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 107 |  |
Ending balance |  |  | $ 107 |
Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 307 |  |
Ending balance |  |  | 307 |
Financial Asset Acquired with Credit Deterioration |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Additions in allowance for credit loss |  | 287 |  |
Funded and Unfunded Loan Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 1,048 | 206 |  |
Ending balance | 736 | 1,048 | 206 |
Funded Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Provision for credit losses | (291) | 489 | 47 |
Unfunded Commitment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 85 | 6 | 7 |
Provision for credit losses | (19) | 14 | (1) |
Initial reserve on loans acquired |  | 41 |  |
Ending balance | 66 | 85 | 6 | $ 7
Unfunded Commitment | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 24 |  |
Ending balance |  |  | 24 |
Unfunded Commitment | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 30 |  |
Ending balance |  |  | 30 |
Commercial |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Loans and leases | 31,068 | 33,104 |  |
Commercial | C&I |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 453 | 123 | 99 |
Charge-offs | (34) | (129) | (34) |
Recoveries | 21 | 9 | 7 |
Initial allowance on loans purchased with credit deterioration |  | 138 |  |
Ending balance | 334 | 453 | 123 | 99
Loans and leases | 31,068 | 33,104 |  |
Commercial | C&I | PCD Loans |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Charge-offs |  | (237) |  |
Commercial | C&I | Non-PCD Loans |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Provision for credit losses |  | 147 |  |
Commercial | C&I | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 19 |  |
Ending balance |  |  | 19 |
Commercial | C&I | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 142 |  |
Ending balance |  |  | 142 |
Commercial | C&I | Paycheck Protection Plan |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Loans and leases | 1,000 | 4,100 |  |
Commercial | C&I | Funded and Unfunded Loan Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 518 | 127 |  |
Ending balance | 380 | 518 | 127 |
Commercial | C&I | Funded Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Provision for credit losses | (106) | 293 | 51 |
Commercial | C&I | Unfunded Commitment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 65 | 4 | 4 |
Provision for credit losses | (19) | 32 | 0 |
Initial reserve on loans acquired |  | 12 |  |
Ending balance | 46 | 65 | 4 | 4
Commercial | C&I | Unfunded Commitment | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 17 |  |
Ending balance |  |  | 17 |
Commercial | C&I | Unfunded Commitment | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 21 |  |
Ending balance |  |  | 21 |
Commercial | Commercial Real Estate |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 242 | 36 | 31 |
Charge-offs | (5) | (5) | (1) |
Recoveries | 5 | 4 | 1 |
Initial allowance on loans purchased with credit deterioration |  | 100 |  |
Ending balance | 154 | 242 | 36 | 31
Loans and leases | 12,109 | 12,275 |  |
Commercial | Commercial Real Estate | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | (7) |  |
Ending balance |  |  | (7) |
Commercial | Commercial Real Estate | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 29 |  |
Ending balance |  |  | 29 |
Commercial | Commercial Real Estate | Funded and Unfunded Loan Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 252 | 38 |  |
Ending balance | 166 | 252 | 38 |
Commercial | Commercial Real Estate | Funded Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Provision for credit losses | (88) | 114 | 5 |
Commercial | Commercial Real Estate | Unfunded Commitment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 10 | 2 | 3 |
Provision for credit losses | 2 | (19) | (1) |
Initial reserve on loans acquired |  | 26 |  |
Ending balance | 12 | 10 | 2 | 3
Commercial | Commercial Real Estate | Unfunded Commitment | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 1 |  |
Ending balance |  |  | 1 |
Commercial | Commercial Real Estate | Unfunded Commitment | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 3 |  |
Ending balance |  |  | 3 |
Consumer |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Loans and leases | 10,772 | 11,725 |  |
Consumer | Consumer real estate |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 242 | 28 | 37 |
Charge-offs | (5) | (8) | (8) |
Recoveries | 27 | 18 | 20 |
Initial allowance on loans purchased with credit deterioration |  | 44 |  |
Ending balance | 163 | 242 | 28 | 37
Loans and leases | 10,772 | 11,725 |  |
Consumer | Consumer real estate | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 93 |  |
Ending balance |  |  | 93 |
Consumer | Consumer real estate | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 121 |  |
Ending balance |  |  | 121 |
Consumer | Consumer real estate | Funded and Unfunded Loan Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 252 | 28 |  |
Ending balance | 171 | 252 | 28 |
Consumer | Consumer real estate | Funded Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Provision for credit losses | (101) | 67 | (21) |
Consumer | Consumer real estate | Unfunded Commitment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 10 | 0 | 0 |
Provision for credit losses | (2) | 1 | 0 |
Initial reserve on loans acquired |  | 3 |  |
Ending balance | 8 | 10 | 0 | 0
Consumer | Consumer real estate | Unfunded Commitment | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 6 |  |
Ending balance |  |  | 6 |
Consumer | Consumer real estate | Unfunded Commitment | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 6 |  |
Ending balance |  |  | 6 |
Consumer | Credit card and other |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 26 | 13 | 13 |
Charge-offs | (15) | (14) | (16) |
Recoveries | 4 | 5 | 4 |
Initial allowance on loans purchased with credit deterioration |  | 5 |  |
Ending balance | 19 | 26 | 13 | 13
Loans and leases | 910 | 1,128 |  |
Consumer | Credit card and other | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 2 |  |
Ending balance |  |  | 2 |
Consumer | Credit card and other | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 15 |  |
Ending balance |  |  | 15 |
Consumer | Credit card and other | Funded and Unfunded Loan Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 26 | 13 |  |
Ending balance | 19 | 26 | 13 |
Consumer | Credit card and other | Funded Commitments |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Provision for credit losses | 4 | 15 | 12 |
Consumer | Credit card and other | Unfunded Commitment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance | 0 | 0 | 0 |
Provision for credit losses | 0 | 0 | 0 |
Initial reserve on loans acquired |  | 0 |  |
Ending balance | $ 0 | 0 | 0 | $ 0
Consumer | Credit card and other | Unfunded Commitment | Adjustment |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | 0 |  |
Ending balance |  |  | 0 |
Consumer | Credit card and other | Unfunded Commitment | Adjusted Balance |  |  |  |
Allowance for Loan and Lease Losses [Roll Forward] |  |  |  |
Beginning balance |  | $ 0 |  |
Ending balance |  |  | $ 0 |

X
- Definition Financing Receivable, Credit Loss, Initial Reserve on Loans Acquired + References No definition available. + Details
Name: | fhn_FinancingReceivableCreditLossInitialReserveOnLoansAcquired
Namespace Prefix: | fhn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
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