Fair Value of Assets and Liabilities - Summary Of Book Value And Estimated Fair Value Of Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	$ 61,018	$ 57,417
Short-term financial assets:
Interest-bearing deposits with banks	1,917	1,384
Securities purchased under agreements to resell	363	353
Trading securities	1,231	1,375
Loans held for sale:	613	590
Securities available for sale at fair value	8,100	8,836
Securities held to maturity	1,335	1,371
Derivative assets	861	458
Other Assets Financial Instruments [Abstract]
Total assets	82,533	78,953
Liabilities:
Trading liabilities	366	335
Short Term Financial Liabilities [Abstract]
Securities sold under agreements to repurchase	1,707	1,013
Long-Term Debt, Unclassified [Abstract]
Other long-term borrowings	1,157	1,597
Derivative liabilities	1,076	929
Total liabilities	73,740	70,406
Fair Value, Inputs, Level 3 | FHLB-Cincinnati Stock
Long-Term Debt, Unclassified [Abstract]
Restricted investments	51	50
Fair Value, Inputs, Level 3 | FRB Stock
Long-Term Debt, Unclassified [Abstract]
Restricted investments	203	203
Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	61,018	57,417
Short-term financial assets:
Interest-bearing deposits with banks	1,917	1,384
Federal funds sold	53	129
Securities purchased under agreements to resell	363	353
Total short-term financial assets	2,333	1,866
Trading securities	1,231	1,375
Loans held for sale:	613	590
Securities available for sale at fair value	8,100	8,836
Securities held to maturity	1,335	1,371
Derivative assets	863	460
Other Assets Financial Instruments [Abstract]
Tax credit investments	578	547
Deferred compensation mutual funds	99	112
Equity, mutual funds, and other	277	275
Total other assets	954	934
Total assets	76,447	72,849
Liabilities:
Defined maturity deposits	7,783	2,887
Trading liabilities	366	335
Short Term Financial Liabilities [Abstract]
Federal funds purchased	309	400
Securities sold under agreements to repurchase	1,706	1,013
Other short-term borrowings	492	1,093
Total short-term financial liabilities	2,507	2,506
Long-Term Debt, Unclassified [Abstract]
Real estate investment trust-preferred	46	46
Term borrowings—new market tax credit investment	65	66
Secured borrowings	12	3
Junior subordinated debentures	150	148
Other long-term borrowings	884	1,334
Total term borrowings	1,157	1,597
Derivative liabilities	1,102	958
Total liabilities	12,915	8,283
Reported Value Measurement | Commercial, financial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	32,828	31,473
Reported Value Measurement | Commercial Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	13,952	13,082
Reported Value Measurement | Consumer Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	13,457	12,053
Reported Value Measurement | Credit card and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	781	809
Reported Value Measurement | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held for sale:	88	51
Reported Value Measurement | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale:	496	506
Reported Value Measurement | Mortgage loans - LOCOM
Short-term financial assets:
Loans held for sale:	29	33
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	59,101	56,982
Short-term financial assets:
Interest-bearing deposits with banks	1,917	1,384
Federal funds sold	53	129
Securities purchased under agreements to resell	363	353
Total short-term financial assets	2,333	1,866
Trading securities	1,231	1,375
Loans held for sale:	617	596
Securities available for sale at fair value	8,100	8,836
Securities held to maturity	1,104	1,209
Derivative assets	863	460
Other Assets Financial Instruments [Abstract]
Tax credit investments	570	542
Deferred compensation mutual funds	99	112
Equity, mutual funds, and other	277	275
Total other assets	946	929
Total assets	74,295	72,253
Liabilities:
Defined maturity deposits	7,830	2,890
Trading liabilities	366	335
Short Term Financial Liabilities [Abstract]
Federal funds purchased	309	400
Securities sold under agreements to repurchase	1,706	1,013
Other short-term borrowings	492	1,093
Total short-term financial liabilities	2,507	2,506
Long-Term Debt, Unclassified [Abstract]
Real estate investment trust-preferred	47	47
Term borrowings—new market tax credit investment	59	59
Secured borrowings	12	3
Junior subordinated debentures	150	150
Other long-term borrowings	809	1,301
Total term borrowings	1,077	1,560
Derivative liabilities	1,102	958
Total liabilities	12,882	8,249
Unfunded Commitments [Abstract]
Loan commitments	2	1
Standby and other commitments	7	7
Estimate of Fair Value Measurement | Commercial, financial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	32,205	31,329
Estimate of Fair Value Measurement | Commercial Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	13,661	12,909
Estimate of Fair Value Measurement | Consumer Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	12,480	11,934
Estimate of Fair Value Measurement | Credit card and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	755	810
Estimate of Fair Value Measurement | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held for sale:	88	51
Estimate of Fair Value Measurement | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale:	500	512
Estimate of Fair Value Measurement | Mortgage loans - LOCOM
Short-term financial assets:
Loans held for sale:	29	33
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Short-term financial assets:
Interest-bearing deposits with banks	1,917	1,384
Federal funds sold	0	0
Securities purchased under agreements to resell	0	0
Total short-term financial assets	1,917	1,384
Trading securities	0	0
Loans held for sale:	0	0
Securities available for sale at fair value	0	0
Securities held to maturity	0	0
Derivative assets	10	9
Other Assets Financial Instruments [Abstract]
Tax credit investments	0	0
Deferred compensation mutual funds	99	112
Equity, mutual funds, and other	23	22
Total other assets	122	134
Total assets	2,049	1,527
Liabilities:
Defined maturity deposits	0	0
Trading liabilities	0	0
Short Term Financial Liabilities [Abstract]
Federal funds purchased	0	0
Securities sold under agreements to repurchase	0	0
Other short-term borrowings	0	0
Total short-term financial liabilities	0	0
Long-Term Debt, Unclassified [Abstract]
Real estate investment trust-preferred	0	0
Term borrowings—new market tax credit investment	0	0
Secured borrowings	0	0
Junior subordinated debentures	0	0
Other long-term borrowings	0	0
Total term borrowings	0	0
Derivative liabilities	8	8
Total liabilities	8	8
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1 | Commercial, financial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1 | Commercial Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1 | Consumer Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1 | Credit card and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1 | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held for sale:	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1 | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale:	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1 | Mortgage loans - LOCOM
Short-term financial assets:
Loans held for sale:	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Short-term financial assets:
Interest-bearing deposits with banks	0	0
Federal funds sold	53	129
Securities purchased under agreements to resell	363	353
Total short-term financial assets	416	482
Trading securities	1,208	1,350
Loans held for sale:	567	541
Securities available for sale at fair value	8,100	8,836
Securities held to maturity	1,104	1,209
Derivative assets	853	451
Other Assets Financial Instruments [Abstract]
Tax credit investments	0	0
Deferred compensation mutual funds	0	0
Equity, mutual funds, and other	0	0
Total other assets	0	0
Total assets	12,248	12,869
Liabilities:
Defined maturity deposits	7,830	2,890
Trading liabilities	366	335
Short Term Financial Liabilities [Abstract]
Federal funds purchased	309	400
Securities sold under agreements to repurchase	1,706	1,013
Other short-term borrowings	492	1,093
Total short-term financial liabilities	2,507	2,506
Long-Term Debt, Unclassified [Abstract]
Real estate investment trust-preferred	0	0
Term borrowings—new market tax credit investment	0	0
Secured borrowings	0	0
Junior subordinated debentures	0	0
Other long-term borrowings	809	1,301
Total term borrowings	809	1,301
Derivative liabilities	1,068	923
Total liabilities	12,580	7,955
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | Commercial, financial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | Commercial Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | Consumer Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | Credit card and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held for sale:	67	29
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale:	500	512
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | Mortgage loans - LOCOM
Short-term financial assets:
Loans held for sale:	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	59,101	56,982
Short-term financial assets:
Interest-bearing deposits with banks	0	0
Federal funds sold	0	0
Securities purchased under agreements to resell	0	0
Total short-term financial assets	0	0
Trading securities	23	25
Loans held for sale:	50	55
Securities available for sale at fair value	0	0
Securities held to maturity	0	0
Derivative assets	0	0
Other Assets Financial Instruments [Abstract]
Tax credit investments	570	542
Deferred compensation mutual funds	0	0
Equity, mutual funds, and other	254	253
Total other assets	824	795
Total assets	59,998	57,857
Liabilities:
Defined maturity deposits	0	0
Trading liabilities	0	0
Short Term Financial Liabilities [Abstract]
Federal funds purchased	0	0
Securities sold under agreements to repurchase	0	0
Other short-term borrowings	0	0
Total short-term financial liabilities	0	0
Long-Term Debt, Unclassified [Abstract]
Real estate investment trust-preferred	47	47
Term borrowings—new market tax credit investment	59	59
Secured borrowings	12	3
Junior subordinated debentures	150	150
Other long-term borrowings	0	0
Total term borrowings	268	259
Derivative liabilities	26	27
Total liabilities	294	286
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Commercial, financial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	32,205	31,329
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Commercial Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	13,661	12,909
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Consumer Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	12,480	11,934
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Credit card and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	755	810
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held for sale:	21	22
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale:	0	0
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Mortgage loans - LOCOM
Short-term financial assets:
Loans held for sale:	29	33
Contractual Amount
Unfunded Commitments [Abstract]
Loan commitments	25,402	25,953
Standby and other commitments	$ 728	$ 754