Fair Value of Assets and Liabilities - Summary Of Book Value And Estimated Fair Value Of Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	$ 54,390	$ 54,189
Short-term financial assets:
Interest-bearing deposits with banks	13,548	14,907
Securities purchased under agreements to resell	567	488
Trading securities	1,823	1,601
Loans held for sale	1,014	1,172
Securities available-for-sale	9,242	8,707
Securities held to maturity	701	712
Derivative assets	211	323
Other assets:
Total assets	88,660	89,092
Liabilities:
Trading liabilities	513	426
Short-term financial liabilities:
Securities sold under agreements to repurchase	759	1,247
Term borrowings:
Other long term borrowings	1,591	1,590
Derivative liabilities	430	103
Total liabilities	79,964	80,598
Fair Value, Inputs, Level 3 | FHLB-Cincinnati Stock
Term borrowings:
Restricted investments	29	29
Fair Value, Inputs, Level 3 | FRB Stock
Term borrowings:
Restricted investments	203	203
Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	54,390	54,189
Short-term financial assets:
Interest-bearing deposits with banks	13,548	14,907
Federal funds sold	73	153
Securities purchased under agreements to resell	567	488
Total short-term financial assets	14,188	15,548
Trading securities	1,823	1,601
Loans held for sale	1,014	1,172
Securities available-for-sale	9,242	8,707
Securities held to maturity	701	712
Derivative assets	220	324
Other assets:
Tax credit investments	486	456
Deferred compensation mutual funds	123	125
Equity, mutual funds, and other	255	257
Total other assets	864	838
Total assets	82,442	83,091
Liabilities:
Defined maturity deposits	3,165	3,500
Trading liabilities	513	426
Short-term financial liabilities:
Federal funds purchased	798	775
Securities sold under agreements to repurchase	760	1,247
Other short-term borrowings	161	102
Total short-term financial liabilities	1,719	2,124
Term borrowings:
Real estate investment trust-preferred	46	46
Term borrowings—new market tax credit investment	59	59
Secured borrowings	6	6
Junior subordinated debentures	148	148
Other long term borrowings	1,332	1,331
Total term borrowings	1,591	1,590
Derivative liabilities	447	128
Total liabilities	7,435	7,768
Reported Value Measurement | Commercial, financial and industrial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	30,511	30,734
Reported Value Measurement | Commercial Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	12,336	11,955
Reported Value Measurement | Consumer Real Estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	10,710	10,609
Reported Value Measurement | Credit card and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	833	891
Reported Value Measurement | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held for sale	193	258
Reported Value Measurement | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale	783	853
Reported Value Measurement | Other loans - LOCOM
Short-term financial assets:
Loans held for sale	4	24
Reported Value Measurement | Mortgage loans - LOCOM
Short-term financial assets:
Loans held for sale	34	37
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net loans and leases	55,425	55,023
Short-term financial assets:
Interest-bearing deposits with banks	13,548	14,907
Federal funds sold	73	153
Securities purchased under agreements to resell	567	488
Total short-term financial assets	14,188	15,548
Trading securities	1,823	1,601
Loans held for sale	1,016	1,175
Securities available-for-sale	9,242	8,707
Securities held to maturity	650	705
Derivative assets	220	324
Other assets:
Tax credit investments	480	450
Deferred compensation mutual funds	123	125
Equity, mutual funds, and other	255	257
Total other assets	858	832
Total assets	83,422	83,915
Liabilities:
Defined maturity deposits	3,175	3,524
Trading liabilities	513	426
Short-term financial liabilities:
Federal funds purchased	798	775
Securities sold under agreements to repurchase	760	1,247
Other short-term borrowings	161	102
Total short-term financial liabilities	1,719	2,124
Term borrowings:
Real estate investment trust-preferred	47	47
Term borrowings—new market tax credit investment	56	58
Secured borrowings	6	6
Junior subordinated debentures	150	150
Other long term borrowings	1,392	1,452
Total term borrowings	1,651	1,713
Derivative liabilities	447	128
Total liabilities	7,505	7,915
Unfunded Commitments:
Loan commitments	1	1
Standby and other commitments	6	6
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	30,927	31,020
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	12,735	11,986
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	10,893	11,111
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	870	906
Estimate of Fair Value Measurement | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held for sale	193	258
Estimate of Fair Value Measurement | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale	785	856
Estimate of Fair Value Measurement | Other loans - LOCOM
Short-term financial assets:
Loans held for sale	4	24
Estimate of Fair Value Measurement | Mortgage loans - LOCOM
Short-term financial assets:
Loans held for sale	34	37
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	13,548	14,907
Federal funds sold	0	0
Securities purchased under agreements to resell	0	0
Total short-term financial assets	13,548	14,907
Trading securities	0	0
Loans held for sale	0	0
Securities available-for-sale	0	0
Securities held to maturity	0	0
Derivative assets	85	12
Other assets:
Tax credit investments	0	0
Deferred compensation mutual funds	123	125
Equity, mutual funds, and other	23	25
Total other assets	146	150
Total assets	13,779	15,069
Liabilities:
Defined maturity deposits	0	0
Trading liabilities	0	0
Short-term financial liabilities:
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
Term borrowings:
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	70	11
Total liabilities	70	11
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 | Other 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	73	153
Securities purchased under agreements to resell	567	488
Total short-term financial assets	640	641
Trading securities	1,811	1,563
Loans held for sale	949	1,109
Securities available-for-sale	9,242	8,707
Securities held to maturity	650	705
Derivative assets	135	312
Other assets:
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	13,427	13,037
Liabilities:
Defined maturity deposits	3,175	3,524
Trading liabilities	513	426
Short-term financial liabilities:
Federal funds purchased	798	775
Securities sold under agreements to repurchase	760	1,247
Other short-term borrowings	161	102
Total short-term financial liabilities	1,719	2,124
Term borrowings:
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	1,392	1,452
Total term borrowings	1,392	1,452
Derivative liabilities	359	94
Total liabilities	7,158	7,620
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	161	230
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale	784	855
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2 | Other loans - LOCOM
Short-term financial assets:
Loans held for sale	4	24
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	55,425	55,023
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	12	38
Loans held for sale	67	66
Securities available-for-sale	0	0
Securities held to maturity	0	0
Derivative assets	0	0
Other assets:
Tax credit investments	480	450
Deferred compensation mutual funds	0	0
Equity, mutual funds, and other	232	232
Total other assets	712	682
Total assets	56,216	55,809
Liabilities:
Defined maturity deposits	0	0
Trading liabilities	0	0
Short-term financial liabilities:
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
Term borrowings:
Real estate investment trust-preferred	47	47
Term borrowings—new market tax credit investment	56	58
Secured borrowings	6	6
Junior subordinated debentures	150	150
Other long term borrowings	0	0
Total term borrowings	259	261
Derivative liabilities	18	23
Total liabilities	277	284
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	30,927	31,020
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	12,735	11,986
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	10,893	11,111
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	870	906
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held for sale	32	28
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | USDA & SBA loans - LOCOM
Short-term financial assets:
Loans held for sale	1	1
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 3 | Other 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	34	37
Contractual Amount
Unfunded Commitments:
Loan commitments	24,607	24,229
Standby and other commitments	$ 698	$ 810