Fair Value of Assets and Liabilities - Summary Of Book Value And Estimated Fair Value Of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets
Total loans, net of unearned income and allowance for loan losses	$ 57,269	$ 30,861
Short-term financial assets:
Interest-bearing deposits with banks	8,351	482
Securities purchased under agreements to resell	380	587
Trading securities:	1,176	1,346
Loans held-for-sale	1,022	594
Securities available for sale at fair value	8,047	4,445
Gross amounts of recognized assets	765	183
Other assets:
Total assets	84,209	43,311
Liabilities:
Trading liabilities	353	506
Short-term financial liabilities:
Securities sold under agreements to repurchase	1,187	717
Term borrowings:
Other long term borrowings	1,670	791
Gross amounts of recognized liabilities	125	44
Total liabilities	75,902	38,235
Level 3 | FHLB-Cincinnati Stock
Term borrowings:
Restricted investments	61	76
Level 3 | FRB Stock
Term borrowings:
Restricted investments	202	131
Reported Value Measurement
Assets
Total loans, net of unearned income and allowance for loan losses	57,269	30,861
Short-term financial assets:
Interest-bearing deposits with banks	8,351	482
Federal funds sold	65	46
Securities purchased under agreements to resell	380	587
Total short-term financial assets	8,796	1,115
Trading securities:	1,176	1,346
Loans held-for-sale	1,022	594
Securities available for sale at fair value	8,047	4,445
Net loans and leases		10
Gross amounts of recognized assets	770	183
Other assets:
Tax credit investments	400	247
Deferred compensation mutual funds	118	47
Equity, mutual funds, and other	288	229
Total other assets	806	523
Total assets	77,886	39,077
Liabilities:
Defined maturity	5,070	3,618
Trading liabilities	353	506
Short-term financial liabilities:
Federal funds purchased	845	548
Securities sold under agreements to repurchase	1,187	717
Other short-term borrowings	166	2,253
Total short-term financial liabilities	2,198	3,518
Term borrowings:
Real estate investment trust-preferred	46	46
Term borrowings—new market tax credit investment	45
Secured borrowings	15	22
Junior subordinated debentures	238	145
Other long term borrowings	1,326	578
Total term borrowings	1,670	791
Gross amounts of recognized liabilities	149	67
Total liabilities	9,440	8,500
Reported Value Measurement | Commercial and industrial
Assets
Total loans, net of unearned income and allowance for loan losses	32,651	19,929
Reported Value Measurement | Commercial real estate
Assets
Total loans, net of unearned income and allowance for loan losses	12,033	4,301
Reported Value Measurement | Consumer real estate
Assets
Total loans, net of unearned income and allowance for loan losses	11,483	6,149
Reported Value Measurement | Credit Card and Other
Assets
Total loans, net of unearned income and allowance for loan losses	1,102	482
Reported Value Measurement | Mortgage Loans
Short-term financial assets:
Loans held-for-sale	405	14
Reported Value Measurement | Government guaranteed loans (SBA and USDA)
Short-term financial assets:
Loans held-for-sale	509	494
Reported Value Measurement | Other Consumer Loans Class
Short-term financial assets:
Loans held-for-sale	31	5
Reported Value Measurement | Mortgage Loan - LOCOM
Short-term financial assets:
Loans held-for-sale	77	81
Estimate of Fair Value Measurement
Assets
Total loans, net of unearned income and allowance for loan losses	57,695	31,218
Short-term financial assets:
Interest-bearing deposits with banks	8,351	482
Federal funds sold	65	46
Securities purchased under agreements to resell	380	587
Total short-term financial assets	8,796	1,115
Trading securities:	1,176	1,346
Loans held-for-sale	1,025	597
Securities available for sale at fair value	8,047	4,445
Net loans and leases		10
Gross amounts of recognized assets	769	183
Other assets:
Tax credit investments	371	245
Deferred compensation mutual funds	118	47
Equity, mutual funds, and other	288	230
Total other assets	777	522
Total assets	78,285	39,436
Liabilities:
Defined maturity	5,083	3,631
Trading liabilities	353	506
Short-term financial liabilities:
Federal funds purchased	845	548
Securities sold under agreements to repurchase	1,187	717
Other short-term borrowings	166	2,253
Total short-term financial liabilities	2,198	3,518
Term borrowings:
Real estate investment trust-preferred	47	47
Term borrowings—new market tax credit investment	45
Secured borrowings	15	22
Junior subordinated debentures	223	142
Other long term borrowings	1,455	574
Total term borrowings	1,785	785
Gross amounts of recognized liabilities	149	67
Total liabilities	9,568	8,507
Loan commitments	2	4
Standby and other commitments	6	6
Estimate of Fair Value Measurement | Commercial and industrial
Assets
Total loans, net of unearned income and allowance for loan losses	32,582	20,096
Estimate of Fair Value Measurement | Commercial real estate
Assets
Total loans, net of unearned income and allowance for loan losses	12,079	4,301
Estimate of Fair Value Measurement | Consumer real estate
Assets
Total loans, net of unearned income and allowance for loan losses	11,903	6,334
Estimate of Fair Value Measurement | Credit Card and Other
Assets
Total loans, net of unearned income and allowance for loan losses	1,131	487
Estimate of Fair Value Measurement | Mortgage Loans
Short-term financial assets:
Loans held-for-sale	405	14
Estimate of Fair Value Measurement | Government guaranteed loans (SBA and USDA)
Short-term financial assets:
Loans held-for-sale	512	497
Estimate of Fair Value Measurement | Other Consumer Loans Class
Short-term financial assets:
Loans held-for-sale	31	5
Estimate of Fair Value Measurement | Mortgage Loan - LOCOM
Short-term financial assets:
Loans held-for-sale	77	81
Estimate of Fair Value Measurement | Level 1
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Short-term financial assets:
Interest-bearing deposits with banks	8,351	482
Federal funds sold	0	0
Securities purchased under agreements to resell	0	0
Total short-term financial assets	8,351	482
Trading securities:	0	0
Loans held-for-sale	0	0
Securities available for sale at fair value	0	0
Net loans and leases		0
Gross amounts of recognized assets	63	20
Other assets:
Tax credit investments	0	0
Deferred compensation mutual funds	118	47
Equity, mutual funds, and other	25	23
Total other assets	143	70
Total assets	8,557	572
Liabilities:
Defined maturity	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
Secured borrowings	0	0
Junior subordinated debentures	0	0
Other long term borrowings	0	0
Total term borrowings	0	0
Gross amounts of recognized liabilities	71	20
Total liabilities	71	20
Estimate of Fair Value Measurement | Level 1 | Commercial and industrial
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Estimate of Fair Value Measurement | Level 1 | Commercial real estate
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Estimate of Fair Value Measurement | Level 1 | Consumer real estate
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Estimate of Fair Value Measurement | Level 1 | Credit Card and Other
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Estimate of Fair Value Measurement | Level 1 | Mortgage Loans
Short-term financial assets:
Loans held-for-sale	0	0
Estimate of Fair Value Measurement | Level 1 | Government guaranteed loans (SBA and USDA)
Short-term financial assets:
Loans held-for-sale	0	0
Estimate of Fair Value Measurement | Level 1 | Other Consumer Loans Class
Short-term financial assets:
Loans held-for-sale	0	0
Estimate of Fair Value Measurement | Level 1 | Mortgage Loan - LOCOM
Short-term financial assets:
Loans held-for-sale	0	0
Estimate of Fair Value Measurement | Level 2
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Short-term financial assets:
Interest-bearing deposits with banks	0	0
Federal funds sold	65	46
Securities purchased under agreements to resell	380	587
Total short-term financial assets	445	633
Trading securities:	1,176	1,345
Loans held-for-sale	935	501
Securities available for sale at fair value	8,015	4,426
Net loans and leases		0
Gross amounts of recognized assets	706	163
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	11,277	7,068
Liabilities:
Defined maturity	5,083	3,631
Trading liabilities	353	506
Short-term financial liabilities:
Federal funds purchased	845	548
Securities sold under agreements to repurchase	1,187	717
Other short-term borrowings	166	2,253
Total short-term financial liabilities	2,198	3,518
Term borrowings:
Real estate investment trust-preferred	0	0
Term borrowings—new market tax credit investment	0
Secured borrowings	0	0
Junior subordinated debentures	0	0
Other long term borrowings	1,455	574
Total term borrowings	1,455	574
Gross amounts of recognized liabilities	64	24
Total liabilities	9,153	8,253
Estimate of Fair Value Measurement | Level 2 | Commercial and industrial
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Estimate of Fair Value Measurement | Level 2 | Commercial real estate
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Estimate of Fair Value Measurement | Level 2 | Consumer real estate
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Estimate of Fair Value Measurement | Level 2 | Credit Card and Other
Assets
Total loans, net of unearned income and allowance for loan losses	0	0
Estimate of Fair Value Measurement | Level 2 | Mortgage Loans
Short-term financial assets:
Loans held-for-sale	393	0
Estimate of Fair Value Measurement | Level 2 | Government guaranteed loans (SBA and USDA)
Short-term financial assets:
Loans held-for-sale	511	496
Estimate of Fair Value Measurement | Level 2 | Other Consumer Loans Class
Short-term financial assets:
Loans held-for-sale	31	5
Estimate of Fair Value Measurement | Level 2 | Mortgage Loan - LOCOM
Short-term financial assets:
Loans held-for-sale	0	0
Estimate of Fair Value Measurement | Level 3
Assets
Total loans, net of unearned income and allowance for loan losses	57,695	31,218
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:	0	1
Loans held-for-sale	90	96
Securities available for sale at fair value	32	19
Net loans and leases		10
Gross amounts of recognized assets	0	0
Other assets:
Tax credit investments	371	245
Deferred compensation mutual funds	0	0
Equity, mutual funds, and other	263	207
Total other assets	634	452
Total assets	58,451	31,796
Liabilities:
Defined maturity	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	45
Secured borrowings	15	22
Junior subordinated debentures	223	142
Other long term borrowings	0	0
Total term borrowings	330	211
Gross amounts of recognized liabilities	14	23
Total liabilities	344	234
Estimate of Fair Value Measurement | Level 3 | Commercial and industrial
Assets
Total loans, net of unearned income and allowance for loan losses	32,582	20,096
Estimate of Fair Value Measurement | Level 3 | Commercial real estate
Assets
Total loans, net of unearned income and allowance for loan losses	12,079	4,301
Estimate of Fair Value Measurement | Level 3 | Consumer real estate
Assets
Total loans, net of unearned income and allowance for loan losses	11,903	6,334
Estimate of Fair Value Measurement | Level 3 | Credit Card and Other
Assets
Total loans, net of unearned income and allowance for loan losses	1,131	487
Estimate of Fair Value Measurement | Level 3 | Mortgage Loans
Short-term financial assets:
Loans held-for-sale	12	14
Estimate of Fair Value Measurement | Level 3 | Government guaranteed loans (SBA and USDA)
Short-term financial assets:
Loans held-for-sale	1	1
Estimate of Fair Value Measurement | Level 3 | Other Consumer Loans Class
Short-term financial assets:
Loans held-for-sale	0	0
Estimate of Fair Value Measurement | Level 3 | Mortgage Loan - LOCOM
Short-term financial assets:
Loans held-for-sale	77	81
Contractual Amount
Term borrowings:
Loan commitments	20,796	12,355
Standby and other commitments	$ 751	$ 459