Fair Value of Assets & Liabilities - Summary Of Book Value And Estimated Fair Value Of Financial Instruments (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Assets:
Total loans, net of unearned income and allowance for loan losses		$ 27,164,255	$ 27,469,374
Short-term financial assets:
Interest-bearing cash		531,681	1,185,600
Federal funds sold		113,722	87,364
Securities purchased under agreements to resell		687,437	725,609
Trading securities		1,930,991	1,416,345
Loans held-for-sale	[1]	725,651	699,377
Securities available-for-sale		4,608,383	5,170,255
Securities held-to-maturity		10,000	10,000
Derivative assets		54,476	81,634
Nonearning assets:
Cash and due from banks		642,051	639,073
Fixed income receivables		177,802	68,693
Total assets		40,635,924	41,423,388
Deposits:
Total deposits		31,008,085	30,620,362
Trading liabilities		739,694	638,515
Short-term financial liabilities:
Federal funds purchased		437,474	399,820
Securities sold under agreements to repurchase		678,510	656,602
Other short-term borrowings		1,069,912	2,626,213
Term borrowings:
Term borrowings		1,200,134	1,218,097
Derivative liabilities		170,324	85,061
Other noninterest-bearing liabilities:
Fixed income payables		36,939	48,996
Total liabilities		35,893,993	36,842,900
Level 3 | FHLB-Cincinnati
Other noninterest-bearing liabilities:
Restricted investments		87,900	87,900
Level 3 | FRB Stock
Other noninterest-bearing liabilities:
Restricted investments		130,700	134,600
Book Value
Assets:
Total loans, net of unearned income and allowance for loan losses		27,164,255	27,469,374
Short-term financial assets:
Interest-bearing cash		531,681	1,185,600
Federal funds sold		113,722	87,364
Securities purchased under agreements to resell		687,437	725,609
Total short-term financial assets		1,332,840	1,998,573
Trading securities		1,930,991	1,416,345
Loans held-for-sale		725,651
Securities available-for-sale		4,608,383	5,170,255
Securities held-to-maturity		10,000	10,000
Derivative assets		54,476	81,634
Other assets:
Tax credit investments		139,983	119,317
Deferred compensation mutual funds		40,912	39,822
Equity, mutual funds, and other		240,667
Total other assets		421,562	159,139
Nonearning assets:
Cash and due from banks			639,073
Fixed income receivables			68,693
Accrued interest receivable			97,239
Accrued interest receivable			805,005
Total assets		36,248,158	37,809,702
Deposits:
Defined maturity			3,322,921
Undefined maturity			27,297,441
Total deposits		4,056,184	30,620,362
Trading liabilities		739,694	638,515
Short-term financial liabilities:
Federal funds purchased		437,474	399,820
Securities sold under agreements to repurchase		678,510	656,602
Other short-term borrowings		1,069,912	2,626,213
Total short-term financial liabilities		2,185,896	3,682,635
Term borrowings:
Real estate investment trust-preferred		46,151	46,100
Term borrowings—new market tax credit investment		18,000	18,000
Secured borrowings		16,621	18,642
Junior subordinated debentures		177,974	187,281
Term borrowings		941,388	948,074
Total term borrowings		1,200,134	1,218,097
Derivative liabilities			85,061
Other noninterest-bearing liabilities:
Fixed income payables			48,996
Accrued interest payable			16,270
Total other noninterest-bearing liabilities			65,266
Total liabilities		8,352,232	36,309,936
Book Value | Commercial, financial and industrial
Assets:
Total loans, net of unearned income and allowance for loan losses		15,943,831	15,959,062
Book Value | Commercial real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		4,203,121	4,186,268
Book Value | Consumer real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		6,164,646	6,330,384
Book Value | Permanent mortgage
Assets:
Total loans, net of unearned income and allowance for loan losses		333,574	383,742
Book Value | Credit card & other
Assets:
Total loans, net of unearned income and allowance for loan losses		519,083	609,918
Book Value | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held-for-sale		16,418	88,173
Book Value | USDA & SBA loans- LOCOM
Short-term financial assets:
Loans held-for-sale		619,160	466,977
Book Value | Other consumer loans- LOCOM
Short-term financial assets:
Loans held-for-sale		28,843	144,227
Book Value | Mortgage loans- LOCOM
Short-term financial assets:
Loans held-for-sale		61,230
Fair Value
Assets:
Total loans, net of unearned income and allowance for loan losses		27,112,576	27,523,017
Short-term financial assets:
Interest-bearing cash		531,681	1,185,600
Federal funds sold		113,722	87,364
Securities purchased under agreements to resell		687,437	725,609
Total short-term financial assets		1,332,840	1,998,573
Trading securities		1,930,991	1,416,345
Loans held-for-sale		731,377
Securities available-for-sale		4,608,383	5,170,255
Securities held-to-maturity		9,756	9,901
Derivative assets		54,476	81,634
Other assets:
Tax credit investments		136,984	112,292
Deferred compensation mutual funds		40,912	39,822
Equity, mutual funds, and other		240,667
Total other assets		418,563	152,114
Nonearning assets:
Cash and due from banks			639,073
Fixed income receivables			68,693
Accrued interest receivable			97,239
Accrued interest receivable			805,005
Total assets		36,198,962	37,857,981
Deposits:
Defined maturity			3,293,650
Undefined maturity			27,297,431
Total deposits		4,024,544	30,591,081
Trading liabilities		739,694	638,515
Short-term financial liabilities:
Federal funds purchased		437,474	399,820
Securities sold under agreements to repurchase		678,510	656,602
Other short-term borrowings		1,069,912	2,626,213
Total short-term financial liabilities		2,185,896	3,682,635
Term borrowings:
Real estate investment trust-preferred		47,470	48,880
Term borrowings—new market tax credit investment		17,915	17,930
Secured borrowings		16,499	18,305
Junior subordinated debentures		177,974	187,281
Term borrowings		957,647	966,292
Total term borrowings		1,217,505	1,238,688
Derivative liabilities		170,324	85,061
Other noninterest-bearing liabilities:
Fixed income payables			48,996
Accrued interest payable			16,270
Total other noninterest-bearing liabilities			65,266
Total liabilities		8,337,963	36,301,246
Loan commitments		2,871	2,617
Standby and other commitments		4,981	5,274
Fair Value | Commercial, financial and industrial
Assets:
Total loans, net of unearned income and allowance for loan losses		15,941,049	15,990,991
Fair Value | Commercial real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		4,198,110	4,215,367
Fair Value | Consumer real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		6,114,607	6,320,308
Fair Value | Permanent mortgage
Assets:
Total loans, net of unearned income and allowance for loan losses		338,736	388,396
Fair Value | Credit card & other
Assets:
Total loans, net of unearned income and allowance for loan losses		520,074	607,955
Fair Value | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held-for-sale		16,418	88,173
Fair Value | USDA & SBA loans- LOCOM
Short-term financial assets:
Loans held-for-sale		624,886	468,737
Fair Value | Other consumer loans- LOCOM
Short-term financial assets:
Loans held-for-sale		28,843	144,227
Fair Value | Mortgage loans- LOCOM
Short-term financial assets:
Loans held-for-sale		61,230
Fair Value | Level 1
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Short-term financial assets:
Interest-bearing cash		531,681	1,185,600
Federal funds sold		0	0
Securities purchased under agreements to resell		0	0
Total short-term financial assets		531,681	1,185,600
Trading securities		0	0
Loans held-for-sale		0
Securities available-for-sale		0	27,017
Securities held-to-maturity		0	0
Derivative assets		20,013	10,161
Other assets:
Tax credit investments		0	0
Deferred compensation mutual funds		40,912	39,822
Equity, mutual funds, and other		22,141
Total other assets		63,053	39,822
Nonearning assets:
Cash and due from banks			639,073
Fixed income receivables			0
Accrued interest receivable			0
Accrued interest receivable			639,073
Total assets		614,747	1,901,673
Deposits:
Defined maturity			0
Undefined maturity			0
Total 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
Term borrowings		0	0
Total term borrowings		0	0
Derivative liabilities		18,770	9,535
Other noninterest-bearing liabilities:
Fixed income payables			0
Accrued interest payable			0
Total other noninterest-bearing liabilities			0
Total liabilities		18,770	9,535
Fair Value | Level 1 | Commercial, financial and industrial
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 1 | Commercial real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 1 | Consumer real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 1 | Permanent mortgage
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 1 | Credit card & other
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 1 | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held-for-sale		0	0
Fair Value | Level 1 | USDA & SBA loans- LOCOM
Short-term financial assets:
Loans held-for-sale		0	0
Fair Value | Level 1 | Other consumer loans- LOCOM
Short-term financial assets:
Loans held-for-sale		0	0
Fair Value | Level 1 | Mortgage loans- LOCOM
Short-term financial assets:
Loans held-for-sale		0
Fair Value | Level 2
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Short-term financial assets:
Interest-bearing cash		0	0
Federal funds sold		113,722	87,364
Securities purchased under agreements to resell		687,437	725,609
Total short-term financial assets		801,159	812,973
Trading securities		1,929,399	1,414,194
Loans held-for-sale		630,749
Securities available-for-sale		4,598,022	4,903,115
Securities held-to-maturity		0	0
Derivative assets		34,463	71,473
Other assets:
Tax credit investments		0	0
Deferred compensation mutual funds		0	0
Equity, mutual funds, and other		0
Total other assets		0	0
Nonearning assets:
Cash and due from banks			0
Fixed income receivables			68,693
Accrued interest receivable			97,239
Accrued interest receivable			165,932
Total assets		7,993,792	7,851,781
Deposits:
Defined maturity			3,293,650
Undefined maturity			27,297,431
Total deposits		4,024,544	30,591,081
Trading liabilities		739,694	638,515
Short-term financial liabilities:
Federal funds purchased		437,474	399,820
Securities sold under agreements to repurchase		678,510	656,602
Other short-term borrowings		1,069,912	2,626,213
Total short-term financial liabilities		2,185,896	3,682,635
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
Term borrowings		957,647	966,292
Total term borrowings		957,647	966,292
Derivative liabilities		117,342	69,881
Other noninterest-bearing liabilities:
Fixed income payables			48,996
Accrued interest payable			16,270
Total other noninterest-bearing liabilities			65,266
Total liabilities		8,025,123	36,013,670
Fair Value | Level 2 | Commercial, financial and industrial
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 2 | Commercial real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 2 | Consumer real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 2 | Permanent mortgage
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 2 | Credit card & other
Assets:
Total loans, net of unearned income and allowance for loan losses		0	0
Fair Value | Level 2 | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held-for-sale		182	6,902
Fair Value | Level 2 | USDA & SBA loans- LOCOM
Short-term financial assets:
Loans held-for-sale		623,863	467,227
Fair Value | Level 2 | Other consumer loans- LOCOM
Short-term financial assets:
Loans held-for-sale		6,704	9,965
Fair Value | Level 2 | Mortgage loans- LOCOM
Short-term financial assets:
Loans held-for-sale		0
Fair Value | Level 3
Assets:
Total loans, net of unearned income and allowance for loan losses		27,112,576	27,523,017
Short-term financial assets:
Interest-bearing cash		0	0
Federal funds sold		0	0
Securities purchased under agreements to resell		0	0
Total short-term financial assets		0	0
Trading securities		1,592	2,151
Loans held-for-sale		100,628
Securities available-for-sale		10,361	240,123
Securities held-to-maturity		9,756	9,901
Derivative assets		0	0
Other assets:
Tax credit investments		136,984	112,292
Deferred compensation mutual funds		0	0
Equity, mutual funds, and other		218,526
Total other assets		355,510	112,292
Nonearning assets:
Cash and due from banks			0
Fixed income receivables			0
Accrued interest receivable			0
Accrued interest receivable			0
Total assets		27,590,423	28,104,527
Deposits:
Defined maturity			0
Undefined maturity			0
Total 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		47,470	48,880
Term borrowings—new market tax credit investment		17,915	17,930
Secured borrowings		16,499	18,305
Junior subordinated debentures		177,974	187,281
Term borrowings		0	0
Total term borrowings		259,858	272,396
Derivative liabilities		34,212	5,645
Other noninterest-bearing liabilities:
Fixed income payables			0
Accrued interest payable			0
Total other noninterest-bearing liabilities			0
Total liabilities		294,070	278,041
Fair Value | Level 3 | Commercial, financial and industrial
Assets:
Total loans, net of unearned income and allowance for loan losses		15,941,049	15,990,991
Fair Value | Level 3 | Commercial real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		4,198,110	4,215,367
Fair Value | Level 3 | Consumer real estate
Assets:
Total loans, net of unearned income and allowance for loan losses		6,114,607	6,320,308
Fair Value | Level 3 | Permanent mortgage
Assets:
Total loans, net of unearned income and allowance for loan losses		338,736	388,396
Fair Value | Level 3 | Credit card & other
Assets:
Total loans, net of unearned income and allowance for loan losses		520,074	607,955
Fair Value | Level 3 | Mortgage loans (elected fair value)
Short-term financial assets:
Loans held-for-sale		16,236	81,271
Fair Value | Level 3 | USDA & SBA loans- LOCOM
Short-term financial assets:
Loans held-for-sale		1,023	1,510
Fair Value | Level 3 | Other consumer loans- LOCOM
Short-term financial assets:
Loans held-for-sale		22,139	134,262
Fair Value | Level 3 | Mortgage loans- LOCOM
Short-term financial assets:
Loans held-for-sale		61,230
Contractual Amount
Other noninterest-bearing liabilities:
Loan commitments		10,829,303	10,678,485
Standby and other commitments		$ 450,745	$ 420,728

[1] September 30, 2018 and December 31, 2017 include $9.2 million and $11.7 million, respectively, of held-for-sale consumer mortgage loans secured by residential real estate in process of foreclosure.