Business Segments - Business Segments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income:
Loans and leases		$ 1,065,137	$ 954,246	$ 850,546
Debt securities available for sale		54,574	33,278	26,573
Debt securities held to maturity		3,970	4,436	4,649
Loans held for sale and other		18,583	27,097	48,962
Funds transfer pricing - credits		0	0	0
Total interest income		1,142,264	1,019,057	930,730
Interest expense:
Deposits		107,113	66,012	61,788
Borrowings		43,144	27,807	20,836
Funds transfer pricing - charges		0	0	0
Total interest expense		150,257	93,819	82,624
Net interest income		992,007	925,238	848,106
Provision for credit losses		46,768	68,443	65,874
Net interest income after provision for credit losses		945,239	856,795	782,232
Non-interest income:
Leasing and equipment finance		185,107	145,039	119,166
Gains on sale of loans, net		33,498	42,787	85,259
Gains (losses) on debt securities, net		348	237	(581)
Other		13,843	11,646	8,883
Total non-interest income		470,885	448,299	465,900
Non-interest expense:
Compensation and employee benefits		497,063	482,512	475,964
Occupancy and equipment		165,812	156,909	149,980
Operating lease depreciation		73,829	55,901	40,359
Foreclosed real estate and repossessed assets, net		17,050	17,756	13,187
Other		260,646	346,856	230,397
Total non-interest expense		1,014,400	1,059,934	909,887
Income before income tax expense (benefit)		401,724	245,160	338,245
Income tax expense (benefit)		86,096	(33,624)	116,528
Income after income tax expense (benefit)		315,628	278,784	221,717
Income attributable to non-controlling interest		11,270	10,147	9,593
Preferred stock dividends		11,588	19,904	19,388
Impact of preferred stock redemption	[1]	3,481	5,779	0
Net income available to common stockholders		289,289	242,954	192,736
Total assets		23,699,612	23,002,159	21,441,326
Revenues from external customers:
Interest income		1,142,264	1,019,057	930,730
Non-interest income		470,885	448,299	465,900
Total revenues from external customers		1,613,149	1,467,356	1,396,630
Fees and service charges
Non-interest income:
Fee revenue		132,201	131,887	137,664
Card revenue
Non-interest income:
Fee revenue		58,864	55,732	54,882
ATM revenue
Non-interest income:
Fee revenue		19,690	19,624	20,445
Servicing fee income
Non-interest income:
Fee revenue		27,334	41,347	40,182
Consumer Banking
Interest income:
Loans and leases		430,762	433,627	397,886
Debt securities available for sale		0	0	0
Debt securities held to maturity		0	0	0
Loans held for sale and other		10,413	22,698	46,073
Funds transfer pricing - credits		404,770	367,149	352,096
Total interest income		845,945	823,474	796,055
Interest expense:
Deposits		79,680	55,237	56,105
Borrowings		43,398	49,879	42,595
Funds transfer pricing - charges		166,787	143,748	137,504
Total interest expense		289,865	248,864	236,204
Net interest income		556,080	574,610	559,851
Provision for credit losses		24,922	48,227	50,819
Net interest income after provision for credit losses		531,158	526,383	509,032
Non-interest income:
Leasing and equipment finance		0	0	0
Gains on sale of loans, net		33,488	42,787	85,205
Gains (losses) on debt securities, net		0	0	0
Other		11,611	10,135	7,364
Total non-interest income		269,180	289,995	336,991
Non-interest expense:
Compensation and employee benefits		215,548	224,420	243,445
Occupancy and equipment		105,000	109,848	96,512
Operating lease depreciation		0	0	0
Foreclosed real estate and repossessed assets, net		14,600	14,097	10,552
Other		331,600	395,364	301,951
Total non-interest expense		666,748	743,729	652,460
Income before income tax expense (benefit)		133,590	72,649	193,563
Income tax expense (benefit)		30,706	49,513	69,523
Income after income tax expense (benefit)		102,884	23,136	124,040
Income attributable to non-controlling interest		0	0	0
Preferred stock dividends		0	0	0
Impact of preferred stock redemption		0	0
Net income available to common stockholders		102,884	23,136	124,040
Total assets		8,193,021	8,894,798	8,885,412
Revenues from external customers:
Interest income		441,175	456,325	443,959
Non-interest income		269,180	289,995	336,991
Total revenues from external customers		710,355	746,320	780,950
Consumer Banking | Fees and service charges
Non-interest income:
Fee revenue		119,541	121,728	130,542
Consumer Banking | Card revenue
Non-interest income:
Fee revenue		58,811	55,728	54,879
Consumer Banking | ATM revenue
Non-interest income:
Fee revenue		19,687	19,621	20,441
Consumer Banking | Servicing fee income
Non-interest income:
Fee revenue		26,042	39,996	38,560
Wholesale Banking
Interest income:
Loans and leases		638,188	527,141	457,908
Debt securities available for sale		0	0	0
Debt securities held to maturity		91	101	172
Loans held for sale and other		306	81	50
Funds transfer pricing - credits		35,370	25,499	21,452
Total interest income		673,955	552,822	479,582
Interest expense:
Deposits		9,611	2,745	1,014
Borrowings		79,660	47,460	25,104
Funds transfer pricing - charges		205,001	143,336	109,811
Total interest expense		294,272	193,541	135,929
Net interest income		379,683	359,281	343,653
Provision for credit losses		21,846	20,216	15,055
Net interest income after provision for credit losses		357,837	339,065	328,598
Non-interest income:
Leasing and equipment finance		185,107	145,039	119,166
Gains on sale of loans, net		10	0	54
Gains (losses) on debt securities, net		221	237	(581)
Other		1,201	1,192	1,491
Total non-interest income		200,547	157,985	128,881
Non-interest expense:
Compensation and employee benefits		94,709	86,397	84,692
Occupancy and equipment		20,141	20,402	10,954
Operating lease depreciation		73,829	55,901	40,359
Foreclosed real estate and repossessed assets, net		2,443	3,279	2,035
Other		120,824	111,452	109,075
Total non-interest expense		311,946	277,431	247,115
Income before income tax expense (benefit)		246,438	219,619	210,364
Income tax expense (benefit)		53,614	(68,883)	70,805
Income after income tax expense (benefit)		192,824	288,502	139,559
Income attributable to non-controlling interest		11,270	10,147	9,593
Preferred stock dividends		0	0	0
Impact of preferred stock redemption		0	0
Net income available to common stockholders		181,554	278,355	129,966
Total assets		12,229,071	11,571,587	10,391,305
Revenues from external customers:
Interest income		634,772	520,801	452,882
Non-interest income		200,547	157,985	128,881
Total revenues from external customers		835,319	678,786	581,763
Wholesale Banking | Fees and service charges
Non-interest income:
Fee revenue		12,660	10,159	7,122
Wholesale Banking | Card revenue
Non-interest income:
Fee revenue		53	4	3
Wholesale Banking | ATM revenue
Non-interest income:
Fee revenue		3	3	4
Wholesale Banking | Servicing fee income
Non-interest income:
Fee revenue		1,292	1,351	1,622
Enterprise Services
Interest income:
Loans and leases		(3,813)	(6,522)	(5,248)
Debt securities available for sale		54,574	33,278	26,573
Debt securities held to maturity		3,879	4,335	4,477
Loans held for sale and other		7,864	4,318	2,839
Funds transfer pricing - credits		(440,140)	(392,648)	(373,548)
Total interest income		(377,636)	(357,239)	(344,907)
Interest expense:
Deposits		17,822	8,030	4,669
Borrowings		(79,914)	(69,532)	(46,863)
Funds transfer pricing - charges		(371,788)	(287,084)	(247,315)
Total interest expense		(433,880)	(348,586)	(289,509)
Net interest income		56,244	(8,653)	(55,398)
Provision for credit losses		0	0	0
Net interest income after provision for credit losses		56,244	(8,653)	(55,398)
Non-interest income:
Leasing and equipment finance		0	0	0
Gains on sale of loans, net		0	0	0
Gains (losses) on debt securities, net		127	0	0
Other		1,031	319	28
Total non-interest income		1,158	319	28
Non-interest expense:
Compensation and employee benefits		186,806	171,695	147,827
Occupancy and equipment		40,671	26,659	42,514
Operating lease depreciation		0	0	0
Foreclosed real estate and repossessed assets, net		7	380	600
Other		(191,778)	(159,960)	(180,629)
Total non-interest expense		35,706	38,774	10,312
Income before income tax expense (benefit)		21,696	(47,108)	(65,682)
Income tax expense (benefit)		1,776	(14,254)	(23,800)
Income after income tax expense (benefit)		19,920	(32,854)	(41,882)
Income attributable to non-controlling interest		0	0	0
Preferred stock dividends		11,588	19,904	19,388
Impact of preferred stock redemption		3,481	5,779
Net income available to common stockholders		4,851	(58,537)	(61,270)
Total assets		3,277,520	2,535,774	2,164,609
Revenues from external customers:
Interest income		66,317	41,931	33,889
Non-interest income		1,158	319	28
Total revenues from external customers		67,475	42,250	33,917
Enterprise Services | Fees and service charges
Non-interest income:
Fee revenue		0	0	0
Enterprise Services | Card revenue
Non-interest income:
Fee revenue		0	0	0
Enterprise Services | ATM revenue
Non-interest income:
Fee revenue		0	0	0
Enterprise Services | Servicing fee income
Non-interest income:
Fee revenue		$ 0	$ 0	$ 0

[1] Amounts represent the deferred stock issuance costs originally recorded in preferred stock that were reclassified to retained earnings.