Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income
Interest and fees on loans	$ 868,881	$ 741,001	$ 651,831
Interest bearing deposits with banks	9,252	4,236	1,486
Federal funds sold and securities purchased under resale agreements	2	4	4
Investment securities	63,315	62,038	61,006
Trading account securities	25	75	108
Federal Home Loan Bank and Federal Reserve Bank stock	4,370	4,287	3,232
Brokerage customer receivables	623	816	797
Total interest income	946,468	812,457	718,464
Interest expense
Interest on deposits	83,326	58,409	48,863
Interest on Federal Home Loan Bank advances	8,798	10,886	9,110
Interest on other borrowings	5,370	4,355	3,627
Interest on subordinated notes	7,116	7,111	7,105
Interest on junior subordinated debentures	9,782	9,503	8,230
Total interest expense	114,392	90,264	76,935
Net interest income	832,076	722,193	641,529
Provision for credit losses	29,768	34,084	32,942
Net interest income after provision for credit losses	802,308	688,109	608,587
Non-interest income
Wealth management	81,766	76,018	73,452
Mortgage banking	113,472	128,743	115,011
Service charges on deposit accounts	34,513	31,210	27,384
Gains on investment securities, net	45	7,645	323
Fees from covered call options	4,402	11,470	15,364
Trading (losses) gains, net	(845)	91	(247)
Operating lease income, net	29,646	16,441	2,728
Other	56,507	53,812	37,582
Total non-interest income	319,506	325,430	271,597
Non-interest expense
Salaries and employee benefits	430,078	405,158	382,080
Equipment	38,358	37,055	32,889
Operating lease equipment depreciation	24,107	13,259	1,749
Occupancy, net	52,920	50,912	48,880
Data processing	31,495	28,776	26,940
Advertising and marketing	30,830	24,776	21,924
Professional fees	27,835	20,411	18,225
Amortization of other intangible assets	4,401	4,789	4,621
FDIC insurance	16,231	16,065	12,386
OREO expenses, net	3,593	5,187	4,483
Other	71,969	75,297	74,242
Total non-interest expense	731,817	681,685	628,419
Income before taxes	389,997	331,854	251,765
Income tax expense	132,315	124,979	95,016
Net income	257,682	206,875	156,749
Preferred stock dividends	9,778	14,513	10,869
Net income applicable to common shares—Basic	$ 247,904	$ 192,362	$ 145,880
Net income per common share - Basic (usd per share)	$ 4.53	$ 3.83	$ 3.05
Net income per common share - Diluted (usd per share)	4.40	3.66	2.93
Cash dividends declared per common share (in usd per share)	$ 0.56	$ 0.48	$ 0.44
Weighted average common shares outstanding (in shares)	54,703	50,278	47,838
Dilutive potential common shares (in shares)	1,983	3,994	4,099
Average common shares and dilutive common shares (in shares)	56,686	54,272	51,937