Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest income:
Loans, including fees	$ 164,133	$ 131,073	$ 315,335	$ 253,673
Securities:
Taxable	21,188	23,527	41,746	48,829
Tax-exempt	57,298	55,435	114,009	112,382
Interest-bearing deposits	13,917	9,076	28,011	15,912
Federal funds sold and resell agreements	1,415	163	2,176	270
Total interest income	257,951	219,274	501,277	431,066
Interest expense:
Deposits	17,575	2,173	28,213	4,041
Federal funds purchased and repurchase agreements	631	187	1,265	326
Junior subordinated deferrable interest debentures	1,311	962	2,453	1,870
Other long-term borrowings	1,164	1,164	2,328	1,532
Total interest expense	20,681	4,486	34,259	7,769
Net interest income	237,270	214,788	467,018	423,297
Provision for loan losses	8,251	8,426	15,196	16,378
Net interest income after provision for loan losses	229,019	206,362	451,822	406,919
Non-interest income:
Trust and investment management fees	29,121	27,727	58,708	54,197
Service charges on deposit accounts	21,142	21,198	41,985	41,967
Insurance commissions and fees	10,556	9,728	26,536	23,549
Interchange and debit card transaction fees	3,446	5,692	6,604	11,266
Other charges, commissions and fees	9,273	9,898	18,280	19,490
Net gain (loss) on securities transactions	(60)	(50)	(79)	(50)
Other	11,588	6,887	24,477	14,361
Total non-interest income	85,066	81,080	176,511	164,780
Non-interest expense:
Salaries and wages	85,204	80,995	171,887	163,507
Employee benefits	17,907	18,198	39,902	39,823
Net occupancy	19,455	19,153	39,195	38,390
Technology, furniture and equipment	20,459	18,250	40,138	36,240
Deposit insurance	4,605	5,570	9,484	10,485
Intangible amortization	369	438	757	896
Other	40,909	45,447	84,156	86,625
Total non-interest expense	188,908	188,051	385,519	375,966
Income before income taxes	125,177	99,391	242,814	195,733
Income taxes	13,836	13,838	24,993	25,239
Net income	111,341	85,553	217,821	170,494
Preferred stock dividends	2,015	2,015	4,031	4,031
Net income available to common shareholders	$ 109,326	$ 83,538	$ 213,790	$ 166,463
Earnings per common share:
Basic	$ 1.70	$ 1.30	$ 3.33	$ 2.59
Diluted	$ 1.68	$ 1.29	$ 3.30	$ 2.57