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	$ 749,000	$ 659,538	$ 615,627
Interest and dividends on investment securities
Taxable	96,909	95,152	100,292
Tax-exempt	32,977	32,049	31,152
Other interest	7,719	4,829	6,591
Total interest income	886,605	791,568	753,662
Interest expense
Interest on deposits	94,025	50,335	33,125
Interest on Federal funds purchased and securities sold under agreements to repurchase	2,527	1,314	943
Interest on other short-term funding	5,677	2,114	465
Interest on long-term funding	43,156	30,532	42,851
Total interest expense	145,385	84,295	77,384
Net interest income	741,220	707,273	676,278
Provision for credit losses	26,000	70,000	37,500
Net interest income after provision for credit losses	715,220	637,273	638,778
Noninterest income
Insurance commissions and fees	81,474	80,795	75,363
Service charges and deposit account fees	64,427	66,609	65,471
Card-based and loan fees	52,688	50,077	47,912
Trust and asset management fees	50,191	46,867	48,840
Brokerage commissions and fees	19,935	16,235	15,378
Mortgage banking, net	19,360	38,121	32,263
Capital markets, net	19,642	22,059	14,558
Bank and corporate owned life insurance	16,250	14,371	9,796
Asset gains (losses), net	(1,244)	(86)	2,540
Investment securities gains (losses), net	434	9,316	8,133
Other	9,523	8,519	9,103
Total noninterest income	332,680	352,883	329,357
Noninterest expense
Personnel	419,778	414,837	404,741
Occupancy	53,842	56,069	60,896
Technology	63,004	57,300	60,613
Equipment	21,201	21,489	23,209
Business development and advertising	28,946	26,351	25,772
Legal and professional	22,509	19,869	17,052
Card issuance and loan costs	11,760	13,641	14,102
Foreclosure / OREO expense, net	4,878	4,844	5,442
FDIC assessment	31,300	34,750	26,000
Other intangible amortization	1,959	2,093	3,094
Other	49,956	51,317	57,426
Total noninterest expense	709,133	702,560	698,347
Income before income taxes	338,767	287,596	269,788
Income tax expense	109,503	87,322	81,487
Net income	229,264	200,274	188,301
Preferred stock dividends	9,347	8,903	7,155
Net income available to common equity	$ 219,917	$ 191,371	$ 181,146
Earnings per common share
Basic	$ 1.45	$ 1.27	$ 1.20
Diluted	$ 1.42	$ 1.26	$ 1.19
Average common shares outstanding
Basic	150,877	148,769	149,350
Diluted	153,647	149,961	150,603