Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income
Interest and fees on loans	$ 565,537	$ 430,738	$ 387,713
Interest on federal funds sold and other short-term investments	16,035	3,495	1,645
Interest and dividends on securities:
Taxable	36,715	32,357	30,744
Tax-exempt	5,519	3,751	3,528
Total interest income	623,806	470,341	423,630
Interest expense
Interest on deposits	49,726	29,125	28,023
Interest on short-term borrowings	1,579	1,584	834
Interest on long-term borrowings	23,504	14,301	10,649
Total interest expense	74,809	45,010	39,506
Net interest income	548,997	425,331	384,124
Provision for loan losses	28,406	24,509	22,574
Net interest income after provision for loan losses	520,591	400,822	361,550
Other income
Fees from trust and brokerage services	19,531	19,037	19,085
Fees from deposit services	33,622	32,858	37,962
Bankcard fees and merchant discounts	4,795	5,215	4,786
Other service charges, commissions, and fees	2,057	2,059	2,141
Income from bank-owned life insurance	5,110	5,794	5,557
Income from mortgage banking	58,907	3,450	2,507
Other income	2,039	1,339	1,433
Total other-than-temporary impairment losses	(60)	339	(113)
Portion of loss recognized in other comprehensive income	0	(372)	66
Net other-than-temporary impairment losses	(60)	(33)	(47)
Net gains on sales/calls of investment securities	5,644	313	202
Net investment securities gains (losses)	5,584	280	155
Total other income	131,645	70,032	73,626
Other expense
Employee compensation	164,247	93,281	88,123
Employee benefits	37,143	28,965	27,086
Net occupancy expense	39,067	27,529	24,301
Other real estate owned (OREO) expense	6,003	5,844	3,613
Equipment expense	10,528	8,622	9,034
Data processing expense	21,019	15,280	14,867
Bankcard processing expense	1,809	1,742	1,505
FDIC insurance expense	7,051	8,548	8,367
Other expense	80,542	58,385	54,791
Total other expense	367,409	248,196	231,687
Income before income taxes	284,827	222,658	203,489
Income taxes	134,246	75,575	65,530
Net income	$ 150,581	$ 147,083	$ 137,959
Earnings per common share:
Basic	$ 1.54	$ 2.00	$ 1.99
Diluted	1.54	1.99	1.98
Dividends per common share	$ 1.33	$ 1.32	$ 1.29
Average outstanding shares:
Basic	97,502,633	73,531,992	69,334,849
Diluted	97,890,078	73,893,127	69,625,531