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 LHFS & LHFI	$ 344,625	$ 299,645	$ 274,433
Interest and fees on acquired loans	24,478	30,144	51,152
Interest on securities:
Taxable	76,192	77,614	80,730
Tax exempt	3,001	3,675	4,323
Interest on federal funds sold and securities purchased under reverse repurchase agreements	33	14	8
Other interest income	1,466	988	1,579
Total Interest Income	449,795	412,080	412,225
Interest Expense
Interest on deposits	22,717	12,748	12,598
Interest on federal funds purchased and securities sold under repurchase agreements	4,152	1,717	801
Other interest expense	15,376	10,082	7,061
Total Interest Expense	42,245	24,547	20,460
Net Interest Income	407,550	387,533	391,765
Provision for loan losses, LHFI	15,094	10,957	8,375
Provision for loan losses, acquired loans	(7,395)	3,757	3,425
Net Interest Income After Provision for Loan Losses	399,851	372,819	379,965
Noninterest Income
Service charges on deposit accounts	44,003	45,253	47,366
Bank card and other fees	28,286	27,906	28,298
Mortgage banking, net	29,902	28,212	30,176
Insurance commissions	38,168	36,764	36,424
Wealth management	30,340	30,492	31,369
Other, net	13,949	5,626	(484)
Securities gains (losses), net	15	(310)	0
Total Noninterest Income	184,663	173,943	173,149
Noninterest Expense
Salaries and employee benefits	234,987	239,637	230,198
Defined benefit plan termination	17,644
Services and fees	60,893	58,695	57,534
Net occupancy - premises	25,767	24,982	25,318
Equipment expense	24,453	24,225	23,859
Other real estate expense	3,672	586	4,903
FDIC assessment expense	11,010	11,243	10,728
Other expense	51,743	47,930	49,122
Total Noninterest Expense	430,169	407,298	401,662
Income Before Income Taxes	154,345	139,464	151,452
Income taxes	48,715	31,053	35,414
Net Income	$ 105,630	$ 108,411	$ 116,038
Earnings Per Share
Basic	$ 1.56	$ 1.60	$ 1.72
Diluted	$ 1.56	$ 1.60	$ 1.71