Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest, fee and dividend income
Interest and fees on loans	$ 300,827	$ 267,096	$ 250,994
Securities available for sale	26,920	28,564	24,033
Securities held to maturity	13,242	10,934	9,852
Other	3,266	2,813	2,068
Total interest, fee and dividend income	344,255	309,407	286,947
Interest expense
Deposits	22,144	14,475	14,366
Short-term borrowings	10,552	5,996	2,309
Long-term debt	1,790	2,299	3,204
Junior subordinated debt	4,140	3,144	2,627
Total interest expense	38,626	25,914	22,506
Net interest income	305,629	283,493	264,441
Provision for loan losses	28,828	30,988	25,431
Net interest income after provision for loan losses	276,801	252,505	239,010
Noninterest income
Insurance and other financial services revenue	24,345	23,532	24,396
Service charges on deposit accounts	17,224	16,750	16,729
ATM and debit card fees	22,699	21,372	19,448
Retirement plan administration fees	26,992	20,213	16,063
Trust	19,524	19,586	18,565
Bank owned life insurance	5,091	5,175	5,195
Net securities (losses) gains	(6,341)	1,867	(644)
Gain on the sale of equity investment	0	818	0
Other	15,228	11,991	15,961
Total noninterest income	124,762	121,304	115,713
Noninterest expense
Salaries and employee benefits	151,685	135,222	132,060
Occupancy	22,318	21,808	20,940
Data processing and communications	17,652	17,068	16,495
Professional fees and outside services	14,376	13,499	13,617
Equipment	17,037	15,225	14,295
Office supplies and postage	6,204	6,284	6,168
FDIC expenses	4,651	4,767	5,111
Advertising	2,782	2,744	2,556
Amortization of intangible assets	4,042	3,960	3,928
Loan collection and other real estate owned, net	4,217	4,763	3,458
Other	19,597	20,308	17,294
Total noninterest expense	264,561	245,648	235,922
Income before income tax expense	137,002	128,161	118,801
Income tax expense	24,436	46,010	40,392
Net income	$ 112,566	$ 82,151	$ 78,409
Earnings per share
Basic (in dollars per share)	$ 2.58	$ 1.89	$ 1.81
Diluted (in dollars per share)	$ 2.56	$ 1.87	$ 1.80