Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest, fee and dividend income
Interest and fees on loans	$ 321,474	$ 300,827	$ 267,096
Securities available for sale	23,303	26,920	28,564
Securities held to maturity	19,105	13,242	10,934
Other	3,652	3,266	2,813
Total interest, fee and dividend income	367,534	344,255	309,407
Interest expense
Deposits	39,986	22,144	14,475
Short-term borrowings	9,693	10,552	5,996
Long-term debt	1,875	1,790	2,299
Junior subordinated debt	4,425	4,140	3,144
Total interest expense	55,979	38,626	25,914
Net interest income	311,555	305,629	283,493
Provision for loan losses	25,412	28,828	30,988
Net interest income after provision for loan losses	286,143	276,801	252,505
Noninterest income
Insurance and other financial services revenue	25,006	24,345	23,532
Service charges on deposit accounts	17,151	17,224	16,750
ATM and debit card fees	23,893	22,699	21,372
Retirement plan administration fees	30,388	26,992	20,213
Trust	19,164	19,524	19,586
Bank owned life insurance	5,355	5,091	5,175
Net securities gains (losses)	4,213	(6,341)	1,867
Gain on the sale of equity investment	0	0	818
Other	18,853	15,228	11,991
Total noninterest income	144,023	124,762	121,304
Noninterest expense
Salaries and employee benefits	156,867	151,685	135,222
Occupancy	22,706	22,318	21,808
Data processing and communications	18,318	17,652	17,068
Professional fees and outside services	14,785	14,376	13,499
Equipment	18,583	17,037	15,225
Office supplies and postage	6,579	6,204	6,284
FDIC expenses	1,946	4,651	4,767
Advertising	2,773	2,782	2,744
Amortization of intangible assets	3,579	4,042	3,960
Loan collection and other real estate owned, net	4,158	4,217	4,763
Other	24,440	19,597	20,308
Total noninterest expense	274,734	264,561	245,648
Income before income tax expense	155,432	137,002	128,161
Income tax expense	34,411	24,436	46,010
Net income	$ 121,021	$ 112,566	$ 82,151
Earnings per share
Basic (in dollars per share)	$ 2.76	$ 2.58	$ 1.89
Diluted (in dollars per share)	$ 2.74	$ 2.56	$ 1.87