Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest, fee, and dividend income
Interest and fees on loans	$ 250,994	$ 241,828	$ 243,324
Securities available for sale	24,033	20,418	24,464
Securities held to maturity	9,852	9,233	5,261
Other	2,068	1,745	2,032
Total interest, fee, and dividend income	286,947	273,224	275,081
Interest expense
Deposits	14,366	14,257	13,638
Short-term borrowings	2,309	783	845
Long-term debt	3,204	3,355	6,555
Junior subordinated debt	2,627	2,221	2,165
Total interest expense	22,506	20,616	23,203
Net interest income	264,441	252,608	251,878
Provision for loan losses	25,431	18,285	19,539
Net interest income after provision for loan losses	239,010	234,323	232,339
Noninterest income
Insurance and other financial services revenue	24,396	24,211	24,517
Service charges on deposit accounts	16,729	17,056	17,941
ATM and debit card fees	19,448	18,248	17,135
Retirement plan administration fees	16,063	14,146	12,129
Trust	18,565	19,026	18,950
Bank owned life insurance income	5,195	4,334	5,349
Net securities (losses) gains	(644)	3,087	92
Gain on the sale of equity investment	0	4,179	19,401
Other	15,961	14,194	10,513
Total noninterest income	115,713	118,481	126,027
Noninterest expense
Salaries and employee benefits	129,702	124,318	119,667
Occupancy	20,940	22,095	22,128
Data processing and communications	16,495	16,588	16,137
Professional fees and outside services	13,617	13,407	14,426
Equipment	14,295	13,408	12,658
Office supplies and postage	6,168	6,367	6,983
FDIC expenses	5,111	5,145	4,944
Advertising	2,556	2,654	2,831
Amortization of intangible assets	3,928	4,864	5,047
Loan collection and other real estate owned	3,458	2,620	3,248
Prepayment penalties on long-term debt	0	0	17,902
Other	19,652	24,710	20,092
Total noninterest expense	235,922	236,176	246,063
Income before income tax expense	118,801	116,628	112,303
Income tax expense	40,392	40,203	37,229
Net income	$ 78,409	$ 76,425	$ 75,074
Earnings per share
Basic (in dollars per share)	$ 1.81	$ 1.74	$ 1.71
Diluted (in dollars per share)	$ 1.80	$ 1.72	$ 1.69