Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest and dividend income:
Loans, including fees	$ 146,794	$ 141,086	$ 131,836
Debt securities:
Taxable	27,772	25,397	25,303
Tax exempt	4,165	3,881	1,509
Dividends	1,324	2,181	2,118
Interest bearing cash at Federal Reserve and other banks	1,347	1,163	648
Total interest and dividend income	181,402	173,708	161,414
Interest expense:
Deposits	3,958	3,483	3,434
Other borrowings	305	9	4
Junior subordinated debt	2,535	2,229	1,978
Total interest expense	6,798	5,721	5,416
Net interest income	174,604	167,987	155,998
Provision (benefit from reversal of provision previously provided) for loan losses	89	(5,970)	(2,210)
Net interest income after provision for loan losses	174,515	173,957	158,208
Noninterest income:
Service charges and fees	37,423	33,226	32,080
Gain on sale of loans	3,109	4,037	3,064
Commissions on sale of non-deposit investment products	2,729	2,329	3,349
Increase in cash value of life insurance	2,685	2,717	2,786
Other	4,075	2,254	4,068
Total noninterest income	50,021	44,563	45,347
Noninterest expense:
Salaries and related benefits	82,930	80,724	71,405
Other	64,094	65,273	59,436
Total noninterest expense	147,024	145,997	130,841
Income before income taxes	77,512	72,523	72,714
Provision for income taxes	36,958	27,712	28,896
Net income	$ 40,554	$ 44,811	$ 43,818
Earnings per share:
Basic	$ 1.77	$ 1.96	$ 1.93
Diluted	$ 1.74	$ 1.94	$ 1.91