CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest income
Loans	$ 79,795	$ 57,903	$ 52,619
Loans held for sale	3,301	1,755	1,396
Securities available for sale, nontaxable	1,668	1,129	35
Securities available for sale, taxable	5,579	6,915	10,141
Securities held to maturity, nontaxable	214	248	96
Securities held to maturity, taxable	1,764	1,989	590
Federal Home Loan Bank stock dividends	961	723	723
Other interest earning assets	228	67	35
Total interest income	93,510	70,729	65,635
Interest expense
Deposits	8,437	5,922	6,526
Federal Home Loan Bank advances	4,699	2,486	1,334
Repurchase agreements and other	21	20	1,253
Total interest expense	13,157	8,428	9,113
Net interest income	80,353	62,301	56,522
Provision for loan losses	4,253	5,387	2,135
Net interest income after provision for loan losses	76,100	56,914	54,387
Non-interest income
Insurance agency income	2,006	1,686
Non-deposit investment income	1,158	1,281	1,115
Deposit related fees	5,636	5,486	5,384
Mortgage servicing fees	3,005	2,833	2,730
Mortgage servicing rights valuation	(9)	39	19
Mortgage servicing rights amortization	(1,944)	(2,094)	(1,800)
Other service fees	125	135	75
Net gains (losses):
Securities available for sale (includes $566, $604 and $142, respectively, accumulated other comprehensive income reclassifications for unrealized net gains on available for sale securities)	566	604	142
Mortgage banking income	6,503	6,444	6,841
Real estate owned and other repossessed assets, net	(189)	(93)	(445)
Debit/credit card fees	4,215	3,846	3,684
Trust fee income	1,618
Other income	2,549	1,909	1,972
Total non-interest income	25,239	22,076	19,717
Non-interest expense
Salaries and employee benefits (includes $0, $1,278 and $315, respectively accumulated other comprehensive income reclassifications for prior service credit on the postretirement plan).	34,807	28,600	26,724
Occupancy	3,943	3,373	3,249
Equipment and data processing	8,944	7,564	6,865
Financial institutions tax	1,648	1,694	1,241
Advertising	991	845	737
Amortization of intangible assets	422	69	54
FDIC insurance premiums	1,078	940	1,241
Other insurance premiums	450	328	355
Legal and consulting fees	724	953	1,227
Other professional fees	2,151	1,046	1,733
Prepayment penalty			1,280
Real estate owned and other repossessed asset expenses	135	191	338
Merger related expenses	5,001	787
Other expenses	7,965	5,629	4,885
Total non-interest expenses	68,259	52,019	49,929
Income before income taxes	33,080	26,971	24,175
Income tax expense (includes $198, $147 and $160 income tax expense from reclassification items)	11,295	8,143	7,893
Earnings available to common shareholders	21,785	18,828	16,282
Net income	21,785	18,828	16,282
Other comprehensive income (loss)
Unrealized gains (losses) on securities available for sale, net of reclassifications and tax of $1,093, $(344) and $444, respectively	2,578	(638)	824
Accretion of unrealized losses on securities transferred from available for sale to held to maturity, net of tax of $66, $86, and $21, respectively	129	160	39
Unrealized gains (losses) and amortization of prior service credit on postretirement plan, net of tax of $0, $(447) and $(46), respectively		(831)	(85)
Reversal of disproportionate tax effect from postretirement plan upon settlement		(511)
Total other comprehensive income (loss)	2,707	(1,820)	778
Comprehensive income	$ 24,492	$ 17,008	$ 17,060
Earnings per share
Basic	$ 0.44	$ 0.40	$ 0.34
Diluted	$ 0.44	$ 0.40	$ 0.34