Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Cash Flows from Operating Activities
Net income		$ 5,641	$ 3,329
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		800	862
Net premium amortization of investment securities:
Provision for loan losses		(261)	580
Deferred income tax (benefit) expense		(10)	18
Mortgage loans originated for sale		(2,557)	(5,324)
Proceeds from sale of mortgage loans		2,537	6,624
Gain on sale of mortgage loans, net	[1]	(95)	(154)
Loss on disposal of premises and equipment, net		0	37
Net loss (gain) on sale and write downs of other real estate		76	(5)
Net loss on sale of available for sale investment securities	[1]	0	9
Unrealized loss on equity investment securities		55	0
Curtailment gain on postretirement benefits plan liability		0	(351)
Increase in cash surrender value of company-owned life insurance		(213)	(216)
Death benefits in excess of cash surrender value on company-owned life insurance		(67)	0
Decrease in accrued interest receivable		363	434
Decrease in other assets		517	1,787
Increase (decrease) in accrued interest payable		4	(32)
Decrease in other liabilities		(1,802)	(2,603)
Net cash provided by operating activities		5,644	5,942
Cash Flows from Investing Activities
Proceeds from maturities and calls of available for sale investment securities		16,715	19,474
Purchase of available for sale investment securities		(1,536)	(31,058)
Purchase of equity investment securities		(695)	(3)
Proceeds from cancelation of cost method investment securities		239	666
Purchase of cost method investment securities		0	(4,236)
Loans originated for investment greater than principal collected, net		(493)	(18,347)
Purchase of loans held for investment		(709)	(732)
Principal collected on purchased loans		1,317	643
Proceeds from death benefits of company-owned life insurance		366	0
Purchase of premises and equipment		(729)	(1,145)
Proceeds from sale of other real estate		346	699
Net cash provided by (used in) investing activities		14,821	(34,039)
Cash Flows from Financing Activities
Net increase in deposits		14,188	18,170
Net decrease in short-term securities sold under agreements to repurchase		(910)	(2,299)
Proceeds from long-term securities sold under agreements to repurchase		1	2
Repayments of long-term securities sold under agreements to repurchase		0	(5,041)
Repayments of Federal Home Loan Bank advances		(43)	0
Dividends paid, common stock		(939)	(751)
Shares issued under employee stock purchase plan		51	46
Net cash provided by financing activities		12,348	10,127
Net increase (decrease) in cash and cash equivalents		32,813	(17,970)
Cash and cash equivalents at beginning of year		120,408	113,534
Cash and cash equivalents at end of period		153,221	95,564
Supplemental Disclosures
Cash paid during the period for interest		883	948
Transfers from loans to other real estate		104	187
Sale and financing of other real estate		84	2,172
Cash dividends payable, common		940	751
Employee Stock Purchase Plan Expense [Member]
Net premium amortization of investment securities:
Noncash compensation expense		8	9
Director Fee Compensation [Member]
Net premium amortization of investment securities:
Noncash compensation expense		18	28
Available-for-sale Securities [Member]
Net premium amortization of investment securities:
Net premium amortization of investment securities		616	897
Held-to-maturity Securities [Member]
Net premium amortization of investment securities:
Net premium amortization of investment securities		$ 14	$ 13

[1] Not within the scope of ASC Topic 606.