Stock Incentive Plan (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Compensation cost, net of forfeitures, related to stock-based compensation

The following table summarizes the compensation cost, net of forfeitures, related to stock-based compensation for the years ended December 31, 2017, 2016 and 2015 (in thousands):

	2017			2016			2015
Stock and stock unit awards:
Pre-tax compensation expense	$	954		$	384		$	378
Income tax benefit	(334		)	(134		)	(132		)
Total share-based compensation expense, net of income taxes	$	620		$	250		$	246

Summary of option activity

A summary of option activity under the SI Plan and the 1997 Stock Incentive Plan as of December 31, 2017, 2016 and 2015, and changes during the years then ended is presented below:

	2017
	Shares	Weighted-Average Exercise Price	Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding, beginning of year	40,500	$24.65
Granted	0	0.00
Exercised	(27,500)	25.42
Forfeited or expired	(2,500)	23.00
Outstanding, end of year	10,500	$23.00	0.96	$	163,170
Exercisable, end of year	10,500	$23.00	0.96	$	163,170

The total intrinsic value of options exercised during 2017 was $259,000. There were no stock options for shares of common stock not considered in computing the aggregate intrinsic value of outstanding shares and exercisable shares for 2017 because they were anti-dilutive.

	2016
	Shares	Weighted-Average Exercise Price	Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding, beginning of year	45,500	$24.67
Granted	0	0.00
Exercised	(2,500)	24.86
Forfeited or expired	(2,500)	24.86
Outstanding, end of year	40,500	$24.65	1.42	$	378,850
Exercisable, end of year	40,500	$24.65	1.42	$	378,850

The total intrinsic value of options exercised during 2016 was $14,000. There were no stock options for shares of common stock not considered in computing the aggregate intrinsic value of outstanding shares and exercisable shares for 2016 because they were anti-dilutive.

	2015
	Shares	Weighted-Average Exercise Price	Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding, beginning of year	52,000	$24.64
Granted	0	0.00
Exercised	0	0.00
Forfeited or expired	(6,500)	24.43
Outstanding, end of year	45,500	$24.67	2.42	$	63,000
Exercisable, end of year	45,500	$24.67	2.42	$	63,000

Stock options, by exercise price range

The following table summarizes information about stock options under the SI Plan outstanding at December 31, 2017:

		Options Outstanding		Options Exercisable
Range of Exercise Prices	Number Outstanding	Weighted-Average Remaining Contractual Life	Weighted-Average Exercise Price	Number Exercisable	Weighted-Average Exercise Price
$22.50 to $24.50	10,500	0.96	$23.00	10,500	$23.00

Schedule of Unvested Restricted Stock and Restricted Stock Units Roll Forward [Table Text Block]

The following table summarizes non-vested stock and stock unit activity for the years ended December 31, 2017, 2016 and 2015:

	2017			2016			2015
	Shares	Weighted-avg Grant-date Fair Value		Shares	Weighted-avg Grant-date Fair Value		Shares	Weighted-avg Grant-date Fair Value
Nonvested, beginning of year	32,338	$22.64		30,169	$20.87		26,897	$22.95
Granted	18,391	30.65		13,912	26.09		18,002	20.14
Vested	(50,729)	25.54		(11,743)	22.18		(14,730)	23.77
Forfeited	0	0.00		0	0.00		0	0.00
Nonvested, end of year	0	$0.00		32,338	$22.64		30,169	$20.87
Fair value of shares vested		$	260,483		$	260,483		$	350,075