Stock Compensation (Tables)

12 Months Ended

Dec. 31, 2017

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

Summary of Transactions of Stock Option Plans

The following table summarizes the transactions of the Company’s stock option plans for the three-year period ended December 31, 2017:

	Number of shares		Weighted-average exercise price
Options outstanding - December 31, 2014	406,640		$	20.90
Options granted	49,510		$	28.33
Options exercised	(86,538	)	$	18.98
Options forfeited	—		n/a
Options outstanding - December 31, 2015	369,612		$	22.35
Options granted	42,302		$	33.98
Options exercised	(27,656	)	$	20.59
Options forfeited	—		n/a
Options outstanding - December 31, 2016	384,258		$	23.75
Options granted	55,223		$	36.75
Options exercised	(53,198	)	$	22.83
Options forfeited	—		n/a
Options outstanding - December 31, 2017	386,283		$	25.74
Price range $ 18.08 — $ 18.30
(weighted-average contractual life of 4.0 years)	101,270		$	18.15
Price range $ 19.21 — $ 27.18
(weighted-average contractual life of 4.3 years)	140,322		$	23.54
Price range $ 28.33 — $ 38.55
(weighted-average contractual life of 8.2 years)	144,691		$	33.18
Options outstanding - December 31, 2017	386,283
Exercisable options —
December 31, 2015	210,940		$	20.48
December 31, 2016	242,522		$	21.01
December 31, 2017	239,043		$	21.59

Assumptions Used for Valuing Options Granted

The following assumptions were used for valuing options granted in the years ended December 31:

	2017		2016
Per share fair value of options granted during the period	$14.38		$13.58
Risk-free interest rate	2.06	%	1.42	%
Dividend yield	1.22	%	1.16	%
Volatility factor	46.6	%	48.3	%
Weighted-average expected life in years	5.3		5.3

Summary of Aggregate Intrinsic Value Related to Options

The following table summarizes the aggregate intrinsic value related to options exercised, outstanding and exercisable as of and for the years ended December 31:

	2017		2016
	(In thousands)
Exercised	$	814	$	379
Outstanding	$	7,966	$	4,288
Exercisable	$	5,921	$	3,370

Schedule of Fair Value of Nonvested Shares

The fair value of nonvested shares is determined based on the market price of the shares on the grant date.

	Shares		Fair value per share
Nonvested at December 31, 2014	136,912		$	23.16
Granted	38,386		$	28.33
Vested	(52,150	)	$	18.08
Forfeited	(2,900	)	$	24.44
Nonvested at December 31, 2015	120,248		$	26.99
Granted	29,268		$	33.98
Vested	(40,700	)	$	25.56
Forfeited	(3,500	)	$	29.18
Nonvested at December 31, 2016	105,316		$	29.41
Granted	50,519		$	40.69
Vested	(40,762	)	$	27.18
Forfeited	(3,600	)	$	33.37
Nonvested at December 31, 2017	111,473		$	35.21