Stock Based Compensation (Tables)

9 Months Ended

Sep. 30, 2015

Share Based Compensation [Abstract]

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2015		2014		2015		2014
Stock options	$	164	$	171	$	548	$	492
Nonvested stock awards and restricted stock units		668		593		2,179		1,758
Employee stock purchase plan		19		18		56		54
Non-elective and elective 401(k) matching contribution in stock		449		413		1,624		1,561
Director stock ownership plan		31		32		93		94
Total share-based compensation expense	$	1,331	$	1,227	$	4,500	$	3,959

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

					Weighted Average
			Weighted Average		Remaining
		Number of	Exercise Price		Contractual
		Options	(per option)		Term (years)
Options outstanding at December 31, 2014		87,075	$	59.09
	Options granted	38,698		87.30
	Options exercised	(21,157)		46.61
	Options forfeited	(4,945)		78.42
Options outstanding at September 30, 2015		99,671	$	71.73		5.3
Options exercisable at September 30, 2015		31,457	$	56.46		4.3

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

						Weighted
						Average	Weighted			Weighted
					Number	Remaining	Average		Number	Average
Range of					of Options	Contractual	Exercise Price		of Options	Exercise Price
Exercise Prices					Outstanding	Term (years)	(per option)		Exercisable	(per option)
$	—	-	$	10.00	—	—	$	—	—	$	—
$	10.01	-	$	20.00	2,367	1.3		18.82	2,367		18.82
$	20.01	-	$	30.00	—	—		—	—		—
$	30.01	-	$	40.00	6,317	3.4		38.13	6,317		38.13
$	40.01	-	$	50.00	—	—		—	—		—
$	50.01	-	$	60.00	21,055	4.4		58.26	11,997		58.26
$	60.01	-	$	70.00	—	—		—	—		—
$	70.01	-	$	80.00	33,786	5.4		73.47	10,776		73.47
$	80.01	-	$	90.00	36,146	6.4		87.30	—		—
					99,671	5.3		71.73	31,457		56.46

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	2015
Number of options granted	38,698
Dividend Yield	1.55	%
Expected Volatility	36.32	%
Risk-free interest rate	1.22	%
Expected term (years)	4.0

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

			Weighted
			Average Grant
		Number of	Date Fair Value
		Shares	(per share)
Nonvested awards, December 31, 2014		124,450	$	61.80
	Granted	27,266	$	86.39
	Vested	(33,681)	$	46.76
	Forfeited	(7,644)	$	61.12
Nonvested awards, September 30, 2015		110,391	$	72.51

			Weighted
			Average Grant
		Number of	Date Fair Value
		Units	(per unit)
Nonvested awards, December 31, 2014		7,158	$	61.03
	Granted	1,450	$	87.30
	Vested	(2,434)	$	43.45
Nonvested awards, September 30, 2015		6,174	$	74.14