Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 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
	March 31,
	2015		2014
Stock options	$	185	$	150
Nonvested stock awards and restricted stock units		752		556
Employee stock purchase plan		18		17
Non-elective and elective 401(k) matching contribution in stock		699		649
Director stock ownership plan		31		16
Total share-based compensation expense	$	1,685	$	1,388

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	(5,335)		45.26
Options outstanding at March 31, 2015		120,438	$	68.77		5.7
Options exercisable at March 31, 2015		46,549	$	53.43		4.7

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

						Weighted	Weighted			Weighted
					Number	Average	Average		Number	Average
Range of					of Options	Contractual	Exercise Price		of Options	Exercise Price
Exercise Prices					Outstanding	Life (years)	(per option)		Exercisable	(per option)
$	—	-	$	10.00	—	—	$	—	—	$	—
$	10.01	-	$	20.00	2,367	1.8		18.82	2,367		18.82
$	20.01	-	$	30.00	—	—		—	—		—
$	30.01	-	$	40.00	14,408	3.9		38.08	14,408		38.08
$	40.01	-	$	50.00	2,192	4.2		46.21	1,462		46.21
$	50.01	-	$	60.00	26,462	4.9		58.26	16,694		58.26
$	60.01	-	$	70.00	—	—		—	—		—
$	70.01	-	$	80.00	36,311	5.9		73.47	11,618		73.47
$	80.01	-	$	90.00	38,698	6.9		87.30	—		—
					120,438	5.7		68.77	46,549		53.43

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	21,260	$	86.54
	Vested	(24,810)	$	40.62
	Forfeited	(2,619)	$	59.89
Nonvested awards, March 31, 2015		118,281	$	70.74

			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	(2,100)	$	38.13
Nonvested awards, March 31, 2015		6,508	$	74.28