Share Based Compensation (Tables)

3 Months Ended

Mar. 31, 2018

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,
	2018		2017
Stock options	$	252	$	227
Nonvested stock awards and restricted stock units		775		802
Employee stock purchase plan		22		23
Non-elective and elective 401(k) matching contribution in stock		—		64
Director stock ownership plan		34		37
Total share-based compensation expense	$	1,083	$	1,153

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

Number of options granted	35,842
Dividend yield	1.37	%
Expected volatility	24.73	%
Risk-free interest rate	2.54	%
Expected term (years)	4.0