Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Apr. 05, 2012
Stock options under 2012 Plan
Stock option details
Shares available for future grants	9,414		800,000
Maximum exercisable period for options granted	10 years
Number of options granted (in shares)	26,500
Stock option activity
Options outstanding at the beginning of the period (in shares)	658,588
Plus: Options granted (in shares)	26,500
Less:
Options exercised (in shares)	10,549
Options forfeited (in shares)	7,263
Options outstanding at the end of the period (in shares)	667,276
Options fully vested and exercisable at the end of the period (in shares)	393,999
Stock Options, Weighted average exercise price
Options outstanding at the beginning, weighted average exercise price (in dollars per share)	$ 27.55
Plus: Options granted, weighted average exercise price (in dollars per share)	16.84
Less:
Options exercised, weighted average exercise price (in dollars per share)	21.37
Options forfeited, weighted average exercise price (in dollars per share)	29.55
Options outstanding at the end, weighted average exercise price (in dollars per share)	27.20
Options fully vested and exercisable at the end, weighted average exercise price (in dollars per share)	$ 22.02
Stock Options, Weighted average remaining contractual term (years)
Options outstanding at the end, weighted average remaining contractual term (years)	5 years 8 months 15 days
Options fully vested and exercisable at the end, weighted average remaining contractual term (years)	4 years 1 month 6 days
Stock Options, Aggregate intrinsic value
Options outstanding at the end, aggregate intrinsic value	$ 2,131
Options fully vested and exercisable at the end, aggregate intrinsic value	1,825
Stock-based compensation expense	219	$ 265
Stock-based compensation cost, unrecognized, related to non-vested options	$ 1,704
Stock-based compensation cost, unrecognized, related to non-vested options, weighted-average period of recognition	1 year 9 months 18 days
Incentive stock options granted to 10% shareholders
Stock option details
Maximum exercisable period for options granted	5 years