Stock Compensation Plans (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Options Outstanding, January 1, 2018 | shares	43,450
Options Outstanding, Forfeited or cancelled | shares	0
Options Outstanding, Exercised | shares	(6,250)
Options Outstanding, Granted | shares	0
Options outstanding, March 31, 2018 | shares	37,200
Options Outstanding, Vested or expected to vest at March 31, 2018 | shares	37,200
Options Outstanding, Exercisable at March 31, 2018 | shares	29,450
Weighted Average Exercise Price, Outstanding, January 1, 2018 | $ / shares	$ 21.62
Weighted Average Exercise Price, Forfeited or cancelled | $ / shares	0
Weighted Average Exercise Price, Exercised | $ / shares	15.53
Weighted Average Exercise Price, Granted | $ / shares	0
Weighted Average Exercise Price, outstanding, March 31, 2018 | $ / shares	22.6
Weighted Average Exercise Price, Vested or expected to vest at March 31, 2018 | $ / shares	22.6
Weighted Average Exercise Price, Exercisable at March 31, 2018 | $ / shares	$ 19.74
Weighted Average Remaining Contractual Term (in years), outstanding, March 31, 2018	3 years 3 months 25 days
Weighted Average Remaining Contractual Term (in years), Vested or expected to vest at March 31, 2018	3 years 3 months 25 days
Weighted Average Remaining Contractual Term (in years), Exercisable at March 31, 2018	2 years 4 months 10 days
Aggregate Intrinsic Value, outstanding, March 31, 2018 | $	$ 1,291
Aggregate Intrinsic Value, Vested or expected to vest at March 31, 2018 | $	1,291
Aggregate Intrinsic Value, Exercisable at March 31, 2018 | $	$ 1,107