Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Taxes
Statutory federal income tax rate (as a percent)			34.00%
Income tax at federal rate	$ 373	$ 1,288	$ 914	$ 2,633
Increase (decrease) resulting from:
State income taxes, net of federal income tax	46	143	113	310
Compensation deduction limitations	104	236	228	354
Expense reflected in tax basis	211		211
Other permanent differences	49	185	154	248
Capital goods excise tax credit	(140)	(303)	(363)	(404)
Total income tax expense	643	1,549	1,257	3,141
Unrecognized Tax Benefits	0		0
Interest or penalties related to tax assessments recognized	$ 0	$ 0	$ 0	$ 0