Income Taxes (Expected Income Tax) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Abstract]
Expected amount	$ 2,966	$ 9,653	$ 3,745
Change in Indiana rate		(85)	(1,407)
State income taxes, net of federal benefit	(387)	612	186
Percentage depletion	(6,021)	(2,606)	(1,996)
Stock-based compensation	(238)		343
Captive insurance	(418)	(419)	(419)
Other	72	283	30
Total tax expected	$ (4,026)	$ 7,438	$ 482