Consolidated Statement of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Revenue		$ 83,096	$ 79,722	$ 244,719	$ 203,829
Costs and expenses:
Operating costs and expenses		71,363	60,230	187,783	145,744
DD&A		11,778	10,815	35,612	32,764
ARO accretion		320	293	943	866
Exploration costs		347	279	835	811
SG&A		2,926	2,519	9,385	8,883
Interest	[1]	3,558	3,261	13,546	10,284
Total costs and expenses		90,292	77,397	248,104	199,352
Income (loss) before income taxes		(7,196)	2,325	(3,385)	4,477
Income tax benefit
Current		(426)	(204)	(577)	(426)
Deferred		(3,047)	(385)	(2,741)	(120)
Total income tax benefit		(3,473)	(589)	(3,318)	(546)
Net income (loss)		$ (3,723)	$ 2,914	$ (67)	$ 5,023
Net income (loss) per share: (Note 11)
Basic and diluted (in Dollars per share)		$ (0.12)	$ 0.09	$ 0.00	$ 0.16
Weighted average shares outstanding:
Basic and diluted (in Shares)		30,249	30,177	30,246	30,038
Coal Sales [Member]
Revenue:
Revenue		$ 82,883	$ 79,055	$ 239,231	$ 202,764
Other Revenue [Member]
Revenue:
Revenue		$ 213	$ 667	$ 5,488	$ 1,065

[1] Interest expense for the nine months ended September 30, 2019 and 2018 includes $3,018 and $136, respectively, for the net change in the estimated fair value of our interest rate swaps. Such amounts were $162 and $(708) for the three months ended September 30, 2019 and 2018, respectively.