Consolidated Statement of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue:
Revenue		$ 72,310	$ 57,243	$ 161,623	$ 124,107
Costs and expenses:
Operating costs and expenses		54,001	38,874	116,420	85,514
DD&A		12,096	11,120	23,834	21,949
ARO accretion		314	291	623	573
Exploration costs		208	315	488	532
SG&A		3,475	2,474	6,459	6,364
Interest	[1]	5,369	4,315	9,988	7,023
Total costs and expenses		75,463	57,389	157,812	121,955
Income before income taxes		(3,153)	(146)	3,811	2,152
Less income tax benefit
Current		78	(19)	(151)	(222)
Deferred		113	(104)	306	265
Total income tax benefit		191	(123)	155	43
Net income		$ (3,344)	$ (23)	$ 3,656	$ 2,109
Net income per share: (Note 11)
Basic and diluted (in Dollars per share)		$ (0.11)	$ 0.00	$ 0.12	$ 0.07
Weighted average shares outstanding:
Basic and diluted (in Shares)		30,245	29,980	30,245	29,968
Coal Sales [Member]
Revenue:
Revenue		$ 71,113	$ 56,922	$ 156,348	$ 123,709
Other Revenue [Member]
Revenue:
Revenue		$ 1,197	$ 321	$ 5,275	$ 398

[1] Interest expense for the six months ended June 30, 2019 and 2018 includes $2,856 and $844, respectively, for the net change in the estimated fair value of our interest rate swaps. Such amounts were $1,843 and $1,003 for the three months ended June 30, 2019 and 2018, respectively.