Consolidated Statement of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Coal sales		$ 268,202	$ 278,924	$ 339,490
Equity income (loss)		365	(1,436)	(1,606)
Other (Note 7)		3,066	3,962	2,236
Revenue		271,633	281,450	340,120
Costs and expenses:
Operating costs and expenses		190,150	192,777	237,897
DD&A		38,495	35,565	43,942
ARO accretion		861	1,029	498
Coal exploration costs		854	1,673	2,039
SG&A		14,978	10,520	12,617
Interest	[1]	12,413	14,842	15,557
Asset impairment (Note 2)			16,560
Total costs and expenses		257,751	272,966	312,550
Income before income taxes		13,882	8,484	27,570
Less income tax expense (benefit)
Current		(2,748)	(167)	(14)
Deferred		(16,446)	(3,859)	7,452
Total income tax expense (benefit)		(19,194)	(4,026)	7,438
Net income	[2]	$ 33,076	$ 12,510	$ 20,132
Net income per share: (Note 9)
Basic and diluted (in Dollars per share)		$ 1.08	$ 0.42	$ 0.68
Weighted average shares outstanding:
Basic and diluted (in Shares)		29,661	29,260	29,031
Interest expense on net change in estimated fair value of interest rate swaps		$ (723)	$ (637)	$ 159
Savoy [Member]
Revenue:
Equity income (loss)		460	(1,187)	(1,532)
Costs and expenses:
Asset impairment (Note 2)		1,000	2,000	2,600
Sunrise Energy [Member]
Revenue:
Equity income (loss)		$ (95)	$ (249)	$ (74)

[1] Included in interest expense is the change in the estimated fair value of our interest rate swaps. Such amounts were $(723), $(637), and $159 for 2017, 2016, and 2015, respectively.

[2] There is no material difference between net income and comprehensive income.