Consolidated Statement of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Revenue:
Revenue		$ 89,313	$ 66,864
Operating Costs and expenses:
Operating costs and expenses		62,419	46,640
DD&A		11,738	10,829
ARO accretion		309	282
Exploration costs		280	217
SG&A		2,984	3,890
Interest	[1]	4,619	2,708
Total costs and expenses		82,349	64,566
Income before income taxes		6,964	2,298
Income tax expense (benefit)
Current		(229)	(203)
Deferred		193	369
Total income tax expense (benefit)		(36)	166
Net income		$ 7,000	$ 2,132
Net income per share: (Note 9)
Basic and diluted (in Dollars per share)		$ 0.23	$ 0.07
Weighted average shares outstanding:
Basic and diluted (in Shares)		30,245	29,955
Coal Sales [Member]
Revenue:
Revenue		$ 85,235	$ 66,787
Other Revenue [Member]
Revenue:
Revenue		$ 4,078	$ 77

[1] Interest expense for the three months ended March 31, 2019 and 2018 includes $1,013 and $(158), respectively, for the net change in the estimated fair value of our interest rate swaps.