Interest Expense (Tables)

9 Months Ended

Sep. 30, 2017

Interest Costs Incurred [Abstract]

Interest Expense

			Three Months Ended				Nine Months Ended
			September 30,				September 30,
			2017		2016		2017		2016
Senior notes			$	6,559	$	9,563	$	21,127	$	28,687
Credit facility unutilized fee				949		1,125		3,328		2,953
Federal coal lease obligations imputed interest				88		87		259		252
Amortization of deferred financing costs and
	original issue discount			1,930		1,118		5,862		3,220
Other				47		74		193		210
		Subtotal		9,573		11,967		30,769		35,322
Premium on early retirement of debt				—		—		880		—
Write-off of deferred financing costs
	and original issue discount			—		1,254		702		1,254
	Total cost of early retirement of debt and refinancings			—		1,254		1,582		1,254
Total interest expense				9,573		13,221		32,351		36,576
Less interest capitalized				—		(189)		—		(1,205)
Net interest expense			$	9,573	$	13,032	$	32,351	$	35,371