Interest Expense

12 Months Ended

Dec. 31, 2015

Interest Costs Incurred [Abstract]

Interest Expense

16. Interest Expense

Interest expense consisted of the following (in thousands):

			Year Ended
			December 31,
			2015		2014		2013
Senior notes			$	38,250	$	40,702	$	50,250
Credit facility commitment fee				2,753		2,485		2,842
Federal coal lease obligations imputed interest				2,960		8,062		13,212
Amortization of deferred financing costs and
	original issue discount			4,174		4,321		4,499
Other				442		260		240
		Subtotal		48,579		55,830		71,043
Premium on early retirement of debt				—		13,837		—
Write-off of deferred financing costs
		and original issue discount		—		7,338		—
Other				—		364		—
Subtotal - cost of early retirement of debt and refinancings				—		21,538		—
Total interest expense				48,579		77,368		71,043
Less interest capitalized				(1,018)		(208)		(29,378)
Net interest expense			$	47,561	$	77,160	$	41,665