Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets
Net operating loss carryforwards	$ 79,208	$ 88,447
Alternative minimum tax carryforwards	9,785	7,197
Percentage depletion carryover	2,442	2,068
Property and equipment	42,757	113
Deferred gain on sale leaseback transaction	32,831	0
Other	7,396	281
Total non-current deferred tax assets	174,419	98,106
Valuation allowance on deferred tax assets	(154,320)	0
Total deferred tax assets, net of valuation allowance	20,099	98,106
Deferred tax liabilities
Unrealized gain on derivatives	5,699	20,145
Property and equipment	0	(145,620)
Other	(14,400)	(5,875)
Total deferred tax liabilities	(20,099)	(171,640)
Net deferred tax liabilities	$ 0	$ (73,534)