Segment Information - Reconciliation of Net Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from External Customer [Line Items]
Segment Adjusted EBITDA	$ 69,824	$ 187,053
Other revenues	226,720	378,290
Cost of other revenues	(7,561)	(7,745)
Depreciation and depletion	(28,692)	(22,233)
Selling, general and administrative	(8,456)	(8,905)
Loss on early extinguishment of debt	0	(9,756)
Other income	1,822	0
Interest expense, net	(7,533)	(8,592)
Income tax expense	(3,241)	(27,984)
Net income	21,545	110,447
Other revenues
Revenue from External Customer [Line Items]
Other revenues	$ 5,382	$ 8,609