Summarized Quarterly Financial Information—Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 23,096	$ 26,872	$ 32,550	$ 33,451	$ 47,988	$ 56,486	$ 60,581	$ 59,966
Loss from operations	(61,864)	(50,617)	(57,796)	(121,887)	478	5,569	10,879	11,323	$ (292,164)	$ 28,249	$ 14,402
Loss available to common stockholders	$ (64,696)	$ (51,910)	$ (61,083)	$ (122,240)	$ 1,745	$ 4,671	$ 9,592	$ 10,043	$ (299,929)	$ 26,051	$ 8,943
Earnings per share, Basic (in usd per share)	$ (0.98)	$ (0.80)	$ (0.94)	$ (1.89)	$ 0.02	$ 0.07	$ 0.15	$ 0.15	$ (4.61)	$ 0.39	$ 0.14
Earnings per share, Diluted (in usd per share)	$ (0.98)	$ (0.80)	$ (0.94)	$ (1.89)	$ 0.02	$ 0.07	$ 0.15	$ 0.15	$ (4.61)	$ 0.39	$ 0.14
Ceiling test write-downs	$ 51,944	$ 40,200	$ 65,500	$ 108,900
Gain on sale of assets			$ 21,500						$ 21,937	$ 0	$ 0