SUMMARIZED QUARTERLY FINANCIAL INFORMATION - UNAUDITED - Results of Operations by Quarter (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Operating revenue	$ 113,107	$ 94,427	$ 89,319	$ 80,677	$ 110,499	$ 132,196	$ 149,525	$ 153,498	$ 377,392	$ 544,649	$ 795,542
Loss from operations	(90,234)	(72,128)	(174,656)	(172,150)	(342,759)	(297,209)	(228,161)	(497,194)	(509,168)	(1,365,323)	(255,338)
Net loss	$ (116,406)	$ (89,635)	$ (195,761)	$ (188,784)	$ (318,656)	$ (291,965)	$ (152,906)	$ (327,388)	$ (590,586)	$ (1,090,915)	$ (189,543)
Basic loss per share (in usd per share)	$ (20.76)	$ (16.01)	$ (35.05)	$ (33.89)	$ (57.63)	$ (52.82)	$ (27.68)	$ (59.33)	$ (105.63)	$ (197.45)	$ (35.95)
Diluted loss per share (in usd per share)	$ (20.76)	$ (16.01)	$ (35.05)	$ (33.89)	$ (57.63)	$ (52.82)	$ (27.68)	$ (59.33)	$ (105.63)	$ (197.45)	$ (35.95)
Write-down of oil and gas properties	$ 73,094	$ 36,484	$ 118,649	$ 129,204	$ 351,062	$ 295,679	$ 224,294	$ 491,412	$ 357,431	$ 1,362,447	$ 351,192
Restructuring fees	13,424	5,784	9,436	953					29,597	0	0
Other operational expenses	6,187	9,059	27,680	12,527					55,453	2,360	862
Reorganization items	$ 10,947	$ 0	$ 0	$ 0					$ 10,947	$ 0	$ 0