SUMMARIZED QUARTERLY FINANCIAL DATA (Unaudited) - Quarterly Operating Results (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
Selected Quarterly Financial Information [Abstract]
Revenues	$ 114,520	$ 184,385	$ 105,765	$ 128,219	$ 192,799	$ 295,571	$ 168,326	$ 221,858	$ 532,889	$ 878,554	$ 1,679,213
Operating income (loss)	(68,596)	90,302	68,875	(301,811)	(915,550)	(348,214)	(161,678)	(12,409)	(211,230)	(1,437,851)	176,961
Income (loss) from continuing operations	(54,470)	53,314	36,759	(203,116)	(590,806)	(227,904)	(111,601)	(15,420)	(167,513)	(945,731)	99,643
Net Income (loss)	$ (54,470)	$ 53,314	$ 36,759	$ (203,116)	$ (590,806)	$ (227,904)	$ (111,601)	$ (15,420)	$ (167,513)	$ (945,731)	$ 568,032
Diluted earnings per average common share
Continuing operations (in dollars per share)	$ (0.56)	$ 0.55	$ 0.38	$ (2.34)	$ (7.50)	$ (2.89)	$ (1.52)	$ (0.21)	$ (1.77)	$ (12.43)	$ 1.36
Net income (loss) (in dollars per share)	(0.56)	0.55	0.38	(2.34)	(7.50)	(2.89)	(1.52)	(0.21)	(1.77)	(12.43)	7.75
Basic earnings per average common share
Continuing operations (in dollars per share)	(0.56)	0.55	0.38	(2.34)	(7.50)	(2.89)	(1.52)	(0.21)	(1.77)	(12.43)	1.37
Net income (loss) (in dollars per share)	$ (0.56)	$ 0.55	$ 0.38	$ (2.34)	$ (7.50)	$ (2.89)	$ (1.52)	$ (0.21)	$ (1.77)	$ (12.43)	$ 7.79