QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Details)-K (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
QUARTERLY FINANCIAL INFORMATION (UNAUDITED)
Total revenues	$ 207,053	$ 119,228	$ 209,631	$ 98,653	$ 133,953	$ 99,615	$ 145,759	$ 90,091	$ 634,565	$ 469,418	$ 376,886
Operating income	37,144	23,850	91,781	13,947	43,430	10,700	47,790	9,294	166,722	111,214	72,465
Net loss	31,929	45,615	(14,733)	(86,331)	18,538	7,433	(76,496)	(23,170)	(23,520)	(73,695)	(127,543)
Net income (loss) attributable to common stockholders	$ 31,930	$ 45,615	$ (14,760)	$ (86,316)	$ 18,533	$ 7,335	$ (76,554)	$ (23,124)	$ (23,531)	$ (73,790)	$ (128,288)
EARNINGS PER SHARE
Basic loss per share: (in dollars per share)	$ 0.81	$ 1.16	$ (0.37)	$ (2.19)	$ 0.47	$ 0.19	$ (1.94)	$ (0.59)	$ (0.60)	$ (1.87)	$ (3.36)
Diluted loss per share: (in dollars per share)	$ (1.18)	$ 0.48	$ (0.37)	$ (2.19)	$ 0.44	$ 0.17	$ (1.94)	$ (0.59)	$ (0.60)	$ (1.87)	$ (3.36)
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Basic (in shares)	39,464	39,465	39,458	39,454	39,454	39,454	39,445	39,441	39,464	39,449	38,127
Diluted (in shares)	43,027	43,171	39,458	39,454	42,529	42,439	39,445	39,441	39,464	39,449	38,127