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 (UNAUDITED)
Total revenues	$ 229,393	$ 203,442	$ 209,163	$ 155,090	$ 207,053	$ 119,228	$ 209,631	$ 98,653	$ 797,088	$ 634,565	$ 469,418
Operating income	40,191	36,544	25,572	16,457	37,144	23,850	91,781	13,947	118,764	166,722	111,214
Net income (loss)	25,881	156,212	50,585	(105,959)	31,929	45,615	(14,733)	(86,331)	126,719	(23,520)	(73,695)
Net income (loss) attributable to common stockholders	$ 25,881	$ 156,224	$ 50,573	$ (105,959)	$ 31,930	$ 45,615	$ (14,760)	$ (86,316)	$ 126,719	$ (23,531)	$ (73,790)
EARNINGS PER SHARE
Basic earnings (loss) per share: (in dollars per share)	$ 0.65	$ 3.96	$ 1.28	$ (2.68)	$ 0.81	$ 1.16	$ (0.37)	$ (2.19)	$ 3.21	$ (0.60)	$ (1.87)
Diluted earnings (loss) per share: (in dollars per share)	$ 0.59	$ 0.76	$ 0.18	$ (2.68)	$ (1.18)	$ 0.48	$ (0.37)	$ (2.19)	$ 1.60	$ (0.60)	$ (1.87)
Weighted average shares outstanding:
Basic (in shares)	39,473,000	39,473,000	39,468,000	39,465,000	39,464,000	39,465,000	39,458,000	39,454,000	39,470	39,464	39,449
Diluted (in shares)	42,743,000	42,913,000	43,197,000	39,465,000	43,027,000	43,171,000	39,458,000	39,454,000	42,754	39,464	39,449