EARNINGS PER SHARE (Details) (USD $) In Thousands, except 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
Basic, numerator:
Net income (loss)	$ 14,543us-gaap_NetIncomeLoss	$ 19,618us-gaap_NetIncomeLoss	$ 17,208us-gaap_NetIncomeLoss	$ (5,193)us-gaap_NetIncomeLoss	$ 10,346us-gaap_NetIncomeLoss	$ 13,982us-gaap_NetIncomeLoss	$ 4,878us-gaap_NetIncomeLoss	$ (13,395)us-gaap_NetIncomeLoss	$ 46,177us-gaap_NetIncomeLoss	$ 15,811us-gaap_NetIncomeLoss	$ (7,732)us-gaap_NetIncomeLoss
Effect of unvested restricted stock awards									(2,300)	(720)	(149)
Adjusted net income (loss)									43,877	15,091	(7,881)
Basic, denominator:
Weighted-average shares	26,073,256	26,054,678	26,005,105	25,876,928	25,785,485	25,736,810	25,694,327	25,638,333	25,993,255	25,714,205	25,564,752
Earnings (loss) per common share (in dollars per share)	$ 0.53us-gaap_EarningsPerShareBasic	$ 0.72us-gaap_EarningsPerShareBasic	$ 0.63us-gaap_EarningsPerShareBasic	$ (0.20)us-gaap_EarningsPerShareBasic	$ 0.38us-gaap_EarningsPerShareBasic	$ 0.52us-gaap_EarningsPerShareBasic	$ 0.18us-gaap_EarningsPerShareBasic	$ (0.52)us-gaap_EarningsPerShareBasic	$ 1.69us-gaap_EarningsPerShareBasic	$ 0.59us-gaap_EarningsPerShareBasic	$ (0.31)us-gaap_EarningsPerShareBasic
Diluted, numerator:
Net income (loss)	14,543us-gaap_NetIncomeLoss	19,618us-gaap_NetIncomeLoss	17,208us-gaap_NetIncomeLoss	(5,193)us-gaap_NetIncomeLoss	10,346us-gaap_NetIncomeLoss	13,982us-gaap_NetIncomeLoss	4,878us-gaap_NetIncomeLoss	(13,395)us-gaap_NetIncomeLoss	46,177us-gaap_NetIncomeLoss	15,811us-gaap_NetIncomeLoss	(7,732)us-gaap_NetIncomeLoss
Effect of unvested restricted stock awards									(2,300)	(720)	(149)
Adjusted net income (loss)									$ 43,877	$ 15,091	$ (7,881)
Diluted, denominator:
Weighted-average shares	26,073,256	26,054,678	26,005,105	25,876,928	25,785,485	25,736,810	25,694,327	25,638,333	25,993,255	25,714,205	25,564,752
Effect of dilutive securities									357
Adjusted weighted-average shares and assumed conversions	26,073,256	26,054,678	26,005,105	25,876,928	25,793,366	25,736,810	25,694,327	25,638,333	25,993,612	25,714,205	25,564,752
Earnings (loss) per common share (in dollars per share)	$ 0.53us-gaap_EarningsPerShareDiluted	$ 0.72us-gaap_EarningsPerShareDiluted	$ 0.63us-gaap_EarningsPerShareDiluted	$ (0.20)us-gaap_EarningsPerShareDiluted	$ 0.38us-gaap_EarningsPerShareDiluted	$ 0.52us-gaap_EarningsPerShareDiluted	$ 0.18us-gaap_EarningsPerShareDiluted	$ (0.52)us-gaap_EarningsPerShareDiluted	$ 1.69us-gaap_EarningsPerShareDiluted	$ 0.59us-gaap_EarningsPerShareDiluted	$ (0.31)us-gaap_EarningsPerShareDiluted

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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