SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND NATURE OF BUSINESS (Details 4) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Diluted earnings per share
Net income attributable to common stockholders									$ 120,561	$ 57,757	$ 42,678
Weighted average common shares - Basic									34,502	34,086	33,825
Weighted average common shares - Diluted									34,774	34,122	33,825
Total diluted earnings per share (in dollars per share)	$ 0.92	$ 1.12	$ 0.39	$ 1.01	$ (0.10)	$ 0.99	$ 0.42	$ 0.35	$ 3.45	$ 1.66	$ 1.22
Common Stock
Diluted earnings per share
Net income attributable to common stockholders									119,840	56,541	41,384
Weighted average common shares - Basic									34,502	34,086	33,825
Weighted average common shares - Diluted									34,774	34,122	33,825
Restricted stock units participating securities
Diluted earnings per share
Net income attributable to common stockholders									$ 721	$ 1,216	$ 1,294
Plus: Dilutive effect of stock options and awards (in shares)									272	36