VARIABLE INTEREST ENTITIES INVESTMENTS IN REAL ESTATE (Pro Forma Information) (Details) RSO (USD $) In Thousands, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended										6 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009	Mar. 31, 2011	Mar. 31, 2010	Jun. 30, 2011	Jun. 30, 2010	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2012 RSO [Member]	Dec. 31, 2011 RSO [Member]
Business Acquisition [Line Items]
Total revenue, as reported	$ 39,374	$ 47,889	$ 35,811	$ 39,996	$ 42,430	$ 45,944	$ 43,276	$ 35,282	$ 25,238	$ 19,400	$ 25,422	$ 78,558	$ 44,822	$ 124,502	$ 70,060	$ 170,900	$ 166,932	$ 88,728	$ 123,698	$ 95,986
Pro Forma revenue																			131,028	111,263
Net income, reported																			63,199	37,716
Pro forma net income																			$ 63,503	$ 37,535
Earnings per share - basic, reported (in dollars per share)	$ (0.02)	$ (0.11)	$ 1.52	$ (0.12)												$ 1.29	$ (0.75)	$ (0.71)	$ 0.71	$ 0.54
Earnings per share - diluted, reported (in dollars per share)	$ (0.02)	$ (0.11)	$ 1.44	$ (0.12)												$ 1.24	$ (0.75)	$ (0.71)	$ 0.71	$ 0.53
Pro forma earnings per share - basic (in dollars per share)																			$ 0.72	$ 0.53
Pro forma earnings per share - diluted (in dollars per share)																			$ 0.71	$ 0.53