VARIABLE INTEREST ENTITIES INVESTMENT SECURITIES AVAILABLE-FOR-SALE (Details) RSO (USD $)	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2012 RSO [Member]	Dec. 31, 2011 RSO [Member]	Dec. 31, 2012 RSO [Member] CMBS [Member] Security	Dec. 31, 2011 RSO [Member] CMBS [Member] Security	Dec. 31, 2012 RSO [Member] ABS [Member] Security	Dec. 31, 2011 RSO [Member] ABS [Member] Security	Dec. 31, 2012 RSO [Member] Corporate bonds [Member] Security
Schedule of Available-for-sale Securities [Line Items]
Number of floating rate investment securities in a loss position for more than 12 months				19	8	9	7
CMBS, at fair value		$ 231,590,000	$ 140,866,000	$ 170,800,000	$ 115,600,000
Net unrealized losses	74,000	180,000	6,898,000	12,000,000	28,700,000	574,000	3,300,000	67,000
Value of investments using dealer quotes				170,800,000	106,700,000
Value of investments valued by using three weighted average measures		0	8,900,000
Fair value of fixed rate positions						27,100,000	25,200,000	33,700,000
Other-than-temporary impairment				0	4,600,000
Number of positions, other-than-temporary impairment					1
Fair value of CMBS investments with other-than-temporary impairment					48,000
Number of securities sold				7	3	5	6	1
Par value of securities sold				31,000,000	15,000,000	4,300,000	8,100,000	2,250,000
Recognized gains on sale				1,400,000	3,500,000	147,000		27,000
Recognized losses on sale							2,400,000
Number of securities redeemed								2
Par value of securities redeemed								2,100,000
Recognized gains on redemption								13,000
Excess of aggregate discount over aggregate premium				$ 8,000,000	$ 13,400,000	$ 3,100,000	$ 3,800,000	$ 604,000