VARIABLE INTEREST ENTITIES - BORROWINGS (Schedule of Debt) (Details) RSO (RSO [Member], USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Senior secured revolving credit agreement		$ 1,734,901,000	$ 1,336,026,000
Unamortized Issuance Costs and Discounts		18,030,000	16,216,000
Outstanding Bowwings		1,716,871,000	1,319,810,000
Weighted Average Borrowing Rate		2.09%	1.87%
Weighted Average Remaining Maturity	13 years 1 month	10 years 0 months
Value of Collateral		2,287,115,000	1,508,603,000
Accrued interest expense		2,123,000	1,693,000
RREF CDO 2006-1 Senior Notes [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		61,423,000	94,209,000
Unamortized Issuance Costs and Discounts		0	205,000
Outstanding Bowwings		61,423,000	94,004,000
Weighted Average Borrowing Rate		2.12%	1.87%
Weighted Average Remaining Maturity	32 years 7 months	31 years 7 months
Value of Collateral		139,242,000	169,115,000
RREF CDO 2007-1 Senior Notes [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		130,340,000	178,556,000
Unamortized Issuance Costs and Discounts		133,000	719,000
Outstanding Bowwings		130,207,000	177,837,000
Weighted Average Borrowing Rate		1.19%	0.84%
Weighted Average Remaining Maturity	32 years 9 months	31 years 9 months
Value of Collateral		271,423,000	318,933,000
RCC CRE Notes 2013 [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		226,840,000
Unamortized Issuance Costs and Discounts		2,683,000
Outstanding Bowwings		224,157,000
Weighted Average Borrowing Rate		2.11%
Weighted Average Remaining Maturity		14 years 0 months
Value of Collateral		249,983,000
RCC CRE Notes 2014 [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		235,344,000
Unamortized Issuance Costs and Discounts		3,687,000
Outstanding Bowwings		231,657,000
Weighted Average Borrowing Rate		1.45%
Weighted Average Remaining Maturity		17 years 4 months
Value of Collateral		346,585,000
Apidos CDO III Senior Notes [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		74,646,000	133,326,000
Unamortized Issuance Costs and Discounts		0	117,000
Outstanding Bowwings		74,646,000	133,209,000
Weighted Average Borrowing Rate		1.18%	0.88%
Weighted Average Remaining Maturity	6 years 8 months	5 years 8 months
Value of Collateral		85,553,000	145,930,000
Apidos Cinco CDO Senior Notes [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		255,664,000	322,000,000
Unamortized Issuance Costs and Discounts		201,000	853,000
Outstanding Bowwings		255,463,000	321,147,000
Weighted Average Borrowing Rate		0.81%	0.74%
Weighted Average Remaining Maturity	6 years 5 months	5 years 5 months
Value of Collateral		272,512,000	342,796,000
Moselle CLO S.A. Senior Notes [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		63,321,000
Unamortized Issuance Costs and Discounts		0
Outstanding Bowwings		63,321,000
Weighted Average Borrowing Rate		1.49%
Weighted Average Remaining Maturity		5 years 0 months
Value of Collateral		93,576,000
Fair value outstanding		63,300,000
Unpaid principal		27,800,000
Moselle CLO S.A. Securitized Borrowings [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		5,619,000
Unamortized Issuance Costs and Discounts		0
Outstanding Bowwings		5,619,000
Weighted Average Borrowing Rate		1.49%
Weighted Average Remaining Maturity		5 years 0 months
Value of Collateral		0
Unsecured Junior Subordinated Debentures [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		51,548,000	51,548,000
Unamortized Issuance Costs and Discounts		343,000	543,000
Outstanding Bowwings		51,205,000	51,005,000
Weighted Average Borrowing Rate		4.19%	4.19%
Weighted Average Remaining Maturity	22 years 10 months	21 years 9 months
Value of Collateral		0	0
Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		115,000,000	115,000,000
Unamortized Issuance Costs and Discounts		6,626,000	8,465,000
Outstanding Bowwings		108,374,000	106,535,000
Weighted Average Borrowing Rate		6.00%	6.00%
Weighted Average Remaining Maturity	4 years 11 months	3 years 11 months
Value of Collateral		0	0
CRE - Term Repurchase Facility [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		207,640,000
Unamortized Issuance Costs and Discounts		1,958,000
Outstanding Bowwings		205,682,000
Weighted Average Borrowing Rate		2.43%
Weighted Average Remaining Maturity		20 days
Value of Collateral		297,571,000
CMBS - Term Repurchase Facilities [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		24,967,000	47,613,000
Unamortized Issuance Costs and Discounts		0	12,000
Outstanding Bowwings		24,967,000	47,601,000
Weighted Average Borrowing Rate		1.35%	1.38%
Weighted Average Remaining Maturity	21 days	20 days
Value of Collateral		30,180,000	56,949,000
Accrued interest expense		12,000	22,000
RMBS - Term Repurchase Facility [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		22,248,000
Unamortized Issuance Costs and Discounts		36,000
Outstanding Bowwings		22,212,000
Weighted Average Borrowing Rate		1.16%
Weighted Average Remaining Maturity		1 day
Value of Collateral		27,885,000
Accrued interest expense		20,000,000
Residential Mortgage Financing Agreements [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		102,576,000
Unamortized Issuance Costs and Discounts		0
Outstanding Bowwings		102,576,000
Weighted Average Borrowing Rate		2.78%
Weighted Average Remaining Maturity		207 days
Value of Collateral		147,472,000
CMBS - Short Term Repurchase Agreements [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		44,225,000
Unamortized Issuance Costs and Discounts		0
Outstanding Bowwings		44,225,000
Weighted Average Borrowing Rate		1.63%
Weighted Average Remaining Maturity		17 days
Value of Collateral		62,446,000
Accrued interest expense		31,000,000
Senior Secured Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement		113,500,000
Unamortized Issuance Costs and Discounts		2,363,000
Outstanding Bowwings		111,137,000
Weighted Average Borrowing Rate		2.66%
Weighted Average Remaining Maturity		2 years 8 months
Value of Collateral		262,687,000
Principal receivable		14,900,000
CRE Notes 2013 [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement			260,840,000
Unamortized Issuance Costs and Discounts			4,269,000
Outstanding Bowwings			256,571,000
Weighted Average Borrowing Rate			2.03%
Weighted Average Remaining Maturity	15 years 0 months
Value of Collateral			305,586,000
Apidos CDO I Senior Notes [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement			87,131,000
Unamortized Issuance Costs and Discounts			0
Outstanding Bowwings			87,131,000
Weighted Average Borrowing Rate			1.68%
Weighted Average Remaining Maturity	3 years 7 months
Value of Collateral			103,736,000
Whitney CLO I Securitized Borrowings [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement			440,000
Unamortized Issuance Costs and Discounts			0
Outstanding Bowwings			440,000
Weighted Average Borrowing Rate			0.00%
Value of Collateral			885,000
Repurchase Agreements Debt [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement			30,736,000
Unamortized Issuance Costs and Discounts			1,033,000
Outstanding Bowwings			29,703,000
Weighted Average Borrowing Rate			2.67%
Weighted Average Remaining Maturity	21 days
Value of Collateral			48,186,000
Residential Mortgage [Member]
Debt Instrument [Line Items]
Senior secured revolving credit agreement			14,627,000
Unamortized Issuance Costs and Discounts			0
Outstanding Bowwings			14,627,000
Weighted Average Borrowing Rate			4.24%
Weighted Average Remaining Maturity	56 days
Value of Collateral			16,487,000
CRE Repurchase Facilities [Member]
Debt Instrument [Line Items]
Accrued interest expense		$ 198,000	$ 26,000