| FAIR VALUE - Fair Value of Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified | Jun. 30, 2013 | Dec. 31, 2012 | Jun. 30, 2012 | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Financial Instruments | ||||||||||||||||||
| Real estate securities, available-for-sale | $ 777,102 | [1] | $ 1,691,575 | |||||||||||||||
| Real estate related loans, held-for-sale, net | 837,427 | 843,132 | ||||||||||||||||
| Residential mortgage loans, held-for-investment, net | 273,332 | 292,461 | ||||||||||||||||
| Residential mortgage loans, held-for-sale, net | 2,266 | 2,471 | ||||||||||||||||
| Subprime mortgage loans subject to call option | 406,217 | 405,814 | ||||||||||||||||
| Restricted Cash | 7,173 | 2,064 | ||||||||||||||||
| Cash and Cash Equivalents | 271,052 | 231,898 | 102,647 | |||||||||||||||
| Non-hedge derivative assets | 43,470 | 165 | ||||||||||||||||
| Other investments | 24,907 | 24,907 | ||||||||||||||||
| Due from affiliates | 1,254 | |||||||||||||||||
| Receivables and other assets | 19,907 | 17,197 | ||||||||||||||||
| Total Assets | 2,845,334 | 3,945,312 | ||||||||||||||||
| Financial Instruments | ||||||||||||||||||
| CDO bonds payable | 844,484 | 1,091,354 | ||||||||||||||||
| Other bonds and notes payable | 163,718 | 183,390 | ||||||||||||||||
| Repurchase agreements | 311,276 | 929,435 | ||||||||||||||||
| Mortgage notes payable | 120,525 | 120,525 | ||||||||||||||||
| Financing of subprime mortgage loans subject to call option (B) | 406,217 | 405,814 | ||||||||||||||||
| Junior subordinated notes payable | 51,240 | 51,243 | ||||||||||||||||
| Due to affiliates | 3,216 | 3,620 | ||||||||||||||||
| Total Liabilities | 1,981,708 | 2,872,252 | ||||||||||||||||
| Total Mortgage Notes Payable | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 3.79% | |||||||||||||||||
| Weighted Average Maturity (Years) | 5 years 3 months 18 days | |||||||||||||||||
| Junior Subordinated Debt | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 7.40% | |||||||||||||||||
| Weighted Average Maturity (Years) | 21 years 9 months 18 days | |||||||||||||||||
| CDO Bonds Payable | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 1.83% | |||||||||||||||||
| Weighted Average Maturity (Years) | 2 years 1 month 6 days | |||||||||||||||||
| Other Bonds and Notes Payable | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 5.19% | |||||||||||||||||
| Weighted Average Maturity (Years) | 3 years 10 months 24 days | |||||||||||||||||
| Repurchase Agreements | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 0.39% | |||||||||||||||||
| Weighted Average Maturity (Years) | 0 years 1 month 6 days | |||||||||||||||||
| Financing on Subprime Mortgage Loans subject to Call Options | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 9.09% | |||||||||||||||||
| Weighted Average Maturity (Years) | (B) | |||||||||||||||||
| Interest Rate Swap Agreements | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | N/A | |||||||||||||||||
| Weighted Average Maturity (Years) | (E) | |||||||||||||||||
| Non Hedge Derivative Liabilities | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | N/A | |||||||||||||||||
| Weighted Average Maturity (Years) | (C) | |||||||||||||||||
| Real Estate Related and Other Loans Held For Sale | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 11.25% | |||||||||||||||||
| Weighted Average Maturity (Years) | 1 year 3 months 18 days | |||||||||||||||||
| Residential Mortgage Loans Held For Investment | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 8.30% | |||||||||||||||||
| Weighted Average Maturity (Years) | 5 years 9 months 18 days | |||||||||||||||||
| Residential Mortgage Loans Held For Sale | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 18.89% | |||||||||||||||||
| Weighted Average Maturity (Years) | 4 years 7 months 6 days | |||||||||||||||||
| Subprime Mortgage Loans Subject to Call | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 9.09% | |||||||||||||||||
| Weighted Average Maturity (Years) | (B) | |||||||||||||||||
| Real Estate Securities Available For Sale | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | 6.22% | |||||||||||||||||
| Weighted Average Maturity (Years) | 3 years 3 months 18 days | |||||||||||||||||
| Derivative Financial Instruments, Assets | ||||||||||||||||||
| Weighted Average | ||||||||||||||||||
| Weighted Average Yield/Funding Cost | N/A | |||||||||||||||||
| Weighted Average Maturity (Years) | (C) | |||||||||||||||||
| Measured on a Recurring Basis | Principal Balance | ||||||||||||||||||
| Financial Instruments | ||||||||||||||||||
| Real estate securities, available-for-sale | 1,011,205 | [2] | ||||||||||||||||
| Real estate related loans, held-for-sale, net | 1,354,899 | |||||||||||||||||
| Residential mortgage loans, held-for-investment, net | 303,303 | |||||||||||||||||
| Residential mortgage loans, held-for-sale, net | 3,345 | |||||||||||||||||
| Subprime mortgage loans subject to call option | 406,217 | [3] | ||||||||||||||||
| Restricted Cash | 7,173 | [2] | ||||||||||||||||
| Cash and Cash Equivalents | 271,052 | [2] | ||||||||||||||||
| Non-hedge derivative assets | 140,206 | [2],[4],[5] | ||||||||||||||||
| Financial Instruments | ||||||||||||||||||
| CDO bonds payable | 843,656 | [6] | ||||||||||||||||
| Other bonds and notes payable | 167,806 | [6] | ||||||||||||||||
| Repurchase agreements | 311,276 | |||||||||||||||||
| Mortgage notes payable | 120,525 | |||||||||||||||||
| Financing of subprime mortgage loans subject to call option (B) | 406,217 | [3] | ||||||||||||||||
| Junior subordinated notes payable | 51,004 | |||||||||||||||||
| Interest rate swaps, treated as hedges | 105,749 | [2],[5],[7] | ||||||||||||||||
| Non-hedge derivatives | 186,140 | [2],[4],[5] | ||||||||||||||||
| Measured on a Recurring Basis | Carrying Amount | ||||||||||||||||||
| Financial Instruments | ||||||||||||||||||
| Real estate securities, available-for-sale | 777,102 | [2] | ||||||||||||||||
| Real estate related loans, held-for-sale, net | 837,427 | |||||||||||||||||
| Residential mortgage loans, held-for-investment, net | 273,332 | |||||||||||||||||
| Residential mortgage loans, held-for-sale, net | 2,266 | |||||||||||||||||
| Subprime mortgage loans subject to call option | 406,217 | [3] | ||||||||||||||||
| Restricted Cash | 7,173 | [2] | ||||||||||||||||
| Cash and Cash Equivalents | 271,052 | [2] | ||||||||||||||||
| Non-hedge derivative assets | 43,470 | [2],[4],[5] | ||||||||||||||||
| Other investments | 24,907 | |||||||||||||||||
| Investments in real estate and intangibles, net | 181,227 | |||||||||||||||||
| Due from affiliates | 1,254 | |||||||||||||||||
| Receivables and other assets | 19,907 | |||||||||||||||||
| Total Assets | 2,845,334 | |||||||||||||||||
| Financial Instruments | ||||||||||||||||||
| CDO bonds payable | 844,484 | [6] | ||||||||||||||||
| Other bonds and notes payable | 163,718 | [6] | ||||||||||||||||
| Repurchase agreements | 311,276 | |||||||||||||||||
| Mortgage notes payable | 120,525 | |||||||||||||||||
| Financing of subprime mortgage loans subject to call option (B) | 406,217 | [3] | ||||||||||||||||
| Junior subordinated notes payable | 51,240 | |||||||||||||||||
| Interest rate swaps, treated as hedges | 8,523 | [2],[5],[7] | ||||||||||||||||
| Non-hedge derivatives | 11,674 | [2],[4],[5] | ||||||||||||||||
| Due to affiliates | 3,216 | |||||||||||||||||
| Dividends payable, accrued expenses and other liabilities | 60,835 | |||||||||||||||||
| Total Liabilities | 1,981,708 | |||||||||||||||||
| Measured on a Recurring Basis | Total Fair Value | ||||||||||||||||||
| Financial Instruments | ||||||||||||||||||
| Real estate securities, available-for-sale | 777,102 | [2] | ||||||||||||||||
| Real estate related loans, held-for-sale, net | 849,562 | |||||||||||||||||
| Residential mortgage loans, held-for-investment, net | 270,596 | |||||||||||||||||
| Residential mortgage loans, held-for-sale, net | 2,266 | |||||||||||||||||
| Restricted Cash | 7,173 | [2] | ||||||||||||||||
| Cash and Cash Equivalents | 271,052 | [2] | ||||||||||||||||
| Non-hedge derivative assets | 43,470 | [2],[4],[5] | ||||||||||||||||
| Other investments | 13,165 | |||||||||||||||||
| Financial Instruments | ||||||||||||||||||
| CDO bonds payable | 641,506 | [6] | ||||||||||||||||
| Other bonds and notes payable | 166,090 | [6] | ||||||||||||||||
| Repurchase agreements | 311,276 | |||||||||||||||||
| Mortgage notes payable | 120,525 | |||||||||||||||||
| Junior subordinated notes payable | 34,267 | |||||||||||||||||
| Interest rate swaps, treated as hedges | 8,523 | [2],[5],[7] | ||||||||||||||||
| Non-hedge derivatives | $ 11,674 | [2],[4],[5] | ||||||||||||||||
| 
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