Fair Value of Investments (Details) - USD ($) $ in Thousands | Jun. 30, 2015 | Dec. 31, 2014 |
Investments, Fair Value Disclosure [Abstract] | | |
Investments in and Advances to Affiliates, at Fair Value | $ 0 | $ 104 |
Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 2,287 | 6,648 |
Consolidated Entities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 66,158 | 1,164,946 |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 35,799 | 1,126,737 |
Investments in and Advances to Affiliates, at Fair Value | 28,072 | 31,457 |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 11,967 | 774,812 |
Forward Contracts [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | | 3,794 |
Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 1,138 | 5,785 |
Derivative Financial Instruments, Liabilities [Member] | Total Return Swap [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 75 | |
Options Held [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | | 56 |
Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 2,001 | 0 |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 2,001 | 0 |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 10,829 | 0 |
Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Forward Contracts [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | | 0 |
Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Liabilities [Member] | Total Return Swap [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | |
Fair Value, Inputs, Level 1 [Member] | Options Held [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | | 0 |
Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 30,359 | 43,268 |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | 7,857 |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 1,138 | 19,694 |
Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 2,287 | 3,850 |
Fair Value, Inputs, Level 2 [Member] | Forward Contracts [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | | 3,794 |
Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 1,138 | 386 |
Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member] | Total Return Swap [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 75 | |
Fair Value, Inputs, Level 2 [Member] | Options Held [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | | 56 |
Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 33,798 | 1,121,678 |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 33,798 | 1,118,880 |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | 755,118 |
Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 0 | 2,798 |
Fair Value, Inputs, Level 3 [Member] | Forward Contracts [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | | 0 |
Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | 5,399 |
Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] | Total Return Swap [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | |
Fair Value, Inputs, Level 3 [Member] | Options Held [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | | 0 |
Credit Default Swap [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 5 | 2,798 |
Credit Default Swap [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 141 | 5,399 |
Credit Default Swap [Member] | Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 0 | 0 |
Credit Default Swap [Member] | Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | 0 |
Credit Default Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 5 | 0 |
Credit Default Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 141 | 0 |
Credit Default Swap [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 0 | 2,798 |
Credit Default Swap [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | 5,399 |
Cashflow Swaps [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 386 |
Cashflow Swaps [Member] | Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 0 |
Cashflow Swaps [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 386 |
Cashflow Swaps [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 0 |
Swaption [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 1,990 | |
Swaption [Member] | Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 0 | |
Swaption [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 1,990 | |
Swaption [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 0 | |
Notes Payable, Other Payables [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 749,719 |
Notes Payable, Other Payables [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 0 |
Notes Payable, Other Payables [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 0 |
Notes Payable, Other Payables [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 749,719 |
Funds [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure | | 104 |
Investments in and Advances to Affiliates, at Fair Value | 28,072 | 31,457 |
Funds [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure | | 0 |
Investments in and Advances to Affiliates, at Fair Value | 0 | 0 |
Funds [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure | | 104 |
Investments in and Advances to Affiliates, at Fair Value | 28,072 | 31,457 |
Funds [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments in Affiliates, Subsidiaries, Associates, and Joint Ventures, Fair Value Disclosure | | 0 |
Investments in and Advances to Affiliates, at Fair Value | 0 | 0 |
Collateralized Debt Obligations [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 9,731 | 359,211 |
Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | 0 |
Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | 0 |
Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 9,731 | 359,211 |
Commercial Mortgage Backed Securities [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 4,535 |
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 0 |
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 0 |
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 4,535 |
Corporate Bond Securities [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 7,857 |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 19,308 |
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 0 |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 0 |
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 7,857 |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 19,308 |
Corporate Bond Securities [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 0 |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | | 0 |
Residential Mortgage Backed Securities [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 13,365 | 78,275 |
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | 0 |
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | 0 |
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 13,365 | 78,275 |
Asset-backed Securities [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 63,174 |
Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 0 |
Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 0 |
Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 63,174 |
Corporate and Other [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 613,685 |
Corporate and Other [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 0 |
Corporate and Other [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | 0 |
Corporate and Other [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | | $ 613,685 |
Exchange Traded Funds [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 2,001 | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 10,829 | |
Exchange Traded Funds [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 2,001 | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 10,829 | |
Exchange Traded Funds [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | |
Exchange Traded Funds [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 0 | |
Real Estate Investment [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 10,702 | |
Real Estate Investment [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | |
Real Estate Investment [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 0 | |
Real Estate Investment [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Investments, Fair Value Disclosure [Abstract] | | |
Investments, Fair Value Disclosure | 10,702 | |
Interest Rate Swaps [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 292 | |
Interest Rate Swaps [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 922 | |
Interest Rate Swaps [Member] | Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 0 | |
Interest Rate Swaps [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | 292 | |
Interest Rate Swaps [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Liabilities [Member] | | |
Liabilities, Fair Value Disclosure [Abstract] | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 922 | |
Interest Rate Swaps [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, Fair Value Disclosure | $ 0 | |