CREDIT FACILITIES AND LONG-TERM DEBT - Mezzanine term debt facilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Borrowing Capacity	$ 503,000	$ 400,000
Outstanding Amount	155,000	227,000
Issuance Costs	(5,965)	(5,071)
Carrying Value	149,035	221,929
Undrawn amounts	348,000	173
Term Debt Facility 2016-M1
Debt Instrument [Line Items]
Borrowing Capacity	149,000	300,000
Outstanding Amount	$ 40,000	$ 166,000
Interest Rate	10.00%	10.00%
Term Debt Facility 2019-M1
Debt Instrument [Line Items]
Borrowing Capacity	$ 54,000	$ 100,000
Outstanding Amount	$ 15,000	$ 61,000
Interest Rate	15.00%	15.00%
Term Debt Facility 2020-M1
Debt Instrument [Line Items]
Borrowing Capacity	$ 300,000
Outstanding Amount	$ 100,000
Interest Rate	10.00%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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