FAIR VALUES OF FINANCIAL INSTRUMENTS - Summary of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial assets [Abstract]
Derivatives at fair value		$ 1,471
Carrying Amount [Member] \| Level 2 [Member]
Financial liabilities [Abstract]
Secured borrowings with initial terms of greater than 120 days	$ 500,000
Unsecured borrowings	98,493	98,392
Fair Value [Member] \| Level 2 [Member]
Financial liabilities [Abstract]
Secured borrowings with initial terms of greater than 120 days	500,100
Unsecured borrowings	59,900	68,100
Interest Rate Swap Agreements [Member] \| Carrying Amount [Member] \| Secured Borrowings [Member] \| Level 2 [Member]
Financial assets [Abstract]
Secured borrowings-related interest rate swap agreements		733
Interest Rate Swap Agreements [Member] \| Carrying Amount [Member] \| Unsecured Borrowings [Member] \| Level 2 [Member]
Financial liabilities [Abstract]
Interest rate swap agreements	41,484	29,156
Interest Rate Swap Agreements [Member] \| Fair Value [Member] \| Secured Borrowings [Member] \| Level 2 [Member]
Financial assets [Abstract]
Secured borrowings-related interest rate swap agreements		733
Interest Rate Swap Agreements [Member] \| Fair Value [Member] \| Unsecured Borrowings [Member] \| Level 2 [Member]
Financial liabilities [Abstract]
Interest rate swap agreements	$ 41,484	29,156
Eurodollar Futures Contract [Member] \| Carrying Amount [Member] \| Level 1 [Member]
Financial assets [Abstract]
Derivatives at fair value		738
Eurodollar Futures Contract [Member] \| Fair Value [Member] \| Level 1 [Member]
Financial assets [Abstract]
Derivatives at fair value		$ 738

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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