Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($)	Dec. 31, 2018	Aug. 20, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 7,882,862		$ 34,347,339
Restricted cash	51,330,950		11,275,263
Total cash, cash equivalents and restricted cash	59,213,812		45,622,602	$ 37,889,596
Restricted cash CRE 2017-FL1, Ltd.
Cash and Cash Equivalents [Line Items]
Restricted cash	24,085,890		0
Restricted cash CRE 2018-FL2, Ltd.
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		$ 59,700,000
Restricted cash	27,245,060		0
Repurchase counterparties as restricted collateral
Cash and Cash Equivalents [Line Items]
Restricted cash	$ 0		$ 11,275,263