SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)			3 Months Ended	9 Months Ended	12 Months Ended	34 Months Ended
		Mar. 08, 2017	Mar. 31, 2017	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2018	Dec. 31, 2016	Sep. 30, 2016	Dec. 15, 2015
Debt and Equity Securities, FV-NI [Line Items]
Maximum exposure to loss from consolidated trusts				$ 5,331,931	$ 27,108,818
Residential loans held in securitization trusts, at fair value	[1]			0	119,756,455	$ 0
Fair value of investments				0	1,290,825,648	0
Available for sale securities				0	1,290,825,648	0
Non-accrual status				0		0
Recognized impairment				0		0
Allowance for loan losses				0		0
Outstanding repurchase agreements				$ 0	$ 1,234,522,000	$ 0
Backstop deferred income, amortization period				5 years
Backstop guarantee, assumed prepayment rate (percentage)				15.00%
Common stock, shares authorized (in shares)				450,000,000	450,000,000	450,000,000
Common stock, par value (in dollars per share)				$ 0.01	$ 0.01	$ 0.01
Common stock, shares issued (in shares)				23,687,664	22,143,758	23,687,664
Common stock, shares outstanding (in shares)				23,687,664	22,143,758	23,687,664
Stock repurchase program, authorized amount									$ 10,000,000
Preferred stock, shares authorized (in shares)				50,000,000	50,000,000	50,000,000
Preferred stock, par value (in dollars per share)				$ 0.01	$ 0.01	$ 0.01
Preferred stock, shares issued (in shares)				1,610,000	1,610,000	1,610,000
Preferred stock, shares outstanding (in shares)				1,610,000	1,610,000	1,610,000
Equity				$ 152,062,266	$ 145,791,277	$ 152,062,266
Stock Repurchase Program
Debt and Equity Securities, FV-NI [Line Items]
Common stock shares repurchased (in shares)				0	126,856	126,856
Weighted average share price of common stock repurchased (in dollars per share)				$ 5.09	$ 5.09
Stock repurchase program, remaining authorized amount				$ 9,400,000		$ 9,400,000
Internal Revenue Service (IRS)
Debt and Equity Securities, FV-NI [Line Items]
Income taxes, interest paid		$ 2,010,000	$ 2,010,000
Income taxes, interest provision							$ 1,860,000	$ 1,860,000
Income taxes, interest expense		$ 150,000	$ 150,000
Multi-Family MBS
Debt and Equity Securities, FV-NI [Line Items]
Fair value of investments					$ 5,742,000
Collateralized Loan Obligations
Debt and Equity Securities, FV-NI [Line Items]
Maximum exposure to loss from consolidated trusts				124,046,671
Residential mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Investment in Multi-Family MBS, carrying value				$ 0	5,413,720	$ 0
Equity					$ 5,413,720

[1] Our consolidated balance sheets include assets and liabilities of consolidated variable interest entities ("VIEs") as the Company is the primary beneficiary of these VIEs. As of September 30, 2018 and December 31, 2017, assets of consolidated VIEs totaled $24,898,204 and $1,255,404,335 respectively, and the liabilities of consolidated VIEs totaled $19,566,273 and $1,228,295,517 respectively