SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)			3 Months Ended		6 Months Ended		13 Months Ended	28 Months Ended
		Mar. 08, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2016	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2016	Dec. 15, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Residential loans held in securitization trusts, at fair value	[1]				$ 0				$ 119,756,455
Maximum exposure to loss from consolidated trusts					4,387,999	$ 27,108,818
AFS investment securities					0				1,290,825,648
Available for sale securities					0				1,290,825,648
Non-accrual status					0
Recognized impairment					0
Allowance for loan losses					0
Outstanding repurchase agreements					$ 0				$ 1,234,522,000
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
Common stock, par value (in dollars per share)					$ 0.01				$ 0.01
Common stock, shares issued (in shares)					23,683,164				22,143,758
Common stock, shares outstanding (in shares)					23,683,164				22,143,758
Stock repurchase program, authorized amount											$ 10,000,000
Preferred stock, shares authorized (in shares)					50,000,000				50,000,000
Preferred stock, par value (in dollars per share)					$ 0.01				$ 0.01
Preferred stock, shares issued (in shares)					1,610,000				1,610,000
Preferred stock, shares outstanding (in shares)					1,610,000				1,610,000
Income taxes, interest paid					$ 10,340,281	$ 6,903,389
Stock Repurchase Program
Schedule of Trading Securities and Other Trading Assets [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
Stock repurchase program, remaining authorized amount					$ 9,400,000
Internal Revenue Service (IRS)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Income taxes, interest paid		$ 2,010,000	$ 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
Schedule of Trading Securities and Other Trading Assets [Line Items]
AFS investment securities									5,742,000
Collateralized Loan Obligations
Schedule of Trading Securities and Other Trading Assets [Line Items]
Maximum exposure to loss from consolidated trusts					58,495,671
Residential mortgage loans
Schedule of Trading Securities and Other Trading Assets [Line Items]
Investment in Multi-Family MBS, carrying value					$ 0				$ 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 June 30, 2018 and December 31, 2017, assets of consolidated VIEs totaled $23,949,942 and $1,255,404,335 respectively, and the liabilities of consolidated VIEs totaled $19,561,943 and $1,228,295,517 respectively