AVAILABLE-FOR-SALE SECURITIES - AFS Securities by Collateral Type (Details) - USD ($)		Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	[1]	$ 1,095,189,264	$ 1,290,825,648
Agency
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		1,095,189,264	1,285,083,648
Agency | Federal Home Loan Mortgage Corporation
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		430,520,486	530,640,091
Agency | Federal National Mortgage Association
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		664,668,778	754,443,557
Multi-Family
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		$ 0	$ 5,742,000

[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 March 31, 2018 and December 31, 2017, assets of consolidated VIEs totaled $1,223,232,702 and $1,255,404,335 respectively, and the liabilities of consolidated VIEs totaled $1,197,735,060 and $1,228,295,517 respectively