AVAILABLE-FOR-SALE SECURITIES - Fair Value of AFS Investment Securities by Rate Type (Details) - USD ($)		Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	[1]	$ 1,290,825,648	$ 870,929,601
Adjustable rate
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		1,284,237,670	796,320,278
Fixed rate
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		6,587,978	74,609,323
Agency
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		1,285,083,648	790,190,233
Agency | Adjustable rate
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		1,284,237,670	788,727,476
Agency | Fixed rate
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		845,978	1,462,757
Non-Agency
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		0	7,592,802
Non-Agency | Adjustable rate
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		0	7,592,802
Non-Agency | Fixed rate
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		0	0
Multi-Family
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		5,742,000	73,146,566
Multi-Family | Adjustable rate
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		0	0
Multi-Family | Fixed rate
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities		$ 5,742,000	$ 73,146,566

[1] Our consolidated balance sheets include assets and liabilities of consolidated variable interest entities (“VIE's) as the Company is the primary beneficiary of these VIEs. As of December 31, 2017 and December 31, 2016, assets of consolidated VIEs totaled $1,255,404,335 and $1,369,120,941, respectively, and the liabilities of consolidated VIEs totaled $1,228,295,517 and $1,344,404,080, respectively