AVAILABLE-FOR-SALE SECURITIES - Components of Interest Income on AFS Securities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Coupon interest	$ 6,362,134	$ 3,652,935	$ 11,784,968	$ 6,696,087
Net (premium amortization)/ discount accretion	296,545	1,678,859	1,696,333	3,534,745
Interest income	6,658,679	5,331,794	13,481,301	10,230,832
Agency
Schedule of Available-for-sale Securities [Line Items]
Coupon interest	6,362,134	2,598,975	11,742,714	4,622,177
Net (premium amortization)/ discount accretion	(214,920)	81,068	251,371	104,252
Interest income	6,147,214	2,680,043	11,994,085	4,726,429
Non-Agency
Schedule of Available-for-sale Securities [Line Items]
Coupon interest	0	796,520	42,254	1,558,601
Net (premium amortization)/ discount accretion	0	379,140	9,946	875,978
Interest income	0	1,175,660	52,200	2,434,579
Multi-Family
Schedule of Available-for-sale Securities [Line Items]
Coupon interest	0	257,440	0	515,309
Net (premium amortization)/ discount accretion	511,465	1,218,651	1,435,016	2,554,515
Interest income	$ 511,465	$ 1,476,091	$ 1,435,016	$ 3,069,824