BORROWINGS (Details 2) - USD ($)		9 Months Ended	12 Months Ended
		Sep. 30, 2016	Dec. 31, 2015
Repurchase Agreement Counterparty [Line Items]
Repurchase Agreement Counterparties, Amount Outstanding		$ 746,625,821	$ 568,432,457	[1]
Repurchase Agreement Counterparties, Percent of total amount outstanding		100.00%	100.00%
Repurchase Agreement Counterparties, Weighted average days to maturity		15 years	26 years
Repurchase Agreement Counterparties, Market Value of collateral held		$ 831,157,394	$ 697,384,372
Merrill Lynch [Member]
Repurchase Agreement Counterparty [Line Items]
Repurchase Agreement Counterparties, Amount Outstanding	[1]		$ 99,770,000
Repurchase Agreement Counterparties, Percent of total amount outstanding			17.55%
Repurchase Agreement Counterparties, Weighted average days to maturity			30 years
Repurchase Agreement Counterparties, Market Value of collateral held			$ 154,005,234
Wells Fargo Securities [Member]
Repurchase Agreement Counterparty [Line Items]
Repurchase Agreement Counterparties, Amount Outstanding		$ 31,533,000	$ 32,192,000	[1]
Repurchase Agreement Counterparties, Percent of total amount outstanding		4.22%	5.66%
Repurchase Agreement Counterparties, Weighted average days to maturity		6 years	10 years
Repurchase Agreement Counterparties, Market Value of collateral held		$ 57,255,816	$ 53,711,547
Other North America [Member]
Repurchase Agreement Counterparty [Line Items]
Repurchase Agreement Counterparties, Amount Outstanding		$ 612,603,000	$ 291,806,000	[1]
Repurchase Agreement Counterparties, Percent of total amount outstanding		82.05%	51.34%
Repurchase Agreement Counterparties, Weighted average days to maturity		15 years	25 years
Repurchase Agreement Counterparties, Market Value of collateral held		$ 650,152,017	$ 315,040,818
Asia [Member]
Repurchase Agreement Counterparty [Line Items]
Repurchase Agreement Counterparties, Amount Outstanding	[1]	$ 80,272,000	$ 88,565,000
Repurchase Agreement Counterparties, Percent of total amount outstanding	[1]	10.75%	15.58%
Repurchase Agreement Counterparties, Weighted average days to maturity	[1]	18 years	16 years
Repurchase Agreement Counterparties, Market Value of collateral held	[1]	$ 91,076,628	$ 97,970,226
Europe [Member]
Repurchase Agreement Counterparty [Line Items]
Repurchase Agreement Counterparties, Amount Outstanding	[1]	$ 22,217,821	$ 56,099,457
Repurchase Agreement Counterparties, Percent of total amount outstanding	[1]	2.98%	9.87%
Repurchase Agreement Counterparties, Weighted average days to maturity	[1]	20 years	46 years
Repurchase Agreement Counterparties, Market Value of collateral held	[1]	$ 32,672,933	$ 76,656,547

[1] Counterparties domiciled in Europe and Asia, or their U.S. subsidiaries.