DERIVATIVE INSTRUMENTS HEDGING AND NON-HEDGING ACTIVITIES - Gains and Losses on Derivative Contracts (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest rate:
Amount of realized gain (loss)	$ 0	$ (1,636,725)	$ 25,984,870	$ 2,049,400
Amount of unrealized appreciation (depreciation)	0	307,263	(5,349,613)	(8,583,100)
Total	0	(1,329,462)	20,635,257	(6,533,700)
Futures
Interest rate:
Amount of realized gain (loss)	0	(1,636,725)	25,984,870	2,049,400
Amount of unrealized appreciation (depreciation)	0	307,263	(5,349,613)	(8,583,100)
Total	$ 0	$ (1,329,462)	$ 20,635,257	$ (6,533,700)