Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income	$ 17,883,055	$ 3,545,483	$ 27,225,480	$ 15,015,398
Reversal of net unrealized losses on securities with other-than-temporary impairment			525,446
Unrealized gain (loss) on bond purchase commitments			(1,956,095)	955,598
Comprehensive income (loss)	11,190,306	5,548,672	1,697,013	46,991,364
Comprehensive income allocated to noncontrolling interest				71,653
Partnership comprehensive income (loss)	11,190,306	5,548,672	1,697,013	46,919,711
Accumulated Other Comprehensive Income (Loss) [Member]
Net income	17,883,055	3,545,483	27,225,480	15,015,398
Reversal of net unrealized losses on securities with other-than-temporary impairment			525,446
Unrealized gain (loss) on securities	(6,744,509)	1,813,314	(24,097,818)	31,020,368
Unrealized gain (loss) on bond purchase commitments			(1,956,095)	955,598
Commitments [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Unrealized gain (loss) on bond purchase commitments	$ 51,760	$ 189,875	$ (1,956,095)	$ 955,598