Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income			$ 20,045,906	$ 27,225,480
Unrealized gain (loss) on bond purchase commitments		$ 51,760
Comprehensive income	$ 28,756,219	11,190,306	62,158,230	1,697,013
Accumulated Other Comprehensive Income (Loss) [Member]
Net income	9,707,903	17,883,055	20,045,906	27,225,480
Reversal of net unrealized losses on securities with other-than-temporary impairment				525,446
Unrealized gain (loss) on securities	$ 19,048,316	(6,744,509)	$ 42,112,324	(24,097,818)
Unrealized gain (loss) on bond purchase commitments		51,760
Commitments [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Unrealized gain (loss) on bond purchase commitments		$ 51,760		$ (1,956,095)