Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (4,256,337)	$ 1,496,356	$ (4,183,767)	$ (19,527,535)
Other comprehensive income (loss):
Increase (decrease) in net unrealized gain (loss) on available-for-sale securities, net	(4,175,111)	(979,421)	(2,954,193)	8,396,200
Reclassification adjustment for net gain (loss) included in net income (loss)	6,362,159	23,914	6,579,724	(6,523,410)
Reclassification adjustment for other-than-temporary impairments included in net income (loss)	0	374,124	0	541,342
Total other comprehensive income (loss)	2,187,048	(581,383)	3,625,531	2,414,132
Less: Dividends to preferred stockholders	(880,509)	(880,509)	(2,631,744)	(2,631,744)
Comprehensive income (loss) attributable to common stockholders	$ (2,949,798)	$ 34,464	$ (3,189,980)	$ (19,745,147)