Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (2,296,571)	$ (7,799,801)	$ 72,570	$ (24,747,415)
Other comprehensive income (loss):
Increase (decrease) in net unrealized gain (loss) on available-for-sale securities, net	(2,478,268)	15,345,158	1,220,918	13,099,145
Reclassification adjustment for net gain (loss) included in net income (loss)	365,849	(7,671,018)	217,565	(6,547,325)
Reclassification adjustment for other-than-temporary impairments included in net income (loss)	0	146,224	0	167,218
Total other comprehensive income (loss)	(2,112,419)	7,820,364	1,438,483	6,719,038
Less: Dividends to preferred stockholders	(870,726)	(870,726)	(1,751,235)	(1,751,235)
Comprehensive income (loss) attributable to common stockholders	$ (5,279,716)	$ (850,163)	$ (240,182)	$ (19,779,612)