Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (21,490,063)	$ (2,296,571)	$ (10,175,063)	$ 72,570
Other comprehensive income (loss):
Increase (decrease) in net unrealized gain (loss) on available-for-sale securities, net	12,154,936	(2,478,268)	0	1,220,918
Reclassification adjustment for net gain (loss) included in net income (loss)	11,328,205	365,849	12,617,794	217,565
Total other comprehensive income (loss)	23,483,141	(2,112,419)	12,617,794	1,438,483
Less: Dividends to preferred stockholders	(870,726)	(870,726)	(1,751,235)	(1,751,235)
Comprehensive income (loss) attributable to common stockholders	$ 1,122,352	$ (5,279,716)	$ 691,496	$ (240,182)