Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Basic and Diluted Income Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Numerator:
Net income (loss)	$ (235,272)	$ 856,595	$ (4,447,933)	$ 1,302,441	$ (64,591,727)
Denominator:
Weighted-average shares outstanding— basic (in shares)	72,753,487	70,122,234	72,369,619	65,632,962
Effect of dilutive securities (in shares)	0	4,763,669	0	4,936,281
Weighted-average shares outstanding— diluted (in shares)	72,753,487	74,885,903	72,369,619	70,569,243
Basic income (loss) per share (in dollars per share)	$ 0.00	$ 0.01	$ (0.06)	$ 0.02
Diluted income (loss) per share (in dollars per share)	$ 0.00	$ 0.01	$ (0.06)	$ 0.02