Stock-Based Compensation, Stock Option Activity (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares shares
Unamortized Stock Compensation Expense [Abstract]
Unamortized stock compensation expense | $	$ 13,294,326	$ 13,294,326
Stock Options [Member]
Number of Shares [Roll Forward]
Options outstanding, beginning balance (in shares) | shares		6,462,795
Granted (in shares) | shares	0	2,322,906
Exercised (in shares) | shares		(198,300)
Forfeited (in shares) | shares		(1,438,027)
Options outstanding, ending balance (in shares) | shares	7,149,374	7,149,374
Vested and expected to vest (in shares) | shares	7,149,374	7,149,374
Exercisable (in shares) | shares	4,120,549	4,120,549
Weighted Average Exercise Price [Roll Forward]
Options outstanding, beginning balance (in dollars per share) | $ / shares		$ 6.50
Granted (in dollars per share) | $ / shares		7.52
Exercised (in dollars per share) | $ / shares		3.64
Forfeited (in dollars per share) | $ / shares		10.13
Options outstanding, ending balance (in dollars per share) | $ / shares	$ 6.18	6.18
Vested and expected to vest (in dollars per share) | $ / shares	6.18	6.18
Exercisable (in dollars per share) | $ / shares	$ 5.54	$ 5.54
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value [Abstract]
Options outstanding, weighted average remaining contractual life		6 years 1 month 17 days
Vested and expected to vest, weighted average remaining contractual life		6 years 1 month 17 days
Exercisable, weighted average remaining contractual life		5 years 8 months 23 days
Options outstanding, aggregate intrinsic value | $	$ 42,723	$ 42,723
Vested and expected to vest, aggregate intrinsic value | $	42,723	42,723
Exercisable, aggregate intrinsic value | $	$ 42,723	$ 42,723
Unamortized Stock Compensation Expense [Abstract]
Period for recognition		2 years 7 months 20 days