Stock Options, Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Unamortized Stock Compensation Expense [Abstract]
Unamortized stock compensation expense | $	$ 22,737,886
Period for recognition	2 years 9 months 18 days
Stock Options [Member]
Number of Shares [Roll Forward]
Options outstanding, beginning balance (in shares) | shares	6,462,795
Granted (in shares) | shares	1,120,100
Exercised (in shares) | shares	(198,300)
Forfeited (in shares) | shares	(43,127)
Options outstanding, ending balance (in shares) | shares	7,341,468
Vested and expected to vest (in shares) | shares	7,341,467
Exercisable (in shares) | shares	4,280,124
Weighted Average Exercise Price [Roll Forward]
Options outstanding, beginning balance (in dollars per share) | $ / shares	$ 6.50
Granted (in dollars per share) | $ / shares	14.42
Exercised (in dollars per share) | $ / shares	3.64
Forfeited (in dollars per share) | $ / shares	12.09
Options outstanding, ending balance (in dollars per share) | $ / shares	7.75
Vested and expected to vest (in dollars per share) | $ / shares	7.75
Exercisable (in dollars per share) | $ / shares	$ 5.53
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value [Abstract]
Options outstanding, weighted average remaining contractual life	7 years 4 months 10 days
Vested and expected to vest, weighted average remaining contractual life	7 years 4 months 10 days
Exercisable, weighted average remaining contractual life	6 years 2 months 12 days
Options outstanding, aggregate intrinsic value | $	$ 151,247
Vested and expected to vest, aggregate intrinsic value | $	151,247
Exercisable, aggregate intrinsic value | $	$ 151,247