Stock Based Compensation - Stock-Based Compensation (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Stock Based Compensation
Total stock-based compensation expense	$ 2,023,874	$ 814,613
Research and development expense
Stock Based Compensation
Total stock-based compensation expense	579,641	216,932
Sales and marketing expense
Stock Based Compensation
Total stock-based compensation expense	96,730	32,325
General and administrative expense
Stock Based Compensation
Total stock-based compensation expense	1,347,503	$ 565,356
Stock options and RSUs
Stock Based Compensation
Unrecognized stock-based compensation expense	$ 2,860,071
Expected weighted average period to be recognized	2 years
Minimum | Non-employee stock options
Estimated grant-date fair value of stock options calculated using the Black-Scholes option-pricing model
Weighted-average volatility (as a percent)	83.60%	85.40%
Weighted-average expected term (years)	9 years 1 month 6 days	9 years 9 months 18 days
Risk-free interest rate (as a percent)	2.60%	2.40%
Minimum | Employee stock options
Estimated grant-date fair value of stock options calculated using the Black-Scholes option-pricing model
Weighted-average volatility (as a percent)	87.40%	74.30%
Weighted-average expected term (years)	5 years 1 month 6 days	5 years 1 month 6 days
Risk-free interest rate (as a percent)	2.60%	2.00%
Maximum | Non-employee stock options
Estimated grant-date fair value of stock options calculated using the Black-Scholes option-pricing model
Weighted-average volatility (as a percent)	89.20%	85.70%
Weighted-average expected term (years)	9 years 8 months 12 days	10 years
Risk-free interest rate (as a percent)	3.00%	2.50%
Maximum | Employee stock options
Estimated grant-date fair value of stock options calculated using the Black-Scholes option-pricing model
Weighted-average volatility (as a percent)	105.90%	90.50%
Weighted-average expected term (years)	5 years 9 months 18 days	5 years 9 months 18 days
Risk-free interest rate (as a percent)	2.90%	2.30%