Stockholders' Equity - Schedule of 2017 Plan Options Outstanding (Details) - 2017 Plan	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Number of Options Outstanding
Outstanding at beginning of period (in shares) | shares	343,550
Annual additional options authorized (in shares) | shares	0
Granted (in shares) | shares	184,700
Exercised (in shares) | shares	0
Forfeited (in shares) | shares	(19,812)
Outstanding at end of period (in shares) | shares	508,438	343,550
Weighted-average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 28.97
Annual additional options authorized | $ / shares	0.00
Granted (in dollars per share) | $ / shares	13.88
Exercised (in dollars per share) | $ / shares	0.00
Forfeited (in dollars per share) | $ / shares	18.72
Outstanding at end of period (in dollars per share) | $ / shares	$ 23.89	$ 28.97
Weighted-average Remaining Contractual Term (years)
Outstanding	8 years 8 months 5 days	8 years 11 months 12 days
Aggregate Intrinsic Value
Outstanding | $	$ 208,166	$ 840