Stock Incentive Plans - Summary of Additional Information on Stock Options Outstanding (Details)	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Number of Options Outstanding, Shares | shares	4,992,807
Options Outstanding Weighted-average Remaining Contractual Life (years)	8 years 7 months 6 days
Options Outstanding Weighted Average Exercise Price	$ 0.77
Number of Option Exercisable, Shares | shares	2,186,414
Options Exercisable Weighted Average Exercise Price	$ 0.81
Range One [Member]
Range of Exercise Prices, Lower	0.28
Range of Exercise Prices, Upper	$ 1.00
Number of Options Outstanding, Shares | shares	4,352,000
Options Outstanding Weighted-average Remaining Contractual Life (years)	8 years 10 months 6 days
Options Outstanding Weighted Average Exercise Price	$ 0.57
Number of Option Exercisable, Shares | shares	2,024,500
Options Exercisable Weighted Average Exercise Price	$ 0.66
Range Two [Member]
Range of Exercise Prices, Lower	1.50
Range of Exercise Prices, Upper	$ 1.80
Number of Options Outstanding, Shares | shares	493,207
Options Outstanding Weighted-average Remaining Contractual Life (years)	8 years 2 months 5 days
Options Outstanding Weighted Average Exercise Price	$ 1.79
Number of Option Exercisable, Shares | shares	134,314
Options Exercisable Weighted Average Exercise Price	$ 1.78
Range Three [Member]
Range of Exercise Prices, Lower	2.60
Range of Exercise Prices, Upper	$ 10.70
Number of Options Outstanding, Shares | shares	147,600
Options Outstanding Weighted-average Remaining Contractual Life (years)	2 years 9 months 14 days
Options Outstanding Weighted Average Exercise Price	$ 3.43
Number of Option Exercisable, Shares | shares	27,600
Options Exercisable Weighted Average Exercise Price	$ 7.27