Shareholders' Equity - Additional Information (Details)				12 Months Ended
	Jan. 01, 2020 shares	Jul. 01, 2019 shares	Jun. 30, 2019 shares	Dec. 31, 2019 Vote $ / shares shares	Dec. 31, 2014 $ / shares shares	Dec. 31, 2018 $ / shares shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares
Class Of Stock [Line Items]
Convertible preferred stock outstanding				0		92,790,094
Preferred stock, shares authorized				10,000,000		0
Preferred stock, par value | $ / shares				$ 0.0001		$ 0.0001
Preferred stock, shares outstanding				0		0
Common stock authorized				340,000,000		131,000,000
Common stock par value | $ / shares				$ 0.0001		$ 0.0001
Common stock voting rights description				Holders of our common stock are entitled to one vote for each share of common stock held
Number of vote for each share | Vote				1
Common stock outstanding				125,238,142		12,841,536
Warrants issued to purchase stock				56,875
Common Stock
Class Of Stock [Line Items]
Warrants issued to purchase stock				20,000
Warrant exercisable term				10 years
Weighted-average exercise price of warrants | $ / shares				$ 0.37
Exercise price of warrants | $ / shares				$ 0.45
Stock issued during period, common stock		54,792		54,792
Series C Convertible Preferred Stock
Class Of Stock [Line Items]
Warrants issued to purchase stock					56,875
Warrant exercisable term					7 years
Weighted-average exercise price of warrants | $ / shares					$ 2.64
Subsequent Event | Employee Stock Purchase Plan
Class Of Stock [Line Items]
Increase in share reserve	1,252,381
Maximum | Common Stock
Class Of Stock [Line Items]
Warrants issued to purchase stock				55,032
Maximum | Subsequent Event | Employee Stock Purchase Plan
Class Of Stock [Line Items]
Percentage of annual increases in number of shares	1.00%
2019 Plan | Subsequent Event
Class Of Stock [Line Items]
Increase in share reserve	6,261,907
2019 Plan | Maximum | Subsequent Event
Class Of Stock [Line Items]
Percentage of annual increases in number of shares	5.00%
Convertible Preferred Stock
Class Of Stock [Line Items]
Conversion of convertible preferred stock			93,039,737
Convertible preferred stock outstanding				93,039,737		92,790,094	92,656,029	87,797,854