Preferred Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Jan. 31, 2012	Oct. 31, 2011	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Sep. 30, 2019	Apr. 30, 2011
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)						225,000,000
Preferred stock, par value (in dollars per share)						$ 0.001
Change in fair value of redeemable convertible preferred stock warrant liability			$ 0	$ 118
Warrant To Purchase Series B Redeemable Preferred Stock
Class of Stock [Line Items]
Number of shares subject to purchase from warrant (in shares)	23,760	94,510					59,140
Proceeds from drawdown	$ 400	$ 1,600
Exercise price of warrants (in dollars per share)							$ 0.34
Class B common stock
Class of Stock [Line Items]
Number of shares issued from exercise of warrants (in shares)					174,347