Convertible Preferred Stock (Details) $ / shares in Units, $ in Thousands	Dec. 31, 2019 USD ($) $ / shares shares	May 31, 2019 $ / shares shares	Dec. 31, 2018 USD ($) series_of_stock $ / shares shares
Temporary Equity [Line Items]
Number of Preferred Stock series | series_of_stock			7
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.00002	$ 0.00002	$ 0.00002
Preferred stock, shares issued (in shares)	0		53,630,213
Preferred stock, shares outstanding (in shares)	0		53,630,213
Preferred stock, shares authorized (in shares)	0	10,000,000	54,148,643
Net carrying amount | $	$ 0		$ 219,584
Liquidation preference | $			$ 220,037
Series Seed Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)			8,049,364
Preferred stock, shares outstanding (in shares)			8,049,364
Preferred stock, shares authorized (in shares)			8,049,365
Net carrying amount | $			$ 1,200
Liquidation preference | $			$ 1,200
Series A Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)			2,733,518
Preferred stock, shares outstanding (in shares)			2,733,518
Preferred stock, shares authorized (in shares)			2,733,520
Net carrying amount | $			$ 1,050
Liquidation preference | $			$ 1,050
Series B Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)			10,945,209
Preferred stock, shares outstanding (in shares)			10,945,209
Preferred stock, shares authorized (in shares)			11,058,835
Net carrying amount | $			$ 11,260
Liquidation preference | $			$ 11,260
Series C Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)			9,753,060
Preferred stock, shares outstanding (in shares)			9,753,060
Preferred stock, shares authorized (in shares)			9,805,905
Net carrying amount | $			$ 41,420
Liquidation preference | $			$ 41,527
Series D Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)			11,627,903
Preferred stock, shares outstanding (in shares)			11,627,903
Preferred stock, shares authorized (in shares)			11,675,463
Net carrying amount | $			$ 74,912
Liquidation preference | $			$ 75,000
Series E Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)			6,609,030
Preferred stock, shares outstanding (in shares)			6,609,030
Preferred stock, shares authorized (in shares)			6,609,032
Net carrying amount | $			$ 49,863
Liquidation preference | $			$ 50,000
Series F Preferred Stock
Temporary Equity [Line Items]
Preferred stock, shares issued (in shares)			3,912,129
Preferred stock, shares outstanding (in shares)			3,912,129
Preferred stock, shares authorized (in shares)			4,216,523
Net carrying amount | $			$ 39,879
Liquidation preference | $			$ 40,000