Stockholders’ Equity - Schedule of Redeemable Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jul. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)	0		58,615,000
Redeemable convertible preferred stock, shares issued (in shares)	0		58,615,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	58,615,488	58,615,000	45,960,000	34,186,000
Net Carrying Value	$ 0		$ 236,929	$ 132,017	$ 79,528
Aggregate Liquidation Preference	$ 0		$ 237,650
Series A
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)			10,394,000
Redeemable convertible preferred stock, shares issued (in shares)			10,394,000
Redeemable convertible preferred stock, shares outstanding (in shares)			10,394,000
Net Carrying Value			$ 10,382
Aggregate Liquidation Preference			$ 10,650
Series B
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)			8,935,000
Redeemable convertible preferred stock, shares issued (in shares)			8,935,000
Redeemable convertible preferred stock, shares outstanding (in shares)			8,935,000
Net Carrying Value			$ 19,957
Aggregate Liquidation Preference			$ 20,000
Series C
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)			14,857,000
Redeemable convertible preferred stock, shares issued (in shares)			14,857,000
Redeemable convertible preferred stock, shares outstanding (in shares)			14,857,000
Net Carrying Value			$ 49,407
Aggregate Liquidation Preference			$ 49,500
Series D
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)			11,774,000
Redeemable convertible preferred stock, shares issued (in shares)			11,774,000
Redeemable convertible preferred stock, shares outstanding (in shares)			11,774,000
Net Carrying Value			$ 52,397
Aggregate Liquidation Preference			$ 52,500
Series E
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)			12,655,000
Redeemable convertible preferred stock, shares issued (in shares)			12,655,000
Redeemable convertible preferred stock, shares outstanding (in shares)			12,655,000
Net Carrying Value			$ 104,786
Aggregate Liquidation Preference			$ 105,000