CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Conversion of Class B Common Stock To Class A Common Stock	Common Stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)	Redeemable convertible preferred stock	Class A common stock	Class A common stock Common Stock	Class A common stock Common Stock Conversion of Class B Common Stock To Class A Common Stock	Class B common stock	Class B common stock Common Stock	Class B common stock Common Stock Conversion of Class B Common Stock To Class A Common Stock
Beginning balance (in shares) at Dec. 31, 2018							165,658,000
Beginning balance at Dec. 31, 2018							$ 331,521
Ending balance (in shares) at Mar. 31, 2019							165,658,000
Ending balance at Mar. 31, 2019							$ 331,521
Beginning balance (in shares) at Dec. 31, 2018			91,542,000
Beginning balance at Dec. 31, 2018	$ (113,505)		$ 85	$ 82,345	$ (195,878)	$ (57)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with acquisition (in shares)			7,000
Issuance of common stock in connection with acquisition	18			18
Issuance of common stock upon exercise of stock options (in shares)			346,000
Issuance of common stock upon exercise of stock options	681		$ 0	681
Repurchases of unvested common stock (in shares)			(9,000)
Issuance of common stock related to early exercised stock options (in shares)			407,000
Vesting of early exercised stock options	496			496
Stock-based compensation	1,128			1,128
Net loss	(17,114)		$ (17,114)		(17,114)
Other comprehensive income (loss)	72					72
Ending balance (in shares) at Mar. 31, 2019			92,293,000
Ending balance at Mar. 31, 2019	(128,224)		$ 85	84,668	(212,992)	15
Beginning balance (in shares) at Dec. 31, 2019							0
Beginning balance at Dec. 31, 2019							$ 0
Ending balance (in shares) at Mar. 31, 2020							0
Ending balance at Mar. 31, 2020							$ 0
Beginning balance (in shares) at Dec. 31, 2019								87,071,783	87,072,000		213,101,364	213,101,000
Beginning balance at Dec. 31, 2019	725,828			1,027,179	(301,706)	61			$ 87			$ 207
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock in connection with acquisition (in shares)									107,000
Issuance of common stock in connection with acquisition	$ 1,104			1,104
Issuance of unvested restricted stock in connection with acquisition (in shares)									841,000
Issuance of common stock upon exercise of stock options (in shares)	1,518,000											1,503,000
Issuance of common stock upon exercise of stock options	$ 2,675			2,674								$ 1
Repurchases of unvested common stock (in shares)									(29,000)
Issuance of common stock related to early exercised stock options (in shares)												15,000
Vesting of early exercised stock options	1,223			1,222								$ 1
Vesting/settlement of restricted stock units (in shares)									32,000			1,123,000
Issuance of common stock related to settlement of RSUs	0			(1)								$ 1
Tax withholding on RSU settlement (in shares)									(11,000)			(397,000)
Tax withholding on RSU settlement	(7,115)			(7,115)
Conversion of Class B to Class A common stock (in shares)										66,610,000			66,610,000
Conversion of Class B to Class A common stock		$ 0								$ 67			$ (67)
Stock-based compensation	13,481			13,481
Net loss	(32,746)				(32,746)				$ (10,876)			$ (21,870)
Other comprehensive income (loss)	1,346					1,346
Ending balance (in shares) at Mar. 31, 2020								154,622,397	154,622,000		148,734,859	148,735,000
Ending balance at Mar. 31, 2020	$ 706,352			$ 1,038,544	$ (333,896)	$ 1,407			$ 154			$ 143