Business Combinations - Narrative (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended
	Jan. 31, 2020	Sep. 30, 2019	Mar. 31, 2020
Business Acquisition [Line Items]
Consideration holdback period	18 months
Repayments of notes payable			$ 0.2
Class A common stock
Business Acquisition [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)		31,381,152
Class B common stock
Business Acquisition [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)		134,276,690
Conversion of Class B Common Stock To Class A Common Stock | Former Employees | Class A common stock
Business Acquisition [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)		15,198,587
Conversion of Class B Common Stock To Class A Common Stock | Former Employees | Class B common stock
Business Acquisition [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)		15,198,587
S2 Systems Corporation
Business Acquisition [Line Items]
Consideration transferred	$ 16.9
Cash payments to acquire businesses	13.6
Cash acquired	0.1
Value of shares issued	1.1
Payments to settle acquiree's outstanding debt	6.9
Consideration held back	2.2
Compensation arrangements value	21.1
Compensation arrangement with individual, compensation expense	$ 6.5		1.4
Compensation arrangement with individual, recorded liability			$ 13.2
Compensation arrangement, weighted-average remaining recognition period			3 years