Stock-Based Incentive Compensation Plans - Narrative (Details) $ in Millions	3 Months Ended	4 Months Ended	8 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($) shares	Apr. 30, 2020	Dec. 31, 2020 USD ($) purchase_period shares	Dec. 31, 2020 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, stock options	$ 2.7
Stock options granted (in shares) | shares	0
Early exercise of stock options, share subject to repurchase (in shares) | shares	3,889		5,836	5,836
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, expected period for recognition (in years)	1 year 8 months 12 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, expected period for recognition (in years)	3 years 2 months 12 days
Unrecognized compensation cost, RSUs	$ 37.8
2018 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock as a percent of fair market value (percent)				85.00%
Employee stock purchase program offering period interval (in months)		6 months	12 months
Number of purchase periods in offering interval | purchase_period			2
Accrued compensation and related expenses for employee payroll deductions	$ 1.3		$ 0.4	$ 0.4