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Share-Based Payments - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Aug. 01, 2020	Jul. 08, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense		$ 31,960	$ 4,456
Share-based compensation arrangement by share-based payment award, vesting term		4 years
Weighted average grant date fair value of stock options granted		$ 30.14	$ 3.34
Total unrecognized compensation cost related to the unvested stock-based awards, Value		$ 69,948
Total unrecognized compensation cost related to the unvested stock-based awards, Weighted average period		2 years 7 months 9 days
Operating Income (Loss) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense		$ 25,527
2020 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Number of Shares Authorized		8,026,772		0	8,376,080
2016 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Award, Number of Shares Authorized				0
Share-based Compensation Arrangement by Share-based Payment Award, Shares Purchased for Award	1,960,547
Share-based Payment Award, Award Vesting Rights		The commencement of vesting was based on the achievement of certain scientific and operational milestones during a two-year period, for which the achievement was discretionary and subject to the approval of the Company’s board of directors.