Leases - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) ft²	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Leases [Line Items]
Operating lease cost | $	$ 18,985	$ 14,697	$ 7,972
Operating lease, payments | $	$ 16,200	$ 8,400
Weighted average remaining lease term	9 years 1 month 6 days
Weighted average discount rate, percent	5.90%
Mission Bay Lease
Leases [Line Items]
Lease space (in sq ft) | ft²	153,203
Third Street Lease
Leases [Line Items]
Lease space (in sq ft) | ft²	135,936