Stock-Based Compensation - Summary of Stock-Based Compensation Expense by Grant Type Included within Condensed Consolidated Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense		$ 50,500	$ 47,400	$ 91,200	$ 88,600
Total stock-based compensation expense included in expenses		50,482	47,377	91,174	88,627
Subtotal		55,654	47,377	100,859	88,627
Capitalized stock-based compensation costs	[1]	(5,172)	0	(9,685)	0
Research and Development Expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		19,806	21,577	36,079	37,990
Selling, General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		30,676	25,800	55,095	50,637
Employee Stock Option
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		15,515	21,135	31,796	44,965
Restricted stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		37,808	25,037	65,335	41,177
Employee Stock Purchase Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense included in expenses		$ 2,331	$ 1,205	$ 3,728	$ 2,485

[1] Prior to the six months ended June 30, 2024, capitalized stock-based compensation costs were not material.