Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, fair value	$ 1,212,061	$ 1,656,563
Recurring Basis [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other non-current assets		2,212
Total	1,739,826	1,870,660
Recurring Basis [Member] | Cash [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	149,231	159,295
Recurring Basis [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	339,223	17,766
Recurring Basis [Member] | Corporate Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	2,149
Marketable securities, fair value	733,290	1,222,379
Recurring Basis [Member] | Certificates of Deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, fair value	78,829	92,417
Recurring Basis [Member] | Commercial Paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	18,406	32,675
Marketable securities, fair value	196,765	262,722
Recurring Basis [Member] | US Treasury Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	20,905
Marketable securities, fair value	14,622
Recurring Basis [Member] | Government-sponsored Enterprise Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, fair value	188,555	79,045
Recurring Basis [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	488,454	177,061
Recurring Basis [Member] | Level 1 [Member] | Cash [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	149,231	159,295
Recurring Basis [Member] | Level 1 [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	339,223	17,766
Recurring Basis [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	1,251,372	1,691,387
Recurring Basis [Member] | Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents		2,149
Marketable securities, fair value	733,290	1,222,379
Recurring Basis [Member] | Level 2 [Member] | Certificates of Deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, fair value	78,829	92,417
Recurring Basis [Member] | Level 2 [Member] | Commercial Paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	18,406	32,675
Marketable securities, fair value	196,765	262,722
Recurring Basis [Member] | Level 2 [Member] | US Treasury Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	20,905
Marketable securities, fair value	14,622
Recurring Basis [Member] | Level 2 [Member] | Government-sponsored Enterprise Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, fair value	$ 188,555	79,045
Recurring Basis [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other non-current assets		2,212
Total		$ 2,212