Investment Securities - Summary of Investment Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 563,917	$ 412,570
Unrealized Gains	1,674	490
Unrealized (Losses)	(45)	(386)
Estimated Fair Value	565,546	412,674
U.S. Government Agency Securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	135,801	150,651
Unrealized Gains	158	148
Unrealized (Losses)	(13)	(204)
Estimated Fair Value	135,946	150,595
FDIC Certificates of Deposit
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	980	4,410
Unrealized Gains	0	2
Unrealized (Losses)	0	(12)
Estimated Fair Value	980	4,400
Certificates of Deposit
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	60,000	60,000
Unrealized Gains	0	0
Unrealized (Losses)	0	0
Estimated Fair Value	60,000	60,000
Commercial Paper
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	51,637	78,610
Unrealized Gains	63	59
Unrealized (Losses)	(1)	(27)
Estimated Fair Value	51,699	78,642
Corporate Notes/Bonds
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	315,499	118,899
Unrealized Gains	1,453	281
Unrealized (Losses)	(31)	(143)
Estimated Fair Value	$ 316,921	$ 119,037

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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