Fair Value Measurements - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Assets:
Marketable securities	$ 827,351	$ 972,611
Fair Value Recurring [Member]
Assets:
Cash equivalents	83,746	135,902
Total assets	911,097	1,108,513
Fair Value Recurring [Member] \| Related Party Revenue Share Liability [Member]
Liabilities:
Total liabilities	45,220	17,940
Fair Value Recurring [Member] \| Commercial Paper [Member]
Assets:
Marketable securities	79,720	251,309
Fair Value Recurring [Member] \| Corporate bonds [Member]
Assets:
Marketable securities	581,799	468,617
Fair Value Recurring [Member] \| Government and agency securities [Member]
Assets:
Marketable securities	143,974	162,886
Fair Value Recurring [Member] \| U.S. treasury bills [Member]
Assets:
Marketable securities	21,858	89,799
Fair Value Recurring [Member] \| Fair value, inputs, level 1 [Member]
Assets:
Cash equivalents	83,746	135,902
Total assets	83,746	135,902
Fair Value Recurring [Member] \| Fair value, inputs, level 2 [Member]
Assets:
Total assets	827,351	972,611
Fair Value Recurring [Member] \| Fair value, inputs, level 2 [Member] \| Commercial Paper [Member]
Assets:
Marketable securities	79,720	251,309
Fair Value Recurring [Member] \| Fair value, inputs, level 2 [Member] \| Corporate bonds [Member]
Assets:
Marketable securities	581,799	468,617
Fair Value Recurring [Member] \| Fair value, inputs, level 2 [Member] \| Government and agency securities [Member]
Assets:
Marketable securities	143,974	162,886
Fair Value Recurring [Member] \| Fair value, inputs, level 2 [Member] \| U.S. treasury bills [Member]
Assets:
Marketable securities	21,858	89,799
Fair Value Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Related Party Revenue Share Liability [Member]
Liabilities:
Total liabilities	$ 45,220	$ 17,940