Significant Accounting Policies - Estimated Fair Value of Assets and Liability (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Asset:
Asset, fair value	$ 195,933	$ 374,911
Money Market Fund
Asset:
Asset, fair value	117,301	95,063
U.S. Treasury Shares
Asset:
Asset, fair value	8,059	23,219
Corporate Bonds
Asset:
Asset, fair value	35,880	83,587
Commercial Paper
Asset:
Asset, fair value	21,519	121,773
Repo Securities
Asset:
Asset, fair value	3,250	8,000
Asset Backed Securities
Asset:
Asset, fair value	2,237	8,816
Certificates of Deposit
Asset:
Asset, fair value	6,297	21,553
Non-US Government
Asset:
Asset, fair value	1,390	12,900
Level 1
Asset:
Asset, fair value	125,360	118,282
Level 1 | Money Market Fund
Asset:
Asset, fair value	117,301	95,063
Level 1 | U.S. Treasury Shares
Asset:
Asset, fair value	8,059	23,219
Level 2
Asset:
Asset, fair value	70,573	256,629
Level 2 | Corporate Bonds
Asset:
Asset, fair value	35,880	83,587
Level 2 | Commercial Paper
Asset:
Asset, fair value	21,519	121,773
Level 2 | Repo Securities
Asset:
Asset, fair value	3,250	8,000
Level 2 | Asset Backed Securities
Asset:
Asset, fair value	2,237	8,816
Level 2 | Certificates of Deposit
Asset:
Asset, fair value	6,297	21,553
Level 2 | Non-US Government
Asset:
Asset, fair value	$ 1,390	$ 12,900