Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 46,851	$ 81,892
Gross Unrealized Gains		5
Estimated Fair Value	46,851	81,897
Federal Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		13,697
Gross Unrealized Gains		3
Estimated Fair Value		13,700
Money Market Funds | Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	44,347	30,360
Estimated Fair Value	44,347	30,360
U.S. Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,504	37,835
Gross Unrealized Gains		2
Estimated Fair Value	2,504	37,837
Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	44,347	30,360
Short-Term Investments
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	$ 2,504	48,994
Other Long-term Investments
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value		$ 2,543