Financial Instruments - Summary of Money Market Funds and Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 92,972	$ 40,195
Unrealized Gain		2
Unrealized Loss	(14)	(7)
Estimated Fair Value	92,958	40,190
Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,152	522
Estimated Fair Value	1,152	522
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	150	150
Estimated Fair Value	150	150
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	86,094	32,213
Unrealized Gain		2
Unrealized Loss	(10)	(2)
Estimated Fair Value	86,084	32,213
Municipal bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,259	6,310
Unrealized Loss	(3)	(5)
Estimated Fair Value	4,256	6,305
U.S. Government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		1,000
Estimated Fair Value		1,000
Corporate debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,317
Unrealized Loss	(1)
Estimated Fair Value	1,316
Cash and cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	53,272	19,619
Unrealized Gain		1
Unrealized Loss	(2)	(1)
Estimated Fair Value	53,270	19,619
Short-term investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	39,550	19,426
Unrealized Gain		1
Unrealized Loss	(12)	(6)
Estimated Fair Value	39,538	19,421
Long Term Restricted Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	150	150
Estimated Fair Value	$ 150	150
Long-term investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		1,000
Estimated Fair Value		$ 1,000