Available-for-Sale Marketable Securities - Summary of Available-for-Sale Marketable Securities by Major Type of Security (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 185,062	$ 219,734
Gross Unrealized Gains	53	123
Gross Unrealized Losses	(58)	(50)
Estimated Fair Value	185,057	219,807
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,106	20,710
Gross Unrealized Gains	3	41
Gross Unrealized Losses		(1)
Estimated Fair Value	10,109	20,750
U.S. Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,572	22,125
Gross Unrealized Gains	5	4
Gross Unrealized Losses	(10)	(1)
Estimated Fair Value	14,567	22,128
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	44,850	49,080
Gross Unrealized Gains	15	61
Gross Unrealized Losses	(31)	(23)
Estimated Fair Value	44,834	49,118
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	99,705	116,139
Gross Unrealized Gains	13	5
Gross Unrealized Losses	(1)	(17)
Estimated Fair Value	99,717	116,127
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,829	11,680
Gross Unrealized Gains	17	12
Gross Unrealized Losses	(16)	(8)
Estimated Fair Value	$ 15,830	$ 11,684