Available-for-Sale Marketable Securities - Additional Information (Detail) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021 USD ($) position	Dec. 31, 2020 USD ($) position
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale allowance for credit loss | $	$ 0	$ 0
Available-for-sale unrealized credit losses | $	$ 0	$ 0
Number of available-for-sale marketable securities in unrealized loss positions	26	30
Total number of positions	59	59
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses | $	$ 0	$ 0
U.S. Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	3
Total number of positions	5
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	10
Total number of positions	20
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	7
Total number of positions	19
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	6
Total number of positions	12