Available-for-Sale Marketable Securities - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) position	Dec. 31, 2019 USD ($) 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	30	16
Total number of positions	59	81
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses | $	$ 0
U.S. Treasury Securities [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	6
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	1
Total number of positions	6
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	8
Total number of positions	18
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	15
Total number of positions	22
Municipal Bonds [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	7