Cash Equivalents and Investments - Schedule of Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Available-for-sale [Line Items]
Available-for-sale Securities	$ 100,763	$ 104,870
Corporate Securities [Member]
Available-for-sale [Line Items]
Available-for-sale Securities	69,897	71,095
Municipal Debt Securities [Member]
Available-for-sale [Line Items]
Available-for-sale Securities	15,897	18,707
Federal Home Loan Securities [Member]
Available-for-sale [Line Items]
Available-for-sale Securities	4,967	8,017
Certificates of Deposit [Member]
Available-for-sale [Line Items]
Available-for-sale Securities	4,717	5,991
U.S. Treasury securities [Member]
Available-for-sale [Line Items]
Available-for-sale Securities	$ 5,285	$ 1,060