Fair Value of Financial Instruments - Schedule of Major Categories of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Commercial Paper [Member]
Assets:
Assets	$ 89,843	$ 79,591
Certificates of Deposit [Member]
Assets:
Assets	190,388	75,000
Level 2 [Member] | Commercial Paper [Member]
Assets:
Assets	89,843	79,591
Level 2 [Member] | Certificates of Deposit [Member]
Assets:
Assets	190,388	75,000
Interest Rate Swap [Member]
Liabilities:
Liabilities	2,976	1,358
Interest Rate Swap [Member] | Level 2 [Member]
Liabilities:
Liabilities	$ 2,976	$ 1,358