Summary of Available-for-Sale Debt Securities in Unrealized Loss Position and Included in Accumulated Other Comprehensive (Loss), Aggregated by Length of Time Investments (Detail) - USD ($) $ in Thousands	May 31, 2022	May 31, 2021
Investments, Debt and Equity Securities [Abstract]
Total investments with unrealized losses, fair value	$ 22,702	$ 8,420
Unrealized losses with a loss position for less than 12 months, fair value	16,273	6,920
Unrealized losses with a loss position for more than 12 months, fair value	6,429	1,500
Total investments with unrealized losses, gross unrealized losses	(1,342)	(184)
Unrealized losses with a loss position for less than 12 months, gross unrealized losses	(543)	(152)
Unrealized losses with a loss position for more than 12 months, gross unrealized losses	$ (799)	$ (32)