Net Loss (Gain) on Marketable Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2021
Net Loss (Gain) on Marketable Securities
Unrealized losses (gains) on marketable equity securities	$ 2,667	$ 19,164	$ (16,133)
Realized (gains) losses on marketable equity securities	(551)	(1,488)	(22,680)
Realized (gains) losses on available-for-sale debt securities	(30)	30	39
Net loss (gain) on marketable securities	$ 2,086	$ 17,706	$ (38,774)