Net Loss (Gain) on Marketable Securities (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Net Loss (Gain) on Marketable Securities
Unrealized losses (gains) on marketable equity securities	$ 8,903	$ (6,650)	$ 11,227	$ (28,469)
Realized (gains) on marketable equity securities	(699)	(2,834)	(1,223)	(1,210)
Realized losses on available-for-sale debt securities	11	4	28	27
Net loss (gain) on marketable securities	$ 8,215	$ (9,480)	$ 10,032	$ (29,652)