Investment in Nikola - Additional Information (Detail) - USD ($)	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019
Marketable Securities [Line Items]
Gains on investment in Nikola	$ 655,102,000	$ 0	$ 0
Proceeds from sale of Nikola shares	634,449,000	0	0
Charitable contribution of Nikola shares	$ 20,653,000	$ 0	$ 0
Nikola Corporation
Marketable Securities [Line Items]
Marketable securities effective date	Jun. 03, 2020
Marketable securities number of shares owned	19,048,020
Gains on investment in Nikola	$ 655,102,000
Proceeds from sale of Nikola shares	634,449,000
Charitable contribution of Nikola shares	20,653,000
Incremental expenses on gains from marketable securities	50,624,000
Profit sharing and bonus expense on marketable securities gain	29,971,000
Marketable securities contribution expense	$ 20,653,000