Leases - Operating Lease Cost and Additional Lease Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019	May 31, 2020
Leases [Abstract]
Operating lease costs	$ 18,100	$ 17,700	$ 35,200	$ 34,900
Other information related to operating leases
Cash paid for amounts included in the measurement of operating lease liabilities			24,565	24,927
Operating lease right-of-use assets obtained in exchange for new and renewed operating lease liabilities			$ 15,735	$ 24,770
Weighted-average remaining lease term - operating leases	5 years 3 days		5 years 3 days		5 years 2 months 8 days
Weighted-average discount rate - operating leases	2.58%		2.58%		2.66%