Employee Benefit Plans - Asset Allocations in the Pension Plan (Details)	May 31, 2021	May 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Target Asset Allocations	100.00%
Actual Asset Allocations	100.00%	100.00%
Large cap equity
Defined Benefit Plan Disclosure [Line Items]
Target Asset Allocations	26.00%
Actual Asset Allocations	29.80%	25.00%
Small cap equity
Defined Benefit Plan Disclosure [Line Items]
Target Asset Allocations	5.00%
Actual Asset Allocations	6.00%	4.40%
International equity
Defined Benefit Plan Disclosure [Line Items]
Target Asset Allocations	8.00%
Actual Asset Allocations	8.30%	6.70%
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Target Asset Allocations	45.00%
Actual Asset Allocations	44.10%	51.50%
Absolute return strategy funds
Defined Benefit Plan Disclosure [Line Items]
Target Asset Allocations	16.00%
Actual Asset Allocations	11.30%	11.90%
Cash
Defined Benefit Plan Disclosure [Line Items]
Target Asset Allocations	0.00%
Actual Asset Allocations	0.50%	0.50%