EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS - Components of Net Periodic Benefit Cost and Other Comprehensive (Income) Loss - Additional Information (Details) $ in Millions	12 Months Ended
	May 31, 2020 USD ($)
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Accumulated losses (as a percent)	10.00%
Estimated net amount of actuarial losses on pension and post-retirement benefits included in AOCI	$ 0.3
Estimated net amount of actuarial losses on pension and post-retirement benefits included in AOCI, net of tax	$ (0.2)
Pension Plans | Minimum
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Average remaining service period	7 years
Pension Plans | Maximum
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Average remaining service period	11 years
Post-Retirement Plan
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Average remaining service period	3 years