EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS - Changes in Plan Assets and Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 26, 2019	May 27, 2018
Pension Plans
Components of other comprehensive income (loss)
Actuarial (gain) loss	$ 0.6	$ 3.3	$ 1.7
Amortization of actuarial gain (loss)	(0.2)
Total recognized in other comprehensive loss (income)	0.4	3.3	1.7
Post-Retirement Plan
Components of other comprehensive income (loss)
Actuarial (gain) loss	(1.0)		4.3
Amortization of prior service benefit			0.2
Amortization of actuarial gain (loss)	(0.6)	(0.7)	(0.5)
Total recognized in other comprehensive loss (income)	$ (1.6)	$ (0.7)	$ 4.0