EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 26, 2019	May 27, 2018
Pension Plans
Components of net periodic benefit cost for our pension and postretirement benefit plans
Service cost	$ 3.1	$ 6.0	$ 7.8
Interest cost	1.1	0.8	0.4
Expected return on plan assets	(0.9)	(0.9)	(0.4)
Actuarial loss	0.2
Net periodic benefit cost	3.5	5.9	7.8
Post-Retirement Plan
Components of net periodic benefit cost for our pension and postretirement benefit plans
Interest cost	0.2	0.3	0.2
Prior service benefit			(0.2)
Actuarial loss	0.6	0.7	0.5
Net periodic benefit cost	$ 0.8	$ 1.0	$ 0.5