EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS - Change in Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 26, 2019	May 27, 2018
Pension Plans
Change in Benefit Obligation
Benefit obligation at beginning of year	$ 27.4	$ 18.9
Service cost	3.1	6.0	$ 7.8
Interest cost	1.1	0.8	0.4
Benefits paid	(0.3)	(0.3)
Plan settlements	(0.4)
Actuarial (gain) loss	6.4	2.0
Benefit obligation at fiscal year-end	37.3	27.4	18.9
Accumulated benefit obligation portion of above	37.3	27.4
Post-Retirement Plan
Change in Benefit Obligation
Benefit obligation at beginning of year	7.3	7.0
Interest cost	0.2	0.3	0.2
Participant contributions	0.2	0.2
Benefits paid	(0.3)	(0.3)
Actuarial (gain) loss	(0.9)	0.1
Benefit obligation at fiscal year-end	$ 6.5	$ 7.3	$ 7.0