EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS - Fair Value Measurements of Plan Assets - Tabular Disclosure (Details) - Pension Plans - USD ($) $ in Millions	May 31, 2020	May 26, 2019	May 27, 2018
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	$ 27.2	$ 17.1	$ 17.3
Level 1
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	19.2	11.8
Level 2
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	8.0	5.3
U.S. equity securities
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	4.1	2.6
U.S. equity securities | Level 2
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	4.1	2.6
International equity securities
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	3.9	2.7
International equity securities | Level 2
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	3.9	2.7
US treasury securities
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	19.2	11.8
US treasury securities | Level 1
EMPLOYEE BENEFIT PLANS AND OTHER POST-RETIREMENT BENEFITS
Pension plan assets	$ 19.2	$ 11.8