PENSION AND POSTRETIREMENT BENEFITS - Components of pension and postretirement plan costs (benefits) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 24, 2024	Nov. 26, 2023	Nov. 24, 2024	Nov. 26, 2023
Pension plan
PENSION AND POSTRETIREMENT BENEFITS
Service cost	$ 1.3	$ 1.4	$ 2.7	$ 2.9
Interest cost	33.4	36.7	67.4	73.4
Expected return on plan assets	(35.8)	(35.8)	(72.4)	(71.6)
Amortization of prior service cost (benefit)	0.4	0.4	0.8	0.8
Total pension and postretirement cost (benefit)	2.3	5.4	3.7	10.3
Total pension and postretirement cost (benefit)	2.3	5.4	3.7	10.3
Pension plan | Company plans
PENSION AND POSTRETIREMENT BENEFITS
Total pension and postretirement cost (benefit)	0.7	(2.7)	1.5	(5.5)
Total pension and postretirement cost (benefit)	0.7	(2.7)	1.5	(5.5)
Pension plan | Multi employer plan
PENSION AND POSTRETIREMENT BENEFITS
Total pension and postretirement cost (benefit)	3.0	2.7	5.2	4.8
Total pension and postretirement cost (benefit)	3.0	2.7	5.2	4.8
Other postretirement benefits plan
PENSION AND POSTRETIREMENT BENEFITS
Service cost	0.1	0.1	0.1	0.1
Interest cost	0.6	0.7	1.2	1.3
Amortization of prior service cost (benefit)	(0.5)	(0.4)	(0.9)	(0.8)
Recognized net actuarial gain	(1.2)	(1.2)	(2.3)	(2.4)
Total pension and postretirement cost (benefit)	(1.0)	(0.8)	(1.9)	(1.8)
Total pension and postretirement cost (benefit)	$ (1.0)	$ (0.8)	$ (1.9)	$ (1.8)