PENSION AND POSTRETIREMENT BENEFITS - Schedule of Fair Value of Plan Assets, Summarized by Level (Details) - USD ($) $ in Millions	May 30, 2021	May 31, 2020
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	$ 3,848.8	$ 3,820.4
Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	213.1	196.6
Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	3,372.3	3,382.8
Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Total
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	3,585.4	3,579.4
Measured at net asset value
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	263.4	241.0
Cash and cash equivalents
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	92.5	82.0
Cash and cash equivalents | Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	7.5	10.1
Cash and cash equivalents | Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	85.0	71.9
Cash and cash equivalents | Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
U.S. equity securities
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	172.6	146.1
U.S. equity securities | Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	78.0	63.9
U.S. equity securities | Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	94.6	82.2
U.S. equity securities | Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
International equity securities
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	122.4	93.1
International equity securities | Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	121.9	92.4
International equity securities | Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.5	0.7
International equity securities | Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Government bonds
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	772.6	743.9
Government bonds | Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Government bonds | Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	772.6	743.9
Government bonds | Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Corporate bonds
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	2,407.2	2,461.7
Corporate bonds | Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Corporate bonds | Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	2,407.2	2,461.7
Corporate bonds | Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Mortgage-backed bonds
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	12.4	22.4
Mortgage-backed bonds | Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Mortgage-backed bonds | Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	12.4	22.4
Mortgage-backed bonds | Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Real estate funds
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Real estate funds | Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Real estate funds | Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Real estate funds | Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Net receivables for unsettled transactions
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	5.7	30.2
Net receivables for unsettled transactions | Level 1
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	5.7	30.2
Net receivables for unsettled transactions | Level 2
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	0.0	0.0
Net receivables for unsettled transactions | Level 3
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension plan assets	$ 0.0	$ 0.0