NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ASU 2016-02 - Impact of Adoption (Details) - USD ($) $ in Millions	May 31, 2020	May 27, 2019	May 26, 2019
New and Recently Issued Accounting Standards
Operating lease assets	$ 167.0	$ 155.0
Operating lease liability	173.0
Retained earnings	1,064.6		$ 803.6
Property, plant and equipment, net	1,535.0		1,597.8
Long-term debt and financing obligations, excluding current portion	$ 2,992.6		2,280.2
Accounting Standards Update 2016-02
New and Recently Issued Accounting Standards
Cumulative effect on retained earnings, before tax			26.6
Accounting Standards Update 2016-02 | Revision of Prior Period, Accounting Standards Update, Adjustment
New and Recently Issued Accounting Standards
Property, plant and equipment, net		(38.7)
Long-term debt and financing obligations, excluding current portion		$ (65.3)
Accounting Standards Update 2016-02 | Cumulative Effect, Period of Adoption, Adjustment
New and Recently Issued Accounting Standards
Retained earnings			$ 20.5