SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounting Changes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	May 30, 2021	May 31, 2020	May 27, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jun. 01, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true
Change in Accounting Principle, Accounting Standards Update, Transition Option Elected [Extensible List]	cag:AccountingStandardUpdate201613ModifiedRetrospectiveMember
Total lease assets	$ 188.5	$ 209.3
Total lease liabilities	$ 224.9
Accounting Standards Update 2016-02
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Total lease assets			$ 238.4
Total lease liabilities			$ 267.0