SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	9 Months Ended
	Feb. 28, 2021
Accounting Policies [Abstract]
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:AccountingStandardsUpdate201613ModifiedRetrospectiveMember