LEASES - Schedule of Maturities of Lease Liabilities (Details) $ in Millions	May 31, 2020 USD ($)
Leases [Abstract]
Operating Leases, 2021	$ 53.0
Operating Leases, 2022	42.1
Operating Leases, 2023	36.5
Operating Leases, 2024	28.0
Operating Leases, 2025	19.7
Operating Leases, Later years	118.6
Operating Leases, Total lease payments	297.9
Less: Operating Leases, Imputed interest	(47.4)
Operating Leases, Total lease liabilities	$ 250.5
Operating Lease, Liability, Statement of Financial Position [Extensible List]	cag:OtherAccruedLiabilitiesAndOtherNoncurrentLiabilitiesMember
Finance Leases, 2021	$ 30.3
Finance Leases, 2022	27.7
Finance Leases, 2023	23.7
Finance Leases, 2024	19.7
Finance Leases, 2025	17.8
Finance Leases, Later years	75.5
Finance Leases, Total lease payments	194.7
Less: Finance Leases, Imputed interest	(39.6)
Finance Leases, Total lease liabilities	155.1
2021	83.3
2022	69.8
2023	60.2
2024	47.7
2025	37.5
Later years	194.1
Total lease payments	492.6
Less: Imputed interest	(87.0)
Total lease liabilities	$ 405.6