BUSINESS SEGMENTS AND RELATED INFORMATION - Narrative (Details) $ in Millions	3 Months Ended								12 Months Ended
	May 28, 2017 USD ($) employee	Feb. 26, 2017 USD ($)	Nov. 27, 2016 USD ($)	Aug. 28, 2016 USD ($)	May 29, 2016 USD ($)	Feb. 28, 2016 USD ($)	Nov. 29, 2015 USD ($)	Aug. 30, 2015 USD ($)	May 28, 2017 USD ($) employee segment	May 29, 2016 USD ($)	May 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments | segment									5
Cumulative net derivative losses from economic hedges recognized in general corporate expenses	$ 3.0								$ 3.0
Net losses incurred during the fiscal year									3.3
Net gains incurred prior to fiscal 2017									0.3
Segment operating results losses expected to be reclassified in fiscal 2018									1.2
Segment operating results losses expected to be reclassified in fiscal 2019 and thereafter									1.8
Total depreciation expense									$ 234.4	$ 243.9	$ 258.3
Number of employees of ConAgra Brands and its subsidiaries | employee	12,600								12,600
Percentage of employees that are parties to collective bargaining agreements									47.00%
Percentage of employees that are parties to collective bargaining agreements scheduled to expire during fiscal 2018									6.00%
Net sales	$ 1,861.7	$ 1,981.2	$ 2,088.4	$ 1,895.6	$ 2,053.0	$ 2,199.3	$ 2,358.8	$ 2,053.0	$ 7,826.9	8,664.1	9,034.0
Payable to suppliers who utilize third-party service	$ 24.6								24.6
Grocery & Snacks
Segment Reporting Information [Line Items]
Derivative losses recognized											10.8
Net sales									3,208.8	3,377.1	3,509.9
Refrigerated & Frozen
Segment Reporting Information [Line Items]
Derivative losses recognized											6.3
Net sales									2,652.7	2,867.8	2,986.6
International
Segment Reporting Information [Line Items]
Derivative losses recognized											2.7
Net sales									816.0	846.6	942.7
Foodservice
Segment Reporting Information [Line Items]
Derivative gains recognized											0.9
Net sales									1,078.3	1,104.5	1,120.1
Outside of the United States
Segment Reporting Information [Line Items]
Net sales									$ 887.2	$ 937.9	$ 1,000.0
Customer Concentration Risk | Net sales | Wal-Mart Stores, Inc. and its affiliates
Segment Reporting Information [Line Items]
Percentage of consolidated net sales attributable to largest customer									24.00%	23.00%	20.00%
Customer Concentration Risk | Net receivables | Wal-Mart Stores, Inc. and its affiliates
Segment Reporting Information [Line Items]
Percentage of consolidated net sales attributable to largest customer									26.00%	25.00%