SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of Reclassifications From Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 26, 2017	Nov. 27, 2016	Nov. 26, 2017	Nov. 27, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense, net	$ (38.0)	$ (54.1)	$ (74.4)	$ (112.3)
Selling, general and administrative expenses	307.3	417.9	546.3	649.6
Income from continuing operations before income taxes and equity method investment earnings	313.0	175.5	556.6	430.2
Income tax expense	(109.5)	(78.4)	(229.5)	(247.6)
Net income attributable to Conagra Brands, Inc.	223.5	122.1	376.0	308.3
Reclassification out of accumulated other comprehensive loss | Derivative adjustments, net of reclassification adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest expense, net	0.1	0.0	0.1	0.0
Income from continuing operations before income taxes and equity method investment earnings	0.1	0.0	0.1	0.0
Income tax expense	0.0	0.0	0.0	0.0
Net income attributable to Conagra Brands, Inc.	0.1	0.0	0.1	0.0
Reclassification out of accumulated other comprehensive loss | Net prior service benefit
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Selling, general and administrative expenses	(0.2)	(0.9)	(0.3)	(1.8)
Income from continuing operations before income taxes and equity method investment earnings	(0.2)	(0.9)	(0.3)	(1.8)
Income tax expense	0.1	0.4	0.1	0.7
Net income attributable to Conagra Brands, Inc.	$ (0.1)	$ (0.5)	$ (0.2)	$ (1.1)