DISCONTINUED OPERATIONS AND OTHER DIVESTITURES - Summary of Comparative Financial Results, Income Statement Items (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 27, 2017	Aug. 28, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity method investment earnings	$ 30.0	$ 13.1
Income (loss) from discontinued operations, net of tax	(0.3)	91.4
Net income (loss) from discontinued operations attributable to Conagra Brands, Inc.	(0.3)	87.8
Lamb Weston | Discontinued operations, spinoff
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales	0.0	771.9
Income (loss) from discontinued operations before income taxes and equity method investment earnings	(0.3)	128.8
Income (loss) before income taxes and equity method investment earnings	(0.3)	128.8
Income tax expense (benefit)	(0.1)	49.5
Equity method investment earnings	0.0	10.6
Income (loss) from discontinued operations, net of tax	(0.2)	89.9
Less: Net income attributable to noncontrolling interests	0.0	3.6
Net income (loss) from discontinued operations attributable to Conagra Brands, Inc.	(0.2)	86.3
Private Brands | Discontinued operations, disposed of by sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net income (loss) from discontinued operations attributable to Conagra Brands, Inc.	$ (0.1)	$ 1.5