EARNINGS PER SHARE - Reconciliation of Income and Average Share Amounts Used to Compute Basic and Diluted Earnings (Loss) Per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Aug. 27, 2017	Aug. 28, 2016
Net income available to Conagra Brands, Inc. common stockholders:
Income from continuing operations attributable to Conagra Brands, Inc. common stockholders	$ 152.8	$ 98.4
Income (loss) from discontinued operations, net of tax, attributable to Conagra Brands, Inc. common stockholders	(0.3)	87.8
Net income attributable to Conagra Brands, Inc.	152.5	186.2
Less: Increase in redemption value of noncontrolling interests in excess of earnings allocated	0.0	0.5
Net income available to Conagra Brands, Inc. common stockholders	$ 152.5	$ 185.7
Weighted average shares outstanding:
Basic weighted average shares outstanding (in shares)	415.1	439.0
Add: Dilutive effect of stock options, restricted stock unit awards, and other dilutive securities (in shares)	4.1	3.7
Diluted weighted average shares outstanding (in shares)	419.2	442.7