EARNINGS (LOSS) PER SHARE - Reconciliation of Income and Average Share Amounts Used to Compute Both Basic and Diluted Earnings (Loss) Per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	May 28, 2017	Feb. 26, 2017	Nov. 27, 2016	Aug. 28, 2016	May 29, 2016	Feb. 28, 2016	Nov. 29, 2015	Aug. 30, 2015	May 28, 2017	May 29, 2016	May 31, 2015
Net income (loss) available to Conagra Brands, Inc. common stockholders:
Income from continuing operations attributable to Conagra Brands, Inc. common stockholders									$ 544.1	$ 126.6	$ 448.8
Income (loss) from discontinued operations, net of tax, attributable to Conagra Brands, Inc. common stockholders									95.2	(803.6)	(701.4)
Net income (loss) attributable to Conagra Brands, Inc.	$ 151.3	$ 179.7	$ 122.1	$ 186.2	$ 117.6	$ 204.6	$ 154.9	$ (1,154.1)	639.3	(677.0)	(252.6)
Less: Increase in redemption value of noncontrolling interests in excess of earnings allocated									0.8	4.8	1.7
Net income (loss) available to Conagra Brands, Inc. common stockholders									$ 638.5	$ (681.8)	$ (254.3)
Weighted average shares outstanding:
Basic weighted average shares outstanding (in shares)									431.9	434.4	426.1
Add: Dilutive effect of stock options, restricted stock unit awards, and other dilutive securities (in shares)									4.1	4.1	5.2
Diluted weighted average shares outstanding (in shares)									436.0	438.5	431.3