QUARTERLY FINANCIAL DATA (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	May 27, 2018	Feb. 25, 2018	Nov. 26, 2017	Aug. 27, 2017	May 28, 2017	Feb. 26, 2017	Nov. 27, 2016	Aug. 28, 2016	May 27, 2018	May 28, 2017	May 29, 2016
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 1,966.2	$ 1,994.5	$ 2,173.4	$ 1,804.2	$ 1,861.7	$ 1,981.2	$ 2,088.4	$ 1,895.6	$ 7,938.3	$ 7,826.9	$ 8,664.1
Gross profit	575.4	598.8	658.3	519.0	529.0	621.0	647.5	544.6
Income from continuing operations, net of tax	70.6	349.2	224.1	153.6	153.6	179.5	114.3	98.6	797.5	546.0	128.5
Income (loss) from discontinued operations, net of tax	(0.3)	14.5	0.4	(0.3)	(1.7)	0.7	11.6	91.4	14.3	102.0	(794.4)
Net income attributable to Conagra Brands, Inc.	$ 69.6	$ 362.8	$ 223.5	$ 152.5	$ 151.3	$ 179.7	$ 122.1	$ 186.2	$ 808.4	$ 639.3	$ (677.0)
Basic earnings per share:
Net income attributable to Conagra Brands, Inc. common stockholders	$ 0.18	$ 0.91	$ 0.55	$ 0.37	$ 0.36	$ 0.42	$ 0.28	$ 0.42	$ 2.00	$ 1.48	$ (1.57)
Diluted earnings per share:
Net income attributable to Conagra Brands, Inc. common stockholders	0.18	0.90	0.54	0.36	0.36	0.41	0.28	0.42	1.98	1.46	(1.56)
Dividends declared per common share (in dollars per share)	0.2125	0.2125	0.2125	0.2125	0.20	0.2	0.25	0.25	0.85	0.90	$ 1.00
Class of Stock [Line Items]
Share price (in dollars per share)	37.41								37.41
High
Class of Stock [Line Items]
Share price (in dollars per share)	38.29	38.50	35.87	39.95	41.50	41.16	48.68	48.39	38.29	41.50
Low
Class of Stock [Line Items]
Share price (in dollars per share)	$ 35.34	$ 35.47	$ 32.43	$ 33.07	$ 37.29	$ 36.47	$ 34.30	$ 45.70	$ 35.34	$ 37.29