QUARTERLY FINANCIAL DATA (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 1,861.7	$ 1,981.2	$ 2,088.4	$ 1,895.6	$ 2,053.0	$ 2,199.3	$ 2,358.8	$ 2,053.0	$ 7,826.9	$ 8,664.1	$ 9,034.0
Gross profit	529.0	621.0	647.5	544.6	580.1	619.8	668.0	561.3
Income (loss) from continuing operations, net of tax	153.6	179.5	114.3	98.6	(116.6)	71.4	80.1	93.6	546.0	128.5	451.3
Income (loss) from discontinued operations, net of tax	(1.7)	0.7	11.6	91.4	237.5	134.9	79.2	(1,246.0)	102.0	(794.4)	(692.1)
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)
Basic earnings per share:
Net income (loss) attributable to Conagra Brands, Inc. common stockholders	$ 0.36	$ 0.42	$ 0.28	$ 0.42	$ 0.27	$ 0.46	$ 0.36	$ (2.68)	$ 1.48	$ (1.57)	$ (0.60)
Diluted earnings per share:
Net income (loss) attributable to Conagra Brands, Inc. common stockholders	0.36	0.41	0.28	0.42	0.27	0.46	0.35	(2.65)	1.46	(1.56)	(0.59)
Dividends declared per common share (in dollars per share)	0.20	0.2	0.25	0.25	0.25	0.25	0.25	0.25	0.90	1.00	$ 1.00
Class of Stock [Line Items]
High (in dollars per share)	39.03								39.03
High
Class of Stock [Line Items]
High (in dollars per share)	41.50	41.16	48.68	48.39	46.43	42.7	42.75	45.49	41.50	46.43
Low
Class of Stock [Line Items]
High (in dollars per share)	$ 37.29	$ 36.47	$ 34.30	$ 45.70	$ 42.06	$ 38.7	$ 38.84	$ 37.42	$ 37.29	$ 42.06