QUARTERLY FINANCIAL DATA (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2020	Feb. 23, 2020	Nov. 24, 2019	Aug. 25, 2019	May 26, 2019	Feb. 24, 2019	Nov. 25, 2018	Aug. 26, 2018	May 31, 2020	May 26, 2019	May 27, 2018
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 3,287.9	$ 2,555.0	$ 2,820.8	$ 2,390.7	$ 2,613.2	$ 2,707.1	$ 2,383.7	$ 1,834.4	$ 11,054.4	$ 9,538.4	$ 7,938.3
Gross profit	922.8	684.4	797.9	664.5	708.0	752.3	677.2	515.5
Income from continuing operations, net of tax	201.3	204.7	261.5	174.3	125.2	242.6	134.3	178.2	841.8	680.3	797.5
Income (loss) from discontinued operations, net of tax	0.0	0.0	0.0	0.0	0.0	0.0	(1.9)	0.0	0.0	(1.9)	14.3
Net income attributable to Conagra Brands, Inc.	$ 201.4	$ 204.4	$ 260.5	$ 173.8	$ 126.5	$ 242.0	$ 131.6	$ 178.2	$ 840.1	$ 678.3	$ 808.4
Basic earnings per share:
Net income attributable to Conagra Brands, Inc. common stockholders	$ 0.41	$ 0.42	$ 0.53	$ 0.36	$ 0.26	$ 0.50	$ 0.31	$ 0.45	$ 1.72	$ 1.53	$ 2.00
Diluted earnings per share:
Net income attributable to Conagra Brands, Inc. common stockholders	0.41	0.42	0.53	0.36	0.26	0.50	0.31	0.45	1.72	1.52	1.98
Dividends declared on common stock (in dollars per share)	$ 0.2125	$ 0.2125	$ 0.2125	$ 0.2125	$ 0.2125	$ 0.2125	$ 0.2125	$ 0.2125	$ 0.85	$ 0.85	$ 0.85