QUARTERLY FINANCIAL DATA (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	May. 31, 2015		Feb. 22, 2015		Nov. 23, 2014		Aug. 24, 2014		May. 25, 2014		Feb. 23, 2014		Nov. 24, 2013		Aug. 25, 2013		May. 31, 2015	May. 25, 2014	May. 26, 2013
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 4,104.7		$ 3,876.7		$ 4,150.0		$ 3,701.0		$ 3,959.4		$ 3,947.3		$ 4,221.1		$ 3,715.8		$ 15,832.4	$ 15,843.6	$ 13,469.3
Gross profit	912.7		820.0		880.1		695.7		843.5		916.5		959.8		792.1
Income from discontinued operations, net of tax	4.6		(0.6)		(10.7)		373.3		74.8		10.8		42.0		13.8		366.6	141.4	87.7
Net income (loss) attributable to ConAgra Foods, Inc.	$ 209.2		$ (954.1)		$ 10.0		$ 482.3		$ (324.2)		$ 234.3		$ 248.7		$ 144.3		$ (252.6)	$ 303.1	$ 773.9
Basic earnings per share:
Net income (loss) attributable to ConAgra Foods, Inc. common stockholders (in dollars per share)	$ 0.49	[1]	$ (2.23)	[1]	$ 0.02	[1]	$ 1.14	[1]	$ (0.77)	[1]	$ 0.56	[1]	$ 0.59	[1]	$ 0.34	[1]	$ (0.60)	$ 0.72	$ 1.88
Diluted earnings per share:
Net income (loss) attributable to ConAgra Foods, Inc. common stockholders (in dollars per share)	0.48	[1]	(2.23)	[1]	0.02	[1]	1.12	[1]	(0.77)	[1]	0.55	[1]	0.58	[1]	0.34	[1]	(0.60)	0.70	1.85
Dividends declared per common share (in dollars per share)	0.25	[1]	0.25	[1]	0.25	[1]	0.25	[1]	0.25	[1]	0.25	[1]	0.25	[1]	0.25	[1]	$ 1.00	$ 1.00	$ 0.99
Share price:
High (in dollars per share)	38.90		37.29		35.65		32.85		31.61		34.05		34.51		37.23
Low (in dollars per share)	$ 33.58		$ 33.57		$ 31.87		$ 28.73		$ 28.26		$ 28.50		$ 30.09		$ 32.83

[1] Basic and diluted earnings per share are calculated independently for each of the quarters presented. Accordingly, the sum of the quarterly earnings per share amounts may not agree with the total year.