BUSINESS SEGMENTS AND RELATED INFORMATION (Details) - USD ($) $ 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
Segment Reporting Information [Line Items]
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
Operating profit (loss)									181.5	1,056.3	1,695.3
Equity method investment earnings									122.1	32.5	37.5
Operating profit (loss) plus equity method investment earnings									303.6	1,088.8	1,732.8
General corporate expenses									345.1	315.6	396.3
Interest expense, net									331.9	379.4	276.2
Income tax expense									234.0	220.1	361.9
Income (loss) from continuing operations									(607.4)	173.7	698.4
Less: Net income attributable to noncontrolling interests									11.8	12.0	12.2
Income (loss) from continuing operations attributable to ConAgra Foods, Inc.									(619.2)	161.7	686.2
Identifiable assets	17,542.2				19,319.5				17,542.2	19,319.5	20,349.8
Held for Sale	0.0				830.6				0.0	830.6	898.7
Additions to property, plant and equipment									471.9	592.3	422.6
Depreciation and amortization									592.3	577.3	418.6
Consumer Foods
Segment Reporting Information [Line Items]
Net sales									7,304.4	7,315.7	7,551.4
Operating profit (loss)									1,069.7	892.0	984.4
Equity method investment earnings									3.0	2.8	1.8
Operating profit (loss) plus equity method investment earnings									1,072.7	894.8	986.2
Identifiable assets	7,568.5				7,666.1				7,568.5	7,666.1	7,845.5
Additions to property, plant and equipment									133.7	183.5	187.9
Depreciation and amortization									200.9	182.2	183.1
Commercial Foods
Segment Reporting Information [Line Items]
Net sales									4,463.2	4,332.2	4,109.7
Operating profit (loss)									568.5	537.7	585.5
Equity method investment earnings									119.1	29.7	35.7
Operating profit (loss) plus equity method investment earnings									687.6	567.4	621.2
Identifiable assets	3,991.1				3,127.4				3,991.1	3,127.4	2,972.4
Additions to property, plant and equipment									117.8	206.4	117.7
Depreciation and amortization									113.5	100.1	84.4
Private Brands
Segment Reporting Information [Line Items]
Net sales									4,064.8	4,195.7	1,808.2
Operating profit (loss)									(1,456.7)	(373.4)	125.4
Operating profit (loss) plus equity method investment earnings									(1,456.7)	(373.4)	125.4
Identifiable assets	5,144.7				6,912.4				5,144.7	6,912.4	7,676.5
Additions to property, plant and equipment									101.6	125.2	57.0
Depreciation and amortization									202.1	214.8	79.9
Corporate
Segment Reporting Information [Line Items]
Identifiable assets	$ 837.9				$ 783.0				837.9	783.0	956.7
Additions to property, plant and equipment									118.8	77.2	60.0
Depreciation and amortization									$ 75.8	$ 80.2	$ 71.2