Summary of Significant Accounting Policies (Details 1) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	May 27, 2012	Feb. 26, 2012	Nov. 27, 2011	Aug. 28, 2011	May 29, 2011	Feb. 27, 2011	Nov. 28, 2010	Aug. 29, 2010	May 27, 2012	May 29, 2011	May 30, 2010	May 31, 2009
Impacts of adjustments made to Consolidated Statement of Operations
Selling, general and administrative expenses									$ 1,997.7	$ 1,509.9	$ 1,987.7
Cost of goods sold									10,435.7	9,389.6	8,966.3
Income tax expense									195.8	421.6	292.3
Income from continuing operations									474.3	830.9	630.3
Net income									474.4	819.4	611.0
Net income (loss) attributable to ConAgra Foods, Inc.	(86.2)	280.1	180.2	93.8	250.1	216.6	202.7	148.2	467.9	817.6	613.5
Income from continuing operations attributable to ConAgra Foods, Inc. common stockholders	$ (0.21)	$ 0.68	$ 0.43	$ 0.23	$ 0.62	$ 0.54	$ 0.46	$ 0.32	$ 1.13	$ 1.92	$ 1.43
Earnings per share attributable to ConAgra Foods-basic	$ (0.21)	$ 0.68	$ 0.43	$ 0.23	$ 0.61	$ 0.51	$ 0.46	$ 0.33	$ 1.13	$ 1.90	$ 1.38
Income from continuing operations attributable to ConAgra Foods, Inc. common stockholders	$ (0.21)	$ 0.67	$ 0.43	$ 0.22	$ 0.61	$ 0.52	$ 0.46	$ 0.32	$ 1.12	$ 1.90	$ 1.41
Earnings per share attributable to ConAgra Foods-diluted	$ (0.21)	$ 0.67	$ 0.43	$ 0.22	$ 0.60	$ 0.50	$ 0.46	$ 0.33	$ 1.12	$ 1.88	$ 1.37
Impacts of adjustments made to Consolidated Balance Sheet
Retained earnings	4,765.1				4,690.3				4,765.1	4,690.3
Accumulated other comprehensive loss	(299.1)				(91.2)				(299.1)	(91.2)	(153.2)	(83.9)
Cash flows from operating activities:
Net income									474.4	819.4	611.0
Income from continuing operations									474.3	830.9	630.3
Pension expense									421.8	54.0	227.4
Other items									(11.3)	212.9	(25.4)
Net cash flows from operating activities									1,052.0	1,352.3	1,472.7
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Beginning balance				4,676.7					4,676.7	4,897.1	4,689.1
Net income	(86.2)	280.1	180.2	93.8	250.1	216.6	202.7	148.2	467.9	817.6	613.5
Pension and postretirement healthcare liabilities, net of tax									(66.7)	23.6	(65.8)
Ending Balance	4,536.0				4,676.7				4,536.0	4,676.7	4,897.1
Impacts of adjustments made to Consolidated Statement of Comprehensive Income
Net income									474.4	819.4	611.0
Pension and postretirement healthcare liabilities, net of tax									(66.7)	23.6	(65.8)
Retained Earnings
Impacts of adjustments made to Consolidated Statement of Operations
Net income (loss) attributable to ConAgra Foods, Inc.									467.9	817.6	613.5
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Beginning balance				4,690.3					4,690.3	4,253.2	3,990.9
Net income									467.9	817.6	613.5
Ending Balance	4,765.1				4,690.3				4,765.1	4,690.3	4,253.2
Accumulated Other Comprehensive Income (Loss)
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Beginning balance				(91.2)					(91.2)	(153.2)	(83.9)
Pension and postretirement healthcare liabilities, net of tax									(66.7)	23.6	(65.8)
Ending Balance	(299.1)				(91.2)				(299.1)	(91.2)	(153.2)
Impacts of adjustments made to Consolidated Statement of Comprehensive Income
Pension and postretirement healthcare liabilities, net of tax									(66.7)	23.6	(65.8)
Previously reported [Member]
Impacts of adjustments made to Consolidated Statement of Operations
Selling, general and administrative expenses										1,511.1	1,819.4
Cost of goods sold										9,389.6	8,953.7
Income tax expense										421.0	360.9
Income from continuing operations										830.3	742.6
Net income										818.8	723.3
Net income (loss) attributable to ConAgra Foods, Inc.										817.0	725.8
Income from continuing operations attributable to ConAgra Foods, Inc. common stockholders										$ 1.92	$ 1.68
Earnings per share attributable to ConAgra Foods-basic										$ 1.90	$ 1.63
Income from continuing operations attributable to ConAgra Foods, Inc. common stockholders										$ 1.90	$ 1.66
Earnings per share attributable to ConAgra Foods-diluted										$ 1.88	$ 1.62
Impacts of adjustments made to Consolidated Balance Sheet
Retained earnings					4,821.8					4,821.8
Accumulated other comprehensive loss					(222.7)					(222.7)
Cash flows from operating activities:
Net income										818.8	723.3
Income from continuing operations										830.3	742.6
Other items										267.5	89.7
Net cash flows from operating activities										1,352.3	1,472.7
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Net income										817.0	725.8
Pension and postretirement healthcare liabilities, net of tax										24.2	(178.1)
Impacts of adjustments made to Consolidated Statement of Comprehensive Income
Net income										818.8	723.3
Pension and postretirement healthcare liabilities, net of tax										24.2	(178.1)
Previously reported [Member] | Retained Earnings
Impacts of adjustments made to Consolidated Statement of Operations
Net income (loss) attributable to ConAgra Foods, Inc.										817.0	725.8
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Beginning balance										4,385.3	4,010.7
Net income										817.0	725.8
Ending Balance					4,821.8					4,821.8	4,385.3
Previously reported [Member] | Accumulated Other Comprehensive Income (Loss)
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Beginning balance										(285.3)	(103.7)
Pension and postretirement healthcare liabilities, net of tax										24.2	(178.1)
Ending Balance					(222.7)					(222.7)	(285.3)
Impacts of adjustments made to Consolidated Statement of Comprehensive Income
Pension and postretirement healthcare liabilities, net of tax										24.2	(178.1)
Effect of Change [Member]
Impacts of adjustments made to Consolidated Statement of Operations
Selling, general and administrative expenses										(1.2)	168.3
Cost of goods sold											12.6
Income tax expense										0.6	(68.6)
Income from continuing operations										0.6	(112.3)
Net income										0.6	(112.3)
Net income (loss) attributable to ConAgra Foods, Inc.										0.6	(112.3)
Income from continuing operations attributable to ConAgra Foods, Inc. common stockholders											$ (0.25)
Earnings per share attributable to ConAgra Foods-basic											$ (0.25)
Income from continuing operations attributable to ConAgra Foods, Inc. common stockholders											$ (0.25)
Earnings per share attributable to ConAgra Foods-diluted											$ (0.25)
Impacts of adjustments made to Consolidated Balance Sheet
Retained earnings					(131.5)					(131.5)
Accumulated other comprehensive loss					131.5					131.5
Cash flows from operating activities:
Net income										0.6	(112.3)
Income from continuing operations										0.6	(112.3)
Pension expense										54.0	227.4
Other items										(54.6)	(115.1)
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Net income										0.6	(112.3)
Pension and postretirement healthcare liabilities, net of tax										(0.6)	112.3
Impacts of adjustments made to Consolidated Statement of Comprehensive Income
Net income										0.6	(112.3)
Pension and postretirement healthcare liabilities, net of tax										(0.6)	112.3
Effect of Change [Member] | Retained Earnings
Impacts of adjustments made to Consolidated Statement of Operations
Net income (loss) attributable to ConAgra Foods, Inc.										0.6	(112.3)
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Beginning balance										(132.1)	(19.8)
Net income										0.6	(112.3)
Ending Balance					(131.5)					(131.5)	(132.1)
Effect of Change [Member] | Accumulated Other Comprehensive Income (Loss)
Impacts of adjustments made to Consolidated Statement of Stockholders' Equity
Beginning balance										132.1	19.8
Pension and postretirement healthcare liabilities, net of tax										(0.6)	112.3
Ending Balance					131.5					131.5	132.1
Impacts of adjustments made to Consolidated Statement of Comprehensive Income
Pension and postretirement healthcare liabilities, net of tax										$ (0.6)	$ 112.3