Consolidated Statements of Common Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interests
Balance at (in shares) at May. 27, 2012		567.9
Balance at at May. 27, 2012	$ 4,536.0	$ 2,839.7	$ 901.5	$ 4,765.1	$ (299.1)	$ (3,767.7)	$ 96.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option and incentive plans	332.7		56.2	(2.2)		278.7
Currency translation adjustment	2.1				2.8		(0.7)
Issuance of treasury shares	269.2		50.1			219.1
Repurchase of common shares	(245.0)					(245.0)
Unrealized gain on securities	0.2				0.2
Derivative adjustment, net of reclassification adjustment	32.8				32.8
Activities of noncontrolling interests	1.2		(1.6)				2.8
Pension and postretirement healthcare benefits	67.2				67.2
Dividends declared on common stock	(407.3)			(407.3)
Net income (loss) attributable to ConAgra Foods, Inc.	773.9			773.9
Balance at (in shares) at May. 26, 2013		567.9
Balance at at May. 26, 2013	5,363.0	$ 2,839.7	1,006.2	5,129.5	(196.1)	(3,514.9)	98.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option and incentive plans	152.1		32.4	(0.8)		120.5
Currency translation adjustment	(25.7)				(21.7)		(4.0)
Repurchase of common shares	(100.0)					(100.0)
Unrealized gain on securities	0.1				0.1
Derivative adjustment, net of reclassification adjustment	65.7				65.7
Activities of noncontrolling interests	0.4		(1.7)				2.1
Pension and postretirement healthcare benefits	17.7				17.7
Dividends declared on common stock	(421.2)			(421.2)
Net income (loss) attributable to ConAgra Foods, Inc.	303.1			303.1
Balance at (in shares) at May. 25, 2014		567.9
Balance at at May. 25, 2014	5,355.2	$ 2,839.7	1,036.9	5,010.6	(134.3)	(3,494.4)	96.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option and incentive plans	193.5		14.2	(0.4)		179.7
Currency translation adjustment	(145.2)				(137.6)		(7.6)
Repurchase of common shares	(50.0)					(50.0)
Unrealized gain on securities	0.4				0.4
Derivative adjustment, net of reclassification adjustment	(0.3)				(0.3)
Activities of noncontrolling interests	(6.8)		(1.7)				(5.1)
Pension and postretirement healthcare benefits	(57.7)				(57.7)
Dividends declared on common stock	(426.5)			(426.5)
Net income (loss) attributable to ConAgra Foods, Inc.	(252.6)			(252.6)
Balance at (in shares) at May. 31, 2015		567.9
Balance at at May. 31, 2015	$ 4,610.0	$ 2,839.7	$ 1,049.4	$ 4,331.1	$ (329.5)	$ (3,364.7)	$ 84.0