STOCKHOLDERS' EQUITY (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Feb. 22, 2015	Feb. 23, 2014	Feb. 22, 2015	Feb. 23, 2014	May 25, 2014
Schedule Of Stockholders Equity [Line Items]
Balance at			$ 5,355.2
Stock option and incentive plans			142.6
Currency translation adjustment			(135.6)
Repurchase of common shares			(38.4)
Unrealized gain on securities			0.4
Derivative adjustment, net of reclassification adjustment			(0.3)
Activities of noncontrolling interests			(6.6)
Pension and postretirement healthcare benefits			2.5
Dividends declared on common stock; $0.75 per share			(319.4)
Net loss attributable to ConAgra Foods, Inc.	(954.1)	234.3	(461.8)	627.3
Balance at	4,538.6		4,538.6
Common Stock
Schedule Of Stockholders Equity [Line Items]
Balance at					2,839.7
Balance at , Shares					567.9
Balance at	2,839.7		2,839.7		2,839.7
Balance at , Shares	567.9		567.9		567.9
Additional Paid-in Capital
Schedule Of Stockholders Equity [Line Items]
Balance at			1,036.9
Stock option and incentive plans			(1.1)
Activities of noncontrolling interests			(1.3)
Balance at	1,034.5		1,034.5
Retained Earnings
Schedule Of Stockholders Equity [Line Items]
Balance at			5,010.6
Stock option and incentive plans			(0.2)
Dividends declared on common stock; $0.75 per share			(319.4)
Net loss attributable to ConAgra Foods, Inc.			(461.8)
Balance at	4,229.2		4,229.2
Accumulated Other Comprehensive Income (Loss)
Schedule Of Stockholders Equity [Line Items]
Balance at			(134.3)
Currency translation adjustment			(129.9)
Unrealized gain on securities			0.4
Derivative adjustment, net of reclassification adjustment			(0.3)
Pension and postretirement healthcare benefits			2.5
Balance at	(261.6)		(261.6)
Treasury Stock
Schedule Of Stockholders Equity [Line Items]
Balance at			(3,494.4)
Stock option and incentive plans			143.9
Repurchase of common shares			(38.4)
Balance at	(3,388.9)		(3,388.9)
Noncontrolling Interests
Schedule Of Stockholders Equity [Line Items]
Balance at			96.7
Currency translation adjustment			(5.7)
Activities of noncontrolling interests			(5.3)
Balance at	$ 85.7		$ 85.7