STOCKHOLDERS' EQUITY (Reconciliation of Stockholders' Equity Accounts) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2016	Feb. 22, 2015	Feb. 28, 2016	Feb. 22, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period			$ 4,610.0
Stock option and incentive plans			251.1
Currency translation adjustment, net			(0.6)
Derivative adjustment, net			(1.3)
Activities of noncontrolling interests			(3.2)
Pension and postretirement healthcare benefits			(3.8)
Dividends declared on common stock; $0.75 per share			(325.1)
Net loss attributable to ConAgra Foods, Inc.	$ 204.6	$ (954.1)	(794.6)	$ (461.8)
Balance at ending of period	3,732.5		3,732.5
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period			$ 2,839.7
Balance at beginning of period (in shares)			567.9
Balance at ending of period	$ 2,839.7		$ 2,839.7
Balance at end of period (in shares)	567.9		567.9
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period			$ 1,049.4
Stock option and incentive plans			62.6
Activities of noncontrolling interests			(4.4)
Balance at ending of period	$ 1,107.6		1,107.6
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period			4,331.1
Stock option and incentive plans			(0.7)
Dividends declared on common stock; $0.75 per share			(325.1)
Net loss attributable to ConAgra Foods, Inc.			(794.6)
Balance at ending of period	3,210.7		3,210.7
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period			(329.5)
Currency translation adjustment, net			5.6
Derivative adjustment, net			(1.3)
Pension and postretirement healthcare benefits			(3.8)
Balance at ending of period	(329.0)		(329.0)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period			(3,364.7)
Stock option and incentive plans			189.2
Balance at ending of period	(3,175.5)		(3,175.5)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period			84.0
Currency translation adjustment, net			(6.2)
Activities of noncontrolling interests			1.2
Balance at ending of period	$ 79.0		$ 79.0