STOCKHOLDERS' EQUITY (Reconciliation of Stockholders' Equity Accounts) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Aug. 30, 2015	Aug. 24, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 4,610.0
Stock option and incentive plans	129.9
Currency translation adjustment	(37.6)
Activities of noncontrolling interests	(0.2)
Pension and postretirement healthcare benefits	4.2
Dividends declared on common stock; $0.25 per share	(107.8)
Net loss attributable to ConAgra Foods, Inc.	(1,154.1)	$ 482.3
Balance at ending of period	3,444.4
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 2,839.7
Balance at beginning of period, Shares (in shares)	567.9
Balance at ending of period	$ 2,839.7
Balance at end of period, Shares (in shares)	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	23.7
Activities of noncontrolling interests	(0.4)
Balance at ending of period	1,072.7
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	4,331.1
Stock option and incentive plans	(0.2)
Dividends declared on common stock; $0.25 per share	(107.8)
Net loss attributable to ConAgra Foods, Inc.	(1,154.1)
Balance at ending of period	3,069.0
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(329.5)
Currency translation adjustment	(34.5)
Pension and postretirement healthcare benefits	4.2
Balance at ending of period	(359.8)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(3,364.7)
Stock option and incentive plans	106.4
Balance at ending of period	(3,258.3)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	84.0
Currency translation adjustment	(3.1)
Activities of noncontrolling interests	0.2
Balance at ending of period	$ 81.1