STOCKHOLDERS' EQUITY - Reconciliation of Stockholders' Equity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Aug. 28, 2016	Aug. 30, 2015
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	$ 3,794.8
Stock option and incentive plans	45.6
Adoption of ASU 2016-09	(3.9)
Currency translation adjustment, net	(11.7)
Repurchase of common shares	(93.9)
Unrealized gain on securities	0.1	$ 0.0
Derivative adjustment, net	(4.9)
Activities of noncontrolling interests	(0.3)
Pension and postretirement healthcare benefits	(2.6)
Dividends declared on common stock; $0.25 per share	(109.8)
Net income attributable to ConAgra Foods, Inc.	186.2	$ (1,154.1)
Balance at ending of period	$ 3,799.6
Common Stock
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period (in shares)	567.9
Balance at beginning of period	$ 2,839.7
Balance at end of period (in shares)	567.9
Balance at ending of period	$ 2,839.7
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	1,136.3
Stock option and incentive plans	8.5
Activities of noncontrolling interests	(0.5)
Balance at ending of period	1,144.3
Retained Earnings
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	3,218.3
Stock option and incentive plans	(0.1)
Adoption of ASU 2016-09	(3.9)
Dividends declared on common stock; $0.25 per share	(109.8)
Net income attributable to ConAgra Foods, Inc.	186.2
Balance at ending of period	3,290.7
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	(344.5)
Currency translation adjustment, net	(11.6)
Unrealized gain on securities	0.1
Derivative adjustment, net	(4.9)
Pension and postretirement healthcare benefits	(2.6)
Balance at ending of period	(363.5)
Treasury Stock
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	(3,136.2)
Stock option and incentive plans	37.2
Repurchase of common shares	(93.9)
Balance at ending of period	(3,192.9)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Balance at beginning of period	81.2
Currency translation adjustment, net	(0.1)
Activities of noncontrolling interests	0.2
Balance at ending of period	$ 81.3