STOCKHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Nov. 26, 2017	Nov. 27, 2016	Nov. 26, 2017	Nov. 27, 2016
Conagra Brands, Inc. Stockholders' Equity
Balance at beginning of period			$ 4,077.8
Stock option and incentive plans			22.1
Spinoff of Lamb Weston			15.5
Currency translation adjustment, net			19.9
Repurchase of common shares			(580.0)
Unrealized gain on securities	$ 0.2	$ 0.2	0.4	$ 0.3
Derivative adjustment, net			0.7
Activities of noncontrolling interests			1.8
Pension and postretirement healthcare benefits			26.7
Dividends declared on common stock; $0.425 per share			$ (174.4)
Dividends declared on common stock (in dollars per share)			$ 0.425
Net income attributable to Conagra Brands, Inc.	223.5	$ 122.1	$ 376.0	$ 308.3
Balance at ending of period	$ 3,786.5		$ 3,786.5
Common Stock
Conagra Brands, Inc. 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		567.9
Balance at ending of period	$ 2,839.7		$ 2,839.7
Additional Paid-in Capital
Conagra Brands, Inc. Stockholders' Equity
Balance at beginning of period			1,171.9
Stock option and incentive plans			(5.1)
Balance at ending of period	1,166.8		1,166.8
Retained Earnings
Conagra Brands, Inc. Stockholders' Equity
Balance at beginning of period			4,247.0
Stock option and incentive plans			0.2
Spinoff of Lamb Weston			15.5
Dividends declared on common stock; $0.425 per share			(174.4)
Balance at ending of period	4,464.3		4,464.3
Accumulated Other Comprehensive Income (Loss)
Conagra Brands, Inc. Stockholders' Equity
Balance at beginning of period			(212.9)
Currency translation adjustment, net			19.9
Unrealized gain on securities			0.4
Derivative adjustment, net			0.7
Balance at ending of period	(165.2)		(165.2)
Treasury Stock
Conagra Brands, Inc. Stockholders' Equity
Balance at beginning of period			(4,054.9)
Stock option and incentive plans			27.0
Repurchase of common shares			(580.0)
Balance at ending of period	(4,607.9)		(4,607.9)
Noncontrolling Interests
Conagra Brands, Inc. Stockholders' Equity
Balance at beginning of period			87.0
Activities of noncontrolling interests			1.8
Balance at ending of period	$ 88.8		$ 88.8