Consolidated Statements of Common Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Revision of Prior Period, Accounting Standards Update, Adjustment	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Revision of Prior Period, Accounting Standards Update, Adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Revision of Prior Period, Accounting Standards Update, Adjustment	Treasury Stock	Noncontrolling Interests
Beginning balance at May. 27, 2018	$ 3,756.6		$ 2,839.7	$ 1,180.0	$ 4,744.9		$ (110.5)		$ (4,977.9)	$ 80.4
Beginning balance (ASU 2016-01) at May. 27, 2018						$ 0.6		$ (0.6)
Beginning balance (ASU 2014-09) at May. 27, 2018		$ 0.5				0.5
Beginning balance (in shares) at May. 27, 2018			567.9
Increase (Decrease) in Stockholders' Equity
Stock option and incentive plans	33.1			(6.7)	0.1				39.6	0.1
Currency translation adjustments	0.2						2.1			(1.9)
Issuance of treasury shares	2,816.3			638.2					2,178.1
Issuance of common stock	555.7		$ 81.5	474.2
Issuance of common stock (in shares)			16.3
Derivative adjustments	32.7						32.7
Activities of noncontrolling interests	0.8			0.3						0.5
Pension and postretirement healthcare benefits	(34.0)						(34.0)
Dividends declared on common stock	(376.5)				(376.5)
Net income attributable to Conagra Brands, Inc.	678.3				678.3
Ending balance at May. 26, 2019	7,463.7		$ 2,921.2	2,286.0	5,047.9		(110.3)		(2,760.2)	79.1
Ending balance (in shares) at May. 26, 2019			584.2
Increase (Decrease) in Stockholders' Equity
Stock option and incentive plans	64.6			37.2	(2.9)				30.3
Currency translation adjustments	(41.3)						(34.8)			(6.5)
Derivative adjustments	(7.7)						(7.7)
Activities of noncontrolling interests	2.0									2.0
Pension and postretirement healthcare benefits	43.2						43.2
Dividends declared on common stock	(413.9)				(413.9)
Net income attributable to Conagra Brands, Inc.	840.1				840.1
Ending balance at May. 31, 2020	7,950.7		$ 2,921.2	2,323.2	5,471.2		(109.6)		(2,729.9)	74.6
Ending balance (ASU 2016-13) at May. 31, 2020		$ (1.1)				$ (1.1)
Ending balance (in shares) at May. 31, 2020			584.2
Increase (Decrease) in Stockholders' Equity
Stock option and incentive plans	64.1			18.9	(3.1)				48.1	0.2
Currency translation adjustments	51.8						48.6			3.2
Repurchase of common shares	(298.1)								(298.1)
Derivative adjustments	(2.0)						(2.0)
Activities of noncontrolling interests	1.6									1.6
Pension and postretirement healthcare benefits	68.8						68.8
Dividends declared on common stock	(503.2)				(503.2)
Net income attributable to Conagra Brands, Inc.	1,298.8				1,298.8
Ending balance at May. 30, 2021	$ 8,631.4		$ 2,921.2	$ 2,342.1	$ 6,262.6		$ 5.8		$ (2,979.9)	$ 79.6
Ending balance (in shares) at May. 30, 2021			584.2