Consolidated Statements of Common Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Noncontrolling Interests
Beginning balance at May. 28, 2017	$ 4,077.8	$ 2,839.7	$ 1,171.9	$ 4,247.0	$ (212.9)	$ (4,054.9)	$ 87.0
Beginning balance (in shares) at May. 28, 2017		567.9
Increase (Decrease) in Stockholders' Equity
Stock option and incentive plans	53.7		10.0	(0.8)		44.3	0.2
Spinoff of Lamb Weston	14.8			14.8
Adoption of ASU | ASU 2018-02				17.4	(17.4)
Currency translation adjustments	0.7				4.6		(3.9)
Repurchase of common shares	(967.3)					(967.3)
Unrealized gain on available-for-sale securities	0.8				0.8
Derivative adjustments	2.1				2.1
Activities of noncontrolling interests	(5.5)		(1.9)		(0.7)		(2.9)
Pension and postretirement healthcare benefits	113.0				113.0
Dividends declared on common stock	(341.9)			(341.9)
Net income attributable to Conagra Brands, Inc.	808.4			808.4
Ending balance at May. 27, 2018	3,756.6	$ 2,839.7	1,180.0	4,744.9	(110.5)	(4,977.9)	80.4
Ending 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
Adoption of ASU | ASU 2016-01				0.6	(0.6)
Adoption of ASU | ASU 2014-09	0.5			0.5
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
Unrealized gain on available-for-sale securities	0.0
Unrealized gain on available-for-sale securities | ASU 2016-01				0.6	(0.6)
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)
Unrealized gain on available-for-sale securities	0.0
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 (in shares) at May. 31, 2020		584.2