Restructuring Initiatives (Schedule of restructuring charges) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Feb. 22, 2015	Feb. 23, 2014	Feb. 22, 2015	Feb. 23, 2014
Restructuring and Related Cost [Line Items]
Severance	$ (2.1)us-gaap_SeveranceCosts1		$ 177.0us-gaap_SeveranceCosts1
Asset write-offs	19.9us-gaap_AssetImpairmentCharges		53.2us-gaap_AssetImpairmentCharges
Pension related	22.2		37.8
Accelerated depreciation	21.6		34.2
Other	9.6us-gaap_OtherRestructuringCosts		16.2us-gaap_OtherRestructuringCosts
Total restructuring charges	71.2us-gaap_RestructuringCharges	0us-gaap_RestructuringCharges	318.4us-gaap_RestructuringCharges	3.5us-gaap_RestructuringCharges
Project Catalyst [Member]
Restructuring and Related Cost [Line Items]
Severance	(24.4)		120.6
Asset write-offs	11.1		11.1
Pension related	6.6		6.6
Accelerated depreciation	0		0
Other	8.0		8.0
Total restructuring charges	1.3		146.3
Project Century [Member]
Restructuring and Related Cost [Line Items]
Severance	22.3		44.0
Asset write-offs	8.8		41.4
Pension related	15.6		31.2
Accelerated depreciation	21.6		34.2
Other	1.6		8.0
Total restructuring charges	69.9		158.8
Combination of Certain Operational Facilities [Member]
Restructuring and Related Cost [Line Items]
Severance	0		13.0
Asset write-offs	0		0.7
Pension related	0		0
Accelerated depreciation	0		0
Other	0		0.2
Total restructuring charges	0		13.9
Charges Associated with Restructuring Actions Previously Announced [Member]
Restructuring and Related Cost [Line Items]
Severance	0		(0.6)
Asset write-offs	0		0
Pension related	0		0
Accelerated depreciation	0		0
Other	0		0
Total restructuring charges	$ 0		$ (0.6)

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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The amount of net gain (loss) recognized in net periodic benefit cost as a result of an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services.

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Amount of other expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses associated with a discontinued operation or an asset retirement obligation.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Amount of accelerated depreciation charged against earnings associated with exit from or disposal of business activities or restructuring plan.

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Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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