Retirement Benefits and Postemployment Benefits (Schedule of level 3 investments of benefit plan assets) (Details) - USD ($) $ in Millions		12 Months Ended
		May 29, 2016		May 31, 2015
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		$ 5,758.5		$ 5,611.8
Fair value at end of year		5,539.9		5,758.5
Defined Benefit Pension Plans [Member] | Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year	[1]	3,187.6
Fair value at end of year	[1]	2,945.4		3,187.6
Defined Benefit Pension Plans [Member] | Real asset investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year	[2]	739.1
Fair value at end of year	[2]	749.4		739.1
Defined Benefit Pension Plans [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year	[3]	0.4
Fair value at end of year	[3]	0.4		0.4
Defined Benefit Pension Plans [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		1,041.4		1,171.4
Net Transfers Out		0.0		0.0
Net Purchases, Sales Issuances, and Settlements		(165.4)		(79.0)
Net Gain (Loss)		(22.6)		(51.0)
Fair value at end of year		853.4		1,041.4
Net change in level 3 assets attributable to unrealized gains (losses)		(108.2)
Defined Benefit Pension Plans [Member] | Level 3 [Member] | Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		542.9	[1]	568.2
Net Transfers Out		0.0		0.0
Net Purchases, Sales Issuances, and Settlements		(92.6)		(61.0)
Net Gain (Loss)		7.7		35.7
Fair value at end of year	[1]	458.0		542.9
Defined Benefit Pension Plans [Member] | Level 3 [Member] | Real asset investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		498.1	[2]	602.9
Net Transfers Out		0.0		0.0
Net Purchases, Sales Issuances, and Settlements		(72.8)		(18.2)
Net Gain (Loss)		(30.3)		(86.6)
Fair value at end of year	[2]	395.0		498.1
Defined Benefit Pension Plans [Member] | Level 3 [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		0.4	[3]	0.3
Net Transfers Out		0.0		0.0
Net Purchases, Sales Issuances, and Settlements		0.0		0.2
Net Gain (Loss)		0.0		(0.1)
Fair value at end of year	[3]	0.4		0.4
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		582.8		517.3
Fair value at end of year		602.4		582.8
Other Postretirement Benefit Plans [Member] | Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year	[1]	278.3
Fair value at end of year	[1]	276.4		278.3
Other Postretirement Benefit Plans [Member] | Real asset investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year	[2]	42.5
Fair value at end of year	[2]	44.4		42.5
Other Postretirement Benefit Plans [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year	[3]	168.9
Fair value at end of year	[3]	171.3		168.9
Other Postretirement Benefit Plans [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		40.3		39.0
Net Transfers Out		0.0		0.0
Net Purchases, Sales Issuances, and Settlements		(3.0)		0.8
Net Gain (Loss)		(0.1)		0.5
Fair value at end of year		37.2		40.3
Net change in level 3 assets attributable to unrealized gains (losses)		(3.2)
Other Postretirement Benefit Plans [Member] | Level 3 [Member] | Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		23.7	[1]	21.1
Net Transfers Out		0.0		0.0
Net Purchases, Sales Issuances, and Settlements		(1.2)		0.3
Net Gain (Loss)		0.9		2.3
Fair value at end of year	[1]	23.4		23.7
Other Postretirement Benefit Plans [Member] | Level 3 [Member] | Real asset investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year		16.6	[2]	17.9
Net Transfers Out		0.0		0.0
Net Purchases, Sales Issuances, and Settlements		(1.8)		0.5
Net Gain (Loss)		(1.0)		(1.8)
Fair value at end of year	[2]	13.8		16.6
Other Postretirement Benefit Plans [Member] | Level 3 [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value at beginning of year	[3]	0.0
Fair value at end of year	[3]	$ 0.0		$ 0.0

[1] Primarily publicly traded common stock and private equity partnerships for purposes of total return and to maintain equity exposure consistent with policy allocations. Investments include: United States and international equity securities, mutual funds, and equity futures valued at closing prices from national exchanges; and commingled funds, privately held securities, and private equity partnerships valued at unit values or net asset value s provided by the investment managers, which are based on the fair value of the underlying investments. Various methods are used to determine fair values and may include the cost of the investment, most recent financing, and expected cash flows. For some o f these investments, realization of the estimated fair value is dependent upon transactions between willing sellers and buyers.

[2] Publicly traded common stock and limited partnerships in the energy and real estate sectors for purposes o f total return. Investments include: energy and real estate securities generally valued at closing prices from national exchanges; and commingled funds, private securities, and limited partnerships valued at unit values or net asset values provided by the investment managers, which are generally based on the fair value of the underlying investments.

[3] Global balanced fund of equity, fixed income, and real estate securities for purposes of meeting Canadian pension plan asset allocation policies, and insur ance and annuity contracts to provide a stable stream of income for retirees and to fund postretirement medical benefits. Fair values are derived from unit values provided by the investment managers, which are generally based on the fair value of the under lying investments and contract fair values from the providers.