Retirement and Postemployment Benefits (Schedule of Components of net periodic benefit (income) expense) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2021	Feb. 23, 2020	Feb. 28, 2021	Feb. 23, 2020
Defined Benefit Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 26.1	$ 23.3	$ 78.1	$ 69.7
Interest cost	48.0	57.7	143.9	173.0
Expected return on plan assets	(105.3)	(112.5)	(315.4)	(337.5)
Amortization of losses (gains)	27.1	26.5	81.1	79.9
Amortization of prior service costs (credits)	0.3	0.4	0.9	1.2
Other adjustments	0.0	0.0	0.0	0.0
Net (income) expense	(3.8)	(4.6)	(11.4)	(13.7)
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.0	2.3	6.3	7.1
Interest cost	4.5	6.8	13.5	20.4
Expected return on plan assets	(8.7)	(10.6)	(26.0)	(31.6)
Amortization of losses (gains)	(1.3)	(0.5)	(3.8)	(1.6)
Amortization of prior service costs (credits)	(1.3)	(1.3)	(4.1)	(4.1)
Other adjustments	0.0	0.0	0.0	0.0
Net (income) expense	(4.8)	(3.3)	(14.1)	(9.8)
Postemployment Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.3	2.1	6.9	6.3
Interest cost	0.4	0.7	1.2	2.0
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of losses (gains)	0.7	0.2	2.1	0.5
Amortization of prior service costs (credits)	0.1	0.1	0.5	0.5
Other adjustments	2.1	2.2	6.5	6.6
Net (income) expense	$ 5.6	$ 5.3	$ 17.2	$ 15.9