Risk Management Activities (Schedule of unallocated corporate items) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 27, 2022	Feb. 28, 2021	Feb. 27, 2022	Feb. 28, 2021
Commodity Price Risk [Abstract]
Net gain on mark-to-market valuation of certain commodity positions	$ 72.3	$ 51.0	$ 119.3	$ 95.0
Net (gain) loss on commodity positions reclassified from unallocated corporate items to segment operating profit	(48.1)	(3.9)	(118.7)	12.8
Net mark-to-market revaluation of certain grain inventories	(44.2)	8.6	15.6	10.2
Net mark-to-market valuation of certain commodity positions recognized in unallocated corporate items	$ (20.0)	$ 55.7	$ 16.2	$ 118.0