Derivative Financial Instruments (Details 3) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Price Risk Derivatives [Abstract]
Net gains (losses) on mark-to-market valuation of unallocated derivative positions	$ 35.4	$ (7.0)	$ 57.5	$ (5.6)
Less: Net gains (losses) on derivative positions reclassified to segment operating profit	1.6	(14.7)	(24.0)	(43.2)
Unallocated derivative gains (losses)	$ 33.8	$ 7.7	$ 81.5	$ 37.6