Derivative Financial Instruments (Details 3) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Price Risk Derivatives [Abstract]
Net gains (losses) on mark-to-market valuation of unallocated derivative positions	$ (7.0)	$ (25.6)	$ (5.6)	$ (54.2)
Less: Net gains (losses) on derivative positions reclassified to segment operating profit	(14.7)	(22.7)	(43.2)	(29.2)
Unallocated derivative gains (losses)	$ 7.7	$ (2.9)	$ 37.6	$ (25.0)

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109998890-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

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Period Type:	duration