Accumulated Other Comprehensive Loss, Reclassification out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Amortization from Accumulated Other Comprehensive Loss [Abstract]
Pension expense	$ (2,738)	$ (3,012)	$ (8,401)	$ (8,257)
Reclassification out of Accumulated Other Comprehensive Loss [Member]
Amortization from Accumulated Other Comprehensive Loss [Abstract]
Pension expense	$ 1,800	$ 1,900	$ 5,500	$ 5,800

Amount of net periodic benefit cost (credit) for defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e2709-114920

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
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-URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4587-114921

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration