Pension and Other Postretirement Plans - Additional Information (Detail) - Pension Plans $ in Thousands	Apr. 30, 2021 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Expected future employer contributions, current fiscal year	$ 68,000
Expected future employer contributions, additional cash contribution	$ 20,000

Amount of contributions received and expected to be received by defined benefit plan from employer in current fiscal year.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118255775&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 18
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921

Name:	us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsCurrentFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant