Retirement Benefit Plans - Schedule of Contributions in U.S. Multi-Employer Retirement Plan for Certain Union Employees (Details) $ in Thousands	12 Months Ended
Sep. 30, 2020 USD ($) plan	Sep. 30, 2019 USD ($)
Retirement Benefits [Abstract]
Multiemployer plans, number of plans \| plan	1
Contributions by the Company \| $	$ 0	$ 55
Amortization period of losses utilized under pension fund	30 years

Amount of cost for employer contribution to multiemployer pension plan determined to be individually significant.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948

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