Retirement and Other Benefit Plans - Additional information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Retirement and Other Benefit Plans
Defined Benefit Plan Before Adoption Of Sfas 158 Recognition Provision Accrued Benefit Liability	$ 600	$ 500
Defined Benefit Plan Amount To Be Amortized	$ 2,700

Amount of cost (credit) included in accumulated other comprehensive (income) loss expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (s)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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