Pension and Retirement Plans - Changes of the benefit obligation, the plan assets and funded status of the plans (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets, Beginning Balance	$ 9,740
Fair Value of Plan Assets, Ending Balance	11,921	$ 9,740
Pension
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	14,829	13,961
Interest cost	254	278
Changes in actuarial assumptions	(664)	331
Foreign exchange impact	670	629
Benefits paid	(433)	(370)
Projected benefit obligation	14,656	14,829
Fair Value of Plan Assets, Beginning Balance	9,740	8,238
Actual gain on plan assets	1,655	929
Company contributions	549	547
Foreign exchange impact	410	396
Benefits paid	(433)	(370)
Fair Value of Plan Assets, Ending Balance	11,921	9,740
Funded status \ net amount recognized	(2,735)	(5,089)
Pension \| U.S.
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	426	514
Interest cost	11	15
Changes in actuarial assumptions	(6)	7
Benefits paid	(92)	(110)
Projected benefit obligation	339	426
Company contributions	92	110
Benefits paid	(92)	(110)
Funded status \ net amount recognized	(339)	(426)
Pension \| International
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	14,403	13,447
Interest cost	243	263
Changes in actuarial assumptions	(658)	324
Foreign exchange impact	670	629
Benefits paid	(341)	(260)
Projected benefit obligation	14,317	14,403
Fair Value of Plan Assets, Beginning Balance	9,740	8,238
Actual gain on plan assets	1,655	929
Company contributions	457	437
Foreign exchange impact	410	396
Benefits paid	(341)	(260)
Fair Value of Plan Assets, Ending Balance	11,921	9,740
Funded status \ net amount recognized	(2,396)	(4,663)
Post Retirement
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	1,703	1,516
Service cost	45	38
Interest cost	42	46
Changes in actuarial assumptions	(120)	103
Projected benefit obligation	1,670	1,703
Funded status \ net amount recognized	(1,670)	(1,703)
Post Retirement \| U.S.
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	1,703	1,516
Service cost	45	38
Interest cost	42	46
Changes in actuarial assumptions	(120)	103
Projected benefit obligation	1,670	1,703
Funded status \ net amount recognized	$ (1,670)	$ (1,703)

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of foreign currency translation gain (loss) which increases (decreases) plan assets of defined benefit plan.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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