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, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets, Beginning Balance	$ 8,270
Fair Value of Plan Assets, Ending Balance	8,238	$ 8,270
Pension
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	13,459	13,962
Interest cost	386	395
Changes in actuarial assumptions	1,288	(172)
Foreign exchange impact	(772)	(364)
Benefits paid	(400)	(362)
Projected benefit obligation	13,961	13,459
Fair Value of Plan Assets, Beginning Balance	8,270	8,239
Actual gain on plan assets	194	291
Company contributions	655	337
Foreign exchange impact	(481)	(235)
Benefits paid	(400)	(362)
Fair Value of Plan Assets, Ending Balance	8,238	8,270
Funded status \ net amount recognized	(5,723)	(5,189)
Pension \| U.S.
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	585	677
Interest cost	24	25
Changes in actuarial assumptions	15	(7)
Benefits paid	(110)	(110)
Projected benefit obligation	514	585
Company contributions	110	110
Benefits paid	(110)	(110)
Funded status \ net amount recognized	(514)	(585)
Pension \| International
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	12,874	13,285
Interest cost	362	370
Changes in actuarial assumptions	1,273	(165)
Foreign exchange impact	(772)	(364)
Benefits paid	(290)	(252)
Projected benefit obligation	13,447	12,874
Fair Value of Plan Assets, Beginning Balance	8,270	8,239
Actual gain on plan assets	194	291
Company contributions	545	227
Foreign exchange impact	(481)	(235)
Benefits paid	(290)	(252)
Fair Value of Plan Assets, Ending Balance	8,238	8,270
Funded status \ net amount recognized	(5,209)	(4,604)
Post Retirement
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	1,318	1,255
Service cost	34	40
Interest cost	53	47
Changes in actuarial assumptions	111	(24)
Projected benefit obligation	1,516	1,318
Funded status \ net amount recognized	(1,516)	(1,318)
Post Retirement \| U.S.
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	1,318	1,255
Service cost	34	40
Interest cost	53	47
Changes in actuarial assumptions	111	(24)
Projected benefit obligation	1,516	1,318
Funded status \ net amount recognized	$ (1,516)	$ (1,318)

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

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