Postretirement Benefits - Benefit Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of fiscal year	$ 11,144	$ 3,565
Benefit obligation through acquisition		7,852
Service cost	599	382	$ 268
Interest cost	118	75	22
Actuarial loss	831	(165)
Benefits paid	(811)	(685)
Employee contributions	273	191
Foreign currency translation	(239)	(71)
Benefit obligation at end of fiscal year	$ 11,915	$ 11,144	$ 3,565

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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- Definition

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

+ References

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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 contributions received by defined benefit plan from participant which increase benefit obligation.

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- Definition

Amount of increase in benefit obligation of defined benefit plan from business combination.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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No definition available.

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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 cost recognized for passage of time related to 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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