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, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets, Beginning Balance	$ 8,825
Fair Value of Plan Assets, Ending Balance	10,034	$ 8,825
Pension:
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, beginning of period	7,987	14,656
Interest cost	442	279
Changes in actuarial assumptions	(321)	(4,595)
Foreign exchange impact	759	(1,873)
Benefits paid	(589)	(480)
Projected benefit obligation, end of period	8,278	7,987
Fair Value of Plan Assets, Beginning Balance	8,825	11,921
Actual gain on plan assets	628	(1,026)
Company contributions	307	321
Foreign exchange impact	863	(1,911)
Benefits paid	(589)	(480)
Fair Value of Plan Assets, Ending Balance	10,034	8,825
Funded status \ net amount recognized	1,756	838
Pension: | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, beginning of period	261	339
Interest cost	13	11
Changes in actuarial assumptions	(4)	(21)
Foreign exchange impact	0	0
Benefits paid	(68)	(68)
Projected benefit obligation, end of period	202	261
Fair Value of Plan Assets, Beginning Balance	0	0
Actual gain on plan assets	0	0
Company contributions	68	68
Foreign exchange impact	0	0
Benefits paid	(68)	(68)
Fair Value of Plan Assets, Ending Balance	0	0
Funded status \ net amount recognized	(202)	(261)
Pension: | International
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, beginning of period	7,726	14,317
Interest cost	429	268
Changes in actuarial assumptions	(317)	(4,574)
Foreign exchange impact	759	(1,873)
Benefits paid	(521)	(412)
Projected benefit obligation, end of period	8,076	7,726
Fair Value of Plan Assets, Beginning Balance	8,825	11,921
Actual gain on plan assets	628	(1,026)
Company contributions	239	253
Foreign exchange impact	863	(1,911)
Benefits paid	(521)	(412)
Fair Value of Plan Assets, Ending Balance	10,034	8,825
Funded status \ net amount recognized	1,958	1,099
Post Retirement:
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, beginning of period	1,186	1,670
Service cost	24	44
Interest cost	62	46
Changes in actuarial assumptions	(125)	(574)
Projected benefit obligation, end of period	1,147	1,186
Funded status \ net amount recognized	(1,147)	(1,186)
Post Retirement: | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, beginning of period	1,186	1,670
Service cost	24	44
Interest cost	62	46
Changes in actuarial assumptions	(125)	(574)
Projected benefit obligation, end of period	1,147	1,186
Funded status \ net amount recognized	(1,147)	(1,186)
Post Retirement: | International
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, beginning of period	0	0
Service cost	0	0
Interest cost	0	0
Changes in actuarial assumptions	0	0
Projected benefit obligation, end of period	0	0
Funded status \ net amount recognized	$ 0	$ 0