Pension and Retirement Plans - Amounts in consolidated balance sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Pension benefits assets	$ 1,958	$ 1,099
Accrued benefit liability	(1,349)	(1,447)
Defined Benefit Plan, Net	609	(348)
Deferred tax	303	330
Accumulated other comprehensive income	86	358
Net amount recognized	998	340
Accumulated benefit obligation	(9,425)	(9,173)
Pension:
Defined Benefit Plan Disclosure [Line Items]
Pension benefits assets	1,756	838
Deferred tax	26	25
Accumulated other comprehensive income	326	640
Net amount recognized	2,108	1,503
Accumulated benefit obligation	(8,278)	(7,987)
Post Retirement:
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(1,147)	(1,186)
Deferred tax	277	305
Accumulated other comprehensive income	(240)	(282)
Net amount recognized	(1,110)	(1,163)
Accumulated benefit obligation	(1,147)	(1,186)
International
Defined Benefit Plan Disclosure [Line Items]
Pension benefits assets	1,958	1,099
Deferred tax	0	0
Accumulated other comprehensive income	318	631
Net amount recognized	2,276	1,730
Accumulated benefit obligation	(8,076)	(7,726)
International | Pension:
Defined Benefit Plan Disclosure [Line Items]
Pension benefits assets	1,958	1,099
Deferred tax	0	0
Accumulated other comprehensive income	318	631
Net amount recognized	2,276	1,730
Accumulated benefit obligation	(8,076)	(7,726)
International | Post Retirement:
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	0	0
Deferred tax	0	0
Accumulated other comprehensive income	0	0
Net amount recognized	0	0
Accumulated benefit obligation	0	0
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(1,349)	(1,447)
Deferred tax	303	330
Accumulated other comprehensive income	(232)	(273)
Net amount recognized	(1,278)	(1,390)
Accumulated benefit obligation	(1,349)	(1,447)
UNITED STATES | Pension:
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(202)	(261)
Deferred tax	26	25
Accumulated other comprehensive income	8	9
Net amount recognized	(168)	(227)
Accumulated benefit obligation	(202)	(261)
UNITED STATES | Post Retirement:
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(1,147)	(1,186)
Deferred tax	277	305
Accumulated other comprehensive income	(240)	(282)
Net amount recognized	(1,110)	(1,163)
Accumulated benefit obligation	$ (1,147)	$ (1,186)