Pension Plans - Change in Benefit Obligation And Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	$ 68,875
Actual return (loss) on plan assets	5,100	$ (1,900)	$ 2,300
Employer contributions	3,700	1,300	3,000
Plan assets at fair value, end of year	77,757	68,875
Unrecognized actuarial loss	15,200	9,600
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, beginning of year	60,433	58,129
Service cost	674	690	1,016
Interest cost	2,368	2,126	550
Actuarial loss (gain)	7,128	(1,589)
Foreign exchange impact	3,319	3,714
Participant contributions	100	96
Benefits paid	(3,162)	(2,968)
Plan amendments	0	235
Settlements	(618)	0
Projected benefit obligation, end of year	70,242	60,433	58,129
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	68,875	67,581
Actual return (loss) on plan assets	5,120	(1,919)
Employer contributions	3,697	1,343
Participant contributions	100	96
Foreign exchange impact	3,745	4,593
Settlements	(618)	0
Benefits paid	(3,162)	(2,968)
Plan amendments	0	149
Plan assets at fair value, end of year	77,757	68,875	$ 67,581
Accumulated benefit obligation, end of year	69,580	59,602
Non-current asset	19,953	19,135
Non-current liability	(12,083)	(10,419)
Current liability	(355)	(274)
Unrecognized actuarial loss	15,230	9,573
Pension Plan | Underfunded Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Underfunded or Overfunded Status	(12,438)	(10,693)
Pension Plan | Overfunded Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Underfunded or Overfunded Status	$ 19,953	$ 19,135