Pension Plans - Change in Benefit Obligation And Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	$ 77,757
Actual return (loss) on plan assets	2,600	$ 5,100	$ (1,900)
Employer contributions	3,200	3,700	1,300
Plan assets at fair value, end of year	83,774	77,757
Unrecognized actuarial loss	13,600	15,200
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, beginning of year	70,242	60,433
Service cost	578	674	690
Interest cost	2,121	2,368	2,126
Actuarial loss (gain)	(2,818)	7,128
Foreign exchange impact	2,896	3,319
Participant contributions	93	100
Benefits paid	(2,711)	(3,162)
Settlements	(941)	(618)
Projected benefit obligation, end of year	69,460	70,242	60,433
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	77,757	68,875
Actual return (loss) on plan assets	2,563	5,120
Employer contributions	3,238	3,697
Participant contributions	93	100
Foreign exchange impact	3,775	3,745
Settlements	(941)	(618)
Benefits paid	(2,711)	(3,162)
Plan assets at fair value, end of year	83,774	77,757	$ 68,875
Accumulated benefit obligation, end of year	68,996	69,580
Non-current asset	25,681	19,953
Non-current liability	(10,979)	(12,083)
Current liability	(388)	(355)
Unrecognized actuarial loss	13,620	15,230
Pension Plan | Underfunded Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Underfunded or Overfunded Status	(11,367)	(12,438)
Pension Plan | Overfunded Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Defined Benefit Plan, Underfunded or Overfunded Status	$ 25,681	$ 19,953