Pension Plans - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Weighted average interest crediting rate used in only cash balance pension plan		6.00%
Defined benefit plan, plan assets, increase (decrease) for actual return (loss)		$ (3,000)	$ 3,500	$ 1,000
Defined benefit plan, plan assets, contributions by employer		$ 2,600	$ 2,600	$ 2,500
Scenario Forecast
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost	$ 2,300
Defined benefit plan, plan assets, contributions by employer	3,500
Defined benefit plan, plan assets, contributions by employer, directly to plans	$ 800
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Weighted average assumptions used to determine net periodic pension cost for fiscal years ended September 30, Rate of return on plan assets		5.40%	5.40%	5.40%
Net periodic pension cost		$ 1,924	$ 1,198	$ 912
Defined benefit plan, plan assets, increase (decrease) for actual return (loss)		(2,990)	3,512
Defined benefit plan, plan assets, contributions by employer		$ 2,622	$ 2,576
Pension Plan | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Current asset allocation target for fixed income securities		100.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plans, vesting period		1 year
Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plans, vesting period		5 years