Pension Plan and Retirement Benefits - Defined Contribution Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Defined Contribution 401K Plan [Member]
Defined Contribution Plans
Expenses associated with plan	$ 2,016	$ 1,748	$ 1,950
Defined Contribution 401K Plan [Member] | Employees with exceptions
Defined Contribution Plans
Percentage employer matches of the employee's percentage contribution matched.	50.00%
Defined Contribution 401K Plan [Member] | Employees with exceptions | Maximum
Defined Contribution Plans
Percentage of employees' gross pay for which the employer contributes a matching contribution	3.00%
Defined Contribution 401K Plan [Member] | Certain employees not eligible for U.S. pension plan
Defined Contribution Plans
Percentage employer matches of the employee's percentage contribution matched.	60.00%
Defined Contribution 401K Plan [Member] | Certain employees not eligible for U.S. pension plan | Maximum
Defined Contribution Plans
Percentage of employees' gross pay for which the employer contributes a matching contribution	6.00%
Profit Sharing Plans [Member]
Defined Contribution Plans
Expenses associated with plan	$ 0	$ 0	$ 0