Pension Plan and Retirement Benefits - Benefit Obligation Assumptions (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2007	Sep. 30, 2027	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Pension Plans Defined Benefit Us [Member]
Assumptions used to determine benefit obligation
Discount rate (as a percent)						5.63%	5.13%
Rate of compensation increase (as a percent)						3.50%	2.50%
Pension Plans Defined Benefit Non Us [Member]
Assumptions used to determine benefit obligation
Discount rate (as a percent)						5.70%	5.90%
Defined Benefit Other Postretirement Benefit Plan
Assumptions relating to health care cost trend rates
Annual rate of increase for the costs of covered health care benefits on the basis of age (as a percent)		5.00%	5.50%	6.00%	6.50%	7.00%
Effect of one percentage point change in assumed health care cost trend rates
Maximum liability related to total retiree health care costs under plan amendment	$ 5,000
Assumptions used to determine benefit obligation
Discount rate (as a percent)						5.63%	5.13%
Defined Benefit Other Postretirement Benefit Plan | Minimum
Assumptions relating to health care cost trend rates
Employee age required to participate in the plan						65 years	65 years
Defined Benefit Other Postretirement Benefit Plan | Maximum
Assumptions relating to health care cost trend rates
Employee age required to participate in the plan							65 years
Defined Benefit Other Postretirement Benefit Plan | Under Sixty Five Age Group [Member]
Assumptions relating to health care cost trend rates
Annual rate of increase for the costs of covered health care benefits on the basis of age (as a percent)							5.00%
Defined Benefit Other Postretirement Benefit Plan | Over Sixty Five Age Group [Member]
Assumptions relating to health care cost trend rates
Annual rate of increase for the costs of covered health care benefits on the basis of age (as a percent)							5.00%