Pension Plan and Retirement Benefits - Defined Benefit Plans - Expense (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2007	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Pension Plan and Retirement Benefits
Accrued pension and postretirement benefits		$ 210,114	$ 164,736
Defined Benefit Pension Plans
Pension Plan and Retirement Benefits
Pension plan expense		2,661	6,464	$ 14,515
Accrued pension and postretirement benefits		95,561	56,007
Contribution to plan		5,237	8,782
Pension Plans Defined Benefit Us [Member]
Pension Plan and Retirement Benefits
Contribution to plan		4,500	8,000	6,000
Pension Plans Defined Benefit Non Us [Member]
Pension Plan and Retirement Benefits
Contribution to plan		737	782	804
Non-qualified pension plan
Pension Plan and Retirement Benefits
Pension plan expense		98	34	19
Accrued pension and postretirement benefits		719	716
Postretirement Health Care Benefits
Pension Plan and Retirement Benefits
Pension plan expense		6,158	7,646	$ 8,920
Accrued pension and postretirement benefits		113,834	108,013
Maximum liability related to total retiree health care costs under plan amendment	$ 5,000
Contribution to plan		$ 3,095	$ 3,663