Retirement Benefits (Schedule of Changes in Plan Assets and Benefit Obligations Recorded in Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Net (gain) loss	$ (20,179)	$ 43,817	$ (13,805)
Prior service cost due to plan amendment		(601)
Amortization of: Net losses	2,523	955	985
Prior service (cost) benefit	(962)	(704)	(551)
Foreign currency exchange rate changes	1,672	(1,318)	(367)
Curtailment arising during the period			(59)
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive losses at beginning of year	67,137	25,273
Net (gain) loss	(19,866)	44,190
Prior service cost due to plan amendment		601
Amortization of: Net losses	(2,476)	(900)
Prior service (cost) benefit	(959)	(709)
Foreign currency exchange rate changes	1,672	(1,318)
Accumulated other comprehensive losses at end of year	45,508	67,137	25,273
Defined Benefit Pension Plan [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive losses at beginning of year	33,917	10,744
Net (gain) loss	(17,420)	24,499
Amortization of: Net losses	(1,430)	(617)
Prior service (cost) benefit	(936)	(709)
Accumulated other comprehensive losses at end of year	14,131	33,917	10,744
Defined Benefit Pension Plan [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive losses at beginning of year	33,220	14,529
Net (gain) loss	(2,446)	19,691
Prior service cost due to plan amendment		601
Amortization of: Net losses	(1,046)	(283)
Prior service (cost) benefit	(23)
Foreign currency exchange rate changes	1,672	(1,318)
Accumulated other comprehensive losses at end of year	31,377	33,220	14,529
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive losses at beginning of year	1	424
Net (gain) loss	(313)	(373)
Amortization of: Net losses	(47)	(55)
Prior service (cost) benefit	(3)	5
Accumulated other comprehensive losses at end of year	$ (362)	$ 1	$ 424