Retirement Benefits (Schedule of Allocation of Plan Assets, Fair Value Hierarchy) (Details) - Defined Benefit Pension Plan [Member] - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 266,709	$ 234,133	$ 227,722
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	201,555	170,556	165,342
Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	65,154	63,577	$ 62,380
Level 1 [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	201,555	170,556
Level 1 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	270	418
Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	64,884	63,159
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,385	2,986
Cash and Cash Equivalents | Level 1 [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,115	2,568
Cash and Cash Equivalents | Level 1 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	270	418
Debt Security, Corporate, US
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70,492	64,514
Debt Security, Corporate, US | Level 1 [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70,492	64,514
Domestic Equity Large Cap Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	65,025	56,829
Domestic Equity Large Cap Fund | Level 1 [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	65,025	56,829
International Equity Large Cap Growth Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	64,923	46,645
International Equity Large Cap Growth Fund | Level 1 [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	64,923	46,645
Private Equity Funds Foreign Japan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,470	2,518
Private Equity Funds Foreign Japan | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,470	2,518
Private Equity Funds Pooled Funds Foreign
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,135	2,226
Private Equity Funds Pooled Funds Foreign | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,135	2,226
Fixed Income Funds Japan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,151	4,915
Fixed Income Funds Japan | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,151	4,915
Fixed Income Funds Foreign
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,734	1,710
Fixed Income Funds Foreign | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,734	1,710
Global Target Return Equity Bond Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,002	12,488
Global Target Return Equity Bond Fund | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13,002	12,488
United Kingdom Index Linked Equity Fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,878	3,738
United Kingdom Index Linked Equity Fund | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,878	3,738
Index linked international equity fund
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,351	5,438
Index linked international equity fund | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,351	5,438
Corporate Debt Securities United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18,055	16,737
Corporate Debt Securities United Kingdom | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18,055	16,737
Pooled funds: Index linked U.K. government securities fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,767	5,491
Pooled funds: Index linked U.K. government securities fund [Member] | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,767	5,491
Pooled funds: Index linked U.K. long-term government securities fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8,341	7,898
Pooled funds: Index linked U.K. long-term government securities fund [Member] | Level 2 [Member] | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 8,341	$ 7,898