Retirement Benefits (Schedule of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,808	$ 2,444	$ 2,802
Interest cost	6,965	6,873	8,084
Expected return on plan assets	(13,134)	(12,799)	(13,679)
Amortization of: Net (gains) losses	2,368	1,538	586
Amortization of: Prior service (benefit) cost	383	384	383
Settlement loss	0	47	0
Net periodic benefit cost	(610)	(1,513)	(1,824)
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	14	22	30
Interest cost	1,244	1,048	1,233
Amortization of: Net (gains) losses	201	156	(73)
Amortization of: Prior service (benefit) cost	(158)	(158)	(158)
Net periodic benefit cost	1,301	1,068	1,032
UNITED STATES | Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,675	1,695	2,018
Interest cost	5,757	5,236	5,956
Expected return on plan assets	(10,529)	(10,140)	(10,647)
Amortization of: Net (gains) losses	1,854	1,292	396
Amortization of: Prior service (benefit) cost	383	384	383
Settlement loss	0	47	0
Net periodic benefit cost	(860)	(1,486)	(1,894)
Duarte Plan, Defined Benefit [Member] | Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement loss		47
Foreign Plan [Member] | Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,133	749	784
Interest cost	1,208	1,637	2,128
Expected return on plan assets	(2,605)	(2,659)	(3,032)
Amortization of: Net (gains) losses	514	246	190
Amortization of: Prior service (benefit) cost	0	0	0
Settlement loss	0	0	0
Net periodic benefit cost	$ 250	$ (27)	$ 70