Intangible Assets, Net (Schedule of Finite-Lived Intangible Assets by Major Class) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 443,475		$ 443,476
Accumulated Amortization	(277,842)		(271,594)
Net Carrying Amount	165,633		171,882
Amortization expense	6,243	$ 6,458
Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	99,515		99,555
Accumulated Amortization	(68,737)		(66,880)
Net Carrying Amount	30,778		32,675
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	323,169		323,187
Accumulated Amortization	(189,798)		(185,562)
Net Carrying Amount	133,371		137,625
Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	19,459		19,422
Accumulated Amortization	(18,315)		(18,196)
Net Carrying Amount	1,144		1,226
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,332		1,312
Accumulated Amortization	(992)		(956)
Net Carrying Amount	340		356
Aerospace [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	358,830		358,830
Accumulated Amortization	(205,802)		(200,279)
Net Carrying Amount	153,028		158,551
Aerospace [Member] | Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	76,605		76,605
Accumulated Amortization	(50,619)		(49,124)
Net Carrying Amount	25,986		27,481
Aerospace [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	282,225		282,225
Accumulated Amortization	(155,183)		(151,155)
Net Carrying Amount	127,042		131,070
Aerospace [Member] | Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	0		0
Accumulated Amortization	0		0
Net Carrying Amount	0		0
Aerospace [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	0		0
Accumulated Amortization	0		0
Net Carrying Amount	0		0
Industrial [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	84,645		84,646
Accumulated Amortization	(72,040)		(71,315)
Net Carrying Amount	12,605		13,331
Industrial [Member] | Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	22,910		22,950
Accumulated Amortization	(18,118)		(17,756)
Net Carrying Amount	4,792		5,194
Industrial [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	40,944		40,962
Accumulated Amortization	(34,615)		(34,407)
Net Carrying Amount	6,329		6,555
Industrial [Member] | Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	19,459		19,422
Accumulated Amortization	(18,315)		(18,196)
Net Carrying Amount	1,144		1,226
Industrial [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,332		1,312
Accumulated Amortization	(992)		(956)
Net Carrying Amount	$ 340		$ 356