Intangible Assets, Net (Schedule of Finite-Lived Intangible Assets by Major Class) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 443,503		$ 443,503		$ 443,476
Accumulated Amortization	(284,055)		(284,055)		(271,594)
Net Carrying Amount	159,448		159,448		171,882
Amortization expense	6,258	$ 6,431	12,501	$ 12,889
Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	99,434		99,434		99,555
Accumulated Amortization	(70,516)		(70,516)		(66,880)
Net Carrying Amount	28,918		28,918		32,675
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	322,868		322,868		323,187
Accumulated Amortization	(193,730)		(193,730)		(185,562)
Net Carrying Amount	129,138		129,138		137,625
Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	19,723		19,723		19,422
Accumulated Amortization	(18,657)		(18,657)		(18,196)
Net Carrying Amount	1,066		1,066		1,226
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,478		1,478		1,312
Accumulated Amortization	(1,152)		(1,152)		(956)
Net Carrying Amount	326		326		356
Aerospace [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	358,055		358,055		358,830
Accumulated Amortization	(210,547)		(210,547)		(200,279)
Net Carrying Amount	147,508		147,508		158,551
Aerospace [Member] | Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	76,372		76,372		76,605
Accumulated Amortization	(51,881)		(51,881)		(49,124)
Net Carrying Amount	24,491		24,491		27,481
Aerospace [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	281,683		281,683		282,225
Accumulated Amortization	(158,666)		(158,666)		(151,155)
Net Carrying Amount	123,017		123,017		131,070
Aerospace [Member] | Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	0		0		0
Accumulated Amortization	0		0		0
Net Carrying Amount	0		0		0
Aerospace [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	0		0		0
Accumulated Amortization	0		0		0
Net Carrying Amount	0		0		0
Industrial [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	85,448		85,448		84,646
Accumulated Amortization	(73,508)		(73,508)		(71,315)
Net Carrying Amount	11,940		11,940		13,331
Industrial [Member] | Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	23,062		23,062		22,950
Accumulated Amortization	(18,635)		(18,635)		(17,756)
Net Carrying Amount	4,427		4,427		5,194
Industrial [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	41,185		41,185		40,962
Accumulated Amortization	(35,064)		(35,064)		(34,407)
Net Carrying Amount	6,121		6,121		6,555
Industrial [Member] | Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	19,723		19,723		19,422
Accumulated Amortization	(18,657)		(18,657)		(18,196)
Net Carrying Amount	1,066		1,066		1,226
Industrial [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,478		1,478		1,312
Accumulated Amortization	(1,152)		(1,152)		(956)
Net Carrying Amount	$ 326		$ 326		$ 356