Intangible Assets, Net (Schedule of Finite-Lived Intangible Assets by Major Class) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 443,476				$ 443,445				$ 443,476	$ 443,445
Accumulated Amortization	(271,594)				(245,795)				(271,594)	(245,795)
Net Carrying Amount	171,882				197,650				171,882	197,650
Amortization expense	6,449	$ 6,439	$ 6,431	$ 6,458	6,727	$ 6,887	$ 6,926	$ 6,946	25,777	27,486	$ 29,241
Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	99,555				99,570				99,555	99,570
Accumulated Amortization	(66,880)				(59,429)				(66,880)	(59,429)
Net Carrying Amount	32,675				40,141				32,675	40,141
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	323,187				323,194				323,187	323,194
Accumulated Amortization	(185,562)				(167,667)				(185,562)	(167,667)
Net Carrying Amount	137,625				155,527				137,625	155,527
Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	19,422				19,435				19,422	19,435
Accumulated Amortization	(18,196)				(17,876)				(18,196)	(17,876)
Net Carrying Amount	1,226				1,559				1,226	1,559
Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,312				1,246				1,312	1,246
Accumulated Amortization	(956)				(823)				(956)	(823)
Net Carrying Amount	356				423				356	423
Aerospace [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	358,830				358,830				358,830	358,830
Accumulated Amortization	(200,279)				(177,387)				(200,279)	(177,387)
Net Carrying Amount	158,551				181,443				158,551	181,443
Aerospace [Member] | Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	76,605				76,605				76,605	76,605
Accumulated Amortization	(49,124)				(43,229)				(49,124)	(43,229)
Net Carrying Amount	27,481				33,376				27,481	33,376
Aerospace [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	282,225				282,225				282,225	282,225
Accumulated Amortization	(151,155)				(134,158)				(151,155)	(134,158)
Net Carrying Amount	131,070				148,067				131,070	148,067
Aerospace [Member] | Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	0				0				0	0
Accumulated Amortization	0				0				0	0
Net Carrying Amount	0				0				0	0
Aerospace [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	0				0				0	0
Accumulated Amortization	0				0				0	0
Net Carrying Amount	0				0				0	0
Industrial [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	84,646				84,615				84,646	84,615
Accumulated Amortization	(71,315)				(68,408)				(71,315)	(68,408)
Net Carrying Amount	13,331				16,207				13,331	16,207
Industrial [Member] | Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	22,950				22,965				22,950	22,965
Accumulated Amortization	(17,756)				(16,200)				(17,756)	(16,200)
Net Carrying Amount	5,194				6,765				5,194	6,765
Industrial [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	40,962				40,969				40,962	40,969
Accumulated Amortization	(34,407)				(33,509)				(34,407)	(33,509)
Net Carrying Amount	6,555				7,460				6,555	7,460
Industrial [Member] | Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	19,422				19,435				19,422	19,435
Accumulated Amortization	(18,196)				(17,876)				(18,196)	(17,876)
Net Carrying Amount	1,226				1,559				1,226	1,559
Industrial [Member] | Other Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1,312				1,246				1,312	1,246
Accumulated Amortization	(956)				(823)				(956)	(823)
Net Carrying Amount	$ 356				$ 423				$ 356	$ 423