Intangible Assets, Net (Schedule of Finite-Lived and Indefinite-Lived Intangible Assets by Major Class) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization of Finite-Lived Intangible	$ (367,884)	$ (399,081)
Net Carrying Amount - Finite-Lived Intangible	548,400
Intangible Assets, Gross, Total	987,605	1,005,792
Intangible Assets, Net, Total	619,721	606,711
Customer Relationships And Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	729,347	710,932
Accumulated Amortization of Finite-Lived Intangible	(263,477)	(253,565)
Net Carrying Amount - Finite-Lived Intangible	465,870	457,367
Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	15,816	15,778
Accumulated Amortization of Finite-Lived Intangible	(15,724)	(15,640)
Net Carrying Amount - Finite-Lived Intangible	92	138
Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	170,876	167,316
Accumulated Amortization of Finite-Lived Intangible	(88,471)	(86,256)
Net Carrying Amount - Finite-Lived Intangible	82,405	81,060
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	245	235
Accumulated Amortization of Finite-Lived Intangible	(212)	(183)
Net Carrying Amount - Finite-Lived Intangible	33	52
Tradenames [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	71,321	68,094
Aerospace [Member]
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization of Finite-Lived Intangible	(264,745)	(260,476)
Intangible Assets, Gross, Total	358,053	358,054
Intangible Assets, Net, Total	93,308	97,578
Aerospace [Member] | Customer Relationships And Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	281,683	281,683
Accumulated Amortization of Finite-Lived Intangible	(199,985)	(196,520)
Net Carrying Amount - Finite-Lived Intangible	81,698	85,163
Aerospace [Member] | Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	76,370	76,371
Accumulated Amortization of Finite-Lived Intangible	(64,760)	(63,956)
Net Carrying Amount - Finite-Lived Intangible	11,610	12,415
Industrial [Member]
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization of Finite-Lived Intangible	(103,139)	(138,605)
Intangible Assets, Gross, Total	629,552	647,738
Intangible Assets, Net, Total	526,413	509,133
Industrial [Member] | Customer Relationships And Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	447,664	429,249
Accumulated Amortization of Finite-Lived Intangible	(63,492)	(57,045)
Net Carrying Amount - Finite-Lived Intangible	384,172	372,204
Industrial [Member] | Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	15,816	15,778
Accumulated Amortization of Finite-Lived Intangible	(15,724)	(15,640)
Net Carrying Amount - Finite-Lived Intangible	92	138
Industrial [Member] | Process Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	94,506	90,945
Accumulated Amortization of Finite-Lived Intangible	(23,711)	(22,300)
Net Carrying Amount - Finite-Lived Intangible	70,795	68,645
Industrial [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value - Finite-Lived Intangible	245	235
Accumulated Amortization of Finite-Lived Intangible	(212)	(183)
Net Carrying Amount - Finite-Lived Intangible	33	52
Industrial [Member] | Tradenames [Member]
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets	$ 71,321	$ 68,094