Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	7 years
Carrying amount, finite-lived intangible assets	$ 502,611	$ 472,266
Accumulated Amortization	(226,851)	(191,706)
Total	275,760	280,560
Indefinite‑lived intangible assets	34,207	34,207
Carrying amount, intangible assets	536,818	506,473
Intangible assets, net	$ 309,967	314,767
Customer related
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	10 years
Carrying amount, finite-lived intangible assets	$ 292,316	290,407
Accumulated Amortization	(83,486)	(64,548)
Total	$ 208,830	225,859
Proprietary technology
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	5 years
Carrying amount, finite-lived intangible assets	$ 61,990	50,725
Accumulated Amortization	(30,886)	(24,187)
Total	$ 31,104	$ 26,538
Finite-lived intangible asset, useful life		10 years
Trademark
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	7 years
Carrying amount, finite-lived intangible assets	$ 27,114	$ 26,432
Accumulated Amortization	(9,142)	(6,245)
Total	17,972	20,187
Backlog
Finite-Lived Intangible Assets [Line Items]
Carrying amount, finite-lived intangible assets	82,181	81,834
Accumulated Amortization	(82,181)	(81,834)
Total	$ 0	$ 0
Finite-lived intangible asset, useful life	1 year	1 year
Other
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	3 years
Carrying amount, finite-lived intangible assets	$ 39,010	$ 22,868
Accumulated Amortization	(21,156)	(14,892)
Total	$ 17,854	$ 7,976
Finite-lived intangible asset, useful life	3 years	4 years
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	1 year
Minimum [Member] | Customer related
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	5 years	5 years
Minimum [Member] | Proprietary technology
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	7 years
Minimum [Member] | Trademark
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	5 years	10 years
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	26 years
Maximum [Member] | Customer related
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	26 years	26 years
Maximum [Member] | Proprietary technology
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	10 years
Maximum [Member] | Trademark
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life	15 years	15 years