Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 898,848	$ 927,535
Accumulated Amortization	(541,916)	(477,534)
Net Carrying Amount	$ 356,932	450,001
Weighted Average Remaining Life (Years)
Net Carrying Amount (excluding goodwill)	$ 356,932	450,001
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	605,736	605,784
Accumulated Amortization	(350,695)	(289,218)
Net Carrying Amount	$ 255,041	$ 316,566
Weighted Average Remaining Life (Years)	5 years	5 years 10 months 24 days
Technology and patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 264,151	$ 292,766
Accumulated Amortization	(166,670)	(169,806)
Net Carrying Amount	$ 97,481	$ 122,960
Weighted Average Remaining Life (Years)	3 years 6 months	3 years 9 months 18 days
Trade names, trademarks and other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 28,961	$ 28,985
Accumulated Amortization	(24,551)	(18,510)
Net Carrying Amount	$ 4,410	$ 10,475
Weighted Average Remaining Life (Years)	1 year 2 months 12 days	1 year 10 months 24 days