Balance Sheet Details - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 334,908	$ 183,308
Accumulated Amortization	(109,008)	(74,405)
Net Carrying Amount	225,900	108,903
Amortization of Intangible Assets	34,600	11,800	$ 11,100
Developed Technology Rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	246,173	126,173
Accumulated Amortization	(76,556)	(53,213)
Net Carrying Amount	169,617	72,960
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	41,242	20,242
Accumulated Amortization	(10,657)	(5,533)
Net Carrying Amount	30,585	14,709
Patents And Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	20,260	19,160
Accumulated Amortization	(14,448)	(11,800)
Net Carrying Amount	5,812	7,360
Trade Names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	24,973	15,473
Accumulated Amortization	(5,174)	(1,836)
Net Carrying Amount	19,799	13,637
Non-Compete Covenants [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,260	2,260
Accumulated Amortization	(2,173)	(2,023)
Net Carrying Amount	$ 87	$ 237