Acquisitions (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands				12 Months Ended
	Nov. 01, 2021	Jul. 06, 2021	Mar. 26, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Business Acquisition [Line Items]
Cash				$ 0	$ 347,554	$ 19,108
Goodwill				341,593	$ 340,477	$ 225,522
Ventus
Business Acquisition [Line Items]
Cash	$ 350,000
Cash	350,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Tangible Assets Acquired (Liabilities) Assumed	20,365
Goodwill	118,635
Total assets acquired and liabilities assumed	350,000
Ctek
Business Acquisition [Line Items]
Cash		$ 12,012
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Contingent Liability		300		0
Business Combination, Contingent Consideration, Liability		422
Total consideration transferred		12,734
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Tangible Assets Acquired (Liabilities) Assumed		397
Deferred tax liability on identifiable intangible assets		(1,000)
Goodwill		4,867
Total assets acquired and liabilities assumed		12,734
Haxiot
Business Acquisition [Line Items]
Cash			$ 7,100
Cash			7,096
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Contingent Liability			5,900	$ 0
Total consideration transferred			12,996
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Tangible Assets Acquired (Liabilities) Assumed			86
Deferred tax liability on identifiable intangible assets			(1,145)
Goodwill			8,605
Total assets acquired and liabilities assumed			12,996
Customer Relationships | Ventus
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	179,000
Customer Relationships | Ctek
Business Acquisition [Line Items]
Identifiable intangible assets		5,100
Customer Relationships | Haxiot
Business Acquisition [Line Items]
Identifiable intangible assets			3,900
Trademarks | Ventus
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	16,000
Trademarks | Ctek
Business Acquisition [Line Items]
Identifiable intangible assets		70
Trademarks | Haxiot
Business Acquisition [Line Items]
Identifiable intangible assets			500
Purchased and Core Technology | Ventus
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	$ 16,000
Purchased and Core Technology | Ctek
Business Acquisition [Line Items]
Identifiable intangible assets		$ 1,300
Purchased and Core Technology | Haxiot
Business Acquisition [Line Items]
Identifiable intangible assets			$ 1,050