Goodwill - Schedule of Goodwill (Details) - USD ($) $ in Thousands			1 Months Ended
	May 16, 2022	Oct. 01, 2020	Jun. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Goodwill:
Goodwill			$ 8,266,809	$ 1,044,383	$ 77,000
Goodwill from acquisitions, net of adjustments	$ 7,222,799	$ 967,383
Goodwill, effect of currency translation			(373)
Heritage AspenTech
Goodwill:
Goodwill			7,222,426	0	0
Goodwill from acquisitions, net of adjustments	$ 7,222,799
Goodwill, effect of currency translation			(373)
OSI Inc.
Goodwill:
Goodwill			967,383	967,383	0
Goodwill from acquisitions, net of adjustments		$ 967,383
SSE
Goodwill:
Goodwill			$ 77,000	$ 77,000	$ 77,000