Summary of Significant Accounting Policies - Goodwill and Other Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Accounting Policies [Abstract]
Restructuring and impairment	$ 0	$ 57,710
Intangible asset estimated useful lives (in years)	10 years
Impairment of intangible assets, finite-lived	$ 0	46,700
Impairment of intangible assets, indefinite-lived	$ 0	$ 43,000