Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024
Goodwill [Roll Forward]
Beginning balance	$ 231,656	$ 159,270
Additions	709,343	70,954
Measurement period adjustments	2,310	1,432
Ending balance	$ 943,309	$ 231,656

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

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+ Details