Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Assets:
Cash and cash equivalents	$ 359,542	$ 315,331
Short-term investments	29,750	43,061
Liabilities:
Deferred compensation	12,418	12,027
Rabbi trust assets
Assets:
Rabbi trust assets	11,784	12,324
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	359,542	315,331
Short-term investments	29,750	43,061
Liabilities:
Deferred compensation	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Rabbi trust assets
Assets:
Rabbi trust assets	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Short-term investments	0	0
Liabilities:
Deferred compensation	12,418	12,027
Significant Other Observable Inputs (Level 2) \| Rabbi trust assets
Assets:
Rabbi trust assets	11,784	12,324
Significant Unobservable Inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Short-term investments	0	0
Liabilities:
Deferred compensation	0	0
Significant Unobservable Inputs (Level 3) \| Rabbi trust assets
Assets:
Rabbi trust assets	$ 0	$ 0