Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Sep. 30, 2023
Assets:
Cash and cash equivalents	$ 323,256	$ 245,875
Short-term investments	42,083	33,134
Liabilities:
Deferred compensation	11,195	9,145
Rabbi trust assets
Assets:
Rabbi trust assets	11,549	9,117
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	323,256	245,875
Short-term investments	42,083	33,134
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	11,195	9,145
Significant Other Observable Inputs (Level 2) | Rabbi trust assets
Assets:
Rabbi trust assets	11,549	9,117
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