Defined Contribution Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Retirement Benefits [Abstract]
Participants annual maximum contribution to defined contribution plan, pre-tax	50.00%
Percentage of annual bonus eligible for defined contribution to plan	100.00%
Loss Contingencies [Line Items]
Expenses recognized for defined contribution plans	$ 104.7	$ 102.3	$ 93.0
Other Plan Changes [Member]
Loss Contingencies [Line Items]
Plan's employer matching contribution	85.00%