Stockholders' Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Class of Stock [Line Items]
Shares repurchased	1.3	1.3	3.8	1.9
Average price per share	$ 65.07	$ 58.08	$ 69.67	$ 56.18
Purchases of treasury stock	$ 83.9	$ 74.6	$ 267.6	$ 107.1
Excise Tax Payable, Current	$ 1.9	$ 1.0	1.9	$ 1.0
Excise tax payment			$ 2.2