Subsequent Events (Details) - USD ($) shares in Millions, $ in Millions	2 Months Ended	9 Months Ended	12 Months Ended
	Nov. 15, 2023	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Nov. 15, 2022
Subsequent Event [Line Items]
Total cost			$ 1,539.6	$ 142.6	$ 127.0
Remaining authorized repurchase amount		$ 211.5	$ 211.5
Common stock
Subsequent Event [Line Items]
Shares repurchased (in shares)		38.9	41.8	4.5	4.8
Total cost		$ 1,431.5	$ 0.5		$ 0.1
Authorized amount for repurchase						$ 1,600.0
Subsequent Event | Common stock
Subsequent Event [Line Items]
Shares repurchased (in shares)	4.2
Total cost	$ 130.1
Remaining authorized repurchase amount	$ 81.4