Stockholders' Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended						9 Months Ended
	May 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2023	Nov. 15, 2022
Equity, Class of Treasury Stock [Line Items]
Stock repurchased and retired, value		$ 1,149.9	$ 171.7	$ 87.5	$ 37.1	$ 34.9	$ 31.4
Remaining authorized repurchase amount		$ 340.4						$ 340.4
Common stock
Equity, Class of Treasury Stock [Line Items]
Authorized shares for repurchase (up to)									$ 1,600.0
Stock repurchased and retired, shares (in shares)		30.1	4.9	2.9	1.2	1.0	0.9	35.0
Stock repurchased and retired, value		$ 0.3		$ 0.1				$ 1,302.6
Tender Offer
Equity, Class of Treasury Stock [Line Items]
Stock repurchased and retired, shares (in shares)	27.0
Shares repurchased price (in dollars per share)	$ 38.00
Stock repurchased and retired, value	$ 1,024.0
Shares repurchased and retired, additional election (in shares)	0.6
Shares repurchased and retired, fees and expenses	$ 16.3
Excise tax recognized	10.2
Tender Offer | Common stock
Equity, Class of Treasury Stock [Line Items]
Authorized shares for repurchase (up to)	$ 1,000.0