Payables and Accrued Expenses - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Jun. 30, 2023
Payables and Accruals [Abstract]
Accounts payable	$ 136.5	$ 157.3
Employee compensation and benefits	229.2	335.6
Accrued dividend payable	94.2	85.6
Accrued broker fees	75.2	148.0
Customer deposits	63.8	65.6
Business process outsourcing administration fees	59.8	61.7
Operating lease liabilities	$ 39.1	$ 40.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Total	Total
Accrued taxes	$ 25.9	$ 69.7
Other	54.6	55.1
Total	$ 778.3	$ 1,019.5