Payables and Accrued Expenses - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Jun. 30, 2024
Payables and Accruals [Abstract]
Accounts payable	$ 198.3	$ 314.0
Employee compensation and benefits	227.3	354.4
Accrued dividend payable	103.0	93.4
Accrued broker fees	102.2	126.3
Customer deposits	67.9	52.7
Business process outsourcing administration fees	61.3	59.9
Accrued taxes	39.9	112.5
Operating lease liabilities	$ 38.5	$ 38.0
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Payables and accrued expenses	Payables and accrued expenses
Other	$ 50.2	$ 43.3
Total	$ 888.6	$ 1,194.4