Corporate Investments and Funds Held for Clients - Expected Maturities of Available-For-Sale Securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Jun. 30, 2024
Investments, Debt and Equity Securities [Abstract]
One year or less	$ 6,807.9
One year to two years	7,555.4
Two years to three years	4,061.8
Three years to four years	5,502.4
After four years	9,092.4
Total available-for-sale securities	$ 33,019.9	$ 31,207.5