Corporate Investments and Funds Held for Clients - Expected Maturities of Available-For-Sale Securities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Jun. 30, 2024
Investments, Debt and Equity Securities [Abstract]
One year or less	$ 8,454.4
One year to two years	6,522.9
Two years to three years	4,144.1
Three years to four years	5,217.7
After four years	9,517.5
Total available-for-sale securities	$ 33,856.6	$ 31,207.5