Corporate Investments and Funds Held for Clients (Expected Maturities of Available-For-Sale Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Jun. 30, 2023
Corporate Investments And Funds Held For Clients [Abstract]
One year or less	$ 6,208.3
One year to two years	6,246.6
Two years to three years	7,275.3
Three years to four years	2,980.7
After four years	6,889.5
Total available-for-sale securities	$ 29,600.4	$ 29,764.9