Corporate Investments and Funds Held for Clients - Expected Maturities of Available-For-Sale Securities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Jun. 30, 2023
Corporate Investments And Funds Held For Clients [Abstract]
One year or less	$ 6,504.0
One year to two years	6,799.5
Two years to three years	7,078.7
Three years to four years	2,336.7
After four years	7,576.6
Total available-for-sale securities	$ 30,295.5	$ 29,764.9