Corporate Investments and Funds Held for Clients - Classification of Corporate Investments on the Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Corporate Investments And Funds Held For Clients [Abstract]
Cash and cash equivalents	$ 4,230.1	$ 3,347.8	$ 2,913.4
Short-term marketable securities (a)	0.0	4,498.8
Long-term marketable securities	138.6	0.0
Total corporate investments	$ 4,368.7	$ 7,846.6