Corporate Investments and Funds Held for Clients - Schedule of Investment of Funds Held for Clients (Details) - USD ($) $ in Millions	Sep. 30, 2024		Jun. 30, 2024	Sep. 30, 2023	[1]
Debt Securities, Available-for-sale [Line Items]
Restricted cash and cash equivalents held to satisfy client funds obligations	$ 686.6	[1]	$ 7,172.6	$ 5,520.5
Total funds held for clients	28,176.9		37,996.1
Current
Debt Securities, Available-for-sale [Line Items]
Restricted short-term and long term marketable securities held to satisfy client funds obligations	1,211.8		5,538.1
Non-current
Debt Securities, Available-for-sale [Line Items]
Restricted short-term and long term marketable securities held to satisfy client funds obligations	$ 26,278.5		$ 25,285.4

[1] See Note 6 for a reconciliation of restricted cash and restricted cash equivalents in funds held for clients on the Consolidated Balance Sheets.