Corporate Investments and Funds Held for Clients - Schedule of Investment of Funds Held for Clients (Details) - USD ($) $ in Millions	Dec. 31, 2023		Jun. 30, 2023	Dec. 31, 2022	[1]
Debt Securities, Available-for-sale [Line Items]
Restricted cash and cash equivalents held to satisfy client funds obligations	$ 12,238.0	[1]	$ 6,688.0	$ 11,937.5
Total funds held for clients	42,509.1		36,333.6
Current
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, restricted	6,479.6		5,601.9
Non-current
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, restricted	$ 23,791.5		$ 24,043.7

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