Corporate Investments and Funds Held for Clients - Schedule of Investment of Funds Held for Clients (Details) - USD ($) $ in Millions	Dec. 31, 2025		Jun. 30, 2025	Dec. 31, 2024	[1]
Debt Securities, Available-for-sale [Line Items]
Restricted cash and cash equivalents held to satisfy client funds obligations	$ 31,237.0	[1]	$ 1,706.8	$ 14,387.8
Total funds held for clients	67,510.1		30,985.7
Current
Debt Securities, Available-for-sale [Line Items]
Restricted short-term and long term marketable securities held to satisfy client funds obligations	7,584.8		3,155.7
Non-current
Debt Securities, Available-for-sale [Line Items]
Restricted short-term and long term marketable securities held to satisfy client funds obligations	$ 28,688.3		$ 26,123.2

[1] See Note 7 for a reconciliation of restricted cash and restricted cash equivalents in funds held for clients on the Consolidated Balance Sheets.