Corporate Investments and Funds Held For Clients - Narrative (Details) - USD ($)	12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 33,777,700,000	$ 31,207,500,000
Client fund obligation repayment period	1 year
Client funds obligations	$ 31,343,300,000	39,503,900,000
Funds held for clients held-in grantor trust	$ 27,355,200,000
Client funds investments with original maturities	90 days
Asset Backed Auto Loan Receivables
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 824,800,000
Fixed Rate Credit Card
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	549,300,000
Asset-Backed Securities, Device Payment Plan Agreement Receivables
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	254,800,000
Federal Farm Credit Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	922,100,000
Federal Home Loan Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	267,200,000
Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	536,000,000.0
Debt Security, Corporate, Non-US
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	550,800,000
Commercial Mortgage-Backed Securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	438,600,000	$ 500,800,000
Supranational Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	230,300,000
Fair Value, Inputs, Level 1
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	0
Fair Value, Inputs, Level 3
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 0