Corporate Investments and Funds Held for Clients - Narrative (Details) - USD ($)	9 Months Ended
	Mar. 31, 2025	Jun. 30, 2024
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 33,856,600,000	$ 31,207,500,000
Client fund obligation repayment period	1 year
Client funds obligations	$ 40,063,200,000	39,503,900,000
Client funds held in grantor trust	$ 35,394,900,000	34,940,000,000
Client funds investments with original maturities	90 days
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
Asset-Backed Auto Loan Receivables
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	816,000,000.0
Fixed Rate Credit Card
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	536,100,000
Asset-Backed Equipment Lease Receivable
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	211,800,000
Federal Farm Credit Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	965,900,000
Federal Home Loan Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	486,800,000
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	445,600,000	$ 500,800,000
Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	532,100,000
Debt Security, Corporate, Non-US
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	330,700,000
Supranational Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 227,700,000