Corporate Investments and Funds Held for Clients (Narrative) (Details) - USD ($)	3 Months Ended
	Sep. 30, 2023	Jun. 30, 2023
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 29,600,400,000	$ 29,764,900,000
Client fund obligation repayment period	1 year
Client funds obligations	$ 37,098,800,000	38,538,600,000
Client funds held in grantor trust	$ 31,932,500,000	32,758,100,000
Client funds investments with original maturities	ninety
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	522,300,000
Fixed Rate Credit Card
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	352,100,000
Asset-Backed Equipment Lease Receivable
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	168,300,000
Federal Farm Credit Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	952,300,000
Federal Home Loan Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	442,100,000
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	609,800,000	$ 632,500,000
Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	521,200,000
Debt Security, Corporate, Non-US
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	375,500,000
Supranational Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 203,200,000