Corporate Investments and Funds Held For Clients (Narrative) (Details) - USD ($)	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 25,292,700,000	$ 24,371,700,000
Client fund obligation repayment period	1 year
Client funds obligations	$ 46,437,100,000	34,403,800,000
Client funds held in grantor trust	$ 43,364,800,000	31,092,300,000
Client funds investments with original maturities	ninety days or less
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	1,196,500,000
Fixed Rate Credit Card
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	806,000,000
Asset-Backed Equipment Lease Receivable
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	239,600,000
Rate Reduction
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	64,100,000
Federal Farm Credit Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	822,000,000
Federal Home Loan Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	530,700,000
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	873,100,000	$ 834,600,000
Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	550,600,000
Debt Security, Corporate, Non-US
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 237,000,000