Corporate Investments and Funds Held for Clients - Narrative (Details) - USD ($)	3 Months Ended
	Sep. 30, 2024	Jun. 30, 2024
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 33,673,100,000	$ 31,207,500,000
Client fund obligation repayment period	1 year
Client funds obligations	$ 28,720,900,000	39,503,900,000
Client funds held in grantor trust	$ 25,338,300,000	34,940,000,000
Client funds investments with original maturities	90 years
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	759,500,000
Fixed Rate Credit Card
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	486,800,000
Asset-Backed Equipment Lease Receivable
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	189,500,000
Federal Farm Credit Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	969,000,000.0
Federal Home Loan Banks
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	482,200,000
Commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	487,900,000	$ 500,800,000
Municipal Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	543,200,000
Debt Security, Corporate, Non-US
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	313,000,000.0
Supranational Bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale	$ 218,300,000