Corporate Investments And Funds Held For Clients (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2018		Jun. 30, 2017
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	$ 22,776.2	[1]	$ 21,901.1
Earliest corporate bond maturity date	July 2018
Latest corporate bond maturity date	May 2026
Earliest non-callable debt maturity date	September 2018
Latest non-callable debt maturity date	March 2026
Client Fund Obligation repayment period	1 year
Client funds obligations	$ 27,493.5		27,189.4
Funds held for Clients Held-in Grantor Trust	$ 24,242.9
Client funds investments with original maturities	ninety days or less
Percentage of the available-for-sale securities were rated AAA or AA	80.00%
Federal Home Loan Banks [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	$ 1,889.5
Federal Farm Credit Banks [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	628.0
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	298.2
Foreign Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	198.8
Supranational Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	141.3
Fixed Rate Credit Card [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	2,033.6
Asset-Backed Auto Loan Receivables [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	1,784.4
Asset-Backed Equipment Lease Receivable [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	472.0
Rate Reduction Receivable [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	201.7
Sovereign Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	110.3
Funds Held For Clients [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	22,765.7		21,890.3
Corporate Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - fair value	$ 10.5		$ 10.8

[1] Included within available-for-sale securities are corporate investments with fair values of $10.5 million and funds held for clients with fair values of $22,765.7 million. All available-for-sale securities are included in Level 2 of the fair value hierarchy.