Corporate Investments nd Funds Held For Clients (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Dec. 31, 2016		Jun. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Earliest Corporate bond debt maturity date	January 2017
Latest corporate debt maturity date	May 2024
Available-for-sale securities - Fair Market Value	$ 21,458.7	[1]	$ 21,605.0	[2]
Length of shortest cash flow of residential mortgages used as collateral for companies mortgage backed securities (in years)	15 years
Length of longest cash flow of residential mortgages used as collateral for company's mortgage backed securities (in years)	30 years
Client Fund obligation repayment period	1 year
Client funds obligations	$ 30,402.6		33,331.8
Client funds investments with original maturities	ninety days or less
Percentage of the available-for-sale securities were rated AAA Or AA	81.00%
Earliest U.S. Treasury maturity date	January 2017
Latest U.S Treasury maturity date	October 2024
Federal Home Loan Banks [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	$ 2,778.3
Federal Farm Credit Banks [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	837.9
Fixed Rate Credit Card [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	2,307.2
Asset-Backed Auto Loan Receivables [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	1,321.4
Asset-Backed Equipment Lease Receivable [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	380.5
Rate Reduction [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	244.5
Supranational Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	153.2
Sovereign Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	148.5
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	98.2
Fair Value, Inputs, Level 1 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	0.0		0.0
Fair Value, Inputs, Level 3 [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities - Fair Market Value	$ 0.0		$ 0.0

[1] Included within available-for-sale securities are corporate investments with fair values of $48.6 million and funds held for clients with fair values of $21,410.1 million. All available-for-sale securities were included in Level 2 of the fair value hierarchy.

[2] Included within available-for-sale securities are corporate investments with fair values of $31.3 million and funds held for clients with fair values of $21,573.7 million. All available-for-sale securities were included in Level 2 of the fair value hierarchy.