Corporate Investments And Funds Held For Clients (Available-For-Sale Securities That Have Been In An Unrealized Loss Position) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Jun. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	$ (131.1)	$ (2.3)
Fair market value of securities in unrealized loss position less than 12 months	6,142.0	609.0
Unrealized losses greater than 12 months	0	(0.4)
Fair market value of securities in unrealized loss positions greater than 12 months	0	20.2
Total gross unrealized losses	(131.1)	(2.7)
Total fair market value of securities in unrealized loss position	6,142.0	629.2
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(56.7)	(1.1)
Fair market value of securities in unrealized loss position less than 12 months	2,724.9	234.8
Unrealized losses greater than 12 months		(0.4)
Fair market value of securities in unrealized loss positions greater than 12 months		20.2
Total gross unrealized losses	(56.7)	(1.5)
Total fair market value of securities in unrealized loss position	2,724.9	255.0
U.S. Treasury And Direct Obligations Of U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(37.4)	(0.1)
Fair market value of securities in unrealized loss position less than 12 months	1,374.6	43.6
Total gross unrealized losses	(37.4)	(0.1)
Total fair market value of securities in unrealized loss position	1,374.6	43.6
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(19.7)
Fair market value of securities in unrealized loss position less than 12 months	1,060.1	13.6
Total gross unrealized losses	(19.7)	0
Total fair market value of securities in unrealized loss position	1,060.1	13.6
Canadian Government Obligations And Canadian Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(4.5)	(0.6)
Fair market value of securities in unrealized loss position less than 12 months	444.7	209.4
Total gross unrealized losses	(4.5)	(0.6)
Total fair market value of securities in unrealized loss position	444.7	209.4
Canadian Provincial Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(5.6)	(0.3)
Fair market value of securities in unrealized loss position less than 12 months	239.7	58.5
Total gross unrealized losses	(5.6)	(0.3)
Total fair market value of securities in unrealized loss position	239.7	58.5
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(4.4)	(0.1)
Fair market value of securities in unrealized loss position less than 12 months	188.7	22.8
Total gross unrealized losses	(4.4)	(0.1)
Total fair market value of securities in unrealized loss position	188.7	22.8
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(2.8)	(0.1)
Fair market value of securities in unrealized loss position less than 12 months	109.3	26.3
Total gross unrealized losses	(2.8)	(0.1)
Total fair market value of securities in unrealized loss position	$ 109.3	$ 26.3