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	3 Months Ended	12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	$ (103.1)	$ (131.1)
Fair market value of securities in unrealized loss position less than 12 months	5,529.6	6,142.0
Unrealized losses greater than 12 months	(1.2)
Fair market value of securities in unrealized loss positions greater than 12 months	16.1
Total available for sale securities - Unrealized Loss	(104.3)	(131.1)
Total fair market value of securities in unrealized loss position	5,545.7	6,142.0
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(41.7)	(56.7)
Fair market value of securities in unrealized loss position less than 12 months	2,224.3	2,724.9
Unrealized losses greater than 12 months	(1.2)
Fair market value of securities in unrealized loss positions greater than 12 months	15.3
Total available for sale securities - Unrealized Loss	(42.9)	(56.7)
Total fair market value of securities in unrealized loss position	2,239.6	2,724.9
US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(32.6)	(37.4)
Fair market value of securities in unrealized loss position less than 12 months	1,361.7	1,374.6
Total available for sale securities - Unrealized Loss	(32.6)	(37.4)
Total fair market value of securities in unrealized loss position	1,361.7	1,374.6
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(14.3)	(19.7)
Fair market value of securities in unrealized loss position less than 12 months	1,001.9	1,060.1
Total available for sale securities - Unrealized Loss	(14.3)	(19.7)
Total fair market value of securities in unrealized loss position	1,001.9	1,060.1
Canadian Government Obligations And Canadian Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(3.6)	(4.5)
Fair market value of securities in unrealized loss position less than 12 months	456.8	444.7
Total available for sale securities - Unrealized Loss	(3.6)	(4.5)
Total fair market value of securities in unrealized loss position	456.8	444.7
Canadian Provincial Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(5.1)	(5.6)
Fair market value of securities in unrealized loss position less than 12 months	240.8	239.7
Total available for sale securities - Unrealized Loss	(5.1)	(5.6)
Total fair market value of securities in unrealized loss position	240.8	239.7
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(3.6)	(4.4)
Fair market value of securities in unrealized loss position less than 12 months	155.0	188.7
Unrealized losses greater than 12 months	0
Fair market value of securities in unrealized loss positions greater than 12 months	0.8
Total available for sale securities - Unrealized Loss	(3.6)	(4.4)
Total fair market value of securities in unrealized loss position	155.8	188.7
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(2.2)	(2.8)
Fair market value of securities in unrealized loss position less than 12 months	89.1	109.3
Total available for sale securities - Unrealized Loss	(2.2)	(2.8)
Total fair market value of securities in unrealized loss position	$ 89.1	$ 109.3