Corporate Investments And Funds Held For Clients (Available-For-Sale Securities That Have Been In An Unrealized Loss Position) (Details) (USD $) In Millions	Sep. 30, 2011	Jun. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than twelve months	$ (7.8)	$ (34.6)
Fair market value less than twelve months	713.2	2,517.0
Available-for-sale securities - gross unrealized losses	(7.8)	(34.6)
Total fair market value	713.2	2,517.0
U.S. Treasury And Direct Obligations Of U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than twelve months	(1.0)	(12.1)
Fair market value less than twelve months	182.5	1,049.0
Available-for-sale securities - gross unrealized losses	(1.0)	(12.1)
Total fair market value	182.5	1,049.0
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than twelve months	(6.4)	(16.9)
Fair market value less than twelve months	470.4	945.2
Available-for-sale securities - gross unrealized losses	(6.4)	(16.9)
Total fair market value	470.4	945.2
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair market value less than twelve months	2.6	0.5
Total fair market value	2.6	0.5
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair market value less than twelve months	28.2	17.3
Total fair market value	28.2	17.3
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than twelve months	(0.1)	(0.6)
Fair market value less than twelve months	5.3	35.0
Available-for-sale securities - gross unrealized losses	(0.1)	(0.6)
Total fair market value	5.3	35.0
Canadian Government Obligations And Canadian Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than twelve months		(1.3)
Fair market value less than twelve months	6.7	227.7
Available-for-sale securities - gross unrealized losses		(1.3)
Total fair market value	6.7	227.7
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than twelve months	(0.3)	(3.7)
Fair market value less than twelve months	17.5	242.3
Available-for-sale securities - gross unrealized losses	(0.3)	(3.7)
Total fair market value	$ 17.5	$ 242.3