Corporate Investments And Funds Held For Clients (Available-For-Sale Securities That Have Been In An Unrealized Loss Position) (Details) (USD $) In Millions	Jun. 30, 2011	Jun. 30, 2010
Unrealized losses less than twelve months	$ (34.6)	$ (10.0)
Fair market value less than twelve months	2,517.0	263.6
Unrealized losses greater than twelve months		(0.2)
Fair market value greater than twelve months		6.5
Available-for-sale securities - gross unrealized losses	(34.6)	(10.2)
Total fair market value	2,517.0	270.1
U.S. Treasury And Direct Obligations Of U.S. Government Agencies [Member]
Unrealized losses less than twelve months	(12.1)
Fair market value less than twelve months	1,049.0	28.0
Unrealized losses greater than twelve months		(0.2)
Fair market value greater than twelve months		6.5
Available-for-sale securities - gross unrealized losses	(12.1)	(0.2)
Total fair market value	1,049.0	34.5
Corporate Bonds [Member]
Unrealized losses less than twelve months	(16.9)	(9.0)
Fair market value less than twelve months	945.2	210.5
Available-for-sale securities - gross unrealized losses	(16.9)	(9.0)
Total fair market value	945.2	210.5
Asset-Backed Securities [Member]
Fair market value less than twelve months	0.5	2.4
Total fair market value	0.5	2.4
Commercial Mortgage-Backed Securities [Member]
Fair market value less than twelve months	17.3	2.1
Total fair market value	17.3	2.1
Municipal Bonds [Member]
Unrealized losses less than twelve months	(0.6)
Fair market value less than twelve months	35.0	10.0
Available-for-sale securities - gross unrealized losses	(0.6)
Total fair market value	35.0	10.0
Canadian Government Obligations And Canadian Government Agency Obligations [Member]
Unrealized losses less than twelve months	(1.3)
Fair market value less than twelve months	227.7
Available-for-sale securities - gross unrealized losses	(1.3)
Total fair market value	227.7
Other Securities [Member]
Unrealized losses less than twelve months	(3.7)	(1.0)
Fair market value less than twelve months	242.3	10.6
Available-for-sale securities - gross unrealized losses	(3.7)	(1.0)
Total fair market value	$ 242.3	$ 10.6