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, 2012	Jun. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	$ (2.3)	$ (34.6)
Fair market value less than 12 months	609.0	2,517.0
Unrealized losses greater than 12 months	(0.4)
Fair market value greater than 12 months	20.2
Total gross unrealized losses	(2.7)	(34.6)
Total fair market value	629.2	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 12 months	(0.1)	(12.1)
Fair market value less than 12 months	43.6	1,049.0
Unrealized losses greater than 12 months
Fair market value greater than 12 months
Total gross unrealized losses	(0.1)	(12.1)
Total fair market value	43.6	1,049.0
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(1.1)	(16.9)
Fair market value less than 12 months	234.8	945.2
Unrealized losses greater than 12 months	(0.4)
Fair market value greater than 12 months	20.2
Total gross unrealized losses	(1.5)	(16.9)
Total fair market value	255.0	945.2
Canadian Provincial Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.3)	(0.8)
Fair market value less than 12 months	58.5	88.5
Unrealized losses greater than 12 months
Fair market value greater than 12 months
Total gross unrealized losses	(0.3)	(0.8)
Total fair market value	58.5	88.5
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair market value less than 12 months	13.6	0.5
Unrealized losses greater than 12 months
Fair market value greater than 12 months
Total fair market value	13.6	0.5
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.1)	(0.6)
Fair market value less than 12 months	22.8	35.0
Unrealized losses greater than 12 months
Fair market value greater than 12 months
Total gross unrealized losses	(0.1)	(0.6)
Total fair market value	22.8	35.0
Canadian Government Obligations And Canadian Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.6)	(1.3)
Fair market value less than 12 months	209.4	227.7
Unrealized losses greater than 12 months
Fair market value greater than 12 months
Total gross unrealized losses	(0.6)	(1.3)
Total fair market value	209.4	227.7
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.1)	(2.9)
Fair market value less than 12 months	26.3	171.1
Unrealized losses greater than 12 months
Fair market value greater than 12 months
Total gross unrealized losses	(0.1)	(2.9)
Total fair market value	$ 26.3	$ 171.1