Corporate Investments And Funds Held For Clients (Available-For-Sale Securities That Have Been In An Unrealized Loss Position) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Jun. 30, 2015
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	$ (6.1)	$ (40.3)
Fair market value of securities in unrealized loss position less than 12 months	1,234.2	4,242.9
Unrealized losses greater than 12 months	(2.2)	(8.3)
Fair market value of securities in unrealized loss positions greater than 12 months	785.3	1,075.4
Total gross unrealized losses	(8.3)	(48.6)
Total fair market value	2,019.5	5,318.3
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(4.4)	(27.3)
Fair market value of securities in unrealized loss position less than 12 months	499.2	2,403.5
Unrealized losses greater than 12 months	(0.7)	(2.3)
Fair market value of securities in unrealized loss positions greater than 12 months	188.8	228.1
Total gross unrealized losses	(5.1)	(29.6)
Total fair market value	688.0	2,631.6
U.S. Treasury and direct obligations of U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.3)	(7.2)
Fair market value of securities in unrealized loss position less than 12 months	127.8	865.1
Unrealized losses greater than 12 months	(0.1)	(2.6)
Fair market value of securities in unrealized loss positions greater than 12 months	224.9	374.0
Total gross unrealized losses	(0.4)	(9.8)
Total fair market value	352.7	1,239.1
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.7)	(3.2)
Fair market value of securities in unrealized loss position less than 12 months	419.8	606.8
Unrealized losses greater than 12 months	(1.1)	(2.9)
Fair market value of securities in unrealized loss positions greater than 12 months	350.8	443.6
Total gross unrealized losses	(1.8)	(6.1)
Total fair market value	770.6	1,050.4
Canadian government obligations and Canadian government agency obligations
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.1)	(0.2)
Fair market value of securities in unrealized loss position less than 12 months	66.0	85.8
Unrealized losses greater than 12 months	0.0	0.0
Fair market value of securities in unrealized loss positions greater than 12 months	0.0	0.0
Total gross unrealized losses	(0.1)	(0.2)
Total fair market value	66.0	85.8
Canadian provincial bonds
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.2)	(0.8)
Fair market value of securities in unrealized loss position less than 12 months	63.6	101.5
Unrealized losses greater than 12 months	0.0	0.0
Fair market value of securities in unrealized loss positions greater than 12 months	10.0	10.0
Total gross unrealized losses	(0.2)	(0.8)
Total fair market value	73.6	111.5
Municipal bonds
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.2)	(1.2)
Fair market value of securities in unrealized loss position less than 12 months	30.8	143.6
Unrealized losses greater than 12 months	(0.2)	(0.2)
Fair market value of securities in unrealized loss positions greater than 12 months	6.3	6.0
Total gross unrealized losses	(0.4)	(1.4)
Total fair market value	37.1	149.6
Other securities
Schedule of Available-for-sale Securities [Line Items]
Unrealized losses less than 12 months	(0.2)	(0.4)
Fair market value of securities in unrealized loss position less than 12 months	27.0	36.6
Unrealized losses greater than 12 months	(0.1)	(0.3)
Fair market value of securities in unrealized loss positions greater than 12 months	4.5	13.7
Total gross unrealized losses	(0.3)	(0.7)
Total fair market value	$ 31.5	$ 50.3