Corporate Investments And Funds Held For Clients (Corporate Investments And Funds Held For Clients) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Jun. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Money market securities and other cash equivalents - Amortized Cost	$ 6,819.9	$ 5,111.1
Money market securities and other cash equivalents - Fair Value	6,819.9	5,111.1
Total available-for-sale securities - Amortized Cost	17,738.4	17,382.9
Total available-for-sale securities - Gross Unrealized Gains	722.7	713.2
Total available-for-sale securities - Gross Unrealized Losses	(4.8)	(2.7)
Total available-for-sale securities - Fair Value	18,456.3	18,093.4
Total corporate investments and funds held for clients - Amortized Cost	24,558.3	22,494.0
Total corporate investments and funds held for clients - Gross Unrealized Gains	722.7	713.2
Total corporate investments and funds held for clients - Gross Unrealized Losses	(4.8)	(2.7)
Total corporate investments and funds held for clients - Fair Value	25,276.2	23,204.5
U.S. Treasury And Direct Obligations Of U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	6,541.9	6,413.8
Total available-for-sale securities - Gross Unrealized Gains	251.8	260.9
Total available-for-sale securities - Gross Unrealized Losses	(1.2)	(0.1)
Total available-for-sale securities - Fair Value	6,792.5	6,674.6
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	7,055.9	7,097.2
Total available-for-sale securities - Gross Unrealized Gains	301.3	272.3
Total available-for-sale securities - Gross Unrealized Losses	(1.3)	(1.5)
Total available-for-sale securities - Fair Value	7,355.9	7,368.0
Canadian Provincial Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	660.1	620.8
Total available-for-sale securities - Gross Unrealized Gains	36.3	35.4
Total available-for-sale securities - Gross Unrealized Losses	(0.2)	(0.3)
Total available-for-sale securities - Fair Value	696.2	655.9
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	772.8	533.9
Total available-for-sale securities - Gross Unrealized Gains	13.4	14.5
Total available-for-sale securities - Gross Unrealized Losses	(0.2)	0
Total available-for-sale securities - Fair Value	786.0	548.4
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	523.9	522.0
Total available-for-sale securities - Gross Unrealized Gains	29.2	31.0
Total available-for-sale securities - Gross Unrealized Losses	(0.4)	(0.1)
Total available-for-sale securities - Fair Value	552.7	552.9
Canadian Government Obligations And Canadian Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	1,040.1	994.2
Total available-for-sale securities - Gross Unrealized Gains	17.6	23.4
Total available-for-sale securities - Gross Unrealized Losses	(1.3)	(0.6)
Total available-for-sale securities - Fair Value	1,056.4	1,017.0
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	1,143.7	1,201.0
Total available-for-sale securities - Gross Unrealized Gains	73.1	75.7
Total available-for-sale securities - Gross Unrealized Losses	(0.2)	(0.1)
Total available-for-sale securities - Fair Value	$ 1,216.6	$ 1,276.6