Corporate Investments And Funds Held For Clients (Corporate Investments And Funds Held For Clients) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Jun. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Money market securities and other cash equivalents - Amortized Cost	$ 13,107.0	$ 5,111.1
Money market securities and other cash equivalents - Fair Value	13,107.0	5,111.1
Total available-for-sale securities - Amortized Cost	18,331.6	17,382.9
Total available-for-sale securities - Gross Unrealized Gains	662.7	713.2
Total available-for-sale securities - Gross Unrealized Losses	(7.7)	(2.7)
Total available-for-sale securities - Fair Value	18,986.6	18,093.4
Total corporate investments and funds held for clients - Amortized Cost	31,438.6	22,494.0
Total corporate investments and funds held for clients - Gross Unrealized Gains	662.7	713.2
Total corporate investments and funds held for clients - Gross Unrealized Losses	(7.7)	(2.7)
Total corporate investments and funds held for clients - Fair Value	32,093.6	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	6,091.6	6,413.8
Total available-for-sale securities - Gross Unrealized Gains	224.1	260.9
Total available-for-sale securities - Gross Unrealized Losses	(2.4)	(0.1)
Total available-for-sale securities - Fair Value	6,313.3	6,674.6
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	7,652.2	7,097.2
Total available-for-sale securities - Gross Unrealized Gains	279.2	272.3
Total available-for-sale securities - Gross Unrealized Losses	(3.0)	(1.5)
Total available-for-sale securities - Fair Value	7,928.4	7,368.0
Canadian Provincial Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	698.4	620.8
Total available-for-sale securities - Gross Unrealized Gains	35.4	35.4
Total available-for-sale securities - Gross Unrealized Losses	(0.3)	(0.3)
Total available-for-sale securities - Fair Value	733.5	655.9
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	1,210.5	533.9
Total available-for-sale securities - Gross Unrealized Gains	11.3	14.5
Total available-for-sale securities - Gross Unrealized Losses	(1.1)	0
Total available-for-sale securities - Fair Value	1,220.7	548.4
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	529.4	522.0
Total available-for-sale securities - Gross Unrealized Gains	27.8	31.0
Total available-for-sale securities - Gross Unrealized Losses	(0.3)	(0.1)
Total available-for-sale securities - Fair Value	556.9	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	1,017.9	994.2
Total available-for-sale securities - Gross Unrealized Gains	17.3	23.4
Total available-for-sale securities - Gross Unrealized Losses	(0.3)	(0.6)
Total available-for-sale securities - Fair Value	1,034.9	1,017.0
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	1,131.6	1,201.0
Total available-for-sale securities - Gross Unrealized Gains	67.6	75.7
Total available-for-sale securities - Gross Unrealized Losses	(0.3)	(0.1)
Total available-for-sale securities - Fair Value	$ 1,198.9	$ 1,276.6