Corporate Investments And Funds Held For Clients (Corporate Investments And Funds Held For Clients) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Jun. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Money market securities and other cash equivalents - Amortized Cost	$ 5,111.1	$ 9,731.8
Money market securities and other cash equivalents - Fair Value	5,111.1	9,731.8
Total available-for-sale securities - Amortized Cost	17,382.9	16,356.6
Total available-for-sale securities - Gross Unrealized Gains	713.2	605.5
Available-for-sale securities - Gross Unrealized Losses	(2.7)	(34.6)
Total available-for-sale securities - Fair Value	18,093.4	16,927.5
Total corporate investments and funds held for clients - Amortized Cost	22,494.0	26,088.4
Total corporate investments and funds held for clients - Gross Unrealized Gains	713.2	605.5
Total corporate investments and funds held for clients - Gross Unrealized Losses	(2.7)	(34.6)
Total corporate investments and funds held for clients - Fair Value	23,204.5	26,659.3
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	6,413.8	6,558.2
Total available-for-sale securities - Gross Unrealized Gains	260.9	213.0
Available-for-sale securities - Gross Unrealized Losses	(0.1)	(12.1)
Total available-for-sale securities - Fair Value	6,674.6	6,759.1
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	7,097.2	5,908.6
Total available-for-sale securities - Gross Unrealized Gains	272.3	234.9
Available-for-sale securities - Gross Unrealized Losses	(1.5)	(16.9)
Total available-for-sale securities - Fair Value	7,368.0	6,126.6
Canadian Provincial Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	620.8	480.0
Total available-for-sale securities - Gross Unrealized Gains	35.4	15.1
Available-for-sale securities - Gross Unrealized Losses	(0.3)	(0.8)
Total available-for-sale securities - Fair Value	655.9	494.3
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	533.9	422.4
Total available-for-sale securities - Gross Unrealized Gains	14.5	25.4
Total available-for-sale securities - Fair Value	548.4	447.8
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	522.0	493.7
Total available-for-sale securities - Gross Unrealized Gains	31.0	23.1
Available-for-sale securities - Gross Unrealized Losses	(0.1)	(0.6)
Total available-for-sale securities - Fair Value	552.9	516.2
Canadian Government Obligations And Canadian Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	994.2	1,082.0
Total available-for-sale securities - Gross Unrealized Gains	23.4	20.8
Available-for-sale securities - Gross Unrealized Losses	(0.6)	(1.3)
Total available-for-sale securities - Fair Value	1,017.0	1,101.5
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	1,201.0	1,411.7
Total available-for-sale securities - Gross Unrealized Gains	75.7	73.2
Available-for-sale securities - Gross Unrealized Losses	(0.1)	(2.9)
Total available-for-sale securities - Fair Value	$ 1,276.6	$ 1,482.0