Corporate Investments And Funds Held For Clients (Corporate Investments And Funds Held For Clients) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Jun. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Money market securities and other cash equivalents - Amortized Cost	$ 3,725.9	$ 5,111.1
Money market securities and other cash equivalents - Fair Value	3,725.9	5,111.1
Total available-for-sale securities - Amortized Cost	17,611.0	17,382.9
Total available-for-sale securities - Gross Unrealized Gains	807.2	713.2
Total available-for-sale securities - Gross Unrealized Losses	(1.2)	(2.7)
Total available-for-sale securities - Fair Value	18,417.0	18,093.4
Total corporate investments and funds held for clients - Amortized Cost	21,336.9	22,494.0
Total corporate investments and funds held for clients - Gross Unrealized Gains	807.2	713.2
Total corporate investments and funds held for clients - Gross Unrealized Losses	(1.2)	(2.7)
Total corporate investments and funds held for clients - Fair Value	22,142.9	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	6,379.1	6,413.8
Total available-for-sale securities - Gross Unrealized Gains	273.8	260.9
Total available-for-sale securities - Gross Unrealized Losses	0	(0.1)
Total available-for-sale securities - Fair Value	6,652.9	6,674.6
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	7,239.2	7,097.2
Total available-for-sale securities - Gross Unrealized Gains	337.5	272.3
Total available-for-sale securities - Gross Unrealized Losses	(0.3)	(1.5)
Total available-for-sale securities - Fair Value	7,576.4	7,368.0
Canadian Provincial Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	653.2	620.8
Total available-for-sale securities - Gross Unrealized Gains	40.3	35.4
Total available-for-sale securities - Gross Unrealized Losses	0	(0.3)
Total available-for-sale securities - Fair Value	693.5	655.9
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	601.0	533.9
Total available-for-sale securities - Gross Unrealized Gains	15.9	14.5
Total available-for-sale securities - Gross Unrealized Losses	(0.1)	0
Total available-for-sale securities - Fair Value	616.8	548.4
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	522.2	522.0
Total available-for-sale securities - Gross Unrealized Gains	33.2	31.0
Total available-for-sale securities - Gross Unrealized Losses	0	(0.1)
Total available-for-sale securities - Fair Value	555.4	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	1,042.3	994.2
Total available-for-sale securities - Gross Unrealized Gains	21.7	23.4
Total available-for-sale securities - Gross Unrealized Losses	(0.6)	(0.6)
Total available-for-sale securities - Fair Value	1,063.4	1,017.0
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities - Amortized Cost	1,174.0	1,201.0
Total available-for-sale securities - Gross Unrealized Gains	84.8	75.7
Total available-for-sale securities - Gross Unrealized Losses	(0.2)	(0.1)
Total available-for-sale securities - Fair Value	$ 1,258.6	$ 1,276.6