Financial Data By Segment (Financial Data By Strategic Business Unit Segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 2,982.8	$ 2,747.8	$ 5,822.5	$ 5,385.3
Earnings from Continuing Operations before Income Taxes	561.1	528.8	1,058.4	994.4
Employer Services [Member]
Segment Reporting Information [Line Items]
Revenues	2,087.0	1,918.2	4,055.0	3,737.1
Earnings from Continuing Operations before Income Taxes	595.8	514.6	1,118.4	969.7
PEO Services [Member]
Segment Reporting Information [Line Items]
Revenues	531.1	465.7	1,036.1	917.6
Earnings from Continuing Operations before Income Taxes	59.5	49.9	111.3	96.2
Dealer Services [Member]
Segment Reporting Information [Line Items]
Revenues	484.2	452.5	957.0	892.6
Earnings from Continuing Operations before Income Taxes	104.7	96.2	201.5	182.1
Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues	(0.2)	0.5	0.1	1.2
Earnings from Continuing Operations before Income Taxes	(79.6)	(42.8)	(147.1)	(90.4)
Client Fund Interest [Member]
Segment Reporting Information [Line Items]
Revenues	(119.3)	(89.1)	(225.7)	(163.2)
Earnings from Continuing Operations before Income Taxes	$ (119.3)	$ (89.1)	$ (225.7)	$ (163.2)