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, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	$ 2,661.3	$ 2,493.7	$ 5,235.1	$ 4,855.7
Earnings from Continuing Operations before Income Taxes	501.1	462.0	953.6	865.6
Employer Services [Member]
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	2,169.9	2,082.1	4,269.0	4,045.3
Earnings from Continuing Operations before Income Taxes	627.4	596.0	1,211.5	1,119.3
PEO Services [Member]
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	625.8	531.1	1,220.8	1,036.1
Earnings from Continuing Operations before Income Taxes	78.7	59.5	145.4	111.4
Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	(2.7)	(0.2)	(2.9)	0
Earnings from Continuing Operations before Income Taxes	(73.3)	(74.2)	(151.5)	(139.4)
Client Fund Interest [Member]
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	(131.7)	(119.3)	(251.8)	(225.7)
Earnings from Continuing Operations before Income Taxes	$ (131.7)	$ (119.3)	$ (251.8)	$ (225.7)