Financial Data By Segment (Financial Data By Strategic Business Unit Segment) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	$ 2,807.0	$ 2,653.6	$ 5,521.0	$ 5,219.6
Earnings from Continuing Operations before Income Taxes	507.9	498.8	1,012.9	949.2
Employer Services [Member]
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	2,212.6	2,141.7	4,343.4	4,213.5
Earnings from Continuing Operations before Income Taxes	637.0	623.5	1,224.3	1,204.4
PEO Services [Member]
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	737.4	625.8	1,438.9	1,220.8
Earnings from Continuing Operations before Income Taxes	93.9	78.7	182.3	145.8
Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	(2.9)	17.6	7.8	36.7
Earnings from Continuing Operations before Income Taxes	(82.9)	(71.9)	(124.6)	(149.6)
Client Fund Interest [Member]
Segment Reporting Information [Line Items]
Revenues from Continuing Operations	(140.1)	(131.5)	(269.1)	(251.4)
Earnings from Continuing Operations before Income Taxes	$ (140.1)	$ (131.5)	$ (269.1)	$ (251.4)

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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