Interim Financial Data By Segment (Financial Data By Strategic Business Unit Segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Segment Reporting Information [Line Items]
Revenues	$ 2,637.5	$ 2,510.9
Earnings from Continuing Operations before Income Taxes	465.6	455.7
Employer Services [Member]
Segment Reporting Information [Line Items]
Revenues	1,819.0	1,708.9
Earnings from Continuing Operations before Income Taxes	421.8	407.2
PEO Services [Member]
Segment Reporting Information [Line Items]
Revenues	451.9	400.5
Earnings from Continuing Operations before Income Taxes	46.2	36.7
Dealer Services [Member]
Segment Reporting Information [Line Items]
Revenues	439.8	402.6
Earnings from Continuing Operations before Income Taxes	76.0	63.4
Other [Member]
Segment Reporting Information [Line Items]
Revenues	0.7	2.8
Earnings from Continuing Operations before Income Taxes	(34.0)	(30.9)
Foreign Exchange [Member]
Segment Reporting Information [Line Items]
Revenues	0.2	44.8
Earnings from Continuing Operations before Income Taxes	1.2	(0.7)
Client Fund Interest [Member]
Segment Reporting Information [Line Items]
Revenues	(74.1)	(48.7)
Earnings from Continuing Operations before Income Taxes	(74.1)	(48.7)
Cost Of Capital Charge [Member]
Segment Reporting Information [Line Items]
Earnings from Continuing Operations before Income Taxes	$ 28.5	$ 28.7