Financial Data By Segment (Financial Data By Strategic Business Unit Segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information [Line Items]
Revenues	$ 3,073.7	$ 3,320.0	$ 2,977.9	$ 2,834.8	$ 2,802.8	$ 3,109.3	$ 2,742.8	$ 2,632.7	$ 12,206.5	$ 11,287.6	$ 10,595.4
Earnings from Continuing Operations before Income Taxes									2,274.6	2,076.1	2,101.7
Assets from Continuing Operations	32,051.7				32,251.4				32,051.7	32,251.4	30,673.6
Capital Expenditures from continuing operations									218.7	174.8	146.2
Depreciation, Depletion and Amortization									336.2	316.7	319.3
Number of Reportable Segments									3
Standard Reconciling Rate Between Actual Interest Income Earned And Interest Credited									4.50%
Employer Services [Member]
Segment Reporting Information [Line Items]
Revenues									8,535.2	7,924.9	7,449.4
Earnings from Continuing Operations before Income Taxes									2,517.8	2,216.8	2,054.6
Assets from Continuing Operations	21,382.2				24,158.2				21,382.2	24,158.2	23,308.0
Capital Expenditures from continuing operations									59.7	57.9	39.9
Depreciation, Depletion and Amortization									152.4	132.2	127.0
PEO Services [Member]
Segment Reporting Information [Line Items]
Revenues									2,270.9	1,973.2	1,771.4
Earnings from Continuing Operations before Income Taxes									234.3	199.7	171.1
Assets from Continuing Operations	472.6				411.4				472.6	411.4	376.5
Capital Expenditures from continuing operations									0.9	0.6	1.2
Depreciation, Depletion and Amortization									1.2	1.2	1.0
Dealer Services [Member]
Segment Reporting Information [Line Items]
Revenues									1,951.4	1,820.2	1,676.2
Earnings from Continuing Operations before Income Taxes									428.1	375.3	322.1
Assets from Continuing Operations	733.0				696.8				733.0	696.8	685.9
Capital Expenditures from continuing operations									43.6	35.1	39.7
Depreciation, Depletion and Amortization									64.7	61.2	57.7
Other [Member]
Segment Reporting Information [Line Items]
Revenues									(0.9)	1.7	5.5
Earnings from Continuing Operations before Income Taxes									(355.5)	(283.3)	(139.0)
Assets from Continuing Operations	9,463.9				6,985.0				9,463.9	6,985.0	6,303.2
Capital Expenditures from continuing operations									114.5	81.2	65.4
Depreciation, Depletion and Amortization									117.9	122.1	133.6
Client Fund Interest [Member]
Segment Reporting Information [Line Items]
Revenues									(550.1)	(432.4)	(307.1)
Earnings from Continuing Operations before Income Taxes									(550.1)	(432.4)	(307.1)
Assets from Continuing Operations	0				0				0	0	0
Capital Expenditures from continuing operations									0	0	0
Depreciation, Depletion and Amortization									$ 0	$ 0	$ 0