Financial Data By Segment (Financial Data By Strategic Business Unit Segment) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Revenues	$ 2,694.5	$ 3,024.3	$ 2,653.6	$ 2,566.1	$ 2,566.6	$ 2,817.8	$ 2,486.6	$ 2,355.4	$ 10,938.5	$ 10,226.4	$ 9,442.0
Earnings from Continuing Operations before Income Taxes	381.6	$ 739.9	$ 498.8	$ 450.4	357.0	$ 659.2	$ 460.5	$ 402.6	2,070.7	1,879.2	1,710.1
Assets from Continuing Operations	33,110.5				29,629.6				33,110.5	29,629.6	30,041.7
Capital Expenditures from continuing operations									171.2	161.0	129.4
Depreciation, Depletion and Amortization									$ 277.9	266.6	251.2
Number of Reportable Segments									2
Standard Reconciling Rate Between Actual Interest Income Earned And Interest Credited									4.50%
Employer Services [Member]
Segment Reporting Information [Line Items]
Revenues									$ 8,897.3	8,506.0	7,899.0
Earnings from Continuing Operations before Income Taxes									2,694.2	2,517.3	2,215.7
Assets from Continuing Operations	27,554.7				21,736.3				27,554.7	21,736.3	24,462.8
Capital Expenditures from continuing operations									95.2	90.8	76.1
Depreciation, Depletion and Amortization									226.6	216.6	190.3
PEO Services [Member]
Segment Reporting Information [Line Items]
Revenues									2,647.2	2,270.9	1,973.2
Earnings from Continuing Operations before Income Taxes									303.6	234.4	199.7
Assets from Continuing Operations	377.7				472.6				377.7	472.6	411.4
Capital Expenditures from continuing operations									1.3	0.9	0.6
Depreciation, Depletion and Amortization									1.2	1.2	1.2
Other [Member]
Segment Reporting Information [Line Items]
Revenues									(12.4)	(0.9)	1.7
Earnings from Continuing Operations before Income Taxes									(333.5)	(322.9)	(273.4)
Assets from Continuing Operations	5,178.1				7,420.7				5,178.1	7,420.7	5,167.5
Capital Expenditures from continuing operations									74.7	69.3	52.7
Depreciation, Depletion and Amortization									50.1	48.8	59.7
Client Fund Interest [Member]
Segment Reporting Information [Line Items]
Revenues									(593.6)	(549.6)	(431.9)
Earnings from Continuing Operations before Income Taxes									(593.6)	(549.6)	(431.9)
Assets from Continuing Operations	$ 0.0				$ 0.0				0.0	0.0	0.0
Capital Expenditures from continuing operations									0.0	0.0	0.0
Depreciation, Depletion and Amortization									$ 0.0	$ 0.0	$ 0.0