Financial Data By Segment And Geographic Area (Financial Data By Strategic Business Unit Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenues	$ 15,005.4	$ 14,589.8	$ 14,110.2
Earnings before income taxes	3,361.2	3,182.6	3,005.6
Assets	48,772.5	39,165.5	41,887.7
Capital expenditures	178.3	168.3	162.7
Depreciation and amortization	510.7	480.0	409.0
Other
Segment Reporting Information [Line Items]
Revenues	(8.1)	(8.3)	(10.3)
Earnings before income taxes	(409.7)	(484.9)	(561.9)
Assets	(3,050.2)	650.6	5,697.3
Capital expenditures	61.6	52.6	64.5
Depreciation and amortization	81.6	88.6	84.5
Employer Services | Operating Segments
Segment Reporting Information [Line Items]
Revenues	10,195.2	10,086.6	9,942.8
Earnings before income taxes	3,052.1	3,058.2	2,954.2
Assets	50,279.3	37,071.7	34,606.3
Capital expenditures	116.7	115.7	98.2
Depreciation and amortization	421.7	388.0	321.0
PEO Services | Operating Segments
Segment Reporting Information [Line Items]
Revenues	4,818.3	4,511.5	4,177.7
Earnings before income taxes	718.8	609.3	613.3
Assets	1,543.4	1,443.2	1,584.1
Capital expenditures	0.0	0.0	0.0
Depreciation and amortization	$ 7.4	$ 3.4	$ 3.5