Financial Data By Segment And Geographic Area (Financial Data By Strategic Business Unit Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 18,012.2	$ 16,498.3	$ 15,005.4
Earnings before income taxes	4,437.6	3,804.1	3,361.2
Capital expenditures	206.0	177.1	178.3
Depreciation and amortization	549.3	515.1	510.7
Other
Segment Reporting Information [Line Items]
Revenues	(14.6)	(15.1)	(8.1)
Earnings before income taxes	(513.9)	(473.4)	(409.7)
Capital expenditures	44.6	51.7	61.6
Depreciation and amortization	74.2	78.3	81.6
Employer Services | Operating Segments
Segment Reporting Information [Line Items]
Revenues	12,042.6	10,967.7	10,195.2
Earnings before income taxes	3,974.2	3,406.3	3,052.1
Capital expenditures	161.4	125.4	116.7
Depreciation and amortization	467.6	428.5	421.7
PEO Services | Operating Segments
Segment Reporting Information [Line Items]
Revenues	5,984.2	5,545.7	4,818.3
Earnings before income taxes	977.3	871.2	718.8
Capital expenditures	0.0	0.0	0.0
Depreciation and amortization	$ 7.5	$ 8.3	$ 7.4