Interim Financial Data by Segment (Financial Data By Strategic Business Unit Segment) (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 4,215.6	$ 3,832.3
Earnings before Income Taxes	1,010.0	900.8
Employer Services
Segment Reporting Information [Line Items]
Revenues	2,790.2	2,571.5
Earnings before Income Taxes	863.5	784.0
PEO Services
Segment Reporting Information [Line Items]
Revenues	1,429.4	1,264.1
Earnings before Income Taxes	230.3	193.0
Other
Segment Reporting Information [Line Items]
Revenues	(4.0)	(3.3)
Earnings before Income Taxes	$ (83.8)	$ (76.2)