Goodwill And Intangible Assets, Net - Changes in Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Goodwill [Roll Forward]
Beginning balance	$ 2,339.4	$ 2,300.5
Additions and other adjustments	24.4	26.2
Currency translation adjustments	(10.2)	12.7
Ending balance	2,353.6	2,339.4
Employer Services
Goodwill [Roll Forward]
Beginning balance	2,334.6	2,295.7
Additions and other adjustments	24.4	26.2
Currency translation adjustments	(10.2)	12.7
Ending balance	2,348.8	2,334.6
PEO Services
Goodwill [Roll Forward]
Beginning balance	4.8	4.8
Additions and other adjustments	0.0	0.0
Currency translation adjustments	0.0	0.0
Ending balance	$ 4.8	$ 4.8