Goodwill And Intangible Assets, Net (Changes In Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Goodwill [Roll Forward]
Beginning balance	$ 2,323.0	$ 2,243.5
Additions and other adjustments	(2.5)	94.3
Currency translation adjustments	(11.1)	(14.8)
Ending balance	2,309.4	2,323.0
Employer Services [Member]
Goodwill [Roll Forward]
Beginning balance	2,318.2	2,238.7
Additions and other adjustments	(2.5)	94.3
Currency translation adjustments	(11.1)	(14.8)
Ending balance	2,304.6	2,318.2
PEO Services [Member]
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