Goodwill And Intangible Assets, Net (Changes In Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Goodwill [Roll Forward]
Beginning balance	$ 1,741.0	$ 1,682.0
Additions and other adjustments	494.9	73.4
Currency translation adjustments	7.6	7.0
Disposition of business		(21.4)
Ending balance	2,243.5	1,741.0
Employer Services [Member]
Goodwill [Roll Forward]
Beginning balance	1,736.2	1,677.2
Additions and other adjustments	494.9	73.4
Currency translation adjustments	7.6	7.0
Disposition of business		(21.4)
Ending balance	2,238.7	1,736.2
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
Disposition of business		0.0
Ending balance	$ 4.8	$ 4.8