Goodwill and Intangibles Assets, net (Changes In Goodwill) (Details) $ in Millions	9 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
Balance at June 30, 2018	$ 2,243.5
Additions and other adjustments	89.1
Currency translation adjustments	(16.5)
Balance at March 31, 2019	2,316.1
Employer Services
Goodwill [Roll Forward]
Balance at June 30, 2018	2,238.7
Additions and other adjustments	89.1
Currency translation adjustments	(16.5)
Balance at March 31, 2019	2,311.3
PEO Services
Goodwill [Roll Forward]
Balance at June 30, 2018	4.8
Additions and other adjustments	0.0
Currency translation adjustments	0.0
Balance at March 31, 2019	$ 4.8