Goodwill and Intangibles Assets, net (Changes In Goodwill) (Details) $ in Millions	3 Months Ended
	Sep. 30, 2019 USD ($)
Goodwill [Roll Forward]
Balance at June 30, 2019	$ 2,323.0
Additions and other adjustments	(3.3)
Currency translation adjustments	(16.4)
Balance at September 30, 2019	2,303.3
Employer Services
Goodwill [Roll Forward]
Balance at June 30, 2019	2,318.2
Additions and other adjustments	(3.3)
Currency translation adjustments	(16.4)
Balance at September 30, 2019	2,298.5
PEO Services
Goodwill [Roll Forward]
Balance at June 30, 2019	4.8
Additions and other adjustments	0.0
Currency translation adjustments	0.0
Balance at September 30, 2019	$ 4.8