Goodwill and Intangibles Assets, net - Changes In Goodwill (Details) $ in Millions	6 Months Ended
	Dec. 31, 2019 USD ($)
Goodwill [Roll Forward]
Balance at June 30, 2019	$ 2,323.0
Additions and other adjustments	(2.5)
Currency translation adjustments	(5.6)
Balance at December 31, 2019	2,314.9
Employer Services
Goodwill [Roll Forward]
Balance at June 30, 2019	2,318.2
Additions and other adjustments	(2.5)
Currency translation adjustments	(5.6)
Balance at December 31, 2019	2,310.1
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 December 31, 2019	$ 4.8