Goodwill and Intangible Assets, net - Changes In Goodwill (Details) $ in Millions	6 Months Ended
	Dec. 31, 2021 USD ($)
Goodwill [Roll Forward]
Balance at June 30, 2020	$ 2,338.4
Additions and other adjustments	11.5
Currency translation adjustments	(19.2)
Balance at December 31, 2021	2,330.7
Employer Services
Goodwill [Roll Forward]
Balance at June 30, 2020	2,333.6
Additions and other adjustments	11.5
Currency translation adjustments	(19.2)
Balance at December 31, 2021	2,325.9
PEO Services
Goodwill [Roll Forward]
Balance at June 30, 2020	4.8
Additions and other adjustments	0.0
Currency translation adjustments	0.0
Balance at December 31, 2021	$ 4.8