Goodwill and Intangibles Assets, net (Changes In Goodwill) (Details) $ in Millions	6 Months Ended
	Dec. 31, 2016 USD ($)
Goodwill [Roll Forward]
Balance at June 30, 2016	$ 1,682.0
Additions and other adjustments, net	13.2
Currency translation adjustments	(20.9)
Disposition of CHSA and COBRA businesses	(21.4)
Balance at December 31, 2016	1,652.9
Employer Services
Goodwill [Roll Forward]
Balance at June 30, 2016	1,677.2
Additions and other adjustments, net	13.2
Currency translation adjustments	(20.9)
Disposition of CHSA and COBRA businesses	(21.4)
Balance at December 31, 2016	1,648.1
PEO Services
Goodwill [Roll Forward]
Balance at June 30, 2016	4.8
Additions and other adjustments, net	0.0
Currency translation adjustments	0.0
Disposition of CHSA and COBRA businesses	0.0
Balance at December 31, 2016	$ 4.8