Goodwill and Intangible Assets, net - Changes In Goodwill (Details) $ in Millions	9 Months Ended
Mar. 31, 2021 USD ($)
Goodwill [Roll Forward]
Balance at June 30, 2020	$ 2,309.4
Currency translation adjustments	24.4
Balance at March 31, 2021	2,333.8
Employer Services
Goodwill [Roll Forward]
Balance at June 30, 2020	2,304.6
Currency translation adjustments	24.4
Balance at March 31, 2021	2,329.0
PEO Services
Goodwill [Roll Forward]
Balance at June 30, 2020	4.8
Currency translation adjustments	0.0
Balance at March 31, 2021	$ 4.8

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant