Revenue - Contract Liability (Details) $ in Millions	6 Months Ended
Dec. 31, 2024 USD ($)
Contract Liability
Contract liability, July 1, 2024	$ 491.6
Recognition of revenue included in beginning of year contract liability	(69.9)
Contract liability, net of revenue recognized on contracts during the period	60.9
Currency translation adjustments	(10.8)
Contract liability, December 31, 2024	$ 471.8

Change In Contract With Customer, Liability [Roll Forward]

No definition available.

Name:	adp_ChangeInContractWithCustomerLiabilityRollForward
Namespace Prefix:	adp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of revenue deferred as an obligation to transfer good or service to customer for which consideration from customer has been received or is due, net of the amount of revenue recognized in the period from deferrals during the period.

+ References

No definition available.

+ Details

Name:	adp_ContractWithCustomerLiabilityDeferralNetOfRevenueRecognizedAndForeignCurrencyTranslation
Namespace Prefix:	adp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Contract With Customer, Liability, Increase (Decrease) From Foreign Currency Translation

+ References

No definition available.

+ Details

Name:	adp_ContractWithCustomerLiabilityIncreaseDecreaseFromForeignCurrencyTranslation
Namespace Prefix:	adp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479837/606-10-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-8

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479837/606-10-45-2

+ Details

Name:	us-gaap_ContractWithCustomerLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-8

+ Details

Name:	us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration