Commitments and Contingencies (Details) $ in Millions	Dec. 31, 2025 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Purchase commitments	$ 2,332.5
Purchase commitments relating to 2026	194.8
Purchase commitments relating to 2027 and 2028	1,032.7
Purchase commitments relating to 2029 and 2031	$ 987.0

Unrecorded Unconditional Purchase Obligation, To Be Paid, Year One Through Two

No definition available.

Name:	adp_UnrecordedUnconditionalPurchaseObligationToBePaidYearOneThroughTwo
Namespace Prefix:	adp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Unrecorded Unconditional Purchase Obligation, To Be Paid, Year Three Through Five

+ References

No definition available.

+ Details

Name:	adp_UnrecordedUnconditionalPurchaseObligationToBePaidYearThreeThroughFive
Namespace Prefix:	adp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of fixed and determinable portion of unrecorded unconditional purchase obligation to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Includes, but is not limited to, lease not yet commenced.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 440
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482648/440-10-50-4

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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

- Definition

Amount of unrecorded obligation to transfer funds in future for fixed or minimum amount or quantity of product and service at fixed or minimum price. Includes, but is not limited to, lease not yet commenced and take-or-pay and throughput contracts.

+ References

+ Details

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