Statements of Consolidated Earnings (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Direct pass-through costs PEO revenues	$ 10,925.8	$ 10,510.6

Direct pass-through costs associated with PEO, primarily consisting of payroll wages and payroll taxes.

No definition available.

Name:	adp_DirectPassThroughCostsPEORevenues
Namespace Prefix:	adp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration