Statements of Consolidated Earnings (Parenthetical) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Direct pass-through costs PEO revenues	$ 12,371.6	$ 11,751.1	$ 22,882.2	$ 21,380.5

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