Statements of Consolidated Earnings (Parenthetical) (Unaudited) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Direct pass-through costs PEO revenues	$ 11,751.1	$ 10,632.3	$ 21,380.5	$ 19,370.8

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