Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 16,498.3	$ 15,005.4	$ 14,589.8
HCM
Disaggregation of Revenue [Line Items]
Revenues	7,174.9	6,655.2	6,563.5
HRO, excluding PEO zero-margin benefits pass-throughs
Disaggregation of Revenue [Line Items]
Revenues	3,116.3	2,690.9	2,538.9
PEO zero-margin benefits pass-throughs
Disaggregation of Revenue [Line Items]
Revenues	3,514.4	3,092.0	2,907.7
Global
Disaggregation of Revenue [Line Items]
Revenues	2,240.9	2,144.9	2,034.5
Interest on funds held for clients
Disaggregation of Revenue [Line Items]
Revenues	451.8	422.4	545.2
Employer Services
Disaggregation of Revenue [Line Items]
Revenues	10,967.7	10,195.2	10,086.6
Employer Services | HCM
Disaggregation of Revenue [Line Items]
Revenues	7,183.1	6,660.7	6,569.0
Employer Services | HRO, excluding PEO zero-margin benefits pass-throughs
Disaggregation of Revenue [Line Items]
Revenues	1,096.1	971.1	941.8
Employer Services | PEO zero-margin benefits pass-throughs
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0
Employer Services | Global
Disaggregation of Revenue [Line Items]
Revenues	2,240.9	2,144.9	2,034.5
Employer Services | Interest on funds held for clients
Disaggregation of Revenue [Line Items]
Revenues	447.6	418.5	541.3
PEO
Disaggregation of Revenue [Line Items]
Revenues	5,545.7	4,818.3	4,511.5
PEO | HCM
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0
PEO | HRO, excluding PEO zero-margin benefits pass-throughs
Disaggregation of Revenue [Line Items]
Revenues	2,027.1	1,722.4	1,599.9
PEO | PEO zero-margin benefits pass-throughs
Disaggregation of Revenue [Line Items]
Revenues	3,514.4	3,092.0	2,907.7
PEO | Global
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0
PEO | Interest on funds held for clients
Disaggregation of Revenue [Line Items]
Revenues	4.2	3.9	3.9
Other
Disaggregation of Revenue [Line Items]
Revenues	(15.1)	(8.1)	(8.3)
Other | HCM
Disaggregation of Revenue [Line Items]
Revenues	(8.2)	(5.5)	(5.5)
Other | HRO, excluding PEO zero-margin benefits pass-throughs
Disaggregation of Revenue [Line Items]
Revenues	(6.9)	(2.6)	(2.8)
Other | PEO zero-margin benefits pass-throughs
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0
Other | Global
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0
Other | Interest on funds held for clients
Disaggregation of Revenue [Line Items]
Revenues	$ 0.0	$ 0.0	$ 0.0