Financial Data by Segment and Geographic Area - Financial Data By Segment And Geographic Area - Depreciation and Amortization Included in Earnings before Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting [Line Items]
Total depreciation and amortization	$ 585.9	$ 582.4	$ 561.9
Other
Segment Reporting [Line Items]
Total depreciation and amortization	58.6	63.3	68.5
Employer Services | Operating Segments
Segment Reporting [Line Items]
Total depreciation and amortization	525.1	512.4	486.6
PEO Services | Operating Segments
Segment Reporting [Line Items]
Total depreciation and amortization	$ 2.2	$ 6.7	$ 6.8