Interim Financial Data by Segment - Schedule of Depreciation and Amortization Included in Earnings Before Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Total depreciation and amortization	$ 146.7	$ 138.6
Other
Segment Reporting Information [Line Items]
Total depreciation and amortization	14.9	16.4
Employer Services | Operating Segments
Segment Reporting Information [Line Items]
Total depreciation and amortization	131.1	120.5
PEO | Operating Segments
Segment Reporting Information [Line Items]
Total depreciation and amortization	$ 0.7	$ 1.7