Accounting Policies - Schedule of Estimated Cash Payments to Settle Claims (Details) $ in Millions	Dec. 31, 2020 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
2021	$ 103.0
2022	67.3
2023	43.6
2024	27.5
2025	17.9
Thereafter	85.9
Total	345.2
Workers’ Compensation
Liability for Claims and Claims Adjustment Expense [Line Items]
2021	78.1
2022	47.4
2023	31.3
2024	20.6
2025	14.9
Thereafter	82.9
Total	275.2
Third-Party Liability Claims
Liability for Claims and Claims Adjustment Expense [Line Items]
2021	24.9
2022	19.9
2023	12.3
2024	6.9
2025	3.0
Thereafter	3.0
Total	$ 70.0