Self-Insurance (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Insurance [Line Items]
Self-insurance reserves - current portion	$ 679.9	$ 774.5
Self-insurance reserves - long-term portion	275.0	235.4
Self-insurance reserves [Member]
Insurance [Line Items]
Self-insurance reserves - current portion	29.9	29.5
Self-insurance reserves - long-term portion	47.4	48.7
Total self-insurance liabilities	$ 77.3	$ 78.2

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