Self-Insurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Self Insurance Reserves [Abstract]
Self insurance reserve	$ 165.0	$ 184.0
Self insurance reserves, noncurrent	101.7	112.9
Accrual receivable	17.5	22.8
Accrued reserves decreased facility operating expense	9.9	35.4
Cash deposits for self insured retention risk	12.7	12.4
Letters of credit associated to the secured self-insured retention risk	71.8	59.5
Cash deposit to collateralize the insurance policy	$ 33.9	$ 37.4