Leases - Future Minimum Lease Payments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 monthly_payment	Dec. 31, 2016 USD ($)
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017		$ 21.4
2018		20.8
2019		17.5
2020		15.4
2021		12.4
Thereafter		35.9
Total minimum lease payments		123.4
Less: interest		(35.7)
Capital lease obligations		87.7
Less: current portion		(13.0)
Long-term capital lease obligations		74.7
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017		70.5
2018		75.3
2019		71.3
2020		69.0
2021		52.9
Thereafter		208.8
Total minimum lease payments		$ 547.8
Forecast
Operating Leased Assets [Line Items]
Number of monthly obligation payments in fiscal year | monthly_payment	11