Long-Term Debt and Finance Leases - Senior Notes (Details) - USD ($) $ in Millions			1 Months Ended	12 Months Ended
	Jul. 17, 2017	Mar. 20, 2017	May 31, 2017	Dec. 31, 2017
Long-Term Debt and Capital Leases
Loss on early extinguishment of debt				$ 32.1
10.25 % Senior Notes
Long-Term Debt and Capital Leases
Repayments of long-term debt	$ 729.9	$ 95.1
Interest rate (as a percent)		10.25%
Accrued interest paid	37.6	$ 1.7
Payment of call premium		4.9
Loss on early extinguishment of debt	19.8	$ 5.0
Prepayment fees	18.7
Revolving Credit Facility
Long-Term Debt and Capital Leases
Loss on early extinguishment of debt			$ 1.0
Proceeds from credit facility used to pay senior note	$ 180.0