Long-Term Debt - Summary of Long-Term Debt (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Senior Notes [Abstract]
Other Long-term Debt		$ 6.9	$ 8.0
Deferred Finance Costs, Noncurrent, Net	[1]	(27.7)	(33.2)
Total long-term debt		1,990.9	1,997.2
Less current portion of long-term debt		4.3	3.5
Total long-term debt, excluding current portion		1,986.6	1,993.7
Revolving Credit Facility [Member]
Summary of Long-term debt
Borrowings under senior secured revolving credit agreement		$ 0.1	$ 10.2
Senior Notes [Abstract]
Weighted average interest rate		7.40%	4.80%
Notes Due January 2021 at Fixed Rated 11.5% Interest Payments [Member]
Summary of Long-term debt
Borrowings under Notes		$ 400.0	$ 400.0
Senior Notes [Abstract]
Fixed rate		11.50%	11.50%
Effective interest rate		12.30%	12.20%
Notes Due April 2021 at Fixed Rate of 6.5% Interest Payments [Member]
Summary of Long-term debt
Borrowings under Notes		$ 900.0	$ 900.0
Senior Notes [Abstract]
Fixed rate		6.50%	6.50%
Effective interest rate		6.80%	6.80%
7.625% Notes [Member]
Summary of Long-term debt
Borrowings under Notes	[2]	$ 352.2	$ 352.5
Senior Notes [Abstract]
Fixed rate		7.625%	7.625%
Effective interest rate		8.00%	8.00%
Notes Due April 2023 at Fixed Rate of 7.75% Interest Payments [Member]
Summary of Long-term debt
Borrowings under Notes		$ 325.0	$ 325.0
Senior Notes [Abstract]
Fixed rate		7.75%	7.75%
Effective interest rate		8.00%	8.00%
Capital Lease Obligations [Member]
Summary of Long-term debt
Capital lease obligations		$ 44.7	$ 46.5
Less unamortized discounts [Member]
Summary of Long-term debt
Less unamortized discounts		(10.3)	(11.8)
Interest Expense [Member] | Fair Value Hedging [Member]
Senior Notes [Abstract]
Liabilities, fair value adjustment		$ 2.2	$ 2.5

[1] Deferred debt issuance costs are being amortized by the effective interest rate method over the lives of the related debt instruments. These amounts are net of accumulated amortization of $19.8 million and $14.5 million at September 30, 2017 and December 31, 2016, respectively.

[2] The balance includes a fair value interest rate hedge adjustment, which increased the debt balance by $2.2 million and $2.5 million as of September 30, 2017 and December 31, 2016, respectively (refer to Note 9 for additional information on the interest rate swap designated as a fair value hedge).