Long-term Debt and Other Financing Debt Instrument Table (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2012	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unamortized discount/premium and debt issuance costs		$ (28.5)	$ (41.7)
Total long-term debt		1,968.8	1,993.7
Gains (losses) on retirement of debt		0.8	2.0	$ (21.3)
Senior Secured Notes Due July 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 380.0	$ 380.0
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)		7.50%	7.50%
Debt Instrument, Maturity Date		Jul. 15, 2023
Assets Pledged as Collateral, Carrying Amount		$ 1,400.0
Debt Instrument, Convertible, Effective Interest Rate		8.30%	8.30%
Senior Secured Notes Due July 2023 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		103.75%
Debt Instrument, Redemption Period, End Date		Jul. 14, 2020
Senior Secured Notes Due July 2023 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		101.875%
Debt Instrument, Redemption Period, Start Date		Jul. 15, 2020
Debt Instrument, Redemption Period, End Date		Jul. 14, 2021
Senior Secured Notes Due July 2023 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		100.00%
Debt Instrument, Redemption Period, Start Date		Jul. 15, 2021
Debt Instrument, Redemption Period, End Date		Jul. 15, 2023
Senior Notes Due October 2021 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 406.2	$ 406.2
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)		7.625%	7.625%
Debt Instrument, Maturity Date		Oct. 01, 2021
Senior Notes Due October 2021 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		100.00%
Debt Instrument, Redemption Period, End Date		Sep. 30, 2021
Senior Notes Due October 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 270.2	$ 274.8
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)		6.375%	6.375%
Debt Instrument, Maturity Date		Oct. 15, 2025
Debt Instrument, Convertible, Effective Interest Rate		7.10%	7.10%
Debt Instrument, Repurchased Face Amount		$ 4.6	$ 5.2
Gains (losses) on retirement of debt				(8.4)
Senior Notes Due October 2025 [Member] | Other Income (Expense) [Member]
Debt Instrument [Line Items]
Gains (losses) on retirement of debt		$ 0.6	0.7
Senior Notes Due October 2025 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Period, End Date		Oct. 14, 2020
Senior Notes Due October 2025 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		103.188%
Debt Instrument, Redemption Period, Start Date		Oct. 15, 2020
Debt Instrument, Redemption Period, End Date		Oct. 14, 2021
Senior Notes Due October 2025 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		101.594%
Debt Instrument, Redemption Period, Start Date		Oct. 15, 2021
Debt Instrument, Redemption Period, End Date		Oct. 14, 2022
Senior Notes Due October 2025 [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		100.00%
Debt Instrument, Redemption Period, Start Date		Oct. 15, 2022
Debt Instrument, Redemption Period, End Date		Oct. 14, 2025
Senior Notes Due March 2027 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 391.6	$ 391.6
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)		7.00%	7.00%
Debt Instrument, Maturity Date		Mar. 15, 2027
Debt Instrument, Repurchased Face Amount			$ 8.4
Gains (losses) on retirement of debt				$ (13.1)
Senior Notes Due March 2027 [Member] | Other Income (Expense) [Member]
Debt Instrument [Line Items]
Gains (losses) on retirement of debt			1.3
Senior Notes Due March 2027 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Period, End Date		Mar. 14, 2022
Senior Notes Due March 2027 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		103.50%
Debt Instrument, Redemption Period, Start Date		Mar. 15, 2022
Debt Instrument, Redemption Period, End Date		Mar. 14, 2023
Senior Notes Due March 2027 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		102.333%
Debt Instrument, Redemption Period, Start Date		Mar. 15, 2023
Debt Instrument, Redemption Period, End Date		Mar. 14, 2024
Senior Notes Due March 2027 [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		101.167%
Debt Instrument, Redemption Period, Start Date		Mar. 15, 2024
Debt Instrument, Redemption Period, End Date		Mar. 14, 2025
Senior Notes Due March 2027 [Member] | Debt Instrument, Redemption, Period Five [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price Percentage		100.00%
Debt Instrument, Redemption Period, Start Date		Mar. 15, 2025
Debt Instrument, Redemption Period, End Date		Mar. 14, 2027
Unsecured Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 73.3
Long-term Debt, Weighted Average Interest Rate, at Point in Time		6.80%
Secured Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 26.0
Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 99.3	99.3
Debt Instrument, Maturity Date Range, Start		Nov. 15, 2020
Debt Instrument, Maturity Date Range, End		Jun. 01, 2028
Exchangeable Senior Notes Due November 2019 [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 0.0	$ 148.5
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)		5.00%	5.00%
Debt Instrument, Maturity Date		Nov. 15, 2019
Debt Instrument, Convertible, Effective Interest Rate		10.80%	10.80%
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	$ 38.7
Carrying Value of Long-term Debt			$ 141.4
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit Facility		$ 450.0	$ 335.0