Debt and Financing - Schedule of Outstanding Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Par Value	$ 1,284.0	$ 902.8
Discount	(21.0)	(28.1)
Commitment Fee	(22.1)
Debt Issuance Costs	(15.5)	(12.5)
Book Value	1,225.4	862.2
Book Value, Current Maturities	(4.0)	(4.1)
Par Value, Excluding Current Maturities	1,280.0	898.7
Premium (Discount), Excluding Current Maturities	(21.0)	(28.1)
Commitment Fee, Excluding Current Maturities	(22.1)
Debt Issuance Costs, Noncurrent	(15.5)	(12.5)
Book Value, Excluding Current Maturities	1,221.4	858.1
Term Loan
Debt Instrument [Line Items]
Par Value	613.0	600.0
Discount	(21.0)	(28.1)
Debt Issuance Costs	(9.3)	(12.0)
Book Value	$ 582.7	$ 559.9
Effective Interest Rate	9.50%	10.50%
ABL Facility | 2014 ABL Facility Credit Agreement
Debt Instrument [Line Items]
Par Value	$ 0.0	$ 0.0
Discount	0.0	0.0
Debt Issuance Costs	0.0	0.0
Book Value	0.0	0.0
Tranche A | UST Loan
Debt Instrument [Line Items]
Par Value	302.3
Commitment Fee	(17.7)
Debt Issuance Costs	(4.6)
Book Value	$ 280.0
Effective Interest Rate	6.50%
Secured Second A&R CDA
Debt Instrument [Line Items]
Par Value	$ 24.1	26.0
Discount	0.0	0.0
Debt Issuance Costs	(0.1)	(0.1)
Book Value	$ 24.0	$ 25.9
Effective Interest Rate	7.70%	7.90%
Tranche B | UST Loan
Debt Instrument [Line Items]
Par Value	$ 74.8
Commitment Fee	(4.4)
Debt Issuance Costs	(1.2)
Book Value	$ 69.2
Effective Interest Rate	6.50%
Unsecured Second A&R CDA
Debt Instrument [Line Items]
Par Value	$ 43.9	$ 45.2
Discount	0.0	0.0
Debt Issuance Costs	(0.1)	(0.1)
Book Value	$ 43.8	$ 45.1
Effective Interest Rate	7.70%	7.90%
Par Value, Current Maturities	$ (1.4)	$ (1.4)
Discount, Current Maturities	0.0	0.0
Commitment Fee, Current Maturities	0.0	0.0
Deferred Issuance Costs, Current	0.0	0.0
Book Value, Current Maturities	(1.4)	(1.4)
Lease financing obligations
Debt Instrument [Line Items]
Par Value	225.9	231.6
Discount	0.0	0.0
Debt Issuance Costs	(0.2)	(0.3)
Book Value	$ 225.7	$ 231.3
Effective Interest Rate	17.20%	16.50%
Par Value, Current Maturities	$ (2.6)	$ (2.7)
Discount, Current Maturities	0.0	0.0
Commitment Fee, Current Maturities	0.0	0.0
Deferred Issuance Costs, Current	0.0	0.0
Book Value, Current Maturities	$ (2.6)	$ (2.7)