Debt and Financing - Schedule of Outstanding Debt (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Par Value	$ 1,593.9
Discount	(18.0)
Commitment Fee	(34.8)
Debt Issuance Costs	(17.4)
Book Value	1,523.7
Book Value, Current Maturities	(4.9)	$ (4.0)
Par Value, Excluding Current Maturities	1,589.0
Premium (Discount), Excluding Current Maturities	(18.0)
Commitment Fee, Excluding Current Maturities	(34.8)
Debt Issuance Costs, Noncurrent	(17.4)
Book Value, Excluding Current Maturities	1,518.8	$ 1,221.4
Term Loan
Debt Instrument [Line Items]
Par Value	612.9
Discount	(18.0)
Commitment Fee	0.0
Debt Issuance Costs	(8.0)
Book Value	$ 586.9
Effective Interest Rate	9.50%
ABL Facility | 2014 ABL Facility Credit Agreement
Debt Instrument [Line Items]
Par Value	$ 0.0
Discount	0.0
Commitment Fee	0.0
Debt Issuance Costs	0.0
Book Value	0.0
Tranche A | UST Loan
Debt Instrument [Line Items]
Par Value	306.7
Discount	0.0
Commitment Fee	(15.3)
Debt Issuance Costs	(4.0)
Book Value	$ 287.4
Effective Interest Rate	6.40%
Tranche B | UST Loan
Debt Instrument [Line Items]
Par Value	$ 381.1
Discount	0.0
Commitment Fee	(19.5)
Debt Issuance Costs	(5.1)
Book Value	$ 356.5
Effective Interest Rate	6.50%
Secured Second A&R CDA
Debt Instrument [Line Items]
Par Value	$ 24.1
Discount	0.0
Commitment Fee	0.0
Debt Issuance Costs	0.0
Book Value	$ 24.1
Effective Interest Rate	7.70%
Unsecured Second A&R CDA
Debt Instrument [Line Items]
Par Value	$ 43.9
Discount	0.0
Commitment Fee	0.0
Debt Issuance Costs	(0.1)
Book Value	$ 43.8
Effective Interest Rate	7.70%
Par Value, Current Maturities	$ (1.3)
Discount, Current Maturities	0.0
Commitment Fee, Current Maturities	0.0
Deferred Issuance Costs, Current	0.0
Book Value, Current Maturities	(1.3)
Lease financing obligations
Debt Instrument [Line Items]
Par Value	225.2
Discount	0.0
Commitment Fee	0.0
Debt Issuance Costs	(0.2)
Book Value	$ 225.0
Effective Interest Rate	17.20%
Par Value, Current Maturities	$ (3.6)
Discount, Current Maturities	0.0
Commitment Fee, Current Maturities	0.0
Deferred Issuance Costs, Current	0.0
Book Value, Current Maturities	$ (3.6)