Long-Term Debt (Credit Facility Terms Narrative) (Details)				9 Months Ended	12 Months Ended
	Jul. 06, 2018 USD ($)	Mar. 23, 2018 USD ($)	Feb. 26, 2018 USD ($)	Sep. 30, 2018 USD ($) item	Dec. 31, 2017 USD ($) item	Apr. 03, 2018 USD ($)
Debt Instrument [Line Items]
Ratio of first lien net debt to EBITDA				4.60
Maximum [Member]
Debt Instrument [Line Items]
Ratio of first lien net debt to EBITDA				5.0
Credit Facility, Name [Member] | Credit Facility, Type of Debt [Member]
Debt Instrument [Line Items]
Aggregate Principal Amount of Each Tranche Available in Future				$ 500,000,000
Minimum Number of Tranches Available in Future | item				1
Debt, Weighted Average Interest Rate				6.50%
Credit Facility, Name [Member] | Credit Facility, Type of Debt, Amendment [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 650,000,000
First Lien net Debt to Current Earnings			5.25
First Lien net Debt to Current Earnings in Period One			5.0
First Lien net Debt to Current Earnings in Period Two			4.75
First Lien net Debt to Current Earnings in Period Three			4.5
First Lien net Debt to Current Earnings in Period Four			4.25
Percentage of Net Cash Proceeds of Asset Sales Applied to Prepay Term Loans, Tier 1			100.00%
Percentage of Net Cash Proceeds of Asset Sales Applied to Prepay Term Loans, Tier 2			50.00%
Percentage of Net Cash Proceeds of Asset Sales Applied to Prepay Term Loans, Tier 3			0.00%
Credit Facility, Name [Member] | Credit Facility, Type of Debt, Amendment [Member] | Minimum [Member]
Debt Instrument [Line Items]
First Lien net Debt to Current Earnings, Tier 1			4.5
First Lien net Debt to Current Earnings, Tier 2			4.0
Credit Facility, Name [Member] | Credit Facility, Type of Debt, Amendment [Member] | Maximum [Member]
Debt Instrument [Line Items]
First Lien net Debt to Current Earnings, Tier 2			4.5
First Lien net Debt to Current Earnings, Tier 3			4.0
Credit Facility, Name [Member] | Credit Facility, Type of Debt, Fourth Amendment and Restatement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,000,000,000
Credit Facility, Revolving Credit Loans [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.50%
Letters of Credit Outstanding, Amount				$ 86,000,000
Line of Credit Facility, Remaining Borrowing Capacity				$ 425,000,000
Line of Credit Facility, Maximum Borrowing Capacity					$ 929,000,000
Credit Facility, Revolving Credit Loans [Member] | Credit Facility, Type of Debt, Fourth Amendment and Restatement [Member]
Debt Instrument [Line Items]
Effective Aggregate Principal Amount of Each Tranche Available in Future		500,000,000
Line of Credit Facility, Maximum Borrowing Capacity		$ 425,000,000
Percentage of Net Cash Proceeds of Asset Sales Applied to Prepay Term Loans, Tier 1		100.00%
Percentage of Net Cash Proceeds of Asset Sales Applied to Prepay Term Loans, Tier 2		50.00%
Percentage of Net Cash Proceeds of Asset Sales Applied to Prepay Term Loans, Tier 3		0.00%
Credit Facility, Revolving Credit Loans [Member] | Credit Facility, Type of Debt, Fourth Amendment and Restatement [Member] | Minimum [Member]
Debt Instrument [Line Items]
First Lien net Debt to Current Earnings, Tier 1		4.25
First Lien net Debt to Current Earnings, Tier 2		4.25
Credit Facility, Revolving Credit Loans [Member] | Credit Facility, Type of Debt, Fourth Amendment and Restatement [Member] | Maximum [Member]
Debt Instrument [Line Items]
First Lien net Debt to Current Earnings, Tier 2		3.75
First Lien net Debt to Current Earnings, Tier 3		3.75
Credit Facility, Revolving Credit Loans, January 27, 2021 [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					$ 739,000,000
Credit Facility, Term Loans [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Equivalent Percentage of Term Loan Facility Related to Net Cash Proceeds of Certain Asset Sales and Dispositions by Company and Its Subsidiaries				100.00%
Equivalent Percentage of Term Loan Facility Related to Net Cash Proceeds of Issuance of Certain Debt Obligations or Receivables Based Financing by Company and Its Subsidiaries				100.00%
Equivalent Percentage of Term Loan Facility Subject to Reduction to Lower Percentage Based on Company Leverage Ratio				75.00%
Credit Facility, Term Loan G [Member]
Debt Instrument [Line Items]
Number of additional amortization payments required | item					0
Credit Facility, Term Loan F, Term Loan G or Term Loan H [Member | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Paydown Percentage of Original Principal				1.00%
Credit Facility, Revolving Credit Loans, Extended and Non-Extended [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 840,000,000
Receivables Facility, June 23, 2017 Amendment [Member] | Receivables Facility [Member]
Debt Instrument [Line Items]
Outstanding Borrowings of Receivables Facility				$ 538,000,000
ABL Credit Agreement [Member]
Debt Instrument [Line Items]
Aggregate principal amount for springing maturity				$ 250,000,000
Line of Credit Facility, Maximum Borrowing Capacity						$ 1,000,000,000
ABL Credit Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.50%
ABL Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage				0.625%
Senior Secured Notes at 8.625, Due 2024 [Member] | Senior Secured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jul. 15, 2024
Debt Instrument, Face Amount	$ 1,033,000,000
Alternate Base Rate [Member] | Credit Facility, Term Loan A [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.75%
Alternate Base Rate [Member] | Credit Facility, Term Loan G [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.75%
Alternate Base Rate [Member] | Credit Facility, Term Loan G [Member] | Credit Facility, Type of Debt, Fourth Amendment and Restatement [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.00%
Alternate Base Rate [Member] | Credit Facility, Term Loan H [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.00%
Alternate Base Rate [Member] | Credit Facility, Term Loan H [Member] | Credit Facility, Type of Debt, Fourth Amendment and Restatement [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		2.25%
Alternate Base Rate [Member] | Credit Facility, Term Loan G and Term Loan H [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Derivative, Floor Interest Rate				2.00%
Alternate Base Rate [Member] | ABL Credit Agreement [Member]
Debt Instrument [Line Items]
Percentage of the Maximum Commitment of Excess Availability, One				1.25%
Percentage of the Maximum Commitment of Excess Availability, Two				1.50%
Percentage of the Maximum Commitment of Excess Availability, Three				1.75%
Federal Funds Effective Rate [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				0.50%
LIBOR [Member] | Credit Facility, Revolving Credit Loans [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.75%
LIBOR [Member] | Credit Facility, Revolving Credit Loans [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.00%
LIBOR [Member] | Credit Facility, Term Loan G [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				2.75%
LIBOR [Member] | Credit Facility, Term Loan G [Member] | Credit Facility, Type of Debt, Fourth Amendment and Restatement [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		3.00%
LIBOR [Member] | Credit Facility, Term Loan H [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate				3.00%
LIBOR [Member] | Credit Facility, Term Loan H [Member] | Credit Facility, Type of Debt, Fourth Amendment and Restatement [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		3.25%
LIBOR [Member] | Credit Facility, Term Loan G and Term Loan H [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Derivative, Floor Interest Rate				1.00%
LIBOR [Member] | ABL Credit Agreement [Member]
Debt Instrument [Line Items]
Percentage of the Maximum Commitment of Excess Availability, One				2.25%
Percentage of the Maximum Commitment of Excess Availability, Two				2.50%
Percentage of the Maximum Commitment of Excess Availability, Three				2.75%
Revolving Credit Facility [Member] | ABL Credit Agreement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						425,000,000
Letter of Credit [Member] | ABL Credit Agreement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						$ 50,000,000