Long-Term Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Debt and lease obligations	$ 13,136	$ 13,405
Less: Unamortized deferred debt issuance costs and note premium	(160)	(147)
Less: Current maturities	(30)	(20)
Total long-term debt	13,106	13,385
ABL Facility
Debt Instrument [Line Items]
Debt and lease obligations		273
Senior Secured Notes \| Senior Secured Notes at 5.125%, Due 2021
Debt Instrument [Line Items]
Debt and lease obligations		1,000
Senior Secured Notes \| Senior Secured Notes at 6.25%, Due 2023
Debt Instrument [Line Items]
Debt and lease obligations	2,675	3,100
Senior Secured Notes \| Senior Secured Notes at 8.625%, Due 2024
Debt Instrument [Line Items]
Debt and lease obligations	1,033	1,033
Senior Secured Notes \| Senior Secured Notes at 6.625% Due 2025
Debt Instrument [Line Items]
Debt and lease obligations	1,462
Senior Secured Notes \| Senior Secured Notes at 8%, Due 2026
Debt Instrument [Line Items]
Debt and lease obligations	2,101	2,101
Senior Secured Notes \| Senior Secured Notes at 8% Due 2027
Debt Instrument [Line Items]
Debt and lease obligations	700	700
Senior Notes \| Senior Notes at 6.875%, Due 2022
Debt Instrument [Line Items]
Debt and lease obligations	231	231
Senior Notes \| Senior Notes at 6.875% Due 2028
Debt Instrument [Line Items]
Debt and lease obligations	1,700	1,700
Junior-Priority Secured Notes \| Junior-Priority Secured Notes at 9.875% Due 2023
Debt Instrument [Line Items]
Debt and lease obligations	1,770	1,770
Junior-Priority Secured Notes \| Junior-Priority Secured Notes at 8.125% Due 2024
Debt Instrument [Line Items]
Debt and lease obligations	1,355	1,355
Finance Lease and Financing Obligations
Debt Instrument [Line Items]
Debt and lease obligations	242	272
Other
Debt Instrument [Line Items]
Debt and lease obligations	$ 27	$ 17

Amount of short-term and long-term debt and lease obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
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Amount of long-term debt and lease obligation, classified as current.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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