Long-Term Debt (Schedule of Debt) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Debt and lease obligations	$ 13,555	$ 13,405
Less: Unamortized deferred debt issuance costs and note premium	(167)	(147)
Less: Current maturities	(30)	(20)
Total long-term debt	13,525	13,385
ABL Facility [Member]
Debt Instrument [Line Items]
Debt and lease obligations	380	273
Senior Notes [Member] \| Senior Notes at 6.875%, Due 2022 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	231	231
Senior Notes [Member] \| Senior Notes At 6.875% Due 2028 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	1,700	1,700
Senior Secured Notes [Member] \| Senior Secured Notes at 5.125%, Due 2021 [Member]
Debt Instrument [Line Items]
Debt and lease obligations		1,000
Senior Secured Notes [Member] \| Senior Secured Notes at 6.25%, Due 2023 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	2,675	3,100
Senior Secured Notes [Member] \| Senior Secured Notes at 8.625%, Due 2024 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	1,033	1,033
Senior Secured Notes [Member] \| Senior Secured Notes at 6.625% Due 2025 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	1,462
Senior Secured Notes [Member] \| Senior Secured Notes at 8%, Due 2026 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	2,101	2,101
Senior Secured Notes [Member] \| Senior Secured Notes At 8% Due 2027 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	700	700
Junior-Priority Secured Notes [Member] \| Junior-Priority Secured Notes At 9.875% Due 2023 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	1,770	1,770
Junior-Priority Secured Notes [Member] \| Junior-Priority Secured Notes at 8.125% Due 2024 [Member]
Debt Instrument [Line Items]
Debt and lease obligations	1,355	1,355
Finance Lease And Financing Obligations [Member]
Debt Instrument [Line Items]
Debt and lease obligations	290	272
Other [Member]
Debt Instrument [Line Items]
Debt and lease obligations	$ 25	$ 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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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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