Fair Value of Financial Instruments (Schedule of Estimated Fair Value of Financial Instruments, by Balance Sheet Grouping) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Assets:
Investments in equity securities	$ 137	$ 137
Available-for-sale securities	100	93
Trading securities	12	11
Carrying Amount [Member]
Assets:
Cash and cash equivalents	157	196
Investments in equity securities	137	137
Available-for-sale securities	100	93
Trading securities	12	11
Carrying Amount [Member] | Credit Facility, Type of Debt [Member] | Credit Facility, Name [Member]
Liabilities:
Credit Facility, Fair Value Disclosure		1,602
Carrying Amount [Member] | Senior Notes [Member] | Senior Notes at 8.0, Due 2019 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	155	155
Carrying Amount [Member] | Senior Notes [Member] | Senior Notes at 7.125, Due 2020 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	121	121
Carrying Amount [Member] | Senior Notes [Member] | Senior Notes at 6.875, Due 2022 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	2,602	2,593
Carrying Amount [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 5.125, Due 2021 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	988	984
Carrying Amount [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 6.25, Due 2023 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	3,073	3,067
Carrying Amount [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 8.625, Due 2024 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,023	1,021
Carrying Amount [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 8.0, Due 2026 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,573
Carrying Amount [Member] | Junior-Priority Secured Notes [Member] | Junior-Priority Secured Notes Due 2023 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,753	1,750
Carrying Amount [Member] | Junior-Priority Secured Notes [Member] | Junior-Priority Secured Notes at 8.125% Due 2024 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,340	1,338
Carrying Amount [Member] | Receivables Facility and Other Debt, Type [Member] | ABL Facility and Other Debt [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	704	734
Estimated Fair Value [Member]
Assets:
Cash and cash equivalents	157	196
Investments in equity securities	137	137
Available-for-sale securities	100	93
Trading securities	12	11
Estimated Fair Value [Member] | Credit Facility, Type of Debt [Member] | Credit Facility, Name [Member]
Liabilities:
Credit Facility, Fair Value Disclosure		1,564
Estimated Fair Value [Member] | Senior Notes [Member] | Senior Notes at 8.0, Due 2019 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	154	146
Estimated Fair Value [Member] | Senior Notes [Member] | Senior Notes at 7.125, Due 2020 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	117	100
Estimated Fair Value [Member] | Senior Notes [Member] | Senior Notes at 6.875, Due 2022 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,998	1,175
Estimated Fair Value [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 5.125, Due 2021 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,002	934
Estimated Fair Value [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 6.25, Due 2023 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	3,089	2,819
Estimated Fair Value [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 8.625, Due 2024 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,072	1,025
Estimated Fair Value [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 8.0, Due 2026 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,602
Estimated Fair Value [Member] | Junior-Priority Secured Notes [Member] | Junior-Priority Secured Notes Due 2023 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,526	1,380
Estimated Fair Value [Member] | Junior-Priority Secured Notes [Member] | Junior-Priority Secured Notes at 8.125% Due 2024 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,088	976
Estimated Fair Value [Member] | Receivables Facility and Other Debt, Type [Member] | ABL Facility and Other Debt [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	$ 704	$ 734