Fair Value of Financial Instruments (Schedule of Estimated Fair Value of Financial Instruments, by Balance Sheet Grouping) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets:
Investments in equity securities	$ 114	$ 141
Available-for-sale debt securities	103	101
Trading securities	12	12
Carrying Amount [Member]
Assets:
Cash and cash equivalents	246	216
Investments in equity securities	114	141
Available-for-sale debt securities	103	101
Trading securities	12	12
Carrying Amount [Member] | Senior Notes [Member] | Senior Notes at 6.875%, Due 2022 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	229	229
Carrying Amount [Member] | Senior Notes [Member] | Senior Secured Notes at 6.625% Due 2025 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,421
Carrying Amount [Member] | Senior Notes [Member] | Senior Secured Notes At 8% Due 2027 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	691	691
Carrying Amount [Member] | Senior Notes [Member] | Senior Notes At 6.875 Percent Due 2028 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,678	1,678
Carrying Amount [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 5.125%, Due 2021 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure		990
Carrying Amount [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 6.25%, Due 2023 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	2,654	3,074
Carrying Amount [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 8.625%, Due 2024 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,024	1,023
Carrying Amount [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 8%, Due 2026 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	2,071	2,070
Carrying Amount [Member] | Junior-Priority Secured Notes [Member] | Junior-Priority Secured Notes At 9.875% Due 2023 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,755	1,754
Carrying Amount [Member] | Junior-Priority Secured Notes [Member] | Junior-Priority Secured Notes at 8.125% Due 2024 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,341	1,340
Carrying Amount [Member] | Receivables Facility and Other Debt, Type [Member] | ABL Facility and Other Debt [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	401	285
Estimated Fair Value [Member]
Assets:
Cash and cash equivalents	246	216
Investments in equity securities	114	141
Available-for-sale debt securities	103	101
Trading securities	12	12
Estimated Fair Value [Member] | Senior Notes [Member] | Senior Notes at 6.875%, Due 2022 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	173	188
Estimated Fair Value [Member] | Senior Notes [Member] | Senior Secured Notes at 6.625% Due 2025 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,379
Estimated Fair Value [Member] | Senior Notes [Member] | Senior Secured Notes At 8% Due 2027 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	602	700
Estimated Fair Value [Member] | Senior Notes [Member] | Senior Notes At 6.875 Percent Due 2028 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	516	1,700
Estimated Fair Value [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 5.125%, Due 2021 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure		1,003
Estimated Fair Value [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 6.25%, Due 2023 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	2,560	3,148
Estimated Fair Value [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 8.625%, Due 2024 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,028	1,099
Estimated Fair Value [Member] | Senior Secured Notes [Member] | Senior Secured Notes at 8%, Due 2026 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	2,004	2,182
Estimated Fair Value [Member] | Junior-Priority Secured Notes [Member] | Junior-Priority Secured Notes At 9.875% Due 2023 [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	1,419	1,539
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	936	1,113
Estimated Fair Value [Member] | Receivables Facility and Other Debt, Type [Member] | ABL Facility and Other Debt [Member]
Liabilities:
Notes Payable, Fair Value Disclosure	$ 401	$ 285