Debt - Schedule of Carrying Values and Fair Values of Debt Outstanding (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other	$ 12	$ 12
Carrying Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other	12	12
Total	3,918	3,980
Carrying Value | 5.125% Senior Secured Notes due 2023 | Senior notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt		59
Carrying Value | 4.000% Notes due 2027 | Senior notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	991	991
Carrying Value | 7.950% Debentures due 2025 | Unsecured debt
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	273	273
Carrying Value | 8.375% Debentures due 2027 | Unsecured debt
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	198	198
Carrying Value | Secured debt | Credit Agreement | Line of credit
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	2,444	2,447
Fair Value
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Other	12	12
Total	3,967	4,092
Fair Value | 5.125% Senior Secured Notes due 2023 | Senior notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt		60
Fair Value | 4.000% Notes due 2027 | Senior notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	981	1,024
Fair Value | 7.950% Debentures due 2025 | Unsecured debt
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	308	318
Fair Value | 8.375% Debentures due 2027 | Unsecured debt
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	229	235
Fair Value | Secured debt | Credit Agreement | Line of credit
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long-term debt	$ 2,437	$ 2,443