- Fair Value of Debt Table (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 0	$ 8,531
Liabilities subject to compromise	8,428	0
Quoted Prices in Active Markets (Level 1) | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt, fair value	0	385
Long-term debt, fair value	0	753
Liabilities subject to compromise	982	0
Quoted Prices in Active Markets (Level 1) | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term debt, fair value	0	360
Long-term debt, fair value	0	622
Liabilities subject to compromise	38	0
Significant Other Observable Inputs (Level 2) | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	8,320
Liabilities subject to compromise	6,184	0
Significant Other Observable Inputs (Level 2) | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	6,085
Liabilities subject to compromise	$ 1,475	$ 0