Borrowings and Other Obligations (Narrative) (Details) - USD ($)			3 Months Ended
	Apr. 20, 2023	Dec. 13, 2019	Mar. 31, 2023	Mar. 24, 2023	Dec. 31, 2022	Oct. 17, 2022	Oct. 27, 2021	Sep. 30, 2021	Aug. 04, 2020	Dec. 12, 2019
Short-term Debt [Line Items]
Letters of credit outstanding, amount			$ 405,000,000
Debt instrument, unused borrowing capacity, amount			147,000,000
Interest Payable, Current			51,000,000		$ 22,000,000
Credit Agreement Minimum Liquidity Requirement						$ 250,000,000
LC Credit Agreement Letters of Credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount			253,000,000
Uncommitted Letters of Credit
Short-term Debt [Line Items]
Letters of credit outstanding, amount			152,000,000
Letters of credit outstanding, cash collateral			146,000,000
Exit Notes, 11.00 Percent Due 2024
Short-term Debt [Line Items]
Long-term debt			105,000,000
Exit Notes, 11.00 Percent Due 2024 | Subsequent Event
Short-term Debt [Line Items]
Long-term debt	$ 105,000,000
Debt Instrument, Redemption Price, Percentage	102.75%
Senior Notes 8.625 Percent Due 2030
Short-term Debt [Line Items]
Face amount of debt							$ 1,600,000,000
Amended LC Credit Agreement
Short-term Debt [Line Items]
Credit agreement, maximum capacity										$ 400,000,000
Senior Notes | Exit Notes, 11.00 Percent Due 2024
Short-term Debt [Line Items]
Debt Instrument, Issued, Principal		$ 2,100,000,000
Stated interest rate on debt										11.00%
Repayments of Senior Debt			20,000,000
Long-term debt			0		105,000,000
Senior Notes | Senior Notes 6.5 Percent Due 2028
Short-term Debt [Line Items]
Stated interest rate on debt								6.50%
Long-term debt			441,000,000		471,000,000
Senior Notes | Senior Notes 8.625 Percent Due 2030
Short-term Debt [Line Items]
Stated interest rate on debt							8.625%
Long-term debt			1,586,000,000		$ 1,586,000,000
Long-Term Debt, Gross			1,600,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net			14,000,000
Secured Debt | Senior Notes 6.5 Percent Due 2028
Short-term Debt [Line Items]
Face amount of debt									$ 500,000,000
Debt Instrument, Repurchase Amount			42,000,000
Long-Term Debt, Gross			450,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net			$ 9,000,000
Line of Credit | Exit Notes | Revolving Credit Facility
Short-term Debt [Line Items]
Debt instrument, covenant, outstanding, amount						50,000,000
Minimum liquidity amount				$ 300,000,000		350,000,000
Line of Credit | Exit Notes | Revolving Credit Facility | Forecast Testing Period
Short-term Debt [Line Items]
Debt instrument, covenant, minimum interest coverage ratio						$ 2.50