Long-Term Debt and Note Payable - Affiliate - Schedule of Long Term Debt (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2021	Dec. 31, 2020
Long-term debt
Long-term debt, gross	$ 3,153
Unamortized premiums, net	5	$ 5
Unamortized debt issuance costs	(53)	(62)
Less current maturities	(949)	(948)
Long-term debt, excluding current maturities	2,156	2,386
Note payable - affiliate	1,158	1,130
Long-term Debt and Lease Obligation, Including Current Maturities, Total	3,105	3,334
Senior notes
Long-term debt
Long-term debt, gross	$ 2,935	3,170
Senior notes \| Minimum
Long-term debt
Stated interest rate	6.50%
Senior notes \| Maximum
Long-term debt
Stated interest rate	7.75%
Term loan
Long-term debt
Long-term debt, gross	$ 215	$ 215
Weighted average interest rate	2.11%	2.15%
Term loan \| London Interbank Offered Rate (LIBOR)
Long-term debt
Basis spread on variable rate	2.00%
Finance lease and other obligations
Long-term debt
Long-term debt, gross	$ 3	$ 6
Note payable - affiliate \| Affiliated entity
Long-term debt
Note payable - affiliate	$ 1,158	$ 1,130
Weighted average interest rate	4.883%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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Weighted average interest rate of short-term debt outstanding calculated at point in time.

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