Fair Value of Financial Instruments - Schedule of Estimated Fair Value of Financial Instruments, by Balance Sheet Grouping (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Carrying Amount
Assets:
Cash and cash equivalents	$ 1,250	$ 1,676
Investments in equity securities	127	129
Available-for-sale debt securities	138	110
Trading securities	12	12
Carrying Amount | Senior Secured Notes | Senior Secured Notes at 6.25%, Due 2023
Liabilities:
Notes payable, fair value disclosure		95
Carrying Amount | Senior Secured Notes | Senior Secured Notes at 8.625%, Due 2024
Liabilities:
Notes payable, fair value disclosure		1,025
Carrying Amount | Senior Secured Notes | Senior Secured Notes at 6.625% Due 2025
Liabilities:
Notes payable, fair value disclosure	1,430	1,427
Carrying Amount | Senior Secured Notes | Senior Secured Notes at 8%, Due 2026
Liabilities:
Notes payable, fair value disclosure	2,076	2,074
Carrying Amount | Senior Secured Notes | Senior Secured Notes at 8% Due 2027
Liabilities:
Notes payable, fair value disclosure	692	692
Carrying Amount | Senior Secured Notes | Senior Secured Notes at 5.625% due 2027
Liabilities:
Notes payable, fair value disclosure	1,813	1,809
Carrying Amount | Senior Secured Notes | Senior Notes at 6% Due 2029
Liabilities:
Notes payable, fair value disclosure	858	857
Carrying Amount | Senior Secured Notes | Senior Secured Notes at 4.750% due 2031
Liabilities:
Notes payable, fair value disclosure	1,090
Carrying Amount | Senior Notes | Senior Notes at 6.875%, Due 2022
Liabilities:
Notes payable, fair value disclosure		125
Carrying Amount | Senior Notes | Senior Notes at 6.875% Due 2028
Liabilities:
Notes payable, fair value disclosure	758	758
Carrying Amount | Junior-Priority Secured Notes | Junior-Priority Secured Notes at 9.875% Due 2023
Liabilities:
Notes payable, fair value disclosure		1,756
Carrying Amount | Junior-Priority Secured Notes | Junior-Priority Secured Notes at 8.125% Due 2024
Liabilities:
Notes payable, fair value disclosure		1,336
Carrying Amount | Junior-Priority Secured Notes | Junior-Priority Secured Notes at 6.875% Due 2029
Liabilities:
Notes payable, fair value disclosure	1,618
Carrying Amount | Junior-Priority Secured Notes | Junior-Priority Secured Notes at 6.125% Due 2030
Liabilities:
Notes payable, fair value disclosure	1,348
Carrying Amount | ABL Facility and Other Debt
Liabilities:
Notes payable, fair value disclosure	21	23
Estimated Fair Value
Assets:
Cash and cash equivalents	1,250	1,676
Investments in equity securities	127	129
Available-for-sale debt securities	138	110
Trading securities	12	12
Estimated Fair Value | Senior Secured Notes | Senior Secured Notes at 6.25%, Due 2023
Liabilities:
Notes payable, fair value disclosure		99
Estimated Fair Value | Senior Secured Notes | Senior Secured Notes at 8.625%, Due 2024
Liabilities:
Notes payable, fair value disclosure		1,080
Estimated Fair Value | Senior Secured Notes | Senior Secured Notes at 6.625% Due 2025
Liabilities:
Notes payable, fair value disclosure	1,545	1,543
Estimated Fair Value | Senior Secured Notes | Senior Secured Notes at 8%, Due 2026
Liabilities:
Notes payable, fair value disclosure	2,268	2,275
Estimated Fair Value | Senior Secured Notes | Senior Secured Notes at 8% Due 2027
Liabilities:
Notes payable, fair value disclosure	779	760
Estimated Fair Value | Senior Secured Notes | Senior Notes at 6% Due 2029
Liabilities:
Notes payable, fair value disclosure	965	973
Estimated Fair Value | Senior Secured Notes | Senior Secured Notes at 4.750% due 2031
Liabilities:
Notes payable, fair value disclosure	1,098
Estimated Fair Value | Senior Notes | Senior Notes at 6.875%, Due 2022
Liabilities:
Notes payable, fair value disclosure		125
Estimated Fair Value | Senior Notes | Senior Secured Notes at 5.625% due 2027
Liabilities:
Notes payable, fair value disclosure	2,029	2,048
Estimated Fair Value | Senior Notes | Senior Notes at 6.875% Due 2028
Liabilities:
Notes payable, fair value disclosure	761	618
Estimated Fair Value | Junior-Priority Secured Notes | Junior-Priority Secured Notes at 9.875% Due 2023
Liabilities:
Notes payable, fair value disclosure		1,861
Estimated Fair Value | Junior-Priority Secured Notes | Junior-Priority Secured Notes at 8.125% Due 2024
Liabilities:
Notes payable, fair value disclosure		1,408
Estimated Fair Value | Junior-Priority Secured Notes | Junior-Priority Secured Notes at 6.875% Due 2029
Liabilities:
Notes payable, fair value disclosure	1,865
Estimated Fair Value | Junior-Priority Secured Notes | Junior-Priority Secured Notes at 6.125% Due 2030
Liabilities:
Notes payable, fair value disclosure	1,460
Estimated Fair Value | ABL Facility and Other Debt
Liabilities:
Notes payable, fair value disclosure	$ 21	$ 23