Indebtedness - Summary of Unsecured Senior Notes (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Unsecured senior notes, net	$ 2,167,000,000	$ 2,366,000,000
Unsecured senior notes
Debt Instrument [Line Items]
Unsecured senior notes principal amount	2,200,000,000	2,398,000,000
Unamortized debt issuance costs, premium and discount	(33,000,000)	(32,000,000)
Unsecured senior notes, net	2,167,000,000	2,366,000,000
Unsecured senior notes \| $850 Face Value, 5.500% interest payable semi-annually, due August 2028
Debt Instrument [Line Items]
Unsecured senior notes principal amount	850,000,000	0
Face value	$ 850,000,000
Interest Rate	5.50%
Unsecured senior notes \| $750 face value, 9.125% interest rate payable semi-annually, due July 2026
Debt Instrument [Line Items]
Unsecured senior notes principal amount	$ 750,000,000	750,000,000
Face value	$ 750,000,000
Interest Rate	9.125%
Unsecured senior notes \| $600 face value, 6.000% interest rate payable semi-annually, due January 2027
Debt Instrument [Line Items]
Unsecured senior notes principal amount	$ 600,000,000	0
Face value	$ 600,000,000
Interest Rate	6.00%
Unsecured senior notes \| $600 face value, 6.500% interest rate payable semi-annually, due July 2021
Debt Instrument [Line Items]
Unsecured senior notes principal amount	$ 0	492,000,000
Face value	$ 600,000,000
Interest Rate	6.50%
Unsecured senior notes \| $300 face value, 6.500% interest rate payable semi-annually, due June 2022
Debt Instrument [Line Items]
Unsecured senior notes principal amount	$ 0	206,000,000
Face value	$ 300,000,000
Interest Rate	6.50%
Unsecured senior notes \| $950 face value, 8.125% interest rate payable semi-annually, due July 2023(4)
Debt Instrument [Line Items]
Unsecured senior notes principal amount	$ 0	$ 950,000,000
Face value	$ 950,000,000
Interest Rate	8.125%

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