Related Party Debt - Schedule of Consolidated Related Party Debt Obligations (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Line Of Credit Facility [Line Items]
Outstanding Balance	$ 2,692	$ 2,692
Unamortized debt issuance costs	(2)	(2)
Total Capacity	3,590	3,590
Available Capacity	$ 896	896
Revolving Credit Facility | Ten Year Fixed Facility
Line Of Credit Facility [Line Items]
Debt instrument term	10 years
Outstanding Balance	$ 600	600
Total Capacity	600	600
Available Capacity	$ 0	0
Revolving Credit Facility | Seven Year Fixed Facility
Line Of Credit Facility [Line Items]
Debt instrument term	7 years
Outstanding Balance	$ 600	600
Total Capacity	600	600
Available Capacity	$ 0	0
Revolving Credit Facility | Five Year Revolver due July 2023
Line Of Credit Facility [Line Items]
Debt instrument term	5 years
Outstanding Balance	$ 494	494
Total Capacity	760	760
Available Capacity	266	266
Revolving Credit Facility | Five Year Revolver due December 2022
Line Of Credit Facility [Line Items]
Outstanding Balance	400	400
Total Capacity	1,000	1,000
Available Capacity	$ 600	600
Revolving Credit Facility | Five Year Fixed Facility
Line Of Credit Facility [Line Items]
Debt instrument term	5 years
Outstanding Balance	$ 600	600
Total Capacity	600	600
Available Capacity	0	0
Revolving Credit Facility | 2019 Zydeco Revolver
Line Of Credit Facility [Line Items]
Outstanding Balance	0	0
Total Capacity	30	30
Available Capacity	$ 30	$ 30