Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income tax expense at statutory federal rate	$ 35	$ 13	$ 8	$ 35
Partnership earnings not subject to tax	(28)	(10)	(2)	(36)
State and local tax, net of federal benefit	1	0	3	0
Other	0	2	2	4
Net income tax expense	$ 8	$ 5	$ 11	$ 3