Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Series A Preferred Limited Partners [Member]	Series B Preferred Limited Partners [Member]	Series C Preferred Limited Partners [Member]	Limited Partners	General Partner	Accumulated Other Comprehensive (Loss) Income	Noncontrolling Interests
Beginning balance at Dec. 31, 2018	$ 7,297	$ 489	$ 156	$ 106	$ 6,418	$ 107	$ (8)	$ 29
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	76	9	3	2	20	41	0	1
Other comprehensive income	0
Total Cash Distribution to Unitholders	(159)	0	(3)	(2)	(111)	(43)	0	0
Distributions to noncontrolling interests	(1)	0	0	0	0	0	0	1
Ending balance at Mar. 31, 2019	7,213	498	156	106	6,327	$ 105	(8)	29
Beginning balance at Dec. 31, 2019	6,633	489	156	106	5,861		(7)	28
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income (loss)	(549)	9	3	2	(564)		0	1
Other comprehensive income	0
Total Cash Distribution to Unitholders	(167)	0	(3)	(2)	(162)		0	0
Distributions to noncontrolling interests	(1)	0	0	0	0		0	(1)
Ending balance at Mar. 31, 2020	$ 5,916	$ 498	$ 156	$ 106	$ 5,135		$ (7)	$ 28