Net Income per Unit (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share Basic [Line Items]
Income from continuing operations									$ 313	$ 58	$ 326
Less: Series A Preferred units									0	2	23
Less: Incentive distribution rights									72	70	85
Less: Distributions on nonvested phantom unit awards									6	6	6
Limited partners’ interest in net income (loss) from continuing operations									235	(20)	212
Loss from discontinued operations, net of taxes									$ 0	$ (265)	$ (177)
Common Units [Member]
Weighted average limited partner units outstanding:
Common units - basic									82,755,520	84,299,893	99,270,120
Common units - equivalents									796,442	520,677	458,234
Common units - diluted									83,551,962	84,820,570	99,728,354
Income (loss) from continuing operations per limited partner unit:
Common - basic	$ 0.76	$ 0.57	$ 0.44	$ 1.08	$ (1.11)	$ 1.16	$ 0.91	$ (1.11)	$ 2.84	$ (0.25)	$ 2.13
Common - diluted	0.75	0.57	0.43	1.07	(1.11)	1.15	0.90	(1.11)	2.82	(0.25)	2.12
Loss from discontinued operations per limited partner unit:
Common - basic	0	0	0	0	0	(0.03)	(0.32)	(2.63)	0	(3.14)	(1.78)
Common - diluted	$ 0	$ 0	$ 0	$ 0	$ 0	$ (0.03)	$ (0.32)	$ (2.63)	$ 0	$ (3.14)	$ (1.78)