Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Limited Partners [Member]	General Partner [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Noncontrolling Interests [Member]
Beginning balance at Dec. 31, 2014	$ 3,026	$ 2,984	$ 18	$ (9)	$ 33
Net income	69	38	31		0
Other comprehensive (loss) income	1			1
Issuance of common units	31	31	0	0	0
Distributions to limited partners and general partner	(120)	(89)	(31)	0	0
Distributions to noncontrolling interests	(1)	0	0	0	(1)
Ending balance at Mar. 31, 2015	3,006	2,964	18	(8)	32
Beginning balance at Dec. 31, 2015	2,805	2,762	18	(8)	33
Net income	72	41	31		0
Other comprehensive (loss) income	0
Distributions to limited partners and general partner	(121)	(90)	(31)
Distributions to noncontrolling interests	(2)				(2)
Ending balance at Mar. 31, 2016	$ 2,754	$ 2,713	$ 18	$ (8)	$ 31