NET INCOME PER COMMON UNIT (Details 2) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income per common unit
Net income attributable to controlling interests	$ 44	$ 37	$ 101	$ 94
Less: Net income allocated to the General Partner, including incentive distributions	(1)	(1)	(2)	(2)
Incentive distributions allocated to the General Partner	(1)		(1)
Common units
Net income per common unit
Net income allocated to limited partners	$ 42	$ 36	$ 98	$ 92
Weighted average common units outstanding (millions) - basic (in units)	63.8	62.3	63.7	62.3
Weighted average common units outstanding (millions) - diluted (in units)	63.8	62.3	63.7	62.3
Net income per common unit - basic (in dollars per unit)	$ 0.66	$ 0.58	$ 1.53	$ 1.48
Net income per common unit - diluted (in dollars per unit)	$ 0.66	$ 0.58	$ 1.53	$ 1.48