NET INCOME PER COMMON UNIT (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		0 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	May 22, 2013 General Partner	Jun. 30, 2013 General Partner
Common units and interest in the partnership
Additional percentage investment held by General Partner					2.00%	2.00%
Net income	$ 23	$ 33	$ 52	$ 72
Net income allocated to General Partner		(1)	(1)	(2)
Net income allocable to common units	$ 23	$ 32	$ 51	$ 70
Weighted average common units outstanding (millions) - basic (in units)	57.4	53.5	55.4	53.5
Weighted average common units outstanding (millions) - diluted (in units)	57.4	53.5	55.4	53.5
Net income per common unit - basic (in dollars per unit)	$ 0.40	$ 0.60	$ 0.92	$ 1.31
Net income per common unit - diluted (in dollars per unit)	$ 0.40	$ 0.60	$ 0.92	$ 1.31