CASH DISTRIBUTIONS (Details) (USD $) In Millions, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
CASH DISTRIBUTIONS
Cash distributions (in dollars per unit)	$ 0.77	$ 0.73	$ 2.27	$ 2.19
Cash distributions (in dollars)	$ 42.0	$ 34.4	$ 112.8	$ 103.3