PARTNERS' CAPITAL (Schedule of Class A Common Unit Equity Issuances) (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	9 Months Ended
		Mar. 31, 2015	Sep. 30, 2015	Sep. 30, 2014
Net Proceeds Including General Partner Contribution		$ 294.8	$ 294.8
General Partner [Member]
General Partner Contribution	[1]	$ 6.0
Class A Common Units [Member]
Number of Class A common units Issued (in shares)		8,000,000
Offering Price per Class A common unit (in dollars per share)		$ 36.70
Net Proceeds to the Partnership (in dollars)		$ 288.8

[1] Contributions made by the General Partner to maintain its 2% general partner interest.