PARTNERS' CAPITAL (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended
	Jan. 02, 2015	Jul. 01, 2014	Dec. 31, 2014	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Repayment of debt						$ 0.0		$ 306.0	$ 12.0
Percentage distributed to General Partner and IDUs (in percentage)				25.00%
Minimum portion of quarterly distribution (in dollars per share)			$ 0.5435	$ 0.5435
First Target Distribution [Member]
Percentage distributed to General Partner and IDUs (in percentage)					15.00%	25.00%	[1]
Minimum portion of quarterly distribution (in dollars per share)					$ 0.295
Second Target Distribution [Member]
Percentage distributed to General Partner and IDUs (in percentage)					25.00%
Minimum portion of quarterly distribution (in dollars per share)					$ 0.35
Over Second Target Distribution [Member]
Percentage distributed to General Partner and IDUs (in percentage)					50.00%
Minimum portion of quarterly distribution (in dollars per share)					$ 0.495
General Partner [Member]
Allocations from capital accounts	$ 1.0					$ 789.5		30.5
Alberta Clipper Pipeline [Member]
Percentage of interest acquired (in percentage)	66.70%
Repayment of debt	$ 306.0
Difference between fair value of consideration and carrying value of noncontrolling interest	364.0
Carrying value of noncontrolling interest	$ 403.7
Class E Units [Member]
Notional value (in dollars per share)	$ 38.31					$ 38.31
Redemption term						30 years
Earnings threshold determining cancellation of units						$ 265.9
Number of partnership units potentially cancellable (in shares)						1,305,142
Amount of gross income threshold resulting in special allocations						$ 40.0
Amount of gross income threshold resulting in special allocations, secondary period						$ 20.0
Class E Units [Member] | Alberta Clipper Pipeline [Member]
Number of units issued (in shares)	18,114,975
Fair value of equity transferred	$ 767.7
Incentive Distribution Units [Member]
Number of units issued in transaction (in shares)						1,000
Distribution period						5 years
Percentage distributed to General Partner and IDUs (in percentage)						23.00%
Minimum portion of quarterly distribution (in dollars per share)						$ 0.5435
Fair value of capital distribution (in dollars)						$ 491.7
Class D Units [Member]
Notional value (in dollars per share)						$ 31.35
Redemption term						30 years
Number of units issued in transaction (in shares)						66,100,000
Redemption rate (in percentage)						105.00%
Preference in liquidation (in percentage)						20.00%
Preference in liquidation, annual increase (in percentage)						20.00%
Maximum preference in liquidation (in percentage)						100.00%
Fair value of capital distribution (in dollars)						$ 2,480.0
I Units [Member]
Allocations from capital accounts	$ 46.7					$ 126.0		$ 362.3
Number of units issued in transaction (in shares)		66,100,000

[1] For distributions in excess of the Minimum Quarterly Distribution, this percentage includes both the General Partner's distributions of 2% and the distribution to the Incentive Distribution Unit holder, a wholly-owned subsidiary of our General Partner.