Equity and Distributions, Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Abstract]
Beginning balance				$ (280.0)				$ (219.2)	$ (280.0)	$ (219.2)
Other comprehensive income (loss) before reclassifications									(44.3)	(151.6)
Amounts reclassified from accumulated other comprehensive loss									152.6	90.8
Total other comprehensive income (loss)									108.3	(60.8)	$ 22.4
Ending balance	$ (171.7)				$ (280.0)				(171.7)	(280.0)	(219.2)
Interest expense									984.6	982.6	961.8
Operating costs and expenses									25,557.5	19,643.5	23,668.7
Total	(797.3)	$ (621.3)	$ (666.0)	(771.0)	(669.7)	$ (643.1)	$ (570.0)	(670.2)	(2,855.6)	(2,553.0)	(2,558.4)
Gains (Losses) on Cash Flow Hedges [Member] | Commodity Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Beginning balance				(83.8)				56.6	(83.8)	56.6
Other comprehensive income (loss) before reclassifications									(38.5)	(193.8)
Amounts reclassified from accumulated other comprehensive loss									112.2	53.4
Total other comprehensive income (loss)									73.7	(140.4)
Ending balance	(10.1)				(83.8)				(10.1)	(83.8)	56.6
Gains (Losses) on Cash Flow Hedges [Member] | Interest Rate Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Beginning balance				(199.8)				(279.5)	(199.8)	(279.5)
Other comprehensive income (loss) before reclassifications									(5.7)	42.3
Amounts reclassified from accumulated other comprehensive loss									40.4	37.4
Total other comprehensive income (loss)									34.7	79.7
Ending balance	(165.1)				(199.8)				(165.1)	(199.8)	(279.5)
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Beginning balance				$ 3.6				$ 3.7	3.6	3.7
Other comprehensive income (loss) before reclassifications									(0.1)	(0.1)
Amounts reclassified from accumulated other comprehensive loss									0.0	0.0
Total other comprehensive income (loss)									(0.1)	(0.1)
Ending balance	$ 3.5				$ 3.6				3.5	3.6	$ 3.7
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Total									152.6	90.8
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member] | Commodity Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Revenue									111.6	53.6
Operating costs and expenses									0.6	(0.2)
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Member] | Interest Rate Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Interest expense									$ 40.4	$ 37.4