Equity and Distributions, Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, December 31, 2012	$ (370.4)
Other comprehensive income before reclassifications	(40.9)
Amounts reclassified from accumulated other comprehensive income	13.2
Total other comprehensive income (loss)	(27.7)	9.6
Balance, March 31, 2013	(398.1)
Gains and Losses on Cash Flow Hedges [Member] | Commodity Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, December 31, 2012	10.1
Other comprehensive income before reclassifications	(47.6)
Amounts reclassified from accumulated other comprehensive income	7.3
Total other comprehensive income (loss)	(40.3)
Balance, March 31, 2013	(30.2)
Gains and Losses on Cash Flow Hedges [Member] | Interest Rate Derivative Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, December 31, 2012	(383.0)
Other comprehensive income before reclassifications	6.7
Amounts reclassified from accumulated other comprehensive income	5.9
Total other comprehensive income (loss)	12.6
Balance, March 31, 2013	(370.4)
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, December 31, 2012	1.7
Other comprehensive income before reclassifications	0
Amounts reclassified from accumulated other comprehensive income	0
Total other comprehensive income (loss)	0
Balance, March 31, 2013	1.7
Post Retirement Benefit Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, December 31, 2012	0.8
Other comprehensive income before reclassifications	0
Amounts reclassified from accumulated other comprehensive income	0
Total other comprehensive income (loss)	0
Balance, March 31, 2013	$ 0.8