Derivative Instruments, Hedging Activities and Fair Value Measurements, Gains and Losses on Derivative Instruments and Related Hedged Items (Details) (USD $) In Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Interest rate derivatives [Member] | Derivatives in fair value hedging relationships [Member] | Location - Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	$ 21.1		$ 11.6		$ 8.8		$ 19.0
Gain/(Loss) Recognized in Income on Hedged Item	(21.0)		(10.8)		(9.7)		(18.2)
Commodity derivatives [Member] | Derivatives in fair value hedging relationships [Member] | Location - Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	(1.6)		4.7		(1.3)		2.9
Gain/(Loss) Recognized in Income on Hedged Item	0.2		(4.3)		(1.1)		(2.4)
Derivatives in fair value hedging relationships [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	19.5		16.3		7.5		21.9
Gain/(Loss) Recognized in Income on Hedged Item	(20.8)		(15.1)		(10.8)		(20.6)
Interest rate derivatives [Member] | Derivatives in cash flow hedging relationships [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Value Recognized in Other Comprehensive Income/(Loss) on Derivative (Effective Portion)	(60.1)		(79.3)		(46.0)		(86.8)
Interest rate derivatives [Member] | Derivatives in cash flow hedging relationships [Member] | Location - Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	(1.5)		(7.2)		(3.0)		(13.3)
Accumulated Other Comprehensive Loss related to interest rate derivative instruments expected to be reclassified to earnings in interest expense over the next twelve months	(7.9)				(7.9)
Commodity derivatives [Member] | Derivatives in cash flow hedging relationships [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated Other Comprehensive Loss related to commodity derivative instruments expected to be reclassified to earnings over the next twelve months	(61.2)				(61.2)
Commodity derivatives [Member] | Derivatives in cash flow hedging relationships [Member] | Location - Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Value Recognized in Other Comprehensive Income/(Loss) on Derivative (Effective Portion)	(19.4)	[1]	93.5	[1]	(174.8)	[1]	86.4	[1]
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	(79.3)		18.3		(148.5)		2.5
Gain Recognized in Income on Derivative (Ineffective Portion)	0.3		0		0.2		0
Accumulated Other Comprehensive Loss related to commodity derivative instruments expected to be reclassified to earnings over the next twelve months	(31.8)				(31.8)
Commodity derivatives [Member] | Derivatives in cash flow hedging relationships [Member] | Location - Operating costs and expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Value Recognized in Other Comprehensive Income/(Loss) on Derivative (Effective Portion)	(2.3)		(1.5)		1.7		(53.3)
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	4.5		(16.8)		4.8		(17.5)
Gain Recognized in Income on Derivative (Ineffective Portion)	0		3.5		0		2.9
Accumulated Other Comprehensive Loss related to commodity derivative instruments expected to be reclassified to earnings over the next twelve months	(29.4)				(29.4)
Foreign currency derivatives [Member] | Derivatives in cash flow hedging relationships [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Value Recognized in Other Comprehensive Income/(Loss) on Derivative (Effective Portion)	0		(0.1)		0		(0.2)
Foreign currency derivatives [Member] | Derivatives in cash flow hedging relationships [Member] | Location - Other income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	0		0		0		0.3
Derivatives in cash flow hedging relationships [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Value Recognized in Other Comprehensive Income/(Loss) on Derivative (Effective Portion)	(81.8)		12.6		(219.1)		(53.9)
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	(76.3)		(5.7)		(146.7)		(28.0)
Gain Recognized in Income on Derivative (Ineffective Portion)	0.3		3.5		0.2		2.9
Interest rate derivatives [Member] | Derivatives not designated as hedging instruments [Member] | Location - Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	(11.9)		0		(10.5)		0
Commodity derivatives [Member] | Derivatives not designated as hedging instruments [Member] | Location - Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	9.5		(8.9)		13.3		(5.0)
Commodity derivatives [Member] | Derivatives not designated as hedging instruments [Member] | Location - Operating costs and expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	0		0		0		(1.5)
Derivatives not designated as hedging instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	$ (2.4)		$ (8.9)		$ 2.8		$ (6.5)

[1] The increase in other comprehensive loss during 2011 is primarily due to the impact of rising crude oil, refined products and NGL prices on our derivative instruments designated as cash flow hedges of future physical sales transactions.