Derivative Instruments, Hedging Activities and Fair Value Measurements, Gains and Losses on Derivative Instruments and Related Hedged Items (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Derivatives in fair value hedging relationships [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	$ (3.7)		$ 41.8		$ 19.6
Gain/(Loss) Recognized in Income on Hedged Item	16.2		(39.4)		(18.8)
Derivatives in fair value hedging relationships [Member] | Interest rate derivatives [Member] | Location - Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	2.7		24.7		16.3
Gain/(Loss) Recognized in Income on Hedged Item	(2.9)		(24.5)		(16.2)
Derivatives in fair value hedging relationships [Member] | Commodity derivatives [Member] | Location - Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	(6.4)		17.1		3.3
Gain/(Loss) Recognized in Income on Hedged Item	19.1		(14.9)		(2.6)
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)	(52.9)		(555.1)		(76.5)
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	(30.4)		(238.6)		(69.3)
Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0.3		(0.1)		(0.9)
Derivatives in cash flow hedging relationships [Member] | Interest rate derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Value Recognized in Other Comprehensive Income/(Loss) on Derivative (Effective Portion)	(70.2)	[1]	(333.2)	[1]	(0.1)	[1]
Derivatives in cash flow hedging relationships [Member] | Interest rate derivatives [Member] | Location - Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	(16.2)		(6.3)		(25.6)
Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0		0		(0.1)
Accumulated other comprehensive loss related to interest rate derivative instruments expected to be reclassified to earnings in interest expense over the next twelve months	(33.3)
Derivatives in cash flow hedging relationships [Member] | Commodity derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity derivative instruments expected to be reclassified to earnings over the next twelve months	10.7
Derivatives in cash flow hedging relationships [Member] | Commodity derivatives [Member] | Location - Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Value Recognized in Other Comprehensive Income/(Loss) on Derivative (Effective Portion)	31.0	[2]	(192.3)	[2]	(7.7)	[2]
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	10.1		(218.4)		2.1
Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0		0.2		0
Accumulated other comprehensive income (loss) related to commodity derivative instruments expected to be reclassified to earnings over the next twelve months	10.3
Derivatives in cash flow hedging relationships [Member] | Commodity derivatives [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)	(13.7)		(29.6)		(68.6)
Gain/(Loss) Reclassified from Accumulated Other Comprehensive Income/(Loss) to Income (Effective Portion)	(24.3)		(13.9)		(46.1)
Gain/(Loss) Recognized in Income on Derivative (Ineffective Portion)	0.3		(0.3)		(0.8)
Accumulated other comprehensive income (loss) related to commodity derivative instruments expected to be reclassified to earnings over the next twelve months	0.4
Derivatives in cash flow hedging relationships [Member] | Foreign currency derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Value Recognized in Other Comprehensive Income/(Loss) on Derivative (Effective Portion)	0		0		(0.1)
Derivatives in cash flow hedging relationships [Member] | Foreign currency derivatives [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		0.3
Derivatives not designated as hedging instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	14.3		17.2		4.6
Derivatives not designated as hedging instruments [Member] | Interest rate derivatives [Member] | Location - Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	(5.6)		(18.5)		(20.1)
Derivatives not designated as hedging instruments [Member] | Commodity derivatives [Member] | Location - Revenue [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	22.7		39.9		24.4
Derivatives not designated as hedging instruments [Member] | Commodity derivatives [Member] | Location - Operating costs and expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	(2.8)		(3.7)		0
Derivatives not designated as hedging instruments [Member] | Foreign currency derivatives [Member] | Location - Other income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain/(Loss) Recognized in Income on Derivative	$ 0		$ (0.5)		$ 0.3

[1] The increase in other comprehensive loss in 2011 and 2012 was primarily due to the impact of decreases in forward London Interbank Offered Rates ("LIBOR") on our forward starting interest rate swap portfolio.

[2] The increase in other comprehensive loss in 2011 was primarily due to the impact of rising commodity prices on our cash flow hedges associated with physical future deliveries of crude oil, refined products and NGLs.