Derivative Instruments, Hedging Activities and Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2012 Derivatives in cash flow hedging relationships [Member] Forward Starting Swaps [Member] Contract	Dec. 31, 2011 Derivatives in cash flow hedging relationships [Member] Forward Starting Swaps [Member] Contract	Dec. 31, 2011 Derivatives in cash flow hedging relationships [Member] Treasury Rate Locks [Member] Contract	Dec. 31, 2012 Interest rate derivatives [Member] Derivatives in cash flow hedging relationships [Member] Forward Starting Swaps [Member] Contract	Dec. 31, 2013 Interest rate derivatives [Member] Derivatives in fair value hedging relationships [Member] Senior Notes AA [Member] Contract	Dec. 31, 2012 Interest rate derivatives [Member] Derivatives in fair value hedging relationships [Member] Interest Rate Swap [Member] Contract	Dec. 31, 2013 Interest rate derivatives [Member] Derivatives in mark-to-market relationships [Member] Undesignated Swaps [Member] Contract	Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Natural gas processing: Forecasted natural gas purchases for plant thermal reduction (PTR) [Member] ft3		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Natural gas processing: Forecasted sales of NGLs [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Octane enhancement: Forecasted purchases of NGLs [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Octane enhancement: Forecasted sales of octane enhancement products [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Natural gas marketing: Forecasted sales of natural gas [Member] ft3		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] NGL marketing: Forecasted purchases of NGLs and related hydrocarbon products [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] NGL marketing: Forecasted sales of NGLs and related hydrocarbon products [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Refined products marketing: Forecasted purchases of refined products [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Refined products marketing: Forecasted sales of refined products [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Crude oil marketing: Forecasted purchases of crude oil [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in cash flow hedging relationships [Member] Crude oil marketing: Forecasted sales of crude oil [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in fair value hedging relationships [Member] Natural gas marketing: Natural gas storage inventory management activities [Member] ft3		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in fair value hedging relationships [Member] Refined products marketing: Refined products inventory management activities [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in mark-to-market relationships [Member] Natural gas risk management activities [Member] ft3		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in mark-to-market relationships [Member] Refined products risk management activities [Member] bbl		Dec. 31, 2013 Commodity derivatives [Member] Derivatives in mark-to-market relationships [Member] Crude oil risk management activities [Member] bbl
Derivative [Line Items]
Expected offset percentage of change in fair value derivative instrument (in hundredths)	80.00%	125.00%
Number of Derivatives Outstanding							10		6
Type of Derivatives Outstanding							fixed-to-floating swaps		floating-to-fixed swaps
Notional Amount							$ 750.0		$ 600.0
Period of Hedge							1/2011 to 2/2016		5/2010 to 7/2014
Rate Swap, fixed rate (in hundredths)							3.20%		2.00%
Rate Swap, floating rate (in hundredths)							1.20%		0.20%
Current Volume										7,000,000,000	[1],[2]	1,100,000	[1],[2]	400,000	[1],[2]	3,100,000	[1],[2]	2,600,000,000	[1],[2]	5,900,000	[1],[2]	5,400,000	[1],[2]	600,000	[1],[2]	1,600,000	[1],[2]	4,000,000	[1],[2]	5,800,000	[1],[2]	8,200,000,000	[1],[2]	100,000	[1],[2]	94,700,000,000	[1],[2],[3],[4]	800,000	[1],[2],[3]	14,400,000	[1],[2],[3]
Long Term Volume																100,000	[1],[2]																			19,700,000,000	[1],[2],[3],[4]
Accounting Treatment										Cash flow hedge		Cash flow hedge		Cash flow hedge		Cash flow hedge		Cash flow hedge		Cash flow hedge		Cash flow hedge		Cash flow hedge		Cash flow hedge		Cash flow hedge		Cash flow hedge		Fair value hedge		Fair value hedge		Mark-to-market		Mark-to-market		Mark-to-market
Number of derivative instruments settled			17	3	2	16		11
Notional amount of settled derivative instruments			850.0	250.0	1,230.0	1,000.0		800.0
Loss (gain) recognized due to settlement of derivative instruments								37.7
Accumulated other comprehensive income (loss) related to interest rate derivative instruments			$ 185.5	$ 5.8	$ 17.4	$ 168.8
Accumulated Other Comprehensive Loss, Forecasted Hedging period			10 years	10 years	25 years	10 years		3 years
Current natural gas hedging volumes designated as an index plus or minus a discount																																				27,500,000,000

[1] The maximum term for derivatives designated as cash flow hedges, derivatives designated as fair value hedges and derivatives not designated as hedging instruments is January 2015, May 2014 and October 2016, respectively.

[2] Volume for derivatives designated as hedging instruments reflects the total amount of volumes hedged whereas volume for derivatives not designated as hedging instruments reflects the absolute value of derivative notional volumes.

[3] Reflects the use of derivative instruments to manage risks associated with transportation, processing and storage assets.

[4] Current volumes include 27.5 Bcf of physical derivative instruments that are predominantly priced at a marked-based index plus a premium or minus a discount related to location differences.