Short-term Borrowings and Long-term Debt (Details) (USD $)										12 Months Ended		12 Months Ended												3 Months Ended			3 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2013 Inventory financing [Member]		Dec. 31, 2012 Inventory financing [Member]		May 01, 2013 Midstream Partnership [Member]	Dec. 31, 2013 Line of Credit [Member]	Dec. 31, 2012 Line of Credit [Member]	Dec. 31, 2013 Senior notes 2016 to 2041 [Member]		Dec. 31, 2012 Senior notes 2016 to 2041 [Member]		Dec. 31, 2013 Commercial Paper [Member]		Dec. 31, 2012 Commercial Paper [Member]		Dec. 31, 2013 Unamortized Discount Premium Member		Dec. 31, 2012 Unamortized Discount Premium Member		Jun. 30, 2013 April 2013 [Member] Senior Notes [Member]	Apr. 30, 2013 April 2013 [Member] Senior Notes [Member]	May 01, 2013 May 2013 [Member] Midstream Partnership [Member]	Jun. 30, 2013 May 2013 [Member] Senior Notes [Member]	Jun. 30, 2013 May 2013 [Member] Commercial Paper [Member]
Debt Instrument [Line Items]
Short-term Debt	$ 43,000,000	[1]	$ 38,000,000	[1]	$ 43,000,000	[1]	$ 38,000,000	[1]
Long-term Debt	0		0		0		0
Long-term Debt, Excluding Current Maturities	2,240,000,000		2,276,000,000									2,168,000,000		2,328,000,000		118,000,000	[2]	0	[2]	(46,000,000)		(52,000,000)
Long-term Debt, Current Maturities	0	[1]	365,000,000	[1]								0	[1]	365,000,000	[1]	0	[1],[2]	0	[1],[2]	0	[1]	0	[1]
Short Term Borrowings And Current Portion Long Term Debt	43,000,000	[1]	403,000,000	[1]
Extinguishment of Debt, Amount																								365,000,000			160,000,000	357,000,000
Debt Instrument, Interest Rate, Stated Percentage																									7.875%		5.95%
Debt repayment by affiliate									1,050,000,000																	1,050,000,000
Extinguishment Of Debt Purchase Price Percentage Of Principal																											103.419%
Size of Facility										600,000,000	950,000,000
Loans										0	0
Letters of Credit										0	0
Commercial Paper										118,000,000	0
Line of Credit Facility, Interest Rate Description										London Interbank Offered Rate plus 150 basis points
Percentage on limitation of debt to total capitalization under covenant (in hundredths)										65.00%
Long-term Debt, Maturities in 2014	0
Long-term Debt, Maturities in 2015	0
Long-term Debt, Maturities in 2016	325,000,000
Long-term Debt, Maturities in 2017	250,000,000
Long-term Debt, Maturities in 2018	$ 418,000,000
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum												4.50%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum												6.625%

[1] Includes amounts due or exchangeable within one year of the date noted.

[2] Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted.