Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended																								6 Months Ended			6 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended			3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Constitution Pipeline Company Llc [Member]	Jun. 30, 2014 Caiman Energy II LLC [Member]	Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Cash and Cash Equivalents [Member]	Dec. 31, 2013 Variable Interest Entity, Primary Beneficiary [Member] Cash and Cash Equivalents [Member]		Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Property Plant And Equipment [Member]	Dec. 31, 2013 Variable Interest Entity, Primary Beneficiary [Member] Property Plant And Equipment [Member]		Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Accounts Payable [Member]	Dec. 31, 2013 Variable Interest Entity, Primary Beneficiary [Member] Accounts Payable [Member]		Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Accrued Liabilities [Member]	Dec. 31, 2013 Variable Interest Entity, Primary Beneficiary [Member] Accrued Liabilities [Member]		Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Other Current Liabilities [Member]	Dec. 31, 2013 Variable Interest Entity, Primary Beneficiary [Member] Other Current Liabilities [Member]		Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Asset Retirement Obligation Costs [Member]	Dec. 31, 2013 Variable Interest Entity, Primary Beneficiary [Member] Asset Retirement Obligation Costs [Member]	Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Other Noncurrent Liabilities [Member]	Dec. 31, 2013 Variable Interest Entity, Primary Beneficiary [Member] Other Noncurrent Liabilities [Member]		Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Gulfstar One [Member]	Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Gulfstar One [Member] Estimated Remaining Construction Costs For Variable Interest Entity [Member]	Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Gunflint [Member] Estimated Remaining Construction Costs For Variable Interest Entity [Member]	Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Constitution Pipeline Company Llc [Member]	Jun. 30, 2014 Variable Interest Entity, Primary Beneficiary [Member] Constitution Pipeline Company Llc [Member] Estimated Remaining Construction Costs For Variable Interest Entity [Member]	Jun. 30, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Laurel Mountain [Member]	Jun. 30, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Laurel Mountain [Member] Equity Method Investments [Member]	Mar. 31, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Bluegrass Pipeline Company Llc [Member]	Jun. 30, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Bluegrass Pipeline Company Llc [Member]	Jun. 30, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Bluegrass Pipeline Company Llc [Member] Income Loss From Equity Method Investment [Member]	Jun. 30, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Moss Lake [Member]	Mar. 31, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Moss Lake [Member] Income Loss From Equity Method Investment [Member]	Jun. 30, 2014 Variable Interest Entity, Not Primary Beneficiary [Member] Moss Lake [Member] Equity Method Investments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Ownership Percentage			41.00%																						51.00%			41.00%		51.00%			50.00%		50.00%
Variable Interest Entity, Financial or Other Support, Amount																									$ 128
Equity Method Investment, Ownership Percentage				58.00%
Other commitment																										50	134		575
Deconsolidation, Gain (Loss), Amount																																0
Our share of impairment of assets of equity method investee																																		67		4
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Variable Interest Entity, Consolidated, Carrying Amount, Assets					78	122	[1]	1,387	1,111	[1]
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities											(120)	(145)	[1]	(4)	(3)	[1]	0	(10)	[1]	(30)	0	(130)	(115)	[1]
Variable Interest Entity, Nonconsolidated, Comparison of Carrying Amount of Assets and Liabilities to Maximum Loss Exposure [Abstract]
Payments to Acquire Equity Method Investments	246	188
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net																															477						1
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount																														$ 477

[1] Amounts presented for December 31, 2013, include balances related to Bluegrass Pipeline. See discussion of the subsequent deconsolidation of Bluegrass Pipeline below.