Quarterly Financial Data (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues	$ 12,279us-gaap_Revenues	$ 13,618us-gaap_Revenues	$ 13,029us-gaap_Revenues	$ 12,232us-gaap_Revenues	$ 12,032us-gaap_Revenues	$ 11,902us-gaap_Revenues	$ 11,551us-gaap_Revenues	$ 10,854us-gaap_Revenues	$ 51,158us-gaap_Revenues	$ 46,339us-gaap_Revenues	$ 15,702us-gaap_Revenues
Gross profit	1,365us-gaap_GrossProfit	1,494us-gaap_GrossProfit	1,393us-gaap_GrossProfit	1,366us-gaap_GrossProfit	1,305us-gaap_GrossProfit	1,248us-gaap_GrossProfit	1,322us-gaap_GrossProfit	1,260us-gaap_GrossProfit	5,618us-gaap_GrossProfit	5,135us-gaap_GrossProfit
Operating income	383us-gaap_OperatingIncomeLoss	668us-gaap_OperatingIncomeLoss	736us-gaap_OperatingIncomeLoss	688us-gaap_OperatingIncomeLoss	(151)us-gaap_OperatingIncomeLoss	526us-gaap_OperatingIncomeLoss	632us-gaap_OperatingIncomeLoss	534us-gaap_OperatingIncomeLoss	2,475us-gaap_OperatingIncomeLoss	1,541us-gaap_OperatingIncomeLoss	1,394us-gaap_OperatingIncomeLoss
Net income	34us-gaap_ProfitLoss	447us-gaap_ProfitLoss	581us-gaap_ProfitLoss	491us-gaap_ProfitLoss	(473)us-gaap_ProfitLoss	404us-gaap_ProfitLoss	413us-gaap_ProfitLoss	424us-gaap_ProfitLoss	1,553us-gaap_ProfitLoss	768us-gaap_ProfitLoss	1,648us-gaap_ProfitLoss
Common Unitholders’ interest in net income (loss)	$ (90)	$ 148	$ 295	$ 253	$ (666)	$ 209	$ 165	$ 194	$ 606	$ (98)	$ 1,108
Basic net income (loss) per Common Unit	$ (0.28)	$ 0.44	$ 0.92	$ 0.76	$ (1.90)	$ 0.55	$ 0.53	$ 0.63	$ 1.77	$ (0.18)	$ 4.43
Diluted net income (loss) per Common Unit	$ (0.28)	$ 0.44	$ 0.92	$ 0.76	$ (1.90)	$ 0.55	$ 0.53	$ 0.63	$ 1.77	$ (0.18)	$ 4.42

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Aggregate amount of net income allocated to limited partners.

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Per unit of ownership amount after tax of income (loss) available to limited partnership (LP) unit-holder and units that would have been outstanding assuming the issuance of limited partner units for dilutive potential units outstanding.

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Per unit of ownership amount after tax of income (loss) available to outstanding limited partnership (LP) unit-holder.

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The net result for the period of deducting operating expenses from operating revenues.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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