Derivative Instruments and Concentration of Credit Risk (Details 4) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Receivables by product or service [Line Items]
Receivables by product or service	$ 688	$ 637
Sale of ngl and related products and svcs [Member]
Receivables by product or service [Line Items]
Receivables by product or service	411	446
Transportation of natural gas and related products [Member]
Receivables by product or service [Line Items]
Receivables by product or service	170	164
Other Receivable [Member]
Receivables by product or service [Line Items]
Receivables by product or service	$ 107	$ 27

The aggregate of amounts due from customers or clients, within one year of the balance sheet date (or one operating cycle, if longer), for goods or services that have been delivered or sold in the normal course of business and an amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date within one year of the balance sheet, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection and net of any write-downs taken for collection uncertainty on the part of the holder, respectively.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3,4)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3, 4

-Article 5

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant