Derivative Instruments and Concentration of Credit Risk (Details 1) (Risk Management, Williams Partners [Member], Not Designated as Hedging Instrument [Member])	Dec. 31, 2012 bbl
Basis Risk
Price Risk Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Derivative, Nonmonetary Notional Amount	(38,256,000)
Central Hub Risk
Price Risk Derivative Instruments Not Designated as Hedging Instruments [Abstract]
Derivative, Nonmonetary Notional Amount	(185,000)

Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

Name:	invest_DerivativeNonmonetaryNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant