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USD ($)

USD ($) / shares

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USD ($)

USD ($) / shares

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 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 1
 -Article 5

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 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 4
 -Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 43
 -Chapter 4
 -Paragraph 5A

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 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 6
 -Article 5

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 -Publisher AICPA
 -Name Accounting Principles Board Opinion (APB)
 -Number 18
 -Paragraph 19
 -Subparagraph c

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 04
 -Paragraph 11
 -Article 7

Reference 3: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 95
 -Paragraph 28

Reference 4: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 9
 -Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Principles Board Opinion (APB)
 -Number 18
 -Paragraph 6
 -Subparagraph b

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 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 34
 -Paragraph 21
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</ElementReferences><IsTotalLabel>false</IsTotalLabel><IsEPS>false</IsEPS><Label>Interest capitalized</Label></Row><Row><Id>15</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><Level>0</Level><ElementName>wpz_InterestIncomeThirdParty</ElementName><ElementPrefix>wpz</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>credit</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>Interest income - third-party.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>verboselabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>true</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>1000000</NumericAmount><RoundedNumericAmount>1</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell><Cell><Id>2</Id><IsNumeric>true</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>3000000</NumericAmount><RoundedNumericAmount>3</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell></Cells><OriginalInstanceReportColumns /><Unit>Monetary</Unit><ElementDataType>xbrli:monetaryItemType</ElementDataType><SimpleDataType>monetary</SimpleDataType><ElementDefenition>Interest income - third-party.</ElementDefenition><ElementReferences>No authoritative reference available.</ElementReferences><IsTotalLabel>false</IsTotalLabel><IsEPS>false</IsEPS><Label>Interest Income</Label></Row><Row><Id>16</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><Level>0</Level><ElementName>us-gaap_OtherNonoperatingIncomeExpense</ElementName><ElementPrefix>us-gaap</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>credit</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>No definition available.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>totallabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>true</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>5000000</NumericAmount><RoundedNumericAmount>5</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell><Cell><Id>2</Id><IsNumeric>true</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>-1000000</NumericAmount><RoundedNumericAmount>-1</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell></Cells><OriginalInstanceReportColumns /><Unit>Monetary</Unit><ElementDataType>xbrli:monetaryItemType</ElementDataType><SimpleDataType>monetary</SimpleDataType><ElementDefenition>The net amount of other nonoperating income and expense, which does not qualify for separate disclosure on the income statement under materiality guidelines.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 9
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 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph A1, A4, A5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 5
 -Subparagraph b

Reference 3: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 29

Reference 4: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 38
 -Subparagraph a

Reference 5: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 38
 -Subparagraph c(1)

</ElementReferences><IsTotalLabel>false</IsTotalLabel><IsEPS>false</IsEPS><Label>Net income</Label></Row><Row><Id>18</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><Level>0</Level><ElementName>us-gaap_NetIncomeLossAttributableToNoncontrollingInterest</ElementName><ElementPrefix>us-gaap</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>debit</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>No definition available.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>totallabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell><Cell><Id>2</Id><IsNumeric>true</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>6000000</NumericAmount><RoundedNumericAmount>6</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell></Cells><OriginalInstanceReportColumns /><Unit>Monetary</Unit><ElementDataType>xbrli:monetaryItemType</ElementDataType><SimpleDataType>monetary</SimpleDataType><ElementDefenition>The portion of net income (loss) attributable to the noncontrolling interest (if any) deducted in order to derive the portion attributable to the parent.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef
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 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 38
 -Subparagraph a

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 38
 -Subparagraph c(1)

Reference 3: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph A1, A4, A5

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 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 19
 -Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 38
 -Subparagraph d

Reference 3: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph A7
 -Appendix A

Reference 4: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 38
 -Subparagraph a

Reference 5: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 04
 -Paragraph 20
 -Article 9

Reference 6: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 130
 -Paragraph 10, 15

Reference 7: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Emerging Issues Task Force (EITF)
 -Number 87-21

Reference 8: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 95
 -Paragraph 28, 29, 30

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 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 19
 -Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 38
 -Subparagraph d

Reference 3: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph A7
 -Appendix A

Reference 4: http://www.xbrl.org/2003/role/presentationRef
 -Publisher AICPA
 -Name Accounting Research Bulletin (ARB)
 -Number 51
 -Paragraph 38
 -Subparagraph a

Reference 5: http://www.xbrl.org/2003/role/presentationRef
 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 04
 -Paragraph 20
 -Article 9

Reference 6: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 130
 -Paragraph 10, 15

Reference 7: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Emerging Issues Task Force (EITF)
 -Number 87-21

Reference 8: http://www.xbrl.org/2003/role/presentationRef
 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 95
 -Paragraph 28, 29, 30

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 -Name Statement of Financial Accounting Standard (FAS)
 -Number 131
 -Paragraph 27

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 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 1
 -Article 5

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 -Publisher FASB
 -Name Statement of Financial Accounting Standard (FAS)
 -Number 131
 -Paragraph 27

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 -Publisher SEC
 -Name Regulation S-X (SX)
 -Number 210
 -Section 03
 -Paragraph 6
 -Article 5

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