| **Variable Interest Entities (Details) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Thousands** | Jul. 31, 2016 | Oct. 31, 2015 |
|-----------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Variable Interest Entity [Line Items]**                                                                             |          |          |
| Total equity method investments in non-utility activities                                                             | $ 239,650     | $ 206,956     |
| Cardinal Pipeline Company                                                                                             |          |          |
| **Variable Interest Entity [Line Items]**                                                                             |          |          |
| Total equity method investments in non-utility activities                                                             | 14,456        | 15,083        |
| Pine Needle Company                                                                                                   |          |          |
| **Variable Interest Entity [Line Items]**                                                                             |          |          |
| Total equity method investments in non-utility activities                                                             | 17,155        | 18,396        |
| South Star Energy Services                                                                                            |          |          |
| **Variable Interest Entity [Line Items]**                                                                             |          |          |
| Total equity method investments in non-utility activities                                                             | 41,371        | 41,325        |
| Hardy Storage                                                                                                         |          |          |
| **Variable Interest Entity [Line Items]**                                                                             |          |          |
| Total equity method investments in non-utility activities                                                             | 41,753        | 39,706        |
| Constitution Pipeline Company                                                                                         |          |          |
| **Variable Interest Entity [Line Items]**                                                                             |          |          |
| Total equity method investments in non-utility activities                                                             | 93,587        | 82,403        |
| Atlantic Coast Pipeline                                                                                               |          |          |
| **Variable Interest Entity [Line Items]**                                                                             |          |          |
| Total equity method investments in non-utility activities                                                             | $ 31,328      | $ 10,043      |

| X                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
+ Details**Name:**us-gaap_VariableInterestEntityLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph a -URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5728-111685
+ Details**Name:**us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                        |
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| X                                                                                                                                                                                              |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| X                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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