| **Regulatory Matters - Assets and Liabilities (Details) - USD ($) $ in Thousands**      | Jul. 31, 2016 | Oct. 31, 2015 |
|-----------------------------------------------------------------------------------------|---------------|---------------|
| **Regulatory Liabilities [Line Items]**                                                 |          |          |
| Regulatory liabilities - current                                                        | $ 3,908       | $ 13,367      |
| Regulatory liabilities - noncurrent                                                     | 598,749       | 590,301       |
| Regulatory liabilities, Total                                                           | 602,657       | 603,668       |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 78,420        | 10,936        |
| Regulatory assets - noncurrent                                                          | 341,124       | 196,726       |
| Regulatory assets, Total                                                                | 419,544       | 207,662       |
| Amounts due to customers                                                                |          |          |
| **Regulatory Liabilities [Line Items]**                                                 |          |          |
| Regulatory liabilities - current                                                        | 3,908         | 13,367        |
| Regulatory cost of removal                                                              |          |          |
| **Regulatory Liabilities [Line Items]**                                                 |          |          |
| Regulatory liabilities - noncurrent                                                     | 533,844       | 521,478       |
| Deferred income taxes                                                                   |          |          |
| **Regulatory Liabilities [Line Items]**                                                 |          |          |
| Regulatory liabilities - noncurrent                                                     | 64,827        | 68,738        |
| Amounts not yet recognized as a component of pension and other retirement benefit costs |          |          |
| **Regulatory Liabilities [Line Items]**                                                 |          |          |
| Regulatory liabilities - noncurrent                                                     | 78            | 85            |
| Unamortized debt expense on reacquired debt                                             |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 238           | 238           |
| Regulatory assets - noncurrent                                                          | 4,488         | 4,666         |
| Amounts due from customers                                                              |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 34,621        | 0             |
| Environmental costs                                                                     |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 1,516         | 1,513         |
| Regulatory assets - noncurrent                                                          | 3,989         | 5,107         |
| Deferred operations and maintenance expenses                                            |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 889           | 847           |
| Regulatory assets - noncurrent                                                          | 3,325         | 3,997         |
| Deferred pipeline integrity expenses                                                    |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 3,470         | 3,470         |
| Regulatory assets - noncurrent                                                          | 31,533        | 29,824        |
| Deferred pension and other retirement benefit costs                                     |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 2,757         | 2,757         |
| Regulatory assets - noncurrent                                                          | 17,509        | 17,861        |
| Amounts not yet recognized as a component of pension and other retirement benefit costs |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - noncurrent                                                          | 109,884       | 114,854       |
| Regulatory cost of removal                                                              |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - noncurrent                                                          | 19,925        | 19,087        |
| Robeson liquefied natural gas (LNG) development costs                                   |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 223           | 381           |
| Regulatory assets - noncurrent                                                          | 0             | 127           |
| Derivatives - gas supply contracts held for utility operations                          |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 33,300        | 0             |
| Regulatory assets - noncurrent                                                          | 149,600       | 0             |
| Other                                                                                   |          |          |
| **Regulatory Assets [Line Items]**                                                      |          |          |
| Regulatory assets - current                                                             | 1,406         | 1,730         |
| Regulatory assets - noncurrent                                                          | $ 871         | $ 1,203       |

| 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.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 405 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394
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| X                                                                                                                                                                                                                                                                                                                                                                                                                      |
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| - Definition
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+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.
+ References
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