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PROPERTY, PLANT AND EQUIPMENT (Tables) | 12 Months Ended
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Dec. 31, 2018
Regulated [Member] |
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment by Property Type | The following table sets forth our property, plant and equipment by property type, for the periods indicated:
|  | December 31, |  | December 31,
|  | 2018 |  | 2017
|  | (Thousands of dollars)
Natural gas distribution pipelines and related equipment |  | $ | 4,861,340 |  |  | $ | 4,572,343 |
Natural gas transmission pipelines and related equipment |  | 517,697 |  |  | 497,791 |
General plant and other |  | 567,580 |  |  | 513,445 |
Construction work in process |  | 126,526 |  |  | 130,333 |
Property, plant and equipment |  | 6,073,143 |  |  | 5,713,912 |
Accumulated depreciation and amortization |  | (1,789,431 | ) |  | (1,706,327 | )
Net property, plant and equipment |  | $ | 4,283,712 |  |  | $ | 4,007,585 |

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- Definition Tabular disclosure of physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, balances by class of assets, depreciation and depletion expense and method used, including composite depreciation, and accumulated deprecation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(13)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
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