XML 58 R51.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Utility Capital Assets (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2016
Regulated Operations [Abstract] |
Schedule of Public Utility Property, Plant, and Equipment | The service life ranges and weighted average remaining service life of the Corporation’s distribution, transmission, generation and other assets as at December 31 were as follows.
|  | 2016 | 2015
(Years) | Service Life Ranges | Weighted Average Remaining Service Life |  | Service Life Ranges | Weighted Average Remaining Service Life
Distribution |  |  |  |  |
| Electric | 5-80 | 32 |  | 5-80 | 30
| Gas | 7-95 | 33 |  | 4-95 | 33
Transmission |  |  |  |  |
| Electric | 20-80 | 41 |  | 20-80 | 29
| Gas | 7-80 | 34 |  | 7-80 | 36
Generation | 5-85 | 26 |  | 5-85 | 27
Other | 3-70 | 14 |  | 3-70 | 8
|  | 2016
(in millions) | Cost |  | Accumulated Depreciation |  | Net Book Value
Distribution |  |  |  |  |
| Electric | $ | 9,616 |  |  | $ | (2,752 | ) |  | $ | 6,864 |
| Gas | 3,956 |  |  | (1,096 | ) |  | 2,860 |
Transmission |  |  |  |  |  |  |  |
| Electric | 12,616 |  |  | (2,876 | ) |  | 9,740 |
| Gas | 1,776 |  |  | (562 | ) |  | 1,214 |
Generation | 6,884 |  |  | (2,474 | ) |  | 4,410 |
Other | 3,497 |  |  | (1,096 | ) |  | 2,401 |
Assets under construction | 1,559 |  |  | — |  |  | 1,559 |
Land | 289 |  |  | — |  |  | 289 |
|  | $ | 40,193 |  |  | $ | (10,856 | ) |  | $ | 29,337 |
10. UTILITY CAPITAL ASSETS (cont’d)
|  | 2015
(in millions) | Cost |  | Accumulated Depreciation |  | Net Book Value
Distribution |  |  |  |  |
| Electric | $ | 9,245 |  |  | $ | (2,634 | ) |  | $ | 6,611 |
| Gas | 3,829 |  |  | (1,021 | ) |  | 2,808 |
Transmission |  |  |  |  |  |  |  |
| Electric | 3,093 |  |  | (997 | ) |  | 2,096 |
| Gas | 1,735 |  |  | (531 | ) |  | 1,204 |
Generation | 6,465 |  |  | (2,241 | ) |  | 4,224 |
Other | 2,429 |  |  | (849 | ) |  | 1,580 |
Assets under construction | 886 |  |  | — |  |  | 886 |
Land | 186 |  |  | — |  |  | 186 |
|  | $ | 27,868 |  |  | $ | (8,273 | ) |  | $ | 19,595 |
Schedule of Jointly Owned Facilities | As at December 31, 2016, interests in jointly owned facilities consisted of the following.
| Ownership |  | Accumulated | Net Book
(in millions) | % | Cost | Depreciation | Value
San Juan Units 1 and 2 | 50.0 | $ | 670 |  | $ | (352 | ) | $ | 318 |
Navajo Units 1, 2 and 3 | 7.5 | 206 |  | (153 | ) | 53 |
Four Corners Units 4 and 5 | 7.0 | 185 |  | (103 | ) | 82 |
Luna Energy Facility | 33.3 | 73 |  | (3 | ) | 70 |
Gila River Common Facilities | 25.0 | 44 |  | (15 | ) | 29 |
Springerville Coal Handling Facilities (1) | 83.0 | 270 |  | (108 | ) | 162 |
Transmission Facilities | 1.0-80.0 | 750 |  | (236 | ) | 514 |
|  | $ | 2,198 |  | $ | (970 | ) | $ | 1,228 |
(1) | In 2016 UNS Energy reclassified an additional 17.05% undivided interest in the Springerville Coal Handling Facilities from assets held for sale (Note 6).

X
- References No definition available. + Details
Name: | us-gaap_RegulatedOperationsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033 + Details
Name: | us-gaap_ScheduleOfJointlyOwnedUtilityPlantsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of public utility 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, deprecation expense and method used, including composite depreciation, and accumulated deprecation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499596&loc=d3e42232-110370 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.13(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_ScheduleOfPublicUtilityPropertyPlantAndEquipmentTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration