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Jointly-Owned Facilities | 12 Months Ended
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Dec. 31, 2017
Jointly Owned Utility Plant, Net Ownership Amount [Abstract] |
Jointly-Owned Facilities | Jointly-Owned Facilities APS shares ownership of some of its generating and transmission facilities with other companies. We are responsible for our share of operating costs which are included in the corresponding operating expenses on our Consolidated Statements of Income. We are also responsible for providing our own financing. Our share of operating expenses and utility plant costs related to these facilities is accounted for using proportional consolidation. The following table shows APS’s interests in those jointly-owned facilities recorded on the Consolidated Balance Sheets at December 31, 2017 (dollars in thousands):
|  | Percent Owned |  |  |  | Plant in Service |  | Accumulated Depreciation |  | Construction Work in Progress |
Generating facilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Palo Verde Units 1 and 3 |  | 29.1 | % |  |  |  | $ | 1,872,104 |  |  | $ | 1,092,049 |  |  | $ | 24,257 |  |
Palo Verde Unit 2 (a) |  | 16.8 | % |  |  |  | 619,263 |  |  | 364,516 |  |  | 14,672 |  |
Palo Verde Common |  | 28.0 | % |  | (b) |  | 726,223 |  |  | 262,065 |  |  | 46,577 |  |
Palo Verde Sale Leaseback |  |  |  |  | (a) |  | 351,050 |  |  | 241,405 |  |  | — |  |
Four Corners Generating Station |  | 63.0 | % |  |  |  | 1,196,683 |  |  | 568,304 |  |  | 240,514 |  |
Cholla common facilities (c) |  | 50.5 | % |  |  |  | 180,907 |  |  | 69,633 |  |  | 1,091 |  |
Transmission facilities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ANPP 500kV System |  | 34.0 | % |  | (b) |  | 130,767 |  |  | 46,400 |  |  | 684 |  |
Navajo Southern System |  | 27.5 | % |  | (b) |  | 85,299 |  |  | 28,915 |  |  | 180 |  |
Palo Verde — Yuma 500kV System |  | 18.1 | % |  | (b) |  | 14,765 |  |  | 6,614 |  |  | 486 |  |
Four Corners Switchyards |  | 63.2 | % |  | (b) |  | 66,386 |  |  | 12,605 |  |  | 327 |  |
Phoenix — Mead System |  | 17.1 | % |  | (b) |  | 39,383 |  |  | 17,600 |  |  | 41 |  |
Palo Verde — Rudd 500kV System |  | 50.0 | % |  |  |  | 97,600 |  |  | 23,884 |  |  | 245 |  |
Morgan — Pinnacle Peak System |  | 64.6 | % |  | (b) |  | 117,721 |  |  | 14,569 |  |  | 1 |  |
Round Valley System |  | 50.0 | % |  |  |  | 515 |  |  | 141 |  |  | — |  |
Palo Verde — Morgan System |  | 90.9 | % |  | (b) |  | 137,887 |  |  | 3,948 |  |  | 94,350 |  |
Hassayampa — North Gila System |  | 80.0 | % |  |  |  | 142,541 |  |  | 6,953 |  |  | — |  |
Cholla 500kV Switchyard |  | 85.7 | % |  |  |  | 5,243 |  |  | 1,312 |  |  | 190 |  |
Saguaro 500kV Switchyard |  | 60.0 | % |  |  |  | 20,473 |  |  | 12,574 |  |  | — |  |
Kyrene — Knox System |  | 50.0 | % |  |  |  | 578 |  |  | 297 |  |  | — |  |
(a) | See Note 18.
(b) | Weighted-average of interests.
(c) | PacifiCorp owns Cholla Unit 4 and APS operates the unit for PacifiCorp. The common facilities at Cholla are jointly-owned.
APS also has a 14% ownership in the Navajo Plant. In the second quarter of 2017, APS’s remaining net book value of its interest was reclassified from property, plant and equipment to a regulatory asset. See “Navajo Plant” in Note 3 for more details. 4CA is a subsidiary that was formed in 2016 as a result of the purchase of El Paso's 7% interest in Four Corners. At December 31, 2017, 4CA had plant in service of $141 million, accumulated depreciation of $83 million and construction work in progress of $25 million.

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