XML 24 R27.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
UTILITY PLANT AND JOINTLY-OWNED FACILITIES (Tables)
 12 Months Ended
Dec. 31, 2019
Regulated Operations [Abstract]  
Public utility PPE
The following table shows Plant in Service on the Consolidated Balance Sheets by major class:
 
Annual Depreciation Rate (3)
 
Average Remaining Life in Years (3)
 
December 31,
($ in millions)
 
 
2019
 
2018
Plant in Service
 
 
 
 
 
 
 
Generation Plant
3.19%
 
20
 
$
3,065

 
$
2,667

Transmission Plant
1.69%
 
37
 
1,060

 
1,010

Distribution Plant
1.56%
 
31
 
1,784

 
1,692

General Plant
5.89%
 
20
 
477

 
409

Intangible Plant, Software Costs, and Other (1)
Various
 
Various
 
271

 
239

Plant Held for Future Use
—
 
—
 
7

 
3

Total Plant in Service (2)
 
 
 
 
$
6,664

 
$
6,020

(1) 
Primarily represents computer software. Unamortized computer software costs were $78 million and $73 million as of December 31, 2019 and 2018, respectively. Amortized computer software costs were $26 million in 2019, $24 million in 2018, and $19 million in 2017. Computer software is being amortized over its expected useful life ranging from three to five years for smaller application software and average remaining life of three years for large enterprise software.
(2) 
Includes plant acquisition adjustments of $(211) million and $(134) million as of December 31, 2019 and 2018, respectively.
(3) 
Based on the 2015 depreciation study available for the major classes of Plant in Service, effective March 1, 2017, as approved by the ACC as part of the 2017 TEP Rate Order. TEP implemented new depreciation rates for Transmission Plant, based on the 2018 depreciation study, effective August 1, 2019, as approved in the 2019 FERC Rate Case.
Schedule of jointly owned utility plants
As of December 31, 2019, TEP was a participant in the following jointly-owned generation facilities and transmission systems:
(in millions)
Ownership Percentage
 
Plant in Service
 
Construction Work in Progress
 
Accumulated Depreciation
 
Net Book Value
San Juan Unit 1
50.0%
 
$
289

 
$
1

 
$
(193
)
 
$
97

Four Corners Units 4 and 5
7.0%
 
175

 
5

 
(77
)
 
103

Luna
33.3%
 
57

 
—

 
(1
)
 
56

Gila River Unit 3
75.0%
 
200

 
2

 
(61
)
 
141

Gila River Common Facilities
43.8%
 
71

 
—

 
(23
)
 
48

Springerville Coal Handling Facilities
83.0%
 
208

 
—

 
(90
)
 
118

Transmission Facilities
Various
 
545

 
5

 
(295
)
 
255

Total
 
 
$
1,545

 
$
13

 
$
(740
)
 
$
818
Schedule of asset retirement obligations The following table reconciles the beginning and ending aggregate carrying amounts of ARO accruals on the Consolidated Balance Sheets:
 
December 31,
(in millions)
2019
 
2018
Beginning of Period
$
72

 
$
46

Liabilities Incurred
—

 
10

Liabilities Settled (1)
(2
)
 
—

Regulatory Deferral/Accretion Expense
2

 
3

Revisions to the Present Value of Estimated Cash Flows (2)
35

 
13

End of Period
$
107

 
$
72

(1) 
Primarily related to the retirement of Navajo.
(2) 
Primarily related to changes due to revised estimates of the timing of cash flows required to settle future liabilities of certain generation facilities.