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Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Thousands | Mar. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Detail of regulatory assets |  |
Current | $ 339,880 | $ 291,713
Non-Current | 1,135,857 | 1,133,987
Pension |  |
Detail of regulatory assets |  |
Current | 0 | 0
Non-Current | 467,423 | 469,953
Deferred fuel and purchased power |  |
Detail of regulatory assets |  |
Current | 228,609 | 175,835
Non-Current | 0 | 0
Income taxes — allowance for funds used during construction (“AFUDC”) equity |  |
Detail of regulatory assets |  |
Current | 7,169 | 7,169
Non-Current | 159,119 | 158,776
Retired power plant costs |  |
Detail of regulatory assets |  |
Current | 28,182 | 28,181
Non-Current | 107,169 | 114,214
Ocotillo deferral |  |
Detail of regulatory assets |  |
Current | 0 | 0
Non-Current | 110,820 | 95,723
SCR deferral |  |
Detail of regulatory assets |  |
Current | 0 | 0
Non-Current | 88,044 | 81,307
Deferred property taxes |  |
Detail of regulatory assets |  |
Current | 8,569 | 8,569
Non-Current | 47,484 | 49,626
Lost fixed cost recovery |  |
Detail of regulatory assets |  |
Current | 45,905 | 41,807
Non-Current | 0 | 0
Deferred compensation |  |
Detail of regulatory assets |  |
Current | 0 | 0
Non-Current | 35,806 | 36,195
Four Corners cost deferral |  |
Detail of regulatory assets |  |
Current | 8,077 | 8,077
Non-Current | 22,056 | 24,075
Income taxes — investment tax credit basis adjustment |  |
Detail of regulatory assets |  |
Current | 1,113 | 1,113
Non-Current | 24,221 | 24,291
Palo Verde VIEs (Note 6) |  |
Detail of regulatory assets |  |
Current | 0 | 0
Non-Current | 21,409 | 21,255
Coal reclamation |  |
Detail of regulatory assets |  |
Current | 1,068 | 1,068
Non-Current | 16,732 | 16,999
Loss on reacquired debt |  |
Detail of regulatory assets |  |
Current | 1,703 | 1,689
Non-Current | 10,486 | 10,877
Mead-Phoenix transmission line contributions in aid of construction (“CIAC”) |  |
Detail of regulatory assets |  |
Current | 332 | 332
Non-Current | 9,297 | 9,380
Demand side management |  |
Detail of regulatory assets |  |
Current | 0 | 0
Non-Current | 7,268 | 7,268
Tax expense adjustor mechanism |  |
Detail of regulatory assets |  |
Current | 5,854 | 6,226
Non-Current | 0 | 0
Tax expense of Medicare subsidy |  |
Detail of regulatory assets |  |
Current | 1,235 | 1,235
Non-Current | 3,626 | 3,704
Deferred fuel and purchased power — mark-to-market (Note 7) |  |
Detail of regulatory assets |  |
Current | 0 | 3,341
Non-Current | 3,728 | 9,244
PSA Interest |  |
Detail of regulatory assets |  |
Current | 46 | 4,355
Non-Current | 0 | 0
Other |  |
Detail of regulatory assets |  |
Current | 2,018 | 2,716
Non-Current | $ 1,169 | $ 1,100

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