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Summary of Significant Accounting Policies - Schedule of Reclassification of Prior Period Adjustments (Details) - USD ($) | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |
Pension and other postretirement benefits |  | $ 0
Derivative instruments |  | 0
Total accumulated other comprehensive loss |  | 0
Accumulated other comprehensive loss | $ (45,002,000) | (43,822,000)
As previously reported |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |
Pension and other postretirement benefits |  | (39,070,000)
Derivative instruments |  | (4,752,000)
Total accumulated other comprehensive loss |  | (43,822,000)
Accumulated other comprehensive loss |  | 0
Reclassifications to conform to current year presentation |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |
Pension and other postretirement benefits |  | 39,070,000
Derivative instruments |  | 4,752,000
Total accumulated other comprehensive loss |  | 43,822,000
Accumulated other comprehensive loss |  | (43,822,000)
ARIZONA PUBLIC SERVICE COMPANY |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |
Pension and other postretirement benefits |  | 0
Derivative instruments |  | 0
Total accumulated other comprehensive loss |  | 0
Accumulated other comprehensive loss | $ (26,983,000) | (25,423,000)
ARIZONA PUBLIC SERVICE COMPANY | As previously reported |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |
Pension and other postretirement benefits |  | (20,671,000)
Derivative instruments |  | (4,752,000)
Total accumulated other comprehensive loss |  | (25,423,000)
Accumulated other comprehensive loss |  | 0
ARIZONA PUBLIC SERVICE COMPANY | Reclassifications to conform to current year presentation |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |
Pension and other postretirement benefits |  | 20,671,000
Derivative instruments |  | 4,752,000
Total accumulated other comprehensive loss |  | 25,423,000
Accumulated other comprehensive loss |  | $ (25,423,000)

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