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Commitments and Contingencies Commitments and Contingencies - Environmental Matters and Financial Assurances (Details) |  |  |  |  | 9 Months Ended | 12 Months Ended
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Jul. 06, 2016 guarantee | Jun. 24, 2016 | Mar. 16, 2016 USD ($) | May 23, 2013 USD ($) | Sep. 30, 2015 USD ($) | Dec. 31, 2016 USD ($)
Environmental Matters [Abstract] |  |  |  |  |  |
Clean power plan, optional extension period |  |  |  |  |  | 2 years
Payment Guarantee |  |  |  |  |  |
Financial Assurances |  |  |  |  |  |
Number of parental guarantees | guarantee | 2 |  |  |  |  |
Four Corners | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Additional expected environment cost |  |  |  |  |  | $ 15,000,000
Cholla Units 1-3 | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Expected environmental cost |  |  |  |  |  | 8,000,000
New Mexico Tax Matter | Four Corners |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Coal severance surtax, penalty, and interest |  |  |  | $ 30,000,000 |  |
Litigation settlement, amount |  |  | $ 1,000,000 |  |  |
New Mexico Tax Matter | Four Corners | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Share of the assessment |  |  |  | 12,000,000 |  |
Partial payment assessment |  |  |  | $ 800,000 |  |
Litigation settlement, amount |  |  | $ 800,000 |  |  |
Letter of credit | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Financial Assurances |  |  |  |  |  |
Outstanding letters of credit |  |  |  |  |  | 35,000,000
Equity Lessors Sale Leaseback Letter of Credit | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Financial Assurances |  |  |  |  |  |
Outstanding letters of credit |  |  |  |  |  | 53,000,000
Four Corners Units 4 and 5 | Four Corners | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Additional expected environment cost |  |  |  |  |  | 45,000,000
Four Corners Units 4 and 5 | Navajo Plant | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Expected environmental cost |  |  |  |  |  | $ 200,000,000
Four Corners Units 4 and 5 | Natural Gas Tolling Letter of Credit | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Percentage share cost of control |  |  |  |  |  | 63.00%
Additional percentage share of cost of control |  |  |  |  |  | 7.00%
Minimum | Four Corners Units 4 and 5 | Four Corners | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Expected environmental cost |  |  |  |  |  | $ 400,000,000
Regional Haze Rules | Cholla | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Expected environmental cost |  |  |  |  | $ 100,000,000 |
Mercury and Air Toxic Standards | Navajo Generating Station | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Expected environmental cost |  |  |  |  |  | 1,000,000
Coal Combustion Waste | Navajo Generating Station | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Additional expected environment cost |  |  |  |  |  | 1,000,000
Coal Combustion Waste | Boron Inclusion on List of Groundwater Constituents | Navajo Generating Station | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Period to complete rulemaking proceeding |  | 3 years |  |  |  |
Coal Combustion Waste | Minimum | Cholla | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Additional expected environment cost |  |  |  |  |  | 5,000,000
Coal Combustion Waste | Maximum | Cholla | ARIZONA PUBLIC SERVICE COMPANY |  |  |  |  |  |
Environmental Matters [Abstract] |  |  |  |  |  |
Additional expected environment cost |  |  |  |  |  | $ 40,000,000
El Paso's Interest in Four Corners | 4CA |  |  |  |  |  |
Financial Assurances |  |  |  |  |  |
Ownership interest acquired | 7.00% |  |  |  |  | 7.00%

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