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Commitments and Contingencies - Environmental Matters and Financial Assurances (Details) $ in Millions |  |  | 3 Months Ended
--- | --- | --- | ---
Jul. 06, 2016 guarantee | Jun. 24, 2016 | Mar. 31, 2017 USD ($)
Arizona Public Service Company | Letter of Credit Expiring in 2016 and 2017 |  |  |
Financial Assurances |  |  |
Outstanding letters of credit |  |  | $ 35
Arizona Public Service Company | Letters of Credit Expiring in 2017 |  |  |
Financial Assurances |  |  |
Surety bonds expiring, amount |  |  | $ 61
4C Acquisition, LLC | Four Corners Units 4 and 5 |  |  |
Environmental Matters |  |  |
Percentage of share of cost of control |  |  | 7.00%
Regional Haze Rules | Arizona Public Service Company | Four Corners Units 4 and 5 |  |  |
Environmental Matters |  |  |
Percentage of share of cost of control |  |  | 63.00%
Expected environmental cost |  |  | $ 400
Regional Haze Rules | Arizona Public Service Company | Natural gas tolling contract obligations | Four Corners Units 4 and 5 |  |  |
Environmental Matters |  |  |
Additional percentage share of cost of control |  |  | 7.00%
Regional Haze Rules | Arizona Public Service Company | Four Corners | Four Corners Units 4 and 5 |  |  |
Environmental Matters |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  | $ 45
Regional Haze Rules | Arizona Public Service Company | Navajo Plant |  |  |
Environmental Matters |  |  |
Expected environmental cost |  |  | 200
Regional Haze Rules | Arizona Public Service Company | Cholla |  |  |
Environmental Matters |  |  |
Expected environmental cost |  |  | 100
Coal combustion waste | Arizona Public Service Company | Four Corners |  |  |
Environmental Matters |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  | 15
Coal combustion waste | Arizona Public Service Company | Navajo Plant |  |  |
Environmental Matters |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  | 1
Coal combustion waste | Arizona Public Service Company | Navajo Plant | Boron Inclusion on List of Groundwater Constituents |  |  |
Environmental Matters |  |  |
Industry litigation, period to complete rulemaking proceeding |  | 3 years |
Payment Guarantee |  |  |
Financial Assurances |  |  |
Number of parental guarantees | guarantee | 2 |  |
Minimum | Coal combustion waste | Arizona Public Service Company | Cholla |  |  |
Environmental Matters |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  | 5
Maximum | Coal combustion waste | Arizona Public Service Company | Cholla |  |  |
Environmental Matters |  |  |
Site contingency increase in loss exposure not accrued, best estimate |  |  | $ 40

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