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Nuclear Decommissioning Trusts (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016 | Dec. 31, 2016
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | $ 841,980 |  | $ 841,980 |  | $ 779,586
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |  |  |
Proceeds from the sale of securities |  |  | 351,860 | $ 447,419 |
Fair value of fixed income securities, summarized by contractual maturities |  |  |  |  |
Total | 841,980 |  | 841,980 |  | 779,586
Arizona Public Service Company |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 841,980 |  | 841,980 |  | 779,586
Unrealized Gains | 244,999 |  | 244,999 |  | 197,911
Unrealized Losses | (2,177) |  | (2,177) |  | (4,962)
Net receivables for securities purchases | 4,378 |  | 4,378 |  | 795
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |  |  |
Realized gains | 598 | $ 4,033 | 3,904 | 8,753 |
Realized losses | (1,022) | (3,345) | (4,634) | (6,481) |
Proceeds from the sale of securities | 76,496 | $ 156,825 | 351,860 | $ 447,419 |
Fair value of fixed income securities, summarized by contractual maturities |  |  |  |  |
Total | 841,980 |  | 841,980 |  | 779,586
Arizona Public Service Company | Equity Securities |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 401,913 |  | 401,913 |  | 353,261
Unrealized Gains | 232,727 |  | 232,727 |  | 188,091
Unrealized Losses | 0 |  | 0 |  | 0
Fair value of fixed income securities, summarized by contractual maturities |  |  |  |  |
Total | 401,913 |  | 401,913 |  | 353,261
Arizona Public Service Company | Fixed income securities. |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 435,689 |  | 435,689 |  | 425,530
Unrealized Gains | 12,272 |  | 12,272 |  | 9,820
Unrealized Losses | (2,177) |  | (2,177) |  | (4,962)
Fair value of fixed income securities, summarized by contractual maturities |  |  |  |  |
Less than one year | 22,498 |  | 22,498 |  |
1 year – 5 years | 103,033 |  | 103,033 |  |
5 years – 10 years | 117,044 |  | 117,044 |  |
Greater than 10 years | 193,114 |  | 193,114 |  |
Total | $ 435,689 |  | $ 435,689 |  | $ 425,530

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