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Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Details) - APS - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021 | Dec. 31, 2021
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | $ 1,422,494 |  | $ 1,422,494 |  | $ 1,653,167
Total Unrealized Gains |  |  | 330,029 |  | 475,670
Total Unrealized Losses |  |  | (57,009) |  | (4,063)
Amortized cost | 971,000 |  | 971,000 |  | 972,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |  |  |
Realized gains | 6,282 | $ 1,406 | 7,305 | $ 4,374 |
Realized losses | (12,439) | (1,146) | (19,674) | (5,294) |
Proceeds from the sale of securities | 330,432 | 207,864 | 691,670 | 587,842 |
Nuclear Decommissioning Trusts |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 1,076,088 |  | 1,076,088 |  | 1,294,757
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |  |  |
Realized gains | 6,282 | 1,406 | 7,305 | 4,374 |
Realized losses | (12,439) | (1,146) | (19,674) | (5,294) |
Proceeds from the sale of securities | 309,966 | 190,340 | 629,659 | 425,068 |
Other Special Use Funds |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 346,406 |  | 346,406 |  | 358,410
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds |  |  |  |  |
Realized gains | 0 | 0 | 0 | 0 |
Realized losses | 0 | 0 | 0 | 0 |
Proceeds from the sale of securities | 20,466 | $ 17,524 | 62,011 | $ 162,774 |
Equity securities |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Equity securities | 502,485 |  | 502,485 |  | 687,882
Total Unrealized Gains |  |  | 327,032 |  | 451,387
Total Unrealized Losses |  |  | (183) |  | 0
Equity securities | Nuclear Decommissioning Trusts |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Equity securities | 473,392 |  | 473,392 |  | 640,312
Equity securities | Other Special Use Funds |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Equity securities | 29,093 |  | 29,093 |  | 47,570
Available for sale-fixed income securities |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 917,670 |  | 917,670 |  | 992,131
Total Unrealized Gains |  |  | 2,997 |  | 24,283
Total Unrealized Losses |  |  | (56,826) |  | (4,063)
Fair value of fixed income securities, summarized by contractual maturities |  |  |  |  |
Less than one year | 100,866 |  | 100,866 |  |
1 year – 5 years | 373,996 |  | 373,996 |  |
5 years – 10 years | 170,310 |  | 170,310 |  |
Greater than 10 years | 272,498 |  | 272,498 |  |
Total | 917,670 |  | 917,670 |  |
Available for sale-fixed income securities | Nuclear Decommissioning Trusts |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 601,295 |  | 601,295 |  | 682,227
Fair value of fixed income securities, summarized by contractual maturities |  |  |  |  |
Less than one year | 13,114 |  | 13,114 |  |
1 year – 5 years | 192,566 |  | 192,566 |  |
5 years – 10 years | 127,287 |  | 127,287 |  |
Greater than 10 years | 268,328 |  | 268,328 |  |
Total | 601,295 |  | 601,295 |  |
Available for sale-fixed income securities | Other Special Use Funds |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 316,375 |  | 316,375 |  | 309,904
Available for sale-fixed income securities | Coal Reclamation Escrow Account |  |  |  |  |
Fair value of fixed income securities, summarized by contractual maturities |  |  |  |  |
Less than one year | 47,528 |  | 47,528 |  |
1 year – 5 years | 31,422 |  | 31,422 |  |
5 years – 10 years | 0 |  | 0 |  |
Greater than 10 years | 4,170 |  | 4,170 |  |
Total | 83,120 |  | 83,120 |  |
Available for sale-fixed income securities | Active Union Employee Medical Account |  |  |  |  |
Fair value of fixed income securities, summarized by contractual maturities |  |  |  |  |
Less than one year | 40,224 |  | 40,224 |  |
1 year – 5 years | 150,008 |  | 150,008 |  |
5 years – 10 years | 43,023 |  | 43,023 |  |
Greater than 10 years | 0 |  | 0 |  |
Total | 233,255 |  | 233,255 |  |
Other |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 2,339 |  | 2,339 |  | (26,846)
Total Unrealized Gains |  |  | 0 |  | 0
Total Unrealized Losses |  |  | 0 |  | 0
Other | Nuclear Decommissioning Trusts |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | 1,401 |  | 1,401 |  | (27,782)
Other | Other Special Use Funds |  |  |  |  |
Nuclear decommissioning trust fund assets |  |  |  |  |
Fair Value | $ 938 |  | $ 938 |  | $ 936

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