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SCHEDULE II - RESERVE FOR UNCOLLECTIBLES (Details) - Reserve for uncollectibles. - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Pinnacle West |  |  |
Changes in reserve for uncollectibles |  |  |
Balance at beginning of period | $ 2,513 | $ 3,037 | $ 3,125
Additions, Charged to cost and expenses | 10,870 | 6,836 | 4,025
Additions, Charged to other accounts | 0 | 0 | 0
Deductions | 9,314 | 7,360 | 4,113
Balance at end of period | 4,069 | 2,513 | 3,037
ARIZONA PUBLIC SERVICE COMPANY |  |  |
Changes in reserve for uncollectibles |  |  |
Balance at beginning of period | 2,513 | 3,037 | 3,125
Additions, Charged to cost and expenses | 10,870 | 6,836 | 4,025
Additions, Charged to other accounts | 0 | 0 | 0
Deductions | 9,314 | 7,360 | 4,113
Balance at end of period | $ 4,069 | $ 2,513 | $ 3,037

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