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Changes in Accumulated Other Comprehensive Loss | 9 Months Ended
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Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items] |
Changes in Accumulated Other Comprehensive Loss | Changes in Accumulated Other Comprehensive Loss The following table shows the changes in Pinnacle West's consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the three and nine months ended September 30, 2018 and 2017 (dollars in thousands):
| Pension and Other Postretirement Benefits |  |  |  | Derivative Instruments |  |  |  | Total
Three Months Ended September 30 |  |  |  |  |  |  |  |  |
Balance June 30, 2018 | $ | (54,233 | ) |  |  |  | $ | (2,391 | ) |  |  |  | $ | (56,624 | )
Amounts reclassified from accumulated other comprehensive loss | 1,099 |  |  | (a) |  | 451 |  |  | (b) |  | 1,550 |
Balance September 30, 2018 | $ | (53,134 | ) |  |  |  | $ | (1,940 | ) |  |  |  | $ | (55,074 | )
Balance June 30, 2017 | $ | (39,881 | ) |  |  |  | $ | (3,745 | ) |  |  |  | $ | (43,626 | )
OCI (loss) before reclassifications | — |  |  |  |  | 9 |  |  |  |  | 9 |
Amounts reclassified from accumulated other comprehensive loss | 790 |  |  | (a) |  | 710 |  |  | (b) |  | 1,500 |
Balance September 30, 2017 | $ | (39,091 | ) |  |  |  | $ | (3,026 | ) |  |  |  | $ | (42,117 | )
| Pension and Other Postretirement Benefits |  |  |  | Derivative Instruments |  |  |  | Total
Nine Months Ended September 30 |  |  |  |  |  |  |  |  |
Balance December 31, 2017 | $ | (42,440 | ) |  |  |  | $ | (2,562 | ) |  |  |  | $ | (45,002 | )
OCI (loss) before reclassifications | (5,928 | ) |  |  |  | (96 | ) |  |  |  | (6,024 | )
Amounts reclassified from accumulated other comprehensive loss | 3,188 |  |  | (a) |  | 1,316 |  |  | (b) |  | 4,504 |
Reclassification of income tax effect related to tax reform | (7,954 | ) |  |  |  | (598 | ) |  |  |  | (8,552 | )
Balance September 30, 2018 | $ | (53,134 | ) |  |  |  | $ | (1,940 | ) |  |  |  | $ | (55,074 | )
Balance December 31, 2016 | $ | (39,070 | ) |  |  |  | $ | (4,752 | ) |  |  |  | $ | (43,822 | )
OCI (loss) before reclassifications | (2,157 | ) |  |  |  | (754 | ) |  |  |  | (2,911 | )
Amounts reclassified from accumulated other comprehensive loss | 2,136 |  |  | (a) |  | 2,480 |  |  | (b) |  | 4,616 |
Balance September 30, 2017 | $ | (39,091 | ) |  |  |  | $ | (3,026 | ) |  |  |  | $ | (42,117 | )
(a) | These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost. See Note 5.
(b) These amounts represent realized gains and losses and are included in the computation of fuel and purchased power costs and are subject to the PSA. See Note 7.
APS |
Accumulated Other Comprehensive Income (Loss) [Line Items] |
Changes in Accumulated Other Comprehensive Loss | The following table shows the changes in APS's consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the three and nine months ended September 30, 2018 and 2017 (dollars in thousands):
| Pension and Other Postretirement Benefits |  |  |  | Derivative Instruments |  |  |  | Total
Three Months Ended September 30 |  |  |  |  |  |  |  |  |
Balance June 30, 2018 | $ | (32,768 | ) |  |  |  | $ | (2,391 | ) |  |  |  | $ | (35,159 | )
Amounts reclassified from accumulated other comprehensive loss | 952 |  |  | (a) |  | 451 |  |  | (b) |  | 1,403 |
Balance September 30, 2018 | $ | (31,816 | ) |  |  |  | $ | (1,940 | ) |  |  |  | $ | (33,756 | )
Balance June 30, 2017 | $ | (21,367 | ) |  |  |  | $ | (3,745 | ) |  |  |  | $ | (25,112 | )
OCI (loss) before reclassifications | — |  |  |  |  | 9 |  |  |  |  | 9 |
Amounts reclassified from accumulated other comprehensive loss | 777 |  |  | (a) |  | 710 |  |  | (b) |  | 1,487 |
Balance September 30, 2017 | $ | (20,590 | ) |  |  |  | $ | (3,026 | ) |  |  |  | $ | (23,616 | )
| Pension and Other Postretirement Benefits |  |  |  | Derivative Instruments |  |  |  | Total
Nine Months Ended September 30 |  |  |  |  |  |  |  |  |
Balance December 31, 2017 | $ | (24,421 | ) |  |  |  | $ | (2,562 | ) |  |  |  | $ | (26,983 | )
OCI (loss) before reclassifications | (5,791 | ) |  |  |  | (96 | ) |  |  |  | (5,887 | )
Amounts reclassified from accumulated other comprehensive loss | 2,836 |  |  | (a) |  | 1,316 |  |  | (b) |  | 4,152 |
Reclassification of income tax effect related to tax reform | (4,440 | ) |  |  |  | (598 | ) |  |  |  | (5,038 | )
Balance September 30, 2018 | $ | (31,816 | ) |  |  |  | $ | (1,940 | ) |  |  |  | $ | (33,756 | )
Balance December 31, 2016 | $ | (20,671 | ) |  |  |  | $ | (4,752 | ) |  |  |  | $ | (25,423 | )
OCI (loss) before reclassifications | (2,121 | ) |  |  |  | (754 | ) |  |  |  | (2,875 | )
Amounts reclassified from accumulated other comprehensive loss | 2,202 |  |  | (a) |  | 2,480 |  |  | (b) |  | 4,682 |
Balance September 30, 2017 | $ | (20,590 | ) |  |  |  | $ | (3,026 | ) |  |  |  | $ | (23,616 | )
(a) | These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost. See Note 5.
(b) These amounts represent realized gains and losses and are included in the computation of fuel and purchased power costs and are subject to the PSA. See Note 7.

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -URI http://asc.fasb.org/topic&trid=2134417 + Details
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