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Changes in Accumulated Other Comprehensive Loss | 12 Months Ended
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Dec. 31, 2017
Changes in accumulated other comprehensive income (loss) including reclassification adjustments, by component: |
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 years ended December 31, 2017 and 2016 (dollars in thousands):
| Pension and Other Postretirement Benefits |  |  |  | Derivative Instruments |  |  |  | Total
Balance December 31, 2015 | $ | (37,593 | ) |  |  |  | $ | (7,155 | ) |  |  |  | $ | (44,748 | )
OCI (loss) before reclassifications | (4,509 | ) |  |  |  | (538 | ) |  |  |  | (5,047 | )
Amounts reclassified from accumulated other comprehensive loss | 3,032 |  |  | (a) |  | 2,941 |  |  | (b) |  | 5,973 |
Balance December 31, 2016 | (39,070 | ) |  |  |  | (4,752 | ) |  |  |  | (43,822 | )
OCI (loss) before reclassifications | (6,438 | ) |  |  |  | (35 | ) |  |  |  | (6,473 | )
Amounts reclassified from accumulated other comprehensive loss | 3,068 |  |  | (a) |  | 2,225 |  |  | (b) |  | 5,293 |
Balance December 31, 2017 | $ | (42,440 | ) |  |  |  | $ | (2,562 | ) |  |  |  | $ | (45,002 | )
(a) | These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost. See Note 7.
(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 16.
ARIZONA PUBLIC SERVICE COMPANY |
Changes in accumulated other comprehensive income (loss) including reclassification adjustments, by component: |
Changes in Accumulated Other Comprehensive Loss | Changes in Accumulated Other Comprehensive Loss - APS The following table shows the changes in APS's accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component for the years ended December 31, 2017 and 2016 (dollars in thousands):
| Pension and Other Postretirement Benefits |  |  |  | Derivative Instruments |  |  |  | Total
Balance December 31, 2015 | $ | (19,942 | ) |  |  |  | $ | (7,155 | ) |  |  |  | $ | (27,097 | )
OCI (loss) before reclassifications | (3,821 | ) |  |  |  | (538 | ) |  |  |  | (4,359 | )
Amounts reclassified from accumulated other comprehensive loss | 3,092 |  |  | (a) |  | 2,941 |  |  | (b) |  | 6,033 |
Balance December 31, 2016 | (20,671 | ) |  |  |  | (4,752 | ) |  |  |  | (25,423 | )
OCI (loss) before reclassifications | (6,884 | ) |  |  |  | (35 | ) |  |  |  | (6,919 | )
Amounts reclassified from accumulated other comprehensive loss | 3,134 |  |  | (a) |  | 2,225 |  |  | (b) |  | 5,359 |
Balance December 31, 2017 | $ | (24,421 | ) |  |  |  | $ | (2,562 | ) |  |  |  | $ | (26,983 | )
(a) | These amounts primarily represent amortization of actuarial loss, and are included in the computation of net periodic pension cost. See Note 7.
(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 16.

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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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -URI http://asc.fasb.org/topic&trid=2134417 + Details
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