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Retirement Plans and Other Postretirement Benefits - Impact to Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands | Dec. 31, 2024 | Dec. 31, 2023
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Pension Plans |  |
Details related to accumulated other comprehensive loss |  |
Net actuarial loss (gain) | $ 793,421 | $ 743,003
Prior service credit | 0 | 0
APS’s portion recorded as a regulatory (asset) liability | (750,976) | (696,476)
Income tax expense (benefit) | (10,354) | (11,506)
Accumulated other comprehensive loss (gain) | 32,091 | 35,021
Other Benefits Plans |  |
Details related to accumulated other comprehensive loss |  |
Net actuarial loss (gain) | (237,889) | (188,630)
Prior service credit | (1,265) | (39,054)
APS’s portion recorded as a regulatory (asset) liability | 238,113 | 226,726
Income tax expense (benefit) | 611 | 691
Accumulated other comprehensive loss (gain) | $ (430) | $ (267)

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- Definition Represents the tax component of accumulated other comprehensive income (loss) of defined benefit pension and other postretirement plans. + References No definition available. + Details
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- Definition Amount related to the pretax cost of benefit changes, a portion of which has been recorded as a regulatory asset, which has not yet been recognized as components of net periodic benefit cost. + References No definition available. + Details
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- Definition Amount, after tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 10A -Subparagraph (j) -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-10A Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 10A -Subparagraph (k) -SubTopic 10 -Topic 220 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-10A Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 10A -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-10A Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (j) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (j) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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