Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Deferred Tax Assets
Employee Benefits	$ 37,456	$ 39,959
Regulatory Liabilities	52,664	56,479
Tax Credit Carryforwards	18,268	21,836
Cost of Removal	35,374	32,993
Asset Retirement Obligations	10,948	9,494
Net Operating Loss Carryforward	2,289	2,336
Other	19,449	11,310
Total Deferred Tax Assets	176,448	174,407
Deferred Tax Liabilities
Differences Related to Property	(375,120)	(347,885)
Retirement Benefits Regulatory Asset	(22,892)	(22,458)
Pension Expense	(26,034)	(24,875)
Other	(20,147)	(16,462)
Total Deferred Tax Liabilities	(444,193)	(411,680)
Deferred Income Taxes	$ (267,745)	$ (237,273)

Amount, before allocation of valuation allowance, of deferred tax asset attributable to cost of removal.

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Amount, before allocation of valuation allowance, of deferred tax liability attributable to excess of tax over book related to pension.

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Represents an amount of deferred tax liability attributable to taxable temporary differences from retirement benefits regulatory assets.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences derived regulatory assets and liabilities.

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Amount, before allocation of a valuation allowances, of deferred tax assets attributable to deductible tax credit carryforwards including, but not limited to, research, foreign, general business, alternative minimum tax, and other deductible tax credit carryforwards.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences from employee benefits, classified as other.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from asset retirement obligations. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset.

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Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting.

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Amount of deferred tax liability attributable to taxable temporary differences classified as other.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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