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Income Taxes - Schedule of Effective Income Tax Rate (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Income Tax Disclosure [Abstract] |  |  |
Income Taxes at Federal Statutory Rate | $ 77,047 | $ 76,332 | $ 75,082
Increases (Decreases) in Tax from: |  |  |
State Taxes on Income, Net of Federal Tax | 14,360 | 14,429 | 15,049
Production Tax Credits (PTCs) | (20,106) | (17,394) | (14,985)
Amortization of Excess Deferred Income Taxes | (2,788) | (2,205) | (1,625)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax | (586) | (586) | (586)
Other, Net | (2,697) | (1,278) | 416
Income Taxes at Effective Tax Rate | $ 65,230 | $ 69,298 | $ 73,351
Income Taxes at Federal Statutory Rate | 21.00% | 21.00% | 21.00%
Increases (Decreases) in Tax from: |  |  |
State Taxes on Income, Net of Federal Tax | 3.90% | 4.00% | 4.20%
Production Tax Credits (PTCs) | (5.50%) | (4.80%) | (4.20%)
Amortization of Excess Deferred Income Taxes | (0.80%) | (0.60%) | (0.50%)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax | (0.20%) | (0.20%) | (0.20%)
Other, Net | (0.60%) | (0.30%) | 0.20%
Income Taxes at Effective Tax Rate | 17.80% | 19.10% | 20.50%

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