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Income Taxes - Effective Income Tax Rate (Details) | 3 Months Ended | 6 Months Ended
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Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021
Income Tax Disclosure [Abstract] |  |  |  |
Federal Statutory Rate | 21.00% | 21.00% | 21.00% | 21.00%
Increases (Decreases) in Tax from: |  |  |  |
State Taxes on Income, Net of Federal Tax | 5.00% | 5.00% | 5.00% | 5.00%
Production Tax Credits (PTCs) | (4.20%) | (6.30%) | (4.30%) | (6.80%)
Amortization of Excess Deferred Income Taxes | 0.00% | (2.00%) | (0.50%) | (2.40%)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax | (0.10%) | (0.30%) | (0.20%) | (0.30%)
Corporate-Owned Life Insurance | 0.90% | (1.00%) | 0.60% | (0.80%)
Other, Net | 0.60% | 0.10% | 0.00% | 0.10%
Effective Tax Rate | 23.20% | 16.50% | 21.60% | 15.80%

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- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32687-109319 + Details
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