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Income Taxes State Audits (Details) - USD ($) | 9 Months Ended |
--- | --- | ---
Sep. 30, 2021 | Dec. 31, 2020
Income Tax Examination [Line Items] |  |
Potential Tax Adjustments | $ 0 |
Unrecognized Tax Benefits, Income Tax Penalties Accrued | 0 | $ 0
WISCONSIN |  |
Income Tax Examination [Line Items] |  |
Potential Tax Adjustments | 0 |
NSP-Minnesota |  |
Income Tax Examination [Line Items] |  |
Potential Tax Adjustments | $ 0 |

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- Definition Amount of statutory penalties accrued for a tax position claimed or expected to be claimed by the entity, in its tax return. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319 + Details
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