Income Taxes State Audits (Details)	9 Months Ended
Sep. 30, 2020 USD ($)
WISCONSIN
Income Tax Examination [Line Items]
Potential Tax Adjustments	$ 0
NSP Minnesota [Member]
Income Tax Examination [Line Items]
Potential Tax Adjustments	$ 0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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