Income Taxes (Details) - USD ($)		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Income Tax Examination [Line Items]
Net Deferred Tax Liability associated with the Unrecognized Tax Benefit Amounts and Related NOLs and Tax Credit Carryforwards		$ (1,600,000)		$ (1,100,000)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	21.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		6.20%	6.20%
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Percent		0.40%	(0.60%)
Regulatory difference - tax credits and tax credit and NOL allowances (net)		(1.50%)	(0.70%)
Effective Income Tax Rate Reconciliation, Other Regulatory Items, Percent	[1]	(0.40%)	(1.60%)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		0.70%	0.40%
Effective Income Tax Rate Reconciliation, Percent		26.40%	24.70%
Unrecognized Tax Benefits [Abstract]
Unrecognized tax benefit — Permanent tax positions		$ 2,500,000		2,000,000.0
Unrecognized tax benefit — Temporary tax positions		800,000		800,000
Total unrecognized tax benefit		3,300,000		2,800,000
NOL and tax credit carryforwards		(2,500,000)		(2,100,000)
Upper bound of decrease in unrecognized tax benefit that is reasonably possible		2,200,000
Amounts accrued for penalties related to unrecognized tax benefits		0		$ 0
Internal Revenue Service (IRS)
Tax Audits [Abstract]
Potential Tax Adjustments		0
State Jurisdiction (Wisconsin)
Tax Audits [Abstract]
Potential Tax Adjustments		$ 0

[1] Regulatory differences for income tax primarily relates to the credit of excess deferred taxes to customers through the average rate assumption method and the impact of AFUDC - equity. Year-to-date variations primarily relate to the impact of AFUDC - equity.