CONSOLIDATED STATEMENTS OF CAPITALIZATION (Parenthetical) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Common Stockholders Equity [Abstract]
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, par value (in dollars per share)	$ 100	$ 100
Common stock, shares outstanding (in shares)	933,000	933,000
First Mortgage Bonds \| Series Due Oct. 1, 2018
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, interest rate stated percentage (in hundredths)	5.25%	5.25%
Debt instrument, maturity date	Oct. 01, 2018	Oct. 01, 2018
First Mortgage Bonds \| Series Due June 15, 2024
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, interest rate stated percentage (in hundredths)	3.30%	3.30%
Debt instrument, maturity date	Jun. 15, 2024	Jun. 15, 2024
First Mortgage Bonds \| Series Due Sept. 1, 2038
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, interest rate stated percentage (in hundredths)	6.375%	6.375%
Debt instrument, maturity date	Sep. 01, 2038	Sep. 01, 2038
First Mortgage Bonds \| Series Due Oct. 1, 2042
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, interest rate stated percentage (in hundredths)	3.70%	3.70%
Debt instrument, maturity date	Oct. 01, 2042	Oct. 01, 2042
First Mortgage Bonds \| Series Due Dec. 1, 2047
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, interest rate stated percentage (in hundredths)	3.75%
Debt instrument, maturity date	Dec. 01, 2047
City of La Crosse Resource Recovery Bond \| Series Due Nov. 1, 2021
Schedule of Capitalization, Long-term Debt [Line Items]
Debt instrument, interest rate stated percentage (in hundredths)	6.00%	6.00%
Debt instrument, maturity date	Nov. 01, 2021	Nov. 01, 2021

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- Definition

Face amount or stated value per share of common stock.

+ References

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- Definition

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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- Definition

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.

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