CONSOLIDATED STATEMENTS OF CAPITALIZATION (Parenthetical) (USD $)	12 Months Ended
Dec. 31, 2012 First Mortgage Bonds [Member] Series Due Oct. 1, 2018 [Member]	Dec. 31, 2012 First Mortgage Bonds [Member] Series Due Sept. 1, 2038 [Member]	Dec. 31, 2012 City of La Crosse Resource Recovery Bond [Member] Series Due Nov. 1, 2021 [Member]	Dec. 31, 2012 Fort McCoy System Acquisition [Member] Due Oct. 15, 2030 [Member]
Long-Term Debt
Debt instrument, interest rate stated percentage (in hundredths)	5.25%	6.375%	6.00%	7.00%
Debt instrument, maturity date	Oct. 01, 2018	Sep. 01, 2038	Nov. 01, 2021	Oct. 15, 2030

Date when the debt instrument is scheduled to be fully repaid, which may be presented in a variety of ways (year, month and year, day, month and year, quarter, etc.).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration