Rate Matters	9 Months Ended
Sep. 30, 2012
Rate Matters [Abstract]
Rate Matters	5. Rate Matters Except to the extent noted below, the circumstances set forth in Note 9 to the consolidated financial statements included in NSP-Wisconsin's Annual Report on Form 10-K for the year ended Dec. 31, 2011 appropriately represent, in all material respects, the current status of other rate matters, and are incorporated herein by reference. Pending Regulatory Proceedings — Public Service Commission of Wisconsin (PSCW) 2012 Electric and Gas Rate Case — In June 2012, NSP-Wisconsin filed a request with the PSCW to increase rates for electric and natural gas service effective Jan. 1, 2013. NSP-Wisconsin requested an overall increase in annual electric rates of $39.1 million, or 6.7 percent, and an increase in natural gas rates of $5.3 million, or 4.9 percent. The electric rate filing was based on a 2013 forecast test year, a return on equity (ROE) of 10.40 percent, an equity ratio of 52.50 percent and an average 2013 electric rate base of approximately $788.6 million. The natural gas rate request was solely due to a proposal to recover the initial costs associated with the environmental cleanup of the Ashland/Northern States Power Lakefront Superfund Site (the Ashland site) in Ashland, Wis. On Oct. 19, 2012, the PSCW Staff and intervenors filed their direct testimony. The PSCW Staff recommended an electric rate increase of $32.9 million, or 5.6 percent, based on a 10.40 percent ROE and a 52.50 percent equity ratio. The major adjustments recommended by the PSCW Staff were a $2.2 million reduction in employee compensation expense primarily related to disallowance of the annual incentive program, and a net $2.9 million reduction in electric fuel expense and fixed production charges. The PSCW Staff testimony acknowledged the unique issues before the PSCW related to the Ashland site cleanup and presented several alternatives for consideration by the PSCW. Rebuttal testimony is expected to be filed on Oct. 31, 2012, and the hearing is expected to be held on Nov. 7, 2012. A PSCW decision is anticipated in December 2012.

5. Rate Matters

Except to the extent noted below, the circumstances set forth in Note 9 to the consolidated financial statements included in NSP-Wisconsin's Annual Report on Form 10-K for the year ended Dec. 31, 2011 appropriately represent, in all material respects, the current status of other rate matters, and are incorporated herein by reference.

Pending Regulatory Proceedings — Public Service Commission of Wisconsin (PSCW)

2012 Electric and Gas Rate Case — In June 2012, NSP-Wisconsin filed a request with the PSCW to increase rates for electric and natural gas service effective Jan. 1, 2013. NSP-Wisconsin requested an overall increase in annual electric rates of $39.1 million, or 6.7 percent, and an increase in natural gas rates of $5.3 million, or 4.9 percent.

The electric rate filing was based on a 2013 forecast test year, a return on equity (ROE) of 10.40 percent, an equity ratio of 52.50 percent and an average 2013 electric rate base of approximately $788.6 million. The natural gas rate request was solely due to a proposal to recover the initial costs associated with the environmental cleanup of the Ashland/Northern States Power Lakefront Superfund Site (the Ashland site) in Ashland, Wis.

On Oct. 19, 2012, the PSCW Staff and intervenors filed their direct testimony. The PSCW Staff recommended an electric rate increase of $32.9 million, or 5.6 percent, based on a 10.40 percent ROE and a 52.50 percent equity ratio. The major adjustments recommended by the PSCW Staff were a $2.2 million reduction in employee compensation expense primarily related to disallowance of the annual incentive program, and a net $2.9 million reduction in electric fuel expense and fixed production charges. The PSCW Staff testimony acknowledged the unique issues before the PSCW related to the Ashland site cleanup and presented several alternatives for consideration by the PSCW.

Rebuttal testimony is expected to be filed on Oct. 31, 2012, and the hearing is expected to be held on Nov. 7, 2012. A PSCW decision is anticipated in December 2012.