Equity method investments	6 Months Ended
Equity method investments	Jun. 30, 2013
Equity Method Investments and Joint Ventures [Abstract]
Equity method investments	Equity method investments Investments in companies in which the Company has the ability to exercise significant influence over operating and financial policies are accounted for using the equity method. The Company's equity method investments at June 30, 2013, include ECTE. In August 2006, MDU Brasil acquired ownership interests in the Brazilian Transmission Lines. The electric transmission lines are primarily in northeastern and southern Brazil. The transmission contracts provide for revenues denominated in the Brazilian Real, annual inflation adjustments and change in tax law adjustments. The functional currency for the Brazilian Transmission Lines is the Brazilian Real. In 2009, multiple sales agreements were signed for the Company to sell its ownership interest in the Brazilian Transmission Lines. In November 2010, the Company completed the sale of its entire ownership interest in ENTE and ERTE and 59.96 percent of the Company's ownership interest in ECTE. The remaining interest in ECTE is being purchased over a four-year period. In August 2012 and November 2011, the Company completed the sale of one-fourth of the remaining interest in each year. Alusa, CEMIG and CELESC hold the remaining ownership interests in ECTE. At June 30, 2013 and 2012, and December 31, 2012, the equity method investments had total assets of $114.8 million, $104.4 million and $129.0 million, respectively, and long-term debt of $56.2 million, $30.3 million and $65.5 million, respectively. The Company's investment in its equity method investments was approximately $5.5 million, $7.4 million and $6.9 million, including undistributed earnings of $2.0 million, $2.3 million and $3.4 million, at June 30, 2013 and 2012, and December 31, 2012, respectively.

The entire disclosure for equity method investments and joint ventures. Equity method investments are investments that give the investor the ability to exercise significant influence over the operating and financial policies of an investee. Joint ventures are entities owned and operated by a small group of businesses as a separate and specific business or project for the mutual benefit of the members of the group.

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