Optim Energy	3 Months Ended
Mar. 31, 2012
Equity Method Investments and Joint Ventures [Abstract]
Optim Energy	Optim Energy Information concerning Optim Energy is discussed in Note 21 of the Notes to Consolidated Financial Statements in the 2011 Annual Reports on Form 10-K. PNMR and ECJV each had a 50 percent ownership interest in Optim Energy, a limited liability company, until September 23, 2011, when Optim Energy was restructured and PNM's interest was reduced to 1%. On January 4, 2012, ECJV exercised its option to acquire PNMR's remaining 1% ownership interest in Optim Energy at fair market value, which was determined to be zero. PNMR accounted for its investment in Optim Energy using the equity method of accounting until September 23, 2011 and then used the cost method through January 4, 2012. PNMR Services Company provided certain corporate services to Optim Energy through December 31, 2011 and is continuing to provide services with respect to certain open tax matters. PNMR fully impaired its investment in Optim Energy at December 31, 2010 and, in accordance with GAAP, did not recognize losses of Optim Energy from January 1, 2011 through September 23, 2011, when PNMR ceased to account for its investment using the equity method of accounting. Accordingly, Optim Energy had no impact on PNMR's December 31, 2011 balance sheet or the statements of earnings and statements of cash flows for 2012 and 2011. Therefore, summarized financial information for Optim Energy is not presented.

Optim Energy

3 Months Ended

Mar. 31, 2012

Equity Method Investments and Joint Ventures [Abstract]

Information concerning Optim Energy is discussed in Note 21 of the Notes to Consolidated Financial Statements in the 2011 Annual Reports on Form 10-K. PNMR and ECJV each had a 50 percent ownership interest in Optim Energy, a limited liability company, until September 23, 2011, when Optim Energy was restructured and PNM's interest was reduced to 1%. On January 4, 2012, ECJV exercised its option to acquire PNMR's remaining 1% ownership interest in Optim Energy at fair market value, which was determined to be zero. PNMR accounted for its investment in Optim Energy using the equity method of accounting until September 23, 2011 and then used the cost method through January 4, 2012. PNMR Services Company provided certain corporate services to Optim Energy through December 31, 2011 and is continuing to provide services with respect to certain open tax matters.

PNMR fully impaired its investment in Optim Energy at December 31, 2010 and, in accordance with GAAP, did not recognize losses of Optim Energy from January 1, 2011 through September 23, 2011, when PNMR ceased to account for its investment using the equity method of accounting. Accordingly, Optim Energy had no impact on PNMR's December 31, 2011 balance sheet or the statements of earnings and statements of cash flows for 2012 and 2011. Therefore, summarized financial information for Optim Energy is not presented.