Subsequent Events	9 Months Ended
Sep. 30, 2014
Subsequent Events [Abstract]
Subsequent Events	18. Subsequent Events Sale of TECO Coal Corporation On Oct. 17, 2014, TECO Diversified entered into an SPA to sell all of its ownership interest in TECO Coal to Cambrian Coal Corporation for $120 million, subject to a working capital adjustment, plus contingent payments of up to $50 million that may be paid between 2015 and 2019 depending on specified coal benchmark prices. The SPA provides for TECO Coal to reorganize as a limited liability company prior to closing and for Cambrian Coal Corporation to acquire all of the membership interests in that limited liability company. Initial net proceeds from the sale (not including any contingent payments) are expected to be used to repay short-term debt of TECO Energy and for general corporate purposes. The SPA contains customary representations, warranties, covenants, and closing conditions, including the purchaser’s obtaining debt financing in order to pay a portion of the purchase price. The SPA also contains indemnification provisions subject to specified limitations as to time and amount. In addition, the SPA is subject to termination by either party if specified closing conditions are not met by Dec. 31, 2014. NMPRC Approval of Amendments to the New Mexico Gas Company 2011 Notes On Feb. 8, 2011, NMGC issued secured notes in an aggregate principal amount of $200 million (NMGC 2011 Notes), maturing Feb. 8, 2021. The NMGC 2011 Notes were issued in a private placement that was not subject to the registration requirements of the Securities Act of 1933. On July 16, 2014, NMGC received approvals from the noteholders of the NMGC 2011 Notes to release the collateral securing the NMGC 2011 Notes by amending the existing note purchase agreement. The amendments to the note purchase agreement were subject to the approval of the NMPRC and on Oct. 22, 2014, NMGC received the required NMPRC approval of the amendments. On Oct. 27, 2014, the amendments became effective and the collateral securing the NMGC 2014 Notes was released.

18. Subsequent Events

Sale of TECO Coal Corporation

On Oct. 17, 2014, TECO Diversified entered into an SPA to sell all of its ownership interest in TECO Coal to Cambrian Coal Corporation for $120 million, subject to a working capital adjustment, plus contingent payments of up to $50 million that may be paid between 2015 and 2019 depending on specified coal benchmark prices. The SPA provides for TECO Coal to reorganize as a limited liability company prior to closing and for Cambrian Coal Corporation to acquire all of the membership interests in that limited liability company. Initial net proceeds from the sale (not including any contingent payments) are expected to be used to repay short-term debt of TECO Energy and for general corporate purposes.

The SPA contains customary representations, warranties, covenants, and closing conditions, including the purchaser’s obtaining debt financing in order to pay a portion of the purchase price. The SPA also contains indemnification provisions subject to specified limitations as to time and amount. In addition, the SPA is subject to termination by either party if specified closing conditions are not met by Dec. 31, 2014.

NMPRC Approval of Amendments to the New Mexico Gas Company 2011 Notes

On Feb. 8, 2011, NMGC issued secured notes in an aggregate principal amount of $200 million (NMGC 2011 Notes), maturing Feb. 8, 2021. The NMGC 2011 Notes were issued in a private placement that was not subject to the registration requirements of the Securities Act of 1933. On July 16, 2014, NMGC received approvals from the noteholders of the NMGC 2011 Notes to release the collateral securing the NMGC 2011 Notes by amending the existing note purchase agreement. The amendments to the note purchase agreement were subject to the approval of the NMPRC and on Oct. 22, 2014, NMGC received the required NMPRC approval of the amendments. On Oct. 27, 2014, the amendments became effective and the collateral securing the NMGC 2014 Notes was released.