Debt and Credit Agreements	6 Months Ended
Jun. 30, 2012
Debt Disclosure [Abstract]
Debt and Credit Agreements	Debt and Credit Agreements 2012 Project Financings Broken Bow and Crofton Bluffs Effective March 30, 2012, EME, through its subsidiaries, Broken Bow Wind, LLC and Crofton Bluffs Wind, LLC, completed two nonrecourse financings of its interests in the Broken Bow and Crofton Bluffs wind projects. The financings included construction loans totaling $79 million that are required to be converted to 15-year amortizing term loans by March 31, 2013, subject to meeting specified conditions, $13.1 million letter of credit facilities and $5.5 million working capital facilities. Interest under the construction and term loans will accrue at London Interbank Offered Rate (LIBOR) plus 2.875%, with the term loan rate increasing 0.125% after the third, sixth, ninth, and twelfth years. Pursuant to the financing agreements, on April 2, 2012 and April 17, 2012, EME's subsidiaries entered into forward starting interest rate swap agreements at 0.8275% and 0.7825%, respectively, to hedge the majority of the variable interest rate debt beginning December 31, 2012 through December 31, 2013 and at 2.96% and 2.7475%, respectively, to hedge the majority of the variable interest rate debt beginning December 31, 2013 through December 31, 2027. Upon conversion to a term loan, distributions from such subsidiaries are subject to compliance with the terms and conditions of their financing agreements, including a 12-month historic debt service coverage ratio test as specified in the agreements of at least 1.20 to 1.00. As of June 30, 2012, $9 million and $6 million were outstanding under the construction loans included in short-term debt on EME's consolidated balance sheet, and letters of credit facilities, respectively. 2011 Project Financings Tapestry Wind In December 2011, EME, through its subsidiary, Tapestry Wind, LLC, completed a nonrecourse financing of its interests in the Taloga, Buffalo Bear and Pinnacle wind projects. A total of $97 million of cash proceeds received from the $214 million 10-year partially amortizing term loan was deposited into an escrow account as of December 31, 2011. On February 22, 2012, a neighbor of the Pinnacle project filed a formal complaint with the West Virginia Public Service Commission regarding, among other things, noise emissions and shadow flicker and requested that the Commission order the project to shut down at night due to alleged noise emissions. This complaint was dismissed on June 1, 2012. On June 27, 2012 and on July 3, 2012, nearly identical complaints were filed with the West Virginia Public Service Commission by two other neighbors. In addition, on June 25, 2012, each of the three neighbors filed separate civil complaints in the Circuit Court of Mineral County, West Virginia against Pinnacle Wind, LLC, EME, Edison Mission Operations and Maintenance, Inc., and other non-affiliated defendants. The civil complaints allege, among other things, that the noise emissions and shadow flicker from the Pinnacle wind farm constitute a nuisance and seek compensatory damages, punitive damages and other equitable relief. The release of the loan proceeds in escrow is subject to resolution of the complaints or further due diligence from the lenders. Big Sky Turbine Financing In October 2009, EME, through its subsidiary, Big Sky Wind, LLC (Big Sky), entered into turbine financing arrangements totaling approximately $206 million for wind turbine purchase obligations related to the 240 MW Big Sky wind project. The loan has a five-year final maturity, however, specific events, including project performance, may trigger earlier repayment which could occur as early as February 2013. Big Sky's repayment obligations were guaranteed by EME until certain conditions were met, including commercial operations. On February 1, 2012, the lender agreed that all conditions had been satisfied and released EME from such guarantee. The loan is secured by a leasehold mortgage on the project's real property assets, a pledge of all other collateral of the Big Sky wind project, as well as a cash reserve account into which one-third of distributable cash flow, if any, of the Big Sky wind project is to be deposited on a monthly basis. The loan is also secured by pledges of Big Sky's direct and indirect ownership interests in the project. Big Sky will need to arrange alternative financing, if available, to repay the loan at maturity or reach agreement with the lender to extend the maturity date of the loan as EME does not plan to make an investment in the project and is under no obligation to do so. If these efforts are unsuccessful, the lender may foreclose on the project resulting in a write off of the entire investment in the project. At June 30, 2012, EME's net investment in the Big Sky wind project was $135 million. Credit Facilities and Letters of Credit In February 2012, EME terminated its $564 million revolving credit facility. Midwest Generation's $500 million credit facility expired in June 2012 as per its terms. In the first quarter of 2012, EME completed a $100 million letter of credit facility for EME's general corporate needs and for its projects, which expires on June 30, 2014. Letters of credit issued under this facility are secured by cash collateral at least equal to the issued amount. Letters of credit under EME's and its subsidiaries' credit facilities aggregated $165 million and were scheduled to expire as follows: $59 million in 2012, $75 million in 2013, $3 million in 2014, $10 million in 2017, and $18 million in 2018. Standby letters of credit include $40 million issued in connection with the power purchase agreement with Southern California Edison Company, an affiliate of EME, under the Walnut Creek credit facility. Certain letters of credit are subject to automatic annual renewal provisions. At June 30, 2012, EME had $51 million of cash collateral supporting its letters of credit.

Debt and Credit Agreements

2012 Project Financings

Broken Bow and Crofton Bluffs

Effective March 30, 2012, EME, through its subsidiaries, Broken Bow Wind, LLC and Crofton Bluffs Wind, LLC, completed two nonrecourse financings of its interests in the Broken Bow and Crofton Bluffs wind projects. The financings included construction loans totaling $79 million that are required to be converted to 15-year amortizing term loans by March 31, 2013, subject to meeting specified conditions, $13.1 million letter of credit facilities and $5.5 million working capital facilities.

Interest under the construction and term loans will accrue at London Interbank Offered Rate (LIBOR) plus 2.875%, with the term loan rate increasing 0.125% after the third, sixth, ninth, and twelfth years. Pursuant to the financing agreements, on April 2, 2012 and April 17, 2012, EME's subsidiaries entered into forward starting interest rate swap agreements at 0.8275% and 0.7825%, respectively, to hedge the majority of the variable interest rate debt beginning December 31, 2012 through December 31, 2013 and at 2.96% and 2.7475%, respectively, to hedge the majority of the variable interest rate debt beginning December 31, 2013 through December 31, 2027.

Upon conversion to a term loan, distributions from such subsidiaries are subject to compliance with the terms and conditions of their financing agreements, including a 12-month historic debt service coverage ratio test as specified in the agreements of at least 1.20 to 1.00.

As of June 30, 2012, $9 million and $6 million were outstanding under the construction loans included in short-term debt on EME's consolidated balance sheet, and letters of credit facilities, respectively.

2011 Project Financings

Tapestry Wind

In December 2011, EME, through its subsidiary, Tapestry Wind, LLC, completed a nonrecourse financing of its interests in the Taloga, Buffalo Bear and Pinnacle wind projects. A total of $97 million of cash proceeds received from the $214 million 10-year partially amortizing term loan was deposited into an escrow account as of December 31, 2011. On February 22, 2012, a neighbor of the Pinnacle project filed a formal complaint with the West Virginia Public Service Commission regarding, among other things, noise emissions and shadow flicker and requested that the Commission order the project to shut down at night due to alleged noise emissions. This complaint was dismissed on June 1, 2012. On June 27, 2012 and on July 3, 2012, nearly identical complaints were filed with the West Virginia Public Service Commission by two other neighbors. In addition, on June 25, 2012, each of the three neighbors filed separate civil complaints in the Circuit Court of Mineral County, West Virginia against Pinnacle Wind, LLC, EME, Edison Mission Operations and Maintenance, Inc., and other non-affiliated defendants. The civil complaints allege, among other things, that the noise emissions and shadow flicker from the Pinnacle wind farm constitute a nuisance and seek compensatory damages, punitive damages and other equitable relief. The release of the loan proceeds in escrow is subject to resolution of the complaints or further due diligence from the lenders.

Big Sky Turbine Financing

In October 2009, EME, through its subsidiary, Big Sky Wind, LLC (Big Sky), entered into turbine financing arrangements totaling approximately $206 million for wind turbine purchase obligations related to the 240 MW Big Sky wind project. The loan has a five-year final maturity, however, specific events, including project performance, may trigger earlier repayment which could occur as early as February 2013. Big Sky's repayment obligations were guaranteed by EME until certain conditions were met, including commercial operations. On February 1, 2012, the lender agreed that all conditions had been satisfied and released EME from such guarantee. The loan is secured by a leasehold mortgage on the project's real property assets, a pledge of all other collateral of the Big Sky wind project, as well as a cash reserve account into which one-third of distributable cash flow, if any, of the Big Sky wind project is to be deposited on a monthly basis. The loan is also secured by pledges of Big Sky's direct and indirect ownership interests in the project.

Big Sky will need to arrange alternative financing, if available, to repay the loan at maturity or reach agreement with the lender to extend the maturity date of the loan as EME does not plan to make an investment in the project and is under no obligation to do so. If these efforts are unsuccessful, the lender may foreclose on the project resulting in a write off of the entire investment in the project. At June 30, 2012, EME's net investment in the Big Sky wind project was $135 million.

Credit Facilities and Letters of Credit

In February 2012, EME terminated its $564 million revolving credit facility. Midwest Generation's $500 million credit facility expired in June 2012 as per its terms. In the first quarter of 2012, EME completed a $100 million letter of credit facility for EME's general corporate needs and for its projects, which expires on June 30, 2014. Letters of credit issued under this facility are secured by cash collateral at least equal to the issued amount.

Letters of credit under EME's and its subsidiaries' credit facilities aggregated $165 million and were scheduled to expire as follows: $59 million in 2012, $75 million in 2013, $3 million in 2014, $10 million in 2017, and $18 million in 2018. Standby letters of credit include $40 million issued in connection with the power purchase agreement with Southern California Edison Company, an affiliate of EME, under the Walnut Creek credit facility. Certain letters of credit are subject to automatic annual renewal provisions. At June 30, 2012, EME had $51 million of cash collateral supporting its letters of credit.