Mergers, Acquisitions and Dispositions (Exelon and Generation)	3 Months Ended
Mar. 31, 2020
Business Combinations [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-bottom:12px;padding-top:12px;text-align:justify;padding-left:0px;text-indent:0px;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;font-weight:bold;">Mergers, Acquisitions and Dispositions</font><font style="font-family:Arial;font-size:9pt;font-weight:bold;"> (Exelon and Generation)</font></div><div style="line-height:120%;padding-left:4px;padding-bottom:12px;padding-top:12px;text-align:justify;padding-left:0px;text-indent:0px;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;font-weight:bold;">CENG Put Option (Exelon and Generation)</font></div><div style="line-height:120%;padding-bottom:12px;padding-top:12px;text-align:justify;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;">Generation owns a 50.01% membership interest in CENG, a joint venture with EDF, which wholly owns the Calvert Cliffs and Ginna nuclear stations and Nine Mile Point Unit 1, in addition to an 82% undivided ownership interest in Nine Mile Point Unit 2. CENG is 100% consolidated in Exelon's and Generation's financial statements. See Note 22 — Variable Interest Entities for additional information.</font></div><div style="line-height:120%;padding-bottom:12px;padding-top:12px;text-align:justify;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;">On April 1, 2014, Generation and EDF entered into various agreements including a Nuclear Operating Services Agreement, an amended LLC Operating Agreement, an Employee Matters Agreement, and a Put Option Agreement, among others. Under the amended Operating Agreement, CENG made a $400 million special distribution to EDF and committed to make preferred distributions to Generation until Generation has received aggregate distributions of $400 million plus a return of 8.50% per annum. Under the Put Option Agreement, EDF has the option to sell its 49.99% equity interest in CENG to Generation exercisable beginning on January 1, 2016 and thereafter until June 30, 2022. On November 20, 2019, Generation received notice of EDF's intention to exercise the put option to sell its interest in CENG to Generation and the put automatically exercised on January 19, 2020 at the end of the sixty-day advance notice period.</font></div><div style="line-height:120%;padding-bottom:12px;padding-top:12px;text-align:justify;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;">Under the terms of the Put Option Agreement, the purchase price is to be determined by agreement of the parties, or absent such agreement, by a third-party arbitration process. The third parties determining fair market value of EDF's 49.99% interest are to take into consideration all rights and obligations under the LLC Operating Agreement and Employee Matters Agreement including but not limited to Generation's rights with respect to any unpaid aggregate preferred distributions and the related return. As of March 31, 2020, the total unpaid aggregate preferred distributions and related return owed to Generation is </font><font style="font-family:Arial;font-size:9pt;background-color:#ffff00;">$571 million</font><font style="font-family:Arial;font-size:9pt;">. At this time, Generation cannot reasonably predict the ultimate purchase price that will be paid to EDF for its interest in CENG. The transaction will require approval by the NYPSC, the FERC and the NRC. The process and regulatory approvals could take one to two years or more to complete.</font></div></div>

Mergers, Acquisitions and Dispositions (Exelon and Generation)

3 Months Ended

Mar. 31, 2020

Mergers, Acquisitions and Dispositions Disclosures [Text Block]

<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-bottom:12px;padding-top:12px;text-align:justify;padding-left:0px;text-indent:0px;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;font-weight:bold;">Mergers, Acquisitions and Dispositions</font><font style="font-family:Arial;font-size:9pt;font-weight:bold;"> (Exelon and Generation)</font></div><div style="line-height:120%;padding-left:4px;padding-bottom:12px;padding-top:12px;text-align:justify;padding-left:0px;text-indent:0px;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;font-weight:bold;">CENG Put Option (Exelon and Generation)</font></div><div style="line-height:120%;padding-bottom:12px;padding-top:12px;text-align:justify;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;">Generation owns a 50.01% membership interest in CENG, a joint venture with EDF, which wholly owns the Calvert Cliffs and Ginna nuclear stations and Nine Mile Point Unit 1, in addition to an 82% undivided ownership interest in Nine Mile Point Unit 2. CENG is 100% consolidated in Exelon's and Generation's financial statements. See Note 22 — Variable Interest Entities for additional information.</font></div><div style="line-height:120%;padding-bottom:12px;padding-top:12px;text-align:justify;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;">On April 1, 2014, Generation and EDF entered into various agreements including a Nuclear Operating Services Agreement, an amended LLC Operating Agreement, an Employee Matters Agreement, and a Put Option Agreement, among others. Under the amended Operating Agreement, CENG made a $400 million special distribution to EDF and committed to make preferred distributions to Generation until Generation has received aggregate distributions of $400 million plus a return of 8.50% per annum. Under the Put Option Agreement, EDF has the option to sell its 49.99% equity interest in CENG to Generation exercisable beginning on January 1, 2016 and thereafter until June 30, 2022. On November 20, 2019, Generation received notice of EDF's intention to exercise the put option to sell its interest in CENG to Generation and the put automatically exercised on January 19, 2020 at the end of the sixty-day advance notice period.</font></div><div style="line-height:120%;padding-bottom:12px;padding-top:12px;text-align:justify;font-size:9pt;"><font style="font-family:Arial;font-size:9pt;">Under the terms of the Put Option Agreement, the purchase price is to be determined by agreement of the parties, or absent such agreement, by a third-party arbitration process. The third parties determining fair market value of EDF's 49.99% interest are to take into consideration all rights and obligations under the LLC Operating Agreement and Employee Matters Agreement including but not limited to Generation's rights with respect to any unpaid aggregate preferred distributions and the related return. As of March 31, 2020, the total unpaid aggregate preferred distributions and related return owed to Generation is </font><font style="font-family:Arial;font-size:9pt;background-color:#ffff00;">$571 million</font><font style="font-family:Arial;font-size:9pt;">. At this time, Generation cannot reasonably predict the ultimate purchase price that will be paid to EDF for its interest in CENG. The transaction will require approval by the NYPSC, the FERC and the NRC. The process and regulatory approvals could take one to two years or more to complete.</font></div></div>