| Document and Entity Information Document | Feb. 21, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 21, 2021 |
| Entity File Number | 001-16169 |
| Entity Registrant Name | EXELON CORPORATION |
| Entity Tax Identification Number | 23-2990190 |
| Entity Incorporation, State or Country Code | PA |
| Entity Address, Address Line One | 10 South Dearborn Street |
| Entity Address, Address Line Two | P.O. Box 805379 |
| Entity Address, City or Town | Chicago |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60680-5379 |
| City Area Code | (800) |
| Local Phone Number | 483-3220 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, without par value |
| Trading Symbol | EXC |
| Security Exchange Name | NASDAQ |
| Entity Central Index Key | 0001109357 |
| Amendment Flag | false |
| Entity Emerging Growth Company | false |
| Exelon Generation Co L L C [Member] | |
| Document Information [Line Items] | |
| Entity File Number | 333-85496 |
| Entity Registrant Name | EXELON GENERATION COMPANY, LLC |
| Entity Tax Identification Number | 23-3064219 |
| Entity Incorporation, State or Country Code | PA |
| Entity Address, Address Line One | 300 Exelon Way |
| Entity Address, City or Town | Kennett Square |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 19348-2473 |
| City Area Code | (610) |
| Local Phone Number | 765-5959 |
| Entity Central Index Key | 0001168165 |
