| Cover Page Document | Dec. 02, 2019 |
| Document Type | 8-K/A |
| Document Period End Date | Dec. 2, 2019 |
| 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 Emerging Growth Company | false |
| Entity Central Index Key | 0001109357 |
| Amendment Flag | false |
| Commonwealth Edison Co [Member] | |
| Entity File Number | 001-01839 |
| Entity Registrant Name | COMMONWEALTH EDISON COMPANY |
| Entity Tax Identification Number | 36-0938600 |
| Entity Incorporation, State or Country Code | IL |
| Entity Address, Address Line One | 440 South LaSalle Street |
| Entity Address, City or Town | Chicago |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60605-1028 |
| City Area Code | (312) |
| Local Phone Number | 394-4321 |
| Entity Central Index Key | 0000022606 |
