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Segment Information - Electric and Gas Revenue by Customer Class (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2023
Sep. 30, 2022
Sep. 30, 2023
Sep. 30, 2022
Revenue, Major Customer [Line Items]        
Total operating revenues $ 5,980 $ 4,845 $ 16,360 $ 14,412
Operating Segment        
Revenue, Major Customer [Line Items]        
Total operating revenues 5,980 4,845 16,360 14,412
Operating Segment | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 0 0 0 6
Commonwealth Edison Co        
Revenue, Major Customer [Line Items]        
Total operating revenues 2,268 1,378 5,836 4,536
Commonwealth Edison Co | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 9 6 14 14
Commonwealth Edison Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 2,126 1,284 5,409 4,351
Commonwealth Edison Co | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues 142 94 427 185
PECO Energy Co        
Revenue, Major Customer [Line Items]        
Total operating revenues 1,037 1,014 2,977 2,877
PECO Energy Co | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 3 6 5
PECO Energy Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 1,023 1,014 2,961 2,864
PECO Energy Co | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues 14 0 16 13
Baltimore Gas and Electric Company        
Revenue, Major Customer [Line Items]        
Total operating revenues 932 870 2,986 2,810
Baltimore Gas and Electric Company | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 3 6 13
Baltimore Gas and Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 949 873 2,922 2,835
Baltimore Gas and Electric Company | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues (17) (3) 64 (25)
Pepco Holdings LLC        
Revenue, Major Customer [Line Items]        
Total operating revenues 1,773 1,598 4,615 4,223
Pepco Holdings LLC | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 3 7 9
Pepco Holdings LLC | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 1,785 1,608 4,545 4,252
Pepco Holdings LLC | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues (12) (10) 70 (29)
Potomac Electric Power Company        
Revenue, Major Customer [Line Items]        
Total operating revenues 822 724 2,174 1,919
Potomac Electric Power Company | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 1 2 5 4
Potomac Electric Power Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 838 731 2,138 1,931
Potomac Electric Power Company | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues (16) (7) 36 (12)
Delmarva Power and Light Company        
Revenue, Major Customer [Line Items]        
Total operating revenues 450 412 1,273 1,176
Delmarva Power and Light Company | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 1 5 5
Delmarva Power and Light Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 451 412 1,260 1,178
Delmarva Power and Light Company | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues (1) 0 13 (2)
Atlantic City Electric Company        
Revenue, Major Customer [Line Items]        
Total operating revenues 502 462 1,172 1,120
Atlantic City Electric Company | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 0 0 1 2
Atlantic City Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 497 465 1,151 1,134
Atlantic City Electric Company | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues 5 (3) 21 (14)
Rate-regulated electric revenues        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 5,684 4,557 14,579 12,972
Rate-regulated electric revenues | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 5,793 4,621 15,056 13,082
Rate-regulated electric revenues | Commonwealth Edison Co        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 2,124 1,284 5,417 4,359
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 2,126 1,284 5,409 4,351
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 9 6 14 14
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 7 6 22 22
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1,047 935 2,744 2,610
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 540 217 1,363 953
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 263 (117) 553 48
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Public authorities & electric railroads        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 11 3 33 22
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 265 246 716 718
Rate-regulated electric revenues | PECO Energy Co        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 957 943 2,478 2,384
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 956 941 2,470 2,378
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 3 5 5
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 3 5 13 11
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 654 620 1,617 1,538
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 148 149 415 386
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 67 93 196 229
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Public authorities & electric railroads        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 7 8 23 23
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 80 71 219 202
Rate-regulated electric revenues | Baltimore Gas and Electric Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 856 761 2,306 2,138
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 853 760 2,298 2,132
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 1 2 4 5
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 4 4 12 11
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 512 406 1,308 1,158
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 86 88 253 239
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 144 158 412 418
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Public authorities & electric railroads        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 7 7 22 20
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 104 101 303 297
Rate-regulated electric revenues | Pepco Holdings LLC        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1,762 1,568 4,399 4,090
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1,761 1,570 4,395 4,095
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 3 7 9
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 3 1 11 4
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 959 808 2,181 2,007
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 199 179 503 461
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 386 401 1,099 1,056
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Public authorities & electric railroads        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 16 16 49 47
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 201 166 563 524
Rate-regulated electric revenues | Potomac Electric Power Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 839 730 2,141 1,930
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 838 731 2,138 1,931
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 1 2 5 4
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 2 1 8 3
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 405 318 954 826
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 54 44 134 117
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 303 303 838 806
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Public authorities & electric railroads        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 9 9 25 25
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 67 57 187 157
Rate-regulated electric revenues | Delmarva Power and Light Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 426 373 1,108 1,017
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 427 374 1,110 1,021
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 1 5 5
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1 0 3 1
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 255 207 626 570
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 70 65 189 173
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 32 43 98 99
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Public authorities & electric railroads        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 3 4 11 11
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 67 55 186 168
Rate-regulated electric revenues | Atlantic City Electric Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 497 465 1,150 1,132
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 497 465 1,151 1,134
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 0 0 1 2
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 299 283 601 611
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 75 70 180 171
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 51 55 163 151
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Public authorities & electric railroads        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 4 3 13 11
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 68 54 194 190
Rate-regulated natural gas revenues        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 188 224 1,268 1,348
Rate-regulated natural gas revenues | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 187 224 1,304 1,330
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | PECO Energy Co        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 67 73 492 487
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 67 73 491 486
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 0 0 1 1
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 2 1
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 43 46 335 335
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 16 20 123 125
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 1 0
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 7 5 20 19
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1 2 12 7
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 96 114 627 699
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 96 113 624 703
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 1 1 2 7
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1 1 5 4
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 57 70 406 448
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 10 13 66 77
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 25 28 124 128
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 4 2 28 50
Rate-regulated natural gas revenues | Pepco Holdings LLC        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 24 38 150 157
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 24 38 150 157
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 12 10 88 77
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 7 6 40 35
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1 3 3 9
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 3 3 11 11
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1 16 8 25
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Delmarva Power and Light Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 24 38 150 157
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 24 38 150 157
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 12 10 88 77
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 7 6 40 35
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1 3 3 9
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 3 3 11 11
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1 16 8 25
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Alternative revenue programs | Commonwealth Edison Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 135 88 405 163
Alternative revenue programs | PECO Energy Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 11 (5) 1 1
Alternative revenue programs | Baltimore Gas and Electric Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues (22) (8) 47 (40)
Alternative revenue programs | Pepco Holdings LLC | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues (15) (11) 59 (33)
Alternative revenue programs | Potomac Electric Power Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues (18) (8) 28 (15)
Alternative revenue programs | Delmarva Power and Light Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues (2) 0 10 (3)
Alternative revenue programs | Atlantic City Electric Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues $ 5 $ (3) $ 21 $ (14)