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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, 2024
Sep. 30, 2023
Sep. 30, 2024
Sep. 30, 2023
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates $ (54) $ 108 $ (29) $ 513
Total operating revenues 6,154 5,980 17,557 16,360
Operating Segment        
Revenue, Major Customer [Line Items]        
Total operating revenues 6,154 5,980 17,557 16,360
Operating Segment | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 0 0 0 0
Commonwealth Edison Co        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (76) 135 (100) 405
Total operating revenues 2,229 2,268 6,403 5,836
Commonwealth Edison Co | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 9 6 14
Commonwealth Edison Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 2,297 2,126 6,493 5,409
Commonwealth Edison Co | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues (68) 142 (90) 427
PECO Energy Co        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 5 11 3 1
Total operating revenues 1,030 1,037 2,975 2,977
PECO Energy Co | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 4 2 7 6
PECO Energy Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 1,018 1,023 2,960 2,961
PECO Energy Co | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues 12 14 15 16
Baltimore Gas and Electric Company        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 9 (22) 28 47
Total operating revenues 1,044 932 3,268 2,986
Baltimore Gas and Electric Company | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 3 2 7 6
Baltimore Gas and Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 1,030 949 3,231 2,922
Baltimore Gas and Electric Company | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues 14 (17) 37 64
Pepco Holdings LLC        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 8 (15) 40 59
Total operating revenues 1,862 1,773 4,938 4,615
Pepco Holdings LLC | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 3 2 7 7
Pepco Holdings LLC | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 1,850 1,785 4,887 4,545
Pepco Holdings LLC | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues 12 (12) 51 70
Potomac Electric Power Company        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 5 (18) 42 28
Total operating revenues 861 822 2,320 2,174
Potomac Electric Power Company | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 1 5 5
Potomac Electric Power Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 853 838 2,270 2,138
Potomac Electric Power Company | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues 8 (16) 50 36
Delmarva Power and Light Company        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (3) (2) 1 10
Total operating revenues 462 450 1,343 1,273
Delmarva Power and Light Company | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 2 5 5
Delmarva Power and Light Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 464 451 1,339 1,260
Delmarva Power and Light Company | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues (2) (1) 4 13
Atlantic City Electric Company        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 6 5 (3) 21
Total operating revenues 540 502 1,280 1,172
Atlantic City Electric Company | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 1 0 2 1
Atlantic City Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Total operating revenues 534 497 1,283 1,151
Atlantic City Electric Company | Other Regulated Revenue        
Revenue, Major Customer [Line Items]        
Total operating revenues 6 5 (3) 21
Rate-regulated electric revenues        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 6,012 5,684 16,379 14,579
Rate-regulated electric revenues | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 5,944 5,793 16,320 15,056
Rate-regulated electric revenues | Commonwealth Edison Co        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 2,303 2,124 6,497 5,417
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 2,297 2,126 6,493 5,409
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 9 6 14
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 8 7 10 22
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1,117 1,047 3,017 2,744
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 603 540 1,755 1,363
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 286 263 875 553
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 11 43 33
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 280 265 803 716
Rate-regulated electric revenues | PECO Energy Co        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 952 957 2,529 2,478
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 948 956 2,523 2,470
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 3 2 5 5
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 7 3 11 13
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 641 654 1,683 1,617
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 153 148 407 415
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 73 67 191 196
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 7 21 23
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 74 80 221 219
Rate-regulated electric revenues | Baltimore Gas and Electric Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 928 856 2,585 2,306
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 926 853 2,582 2,298
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 1 4 4
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 7 12
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 558 512 1,556 1,308
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 96 86 274 253
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 154 144 425 412
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 8 7 24 22
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 110 104 303 303
Rate-regulated electric revenues | Pepco Holdings LLC        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1,828 1,762 4,769 4,399
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1,827 1,761 4,765 4,395
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 3 2 7 7
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 4 3 11 11
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1,016 959 2,537 2,181
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 203 199 519 503
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 365 386 1,034 1,099
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Public authorities & electric railroads        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 18 16 52 49
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 225 201 623 563
Rate-regulated electric revenues | Potomac Electric Power Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 854 839 2,273 2,141
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 853 838 2,270 2,138
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 1 5 5
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 3 2 8 8
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 426 405 1,085 954
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 52 54 141 134
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 281 303 794 838
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 26 25
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 85 67 224 187
Rate-regulated electric revenues | Delmarva Power and Light Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 440 426 1,215 1,108
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 441 427 1,217 1,110
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 2 2 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 1 3 3
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 267 255 725 626
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 69 70 191 189
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 31 32 91 98
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 4 3 12 11
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 70 67 198 186
Rate-regulated electric revenues | Atlantic City Electric Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 533 497 1,281 1,150
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 534 497 1,283 1,151
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 1 0 2 1
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 323 299 727 601
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 82 75 187 180
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Large commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 53 51 149 163
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 5 4 14 13
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 71 68 206 194
Rate-regulated natural gas revenues        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 196 188 1,207 1,268
Rate-regulated natural gas revenues | Operating Segment        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 210 187 1,237 1,304
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 69 67 436 492
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 70 67 437 491
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Related Party        
Revenue, Major Customer [Line Items]        
Operating revenues from affiliates 1 0 2 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 1 2
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 44 43 300 335
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 17 16 106 123
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 0 1
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 7 7 20 20
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 2 1 11 12
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 104 96 648 627
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 104 96 649 624
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 3 2
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 2 5
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Residential        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 58 57 418 406
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 11 10 76 66
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 32 25 143 124
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 3 4 12 28
Rate-regulated natural gas revenues | Pepco Holdings LLC        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 23 24 122 150
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 23 24 122 150
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 11 12 72 88
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Small commercial & industrial        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 6 7 29 40
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 1 4 3
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 4 3 12 11
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Other        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 1 1 5 8
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 23 24 122 150
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 23 24 122 150
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 11 12 72 88
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 6 7 29 40
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 1 4 3
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Transportation        
Revenue, Major Customer [Line Items]        
Electric and natural gas operating revenues 4 3 12 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 1 5 8
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]        
True-up adjustments to decoupling mechanisms and formula rates (76) 135 (100) 405
Alternative revenue programs | PECO Energy Co | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 5 11 3 1
Alternative revenue programs | Baltimore Gas and Electric Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 9 (22) 28 47
Alternative revenue programs | Pepco Holdings LLC | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 8 (15) 40 59
Alternative revenue programs | Potomac Electric Power Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 5 (18) 42 28
Alternative revenue programs | Delmarva Power and Light Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (3) (2) 1 10
Alternative revenue programs | Atlantic City Electric Company | Regulated Operation | Operating Segment        
Revenue, Major Customer [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates $ 6 $ 5 $ (3) $ 21