v3.26.3
Segment Information - Electric and Gas Revenue by Customer Class (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates $ (35) $ (220) $ (138) $ (621)
Total operating revenues 7,319 6,705 20,528 18,846
Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 7,319 6,705 20,528 18,846
Commonwealth Edison Co        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (15) (206) (62) (525)
Total operating revenues 2,470 2,275 6,368 6,176
Commonwealth Edison Co | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 2 2 15 19
Commonwealth Edison Co | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 2,474 2,470 6,389 6,671
Commonwealth Edison Co | Other Regulated Revenue        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues (4) (195) (21) (495)
PECO Energy Co        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 1 2 10 (6)
Total operating revenues 1,240 1,180 3,794 3,513
PECO Energy Co | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 5 3 13 9
PECO Energy Co | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 1,233 1,171 3,761 3,500
PECO Energy Co | Other Regulated Revenue        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 7 9 33 13
Baltimore Gas and Electric Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (18) (20) (35) (63)
Total operating revenues 1,363 1,209 4,409 3,791
Baltimore Gas and Electric Company | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 2 2 7 6
Baltimore Gas and Electric Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 1,376 1,224 4,421 3,843
Baltimore Gas and Electric Company | Other Regulated Revenue        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues (13) (15) (12) (52)
Pepco Holdings LLC        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (3) 6 (51) (27)
Total operating revenues 2,260 2,051 6,002 5,408
Pepco Holdings LLC | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 5 2 10 7
Pepco Holdings LLC | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 2,259 2,041 6,040 5,431
Pepco Holdings LLC | Other Regulated Revenue        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 1 10 (38) (23)
Potomac Electric Power Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 1 (5) (13) (19)
Total operating revenues 1,127 992 2,975 2,626
Potomac Electric Power Company | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 3 2 7 4
Potomac Electric Power Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 1,123 994 2,978 2,642
Potomac Electric Power Company | Other Regulated Revenue        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 4 (2) (3) (16)
Delmarva Power and Light Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (3) (5) (8) (10)
Total operating revenues 556 491 1,632 1,460
Delmarva Power and Light Company | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 3 2 7 6
Delmarva Power and Light Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 558 495 1,637 1,469
Delmarva Power and Light Company | Other Regulated Revenue        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues (2) (4) (5) (9)
Atlantic City Electric Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (1) 16 (30) 2
Total operating revenues 579 570 1,402 1,328
Atlantic City Electric Company | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 1 1 4 3
Atlantic City Electric Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 580 554 1,432 1,326
Atlantic City Electric Company | Other Regulated Revenue        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues (1) 16 (30) 2
Rate-regulated electric revenues        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 7,103 6,690 18,971 17,872
Rate-regulated electric revenues | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 7,079 6,478 18,852 17,283
Rate-regulated electric revenues | Commonwealth Edison Co        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 2,483 2,479 6,415 6,682
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 2,474 2,470 6,389 6,671
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 2 2 15 19
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 11 11 41 30
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1,377 1,365 3,501 3,452
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 621 645 1,632 1,799
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 184 217 436 689
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Public authorities & electric railroads        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 12 14 35 43
Rate-regulated electric revenues | Commonwealth Edison Co | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 280 229 785 688
Rate-regulated electric revenues | PECO Energy Co        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1,150 1,093 3,157 2,932
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1,148 1,089 3,147 2,922
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 4 2 11 7
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 6 6 21 17
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 796 735 2,122 1,921
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 173 167 502 484
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 82 101 254 260
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Public authorities & electric railroads        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 8 8 25 26
Rate-regulated electric revenues | PECO Energy Co | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 89 78 244 231
Rate-regulated electric revenues | Baltimore Gas and Electric Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1,252 1,102 3,554 2,978
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1,248 1,099 3,541 2,973
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 1 1 5 4
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 5 4 18 9
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 795 684 2,254 1,829
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 130 113 368 311
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 200 172 541 456
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Public authorities & electric railroads        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 8 8 25 25
Rate-regulated electric revenues | Baltimore Gas and Electric Company | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 115 122 353 352
Rate-regulated electric revenues | Pepco Holdings LLC        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 2,218 2,016 5,846 5,280
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 2,219 2,014 5,843 5,283
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 5 2 10 7
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 4 4 13 4
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1,283 1,147 3,244 2,847
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 230 210 603 548
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 445 406 1,239 1,144
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Public authorities & electric railroads        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 20 16 59 56
Rate-regulated electric revenues | Pepco Holdings LLC | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 241 235 698 688
Rate-regulated electric revenues | Potomac Electric Power Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1,123 995 2,981 2,641
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1,123 994 2,978 2,642
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 3 2 7 4
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 3 3 10 3
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 583 501 1,485 1,273
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 60 56 163 155
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 370 331 1,012 911
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Public authorities & electric railroads        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 11 8 32 29
Rate-regulated electric revenues | Potomac Electric Power Company | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 99 98 286 274
Rate-regulated electric revenues | Delmarva Power and Light Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 516 467 1,436 1,316
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 518 468 1,440 1,321
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 3 2 7 6
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1 1 3 1
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 319 283 879 792
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 81 72 218 200
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 34 32 98 92
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Public authorities & electric railroads        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 4 4 12 13
Rate-regulated electric revenues | Delmarva Power and Light Company | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 80 77 233 224
Rate-regulated electric revenues | Atlantic City Electric Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 579 553 1,428 1,323
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 580 554 1,432 1,326
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 1 1 4 3
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 381 363 880 782
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 89 82 222 193
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 41 43 129 141
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Public authorities & electric railroads        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 5 4 15 14
Rate-regulated electric revenues | Atlantic City Electric Company | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 64 62 186 196
Rate-regulated natural gas revenues        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 251 235 1,695 1,595
Rate-regulated natural gas revenues | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 240 227 1,676 1,563
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Transportation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Commonwealth Edison Co | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | PECO Energy Co        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 84 82 614 578
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 85 82 614 578
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 1 1 2 2
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 1 2 2
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 54 50 422 396
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 20 23 145 140
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 1 0 1
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Transportation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 9 7 35 28
Rate-regulated natural gas revenues | PECO Energy Co | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 2 1 12 13
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 127 125 883 870
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 128 125 880 870
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Related Party        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Operating revenues from affiliates 1 1 2 2
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 1 5 2
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 67 68 561 555
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 14 14 95 100
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 41 37 182 178
Rate-regulated natural gas revenues | Baltimore Gas and Electric Company | Regulated Operation | Transportation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 6 6 42 37
Rate-regulated natural gas revenues | Pepco Holdings LLC        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 40 27 197 148
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 40 27 197 148
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 15 13 106 86
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 8 7 46 35
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1 1 7 6
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Transportation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 5 4 15 13
Rate-regulated natural gas revenues | Pepco Holdings LLC | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 11 2 23 8
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Transportation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Potomac Electric Power Company | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Delmarva Power and Light Company        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 40 27 197 148
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 40 27 197 148
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 15 13 106 86
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Small commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 8 7 46 35
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Large commercial & industrial        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 1 1 7 6
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Transportation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 5 4 15 13
Rate-regulated natural gas revenues | Delmarva Power and Light Company | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 11 2 23 8
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Residential        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [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        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Transportation        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Rate-regulated natural gas revenues | Atlantic City Electric Company | Regulated Operation | Other        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Electric and natural gas operating revenues 0 0 0 0
Alternative revenue programs | Commonwealth Edison Co | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (15) (206) (62) (525)
Alternative revenue programs | PECO Energy Co | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 1 2 10 (6)
Alternative revenue programs | Baltimore Gas and Electric Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (18) (20) (35) (63)
Alternative revenue programs | Pepco Holdings LLC | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (3) 6 (51) (27)
Alternative revenue programs | Potomac Electric Power Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates 1 (5) (13) (19)
Alternative revenue programs | Delmarva Power and Light Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates (3) (5) (8) (10)
Alternative revenue programs | Atlantic City Electric Company | Regulated Operation | Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
True-up adjustments to decoupling mechanisms and formula rates $ (1) $ 16 $ (30) $ 2