v3.26.1
Segment Information - Electric and Gas Revenue by Customer Class (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 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 $ (70) $ (275) $ (102) $ (402)
Total operating revenues 5,967 5,427 13,209 12,141
Operating Segment        
Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Line Items]        
Total operating revenues 5,967 5,427 13,209 12,141
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 (55) (234) (46) (319)
Total operating revenues 1,985 1,836 3,898 3,901
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 10 13 17
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 2,026 2,060 3,915 4,202
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 (41) (224) (17) (301)
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 5 1 10 (8)
Total operating revenues 1,062 1,000 2,554 2,333
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 3 3 7 6
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 1,049 992 2,527 2,329
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 13 8 27 4
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 5 (13) (18) (43)
Total operating revenues 1,218 1,029 3,046 2,583
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 3 2 5 4
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 1,204 1,037 3,046 2,620
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 14 (8) 0 (37)
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 (24) (29) (48) (32)
Total operating revenues 1,712 1,579 3,742 3,357
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 2 2 5 5
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 1,732 1,606 3,781 3,387
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 (20) (27) (39) (30)
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 (15) (16) (14) (14)
Total operating revenues 859 776 1,849 1,635
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 1 1 4 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 871 791 1,856 1,648
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 (12) (15) (7) (13)
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 2 0 (5) (5)
Total operating revenues 454 421 1,076 969
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 2 2 4 4
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 451 420 1,079 973
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 3 1 (3) (4)
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 (11) (13) (29) (13)
Total operating revenues 401 384 822 757
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 0 2 1
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 412 397 851 770
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 (11) (13) (29) (13)
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 5,710 5,365 11,868 11,182
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 5,639 5,096 11,773 10,804
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 2,038 2,060 3,931 4,203
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 2,026 2,060 3,915 4,202
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 10 13 17
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 14 10 29 18
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 1,101 1,094 2,126 2,087
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 527 553 1,011 1,153
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 131 177 251 472
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 12 23 29
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 255 224 504 461
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 934 876 2,007 1,839
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 929 872 1,998 1,833
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 2 3 6 5
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 7 7 15 11
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 601 555 1,326 1,186
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 157 155 329 317
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 85 75 172 159
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 9 10 17 18
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 77 77 154 153
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 1,044 856 2,302 1,877
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 1,039 853 2,293 1,875
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 2 1 4 3
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 7 4 13 5
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 641 497 1,459 1,145
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 108 90 238 199
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 161 140 342 284
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 17 17
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 121 118 237 230
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 1,694 1,573 3,628 3,264
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 1,692 1,573 3,624 3,267
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 2 2 5 5
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 2 9 2
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 867 780 1,960 1,698
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 180 168 373 338
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 397 370 793 738
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 22 40 39
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 228 233 458 454
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 873 791 1,859 1,645
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 871 791 1,856 1,648
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 1 1 4 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 1 7 1
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 396 348 902 772
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 49 48 103 99
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 321 292 642 581
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 12 21 20
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 94 91 188 176
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 410 386 920 850
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 411 387 922 853
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 2 2 4 4
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 2 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 230 210 559 508
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 66 64 137 128
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 33 31 64 60
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 5 9 9
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 78 77 153 148
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 411 397 849 769
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 412 397 851 770
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 0 2 1
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 241 222 499 418
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 65 56 133 111
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 43 47 87 97
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 5 10 10
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 58 67 122 134
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 327 337 1,443 1,361
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 328 331 1,436 1,337
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 120 120 530 496
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 120 120 529 496
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 0 1 1
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 1 0 2 1
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 84 79 369 346
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 29 31 125 117
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 0 0 0
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 6 8 26 21
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 1 2 9 12
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 166 184 757 745
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 165 184 753 745
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 1 1
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 2 1 5 1
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 93 108 494 486
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 17 23 80 86
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 48 46 141 142
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 7 7 38 31
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 33 157 120
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 33 157 120
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 18 17 92 73
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 9 8 38 28
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 5 4
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 4 4 10 9
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 8 3 12 6
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 33 157 120
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 33 157 120
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 18 17 92 73
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 9 8 38 28
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 5 4
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 4 4 10 9
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 8 3 12 6
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 (55) (234) (46) (319)
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 5 1 10 (8)
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 5 (13) (18) (43)
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 (24) (29) (48) (32)
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 (15) (16) (14) (14)
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 2 0 (5) (5)
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 $ (11) $ (13) $ (29) $ (13)