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Regulatory Matters Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | $ 10,203 | $ 10,388
Regulatory Liability, Current | 644 | 523
Noncurrent regulatory liabilities | 9,559 | 9,865
Deferred income taxes |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 5,228 | 5,241
Nuclear decommissioning |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 2,606 | 3,064
Removal costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 1,547 | 1,573
Over Recovered Energy and Natural Gas Costs [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 294 | 111
Other |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 528 | 399
Commonwealth Edison Co [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 6,343 | 6,577
Regulatory Liability, Current | 293 | 249
Noncurrent regulatory liabilities | 6,050 | 6,328
Commonwealth Edison Co [Member] | Deferred income taxes |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 2,394 | 2,479
Commonwealth Edison Co [Member] | Nuclear decommissioning |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 2,217 | 2,528
Commonwealth Edison Co [Member] | Removal costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 1,368 | 1,338
Commonwealth Edison Co [Member] | Over Recovered Energy and Natural Gas Costs [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 137 | 47
Commonwealth Edison Co [Member] | Other |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 227 | 185
PECO Energy Co [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 596 | 690
Regulatory Liability, Current | 175 | 141
Noncurrent regulatory liabilities | 421 | 549
PECO Energy Co [Member] | Deferred income taxes |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
PECO Energy Co [Member] | Nuclear decommissioning |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 389 | 536
PECO Energy Co [Member] | Removal costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
PECO Energy Co [Member] | Over Recovered Energy and Natural Gas Costs [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 132 | 60
PECO Energy Co [Member] | Other |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 75 | 94
Baltimore Gas and Electric Company [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 1,269 | 1,163
Regulatory Liability, Current | 77 | 62
Noncurrent regulatory liabilities | 1,192 | 1,101
Baltimore Gas and Electric Company [Member] | Deferred income taxes |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 1,132 | 1,032
Baltimore Gas and Electric Company [Member] | Nuclear decommissioning |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
Baltimore Gas and Electric Company [Member] | Removal costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 52 | 105
Baltimore Gas and Electric Company [Member] | Over Recovered Energy and Natural Gas Costs [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 6 | 0
Baltimore Gas and Electric Company [Member] | Other |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 79 | 26
Pepco Holdings LLC [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 1,948 | 1,928
Regulatory Liability, Current | 84 | 56
Noncurrent regulatory liabilities | 1,864 | 1,872
Pepco Holdings LLC [Member] | Deferred income taxes |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 1,702 | 1,730
Pepco Holdings LLC [Member] | Nuclear decommissioning |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
Pepco Holdings LLC [Member] | Removal costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 127 | 130
Pepco Holdings LLC [Member] | Over Recovered Energy and Natural Gas Costs [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 19 | 4
Pepco Holdings LLC [Member] | Other |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 100 | 64
Potomac Electric Power Company [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 829 | 832
Regulatory Liability, Current | 7 | 3
Noncurrent regulatory liabilities | 822 | 829
Potomac Electric Power Company [Member] | Deferred income taxes |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 798 | 809
Potomac Electric Power Company [Member] | Nuclear decommissioning |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
Potomac Electric Power Company [Member] | Removal costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 20 | 20
Potomac Electric Power Company [Member] | Over Recovered Energy and Natural Gas Costs [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
Potomac Electric Power Company [Member] | Other |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 11 | 3
Delmarva Power & Light Company [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 665 | 635
Regulatory Liability, Current | 59 | 42
Noncurrent regulatory liabilities | 606 | 593
Delmarva Power & Light Company [Member] | Deferred income taxes |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 510 | 510
Delmarva Power & Light Company [Member] | Nuclear decommissioning |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
Delmarva Power & Light Company [Member] | Removal costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 107 | 110
Delmarva Power & Light Company [Member] | Over Recovered Energy and Natural Gas Costs [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 18 | 1
Delmarva Power & Light Company [Member] | Other |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 30 | 14
Atlantic City Electric Company [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 420 | 422
Regulatory Liability, Current | 18 | 11
Noncurrent regulatory liabilities | 402 | 411
Atlantic City Electric Company [Member] | Deferred income taxes |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 394 | 411
Atlantic City Electric Company [Member] | Nuclear decommissioning |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
Atlantic City Electric Company [Member] | Removal costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 0 | 0
Atlantic City Electric Company [Member] | Over Recovered Energy and Natural Gas Costs [Member] |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | 1 | 3
Atlantic City Electric Company [Member] | Other |  |
Regulatory Liabilities [Line Items] |  |
Regulatory Liabilities | $ 25 | $ 8

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