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Regulatory Matters Regulatory Matters- Narrative (Details) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended | 7 Months Ended | 9 Months Ended | 12 Months Ended | 48 Months Ended | 60 Months Ended | 78 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 15, 2019 USD ($) | Jan. 04, 2019 USD ($) | Dec. 20, 2018 USD ($) | Dec. 04, 2018 USD ($) | Nov. 19, 2018 USD ($) | Sep. 07, 2018 USD ($) | Aug. 21, 2018 USD ($) | Jul. 01, 2018 USD ($) | Jun. 27, 2018 USD ($) | Jun. 08, 2018 USD ($) | Apr. 20, 2018 USD ($) | [7] | Apr. 17, 2018 USD ($) | [7] | Apr. 16, 2018 USD ($) | Mar. 29, 2018 USD ($) | Mar. 08, 2018 USD ($) | [7] | Mar. 02, 2018 USD ($) | Feb. 09, 2018 USD ($) | Feb. 06, 2018 USD ($) | Jan. 31, 2018 USD ($) | Jan. 18, 2018 USD ($) | Dec. 19, 2017 USD ($) | Dec. 18, 2017 USD ($) | Nov. 16, 2017 USD ($) | Apr. 30, 2016 USD ($) | Dec. 31, 2018 USD ($) | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2017 USD ($) | Sep. 30, 2018 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2023 USD ($) | Dec. 31, 2023 USD ($) | Jul. 21, 2017 USD ($) | Aug. 31, 2010 USD ($)
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 127,000,000 |  |  |  |  |  |  |  |  |  |  | $ 127,000,000 |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,459,000,000 |  |  |  | $ 9,288,000,000 |  |  |  | $ 9,288,000,000 |  |  | 9,459,000,000 |  | $ 9,288,000,000 |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 14,000,000 |  | (10,000,000) |  | $ 76,000,000 |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 35,000,000 |  |  |  | 35,000,000 |  |  |  |  | 35,000,000 |  |  |  |  |  |  |
Regulatory Liability, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 644,000,000 |  |  |  | 523,000,000 |  |  |  | 523,000,000 |  |  | 644,000,000 |  | 523,000,000 |  |  |  |  |  |  |
Regulatory liabilities, noncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,559,000,000 |  |  |  | 9,865,000,000 |  |  |  | 9,865,000,000 |  |  | 9,559,000,000 |  | 9,865,000,000 |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,814,000,000 | $ 9,403,000,000 | $ 8,076,000,000 | $ 9,693,000,000 | 8,384,000,000 | $ 8,768,000,000 | $ 7,665,000,000 | $ 8,747,000,000 |  |  |  | 35,985,000,000 |  | 33,565,000,000 |  | 31,366,000,000 |  |  |  |  |
Business Combination, Integration Related Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,000,000 | [1] | 16,000,000 | [1] | 143,000,000 |  |  |  |  |
Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,203,000,000 |  |  |  | 10,388,000,000 |  |  |  | 10,388,000,000 |  |  | 10,203,000,000 |  | 10,388,000,000 |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,800,000,000 |  |  |  | 3,532,000,000 |  |  |  | 3,532,000,000 |  |  | 3,800,000,000 |  | 3,532,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,594,000,000 |  | 7,584,000,000 |  | 8,553,000,000 |  |  |  |  |
PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 176,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
DC PLUG charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 159,000,000 |  |  |  | 190,000,000 |  |  |  | 190,000,000 |  |  | 159,000,000 |  | 190,000,000 |  |  |  |  |  |  |
Fair value of long-term debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 758,000,000 |  |  |  | 758,000,000 |  |  |  |  | 758,000,000 |  |  |  |  |  |  |
Advanced Metering Infrastructure Legacy Meter Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 328,000,000 |  |  |  | 223,000,000 |  |  |  | 223,000,000 |  |  | 328,000,000 |  | 223,000,000 |  |  |  |  |  |  |
Electric Energy and Natural Gas Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 193,000,000 |  |  |  | 47,000,000 |  |  |  | 47,000,000 |  |  | 193,000,000 |  | 47,000,000 |  |  |  |  |  |  |
Merger integration costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 42,000,000 |  |  |  | 45,000,000 |  |  |  | 45,000,000 |  |  | 42,000,000 |  | 45,000,000 |  |  |  |  |  |  |
Energy efficiency and demand response programs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 545,000,000 |  |  |  | 596,000,000 |  |  |  | 596,000,000 |  |  | 545,000,000 |  | 596,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,670,000,000 |  | 4,829,000,000 |  | 3,785,000,000 |  |  |  |  |
Exelon Generation Co L L C [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  | 0 |  | 0 |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,069,000,000 | 5,278,000,000 | 4,579,000,000 | 5,512,000,000 | 4,657,000,000 | 4,750,000,000 | 4,216,000,000 | 4,878,000,000 |  |  |  | 20,437,000,000 |  | 18,500,000,000 |  | 17,757,000,000 |  |  |  |  |
Purchase Obligation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 235,000,000 |
Business Combination, Integration Related Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,000,000 | [1] | 22,000,000 | [1] | 37,000,000 |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,847,000,000 |  |  |  | 1,773,000,000 |  |  |  | 1,773,000,000 |  |  | 1,847,000,000 |  | 1,773,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,242,000,000 |  | 2,259,000,000 |  | 3,078,000,000 |  |  |  |  |
Exelon Generation Co L L C [Member] | Conowingo [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
License Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 37,000,000 |  |  |  |  |  |  |  |  |
Exelon Generation Co L L C [Member] | One-Time Revenue Adjustment [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 101,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exelon Generation Co L L C [Member] | PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current | [2] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 41,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Exelon Generation Co L L C [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase Obligation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,000,000 |  |  |  |  |  |  |  |  |  |  | 3,000,000 |  |  |  |  |  |  |  |  |
Exelon Generation Co L L C [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase Obligation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,000,000 |  |  |  |  |  |  |  |  |  |  | 7,000,000 |  |  |  |  |  |  |  |  |
Exelon Generation Co L L C [Member] | Zero emission credit costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 438,000,000 |  | $ 311,000,000 |  |  |  |  |  |  |
Other Revenue, Net |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 150,000,000 |  |  | 373,000,000 |  |  |  |  |  |  |  |  |
Commonwealth Edison Co [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
SocialCarbonCost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 16.50 |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | [3] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (44,000,000) |  |  |  |  |  |  |  |  |
Cap on Equity Component of Rate of Return on Common Equity in Federal Energy Regulatory Committee Complaint |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 55.00% |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | [3],[4] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (26,000,000) |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage | [3],[5] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11.50% |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,279,000,000 |  |  |  | 1,279,000,000 |  |  |  |  | $ 1,279,000,000 |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  | 0 |  | 0 |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,000,000 |  |  |  | 3,000,000 |  |  |  |  | 3,000,000 |  |  |  |  |  |  |
Regulatory Liability, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 293,000,000 |  |  |  | 249,000,000 |  |  |  | 249,000,000 |  |  | 293,000,000 |  | 249,000,000 |  |  |  |  |  |  |
Regulatory liabilities, noncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,050,000,000 |  |  |  | 6,328,000,000 |  |  |  | 6,328,000,000 |  |  | 6,050,000,000 |  | 6,328,000,000 |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,373,000,000 | 1,598,000,000 | 1,398,000,000 | 1,512,000,000 | 1,309,000,000 | 1,571,000,000 | 1,357,000,000 | 1,298,000,000 |  |  |  | 5,882,000,000 |  | 5,536,000,000 |  | 5,254,000,000 |  |  |  |  |
Purchase Obligation |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 170,000,000 |
Business Combination, Integration Related Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | [1],[6] | 1,000,000 | [1],[6] | (6,000,000) |  |  |  |  |
Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,343,000,000 |  |  |  | 6,577,000,000 |  |  |  | 6,577,000,000 |  |  | 6,343,000,000 |  | 6,577,000,000 |  |  |  |  |  |  |
Prior Year Revenue Adjustment | [3] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 18,000,000 |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 201,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 607,000,000 |  |  |  | 568,000,000 |  |  |  | 568,000,000 |  |  | 607,000,000 |  | 568,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,126,000,000 |  | 2,250,000,000 |  | 2,734,000,000 |  |  |  |  |
Commonwealth Edison Co [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (58,000,000) |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 34,000,000 |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | [7] |  |  |  | $ (24,000,000) |  |  |  |  |  |  |  |  | $ (23,000,000) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Equity Capital Structure, Percentage |  |  |  |  | 8.69% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 69,000,000 |  |  |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | DC PLUG charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  | 0 |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | Fair value of long-term debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  | 0 |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 136,000,000 |  |  |  | 155,000,000 |  |  |  | 155,000,000 |  |  | 136,000,000 |  | 155,000,000 |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | Electric Energy and Natural Gas Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  | 0 |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | Merger integration costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  | 0 |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | Energy efficiency and demand response programs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  | 0 |  |  |  |  |  |  |
PECO Energy Co [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 22,000,000 |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 410,000,000 |  |  |  | 410,000,000 |  |  |  |  | 410,000,000 |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  | 0 |  | 0 |  |  |  |  |
Regulatory Liability, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 175,000,000 |  |  |  | 141,000,000 |  |  |  | 141,000,000 |  |  | 175,000,000 |  | 141,000,000 |  |  |  |  |  |  |
Regulatory liabilities, noncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 421,000,000 |  |  |  | 549,000,000 |  |  |  | 549,000,000 |  |  | 421,000,000 |  | 549,000,000 |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 765,000,000 | 757,000,000 | 653,000,000 | 866,000,000 | 729,000,000 | 715,000,000 | 630,000,000 | 796,000,000 |  |  |  | 3,038,000,000 |  | 2,870,000,000 |  | 2,994,000,000 |  |  |  |  |
Business Combination, Integration Related Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,000,000 | [1] | 4,000,000 | [1] | 5,000,000 |  |  |  |  |
Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 596,000,000 |  |  |  | 690,000,000 |  |  |  | 690,000,000 |  |  | $ 596,000,000 |  | 690,000,000 |  |  |  |  |  |  |
Public Utilities, Requested Equity Capital Structure, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11.00% |  |  |  |  |  |  |  |  |
Prior Year Revenue Adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 6,000,000 |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 71,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 370,000,000 |  |  |  | 370,000,000 |  |  |  | 370,000,000 |  |  | $ 370,000,000 |  | 370,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 849,000,000 |  | 732,000,000 |  | 686,000,000 |  |  |  |  |
PECO Energy Co [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | [7] |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 82,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | [7] |  |  | $ 25,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PECO Energy Co [Member] | Gas Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  | $ 4,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PECO Energy Co [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |
PECO Energy Co [Member] | PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
PECO Energy Co [Member] | DC PLUG charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  | 0 |  |  |  |  |  |  |
PECO Energy Co [Member] | Fair value of long-term debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  | 0 |  |  |  |  |  |  |
PECO Energy Co [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 36,000,000 |  |  |  | 36,000,000 |  |  |  |  | 36,000,000 |  |  |  |  |  |  |
PECO Energy Co [Member] | Electric Energy and Natural Gas Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,000,000 |  |  |  | 1,000,000 |  |  |  |  | 1,000,000 |  |  |  |  |  |  |
PECO Energy Co [Member] | Merger integration costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  |  | 0 |  |  |  |  |  |  |
PECO Energy Co [Member] | Energy efficiency and demand response programs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,000,000 |  |  |  | 1,000,000 |  |  |  |  | 1,000,000 |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | [3] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000 |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | [3],[4],[8] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 26,000,000 |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.50% |  |  |  |  |  |  |  |  |
Proposed Capital Expenditure |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12,000,000 |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 571,000,000 |  |  |  | 571,000,000 |  |  |  |  | 571,000,000 |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  | 7,000,000 |  | 81,000,000 |  |  |  |  |
Estimated number of smart meters to be installed |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0
Total smart grid smart meter investment grant awarded |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 480,000,000
Doe Reimbursements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 200,000,000
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,000,000 |  |  |  | 5,000,000 |  |  |  |  | 5,000,000 |  |  |  |  |  |  |
Regulatory Liability, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 77,000,000 |  |  |  | 62,000,000 |  |  |  | 62,000,000 |  |  | 77,000,000 |  | 62,000,000 |  |  |  |  |  |  |
Regulatory liabilities, noncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,192,000,000 |  |  |  | 1,101,000,000 |  |  |  | 1,101,000,000 |  |  | 1,192,000,000 |  | 1,101,000,000 |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 799,000,000 | 731,000,000 | 662,000,000 | 977,000,000 | 813,000,000 | 738,000,000 | 674,000,000 | 951,000,000 |  |  |  | 3,169,000,000 |  | 3,176,000,000 |  | 3,233,000,000 |  |  |  |  |
Business Combination, Integration Related Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,000,000 | [1],[6] | 4,000,000 | [1],[6] | (1,000,000) |  |  |  |  |
Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,269,000,000 |  |  |  | 1,163,000,000 |  |  |  | 1,163,000,000 |  |  | 1,269,000,000 |  | 1,163,000,000 |  |  |  |  |  |  |
Prior Year Revenue Adjustment | [3] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,000,000 |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 295,000,000 |  |  |  | 265,000,000 |  |  |  | 265,000,000 |  |  | 295,000,000 |  | 265,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 959,000,000 |  | 882,000,000 |  | 934,000,000 |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 200,000,000 |  |  |
Proposed Capital Expenditure |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 732,000,000 |  |  |
Baltimore Gas and Electric Company [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 72,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Gas Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  | $ 61,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount |  |  | $ 43,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 31,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 18,000,000 |  |  |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 51,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Difference between Carrying Value and Fair Value [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 133,000,000 |  |  |  | 139,000,000 |  |  |  | 139,000,000 |  |  | 133,000,000 |  | 139,000,000 |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | DC PLUG charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  | 0 |  | 0 |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Fair value of long-term debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  | 0 |  | 0 |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | AMI programs - Deployment Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 52,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 48,000,000 |  |  |  | 53,000,000 |  | 56,000,000 |  | 53,000,000 |  |  | 48,000,000 |  | 53,000,000 |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Electric Energy and Natural Gas Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 16,000,000 |  |  |  | 16,000,000 |  |  |  |  | 16,000,000 |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Merger integration costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,000,000 |  |  |  | 6,000,000 |  |  |  |  | 6,000,000 |  |  |  |  |  |  |
Baltimore Gas and Electric Company [Member] | Energy efficiency and demand response programs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 285,000,000 |  |  |  | 285,000,000 |  |  |  |  | 285,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 444,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,047,000,000 |  |  |  | 3,047,000,000 |  |  |  |  | 3,047,000,000 |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 14,000,000 |  | (17,000,000) |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 27,000,000 |  |  |  | 27,000,000 |  |  |  |  | 27,000,000 |  |  |  |  |  |  |
Regulatory Liability, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 84,000,000 |  |  |  | 56,000,000 |  |  |  | 56,000,000 |  |  | 84,000,000 |  | 56,000,000 |  |  |  |  |  |  |
Regulatory liabilities, noncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,864,000,000 |  |  |  | 1,872,000,000 |  |  |  | 1,872,000,000 |  |  | 1,864,000,000 |  | 1,872,000,000 |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,117,000,000 | 1,361,000,000 | 1,076,000,000 | 1,251,000,000 | 1,121,000,000 | 1,310,000,000 | 1,074,000,000 | 1,175,000,000 |  |  |  | 4,805,000,000 |  | 4,679,000,000 |  |  |  |  |  |  |
Business Combination, Integration Related Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | [1],[6] | (6,000,000) | [1],[6] | 28,000,000 |  |  |  |  |
Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,948,000,000 |  |  |  | 1,928,000,000 |  |  |  | 1,928,000,000 |  |  | 1,948,000,000 |  | 1,928,000,000 |  |  |  |  |  |  |
Impairment of Long-Lived Assets to be Disposed of |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 25,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 496,000,000 |  |  |  | 348,000,000 |  |  |  | 348,000,000 |  |  | 496,000,000 |  | 348,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,375,000,000 |  | 1,396,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 84,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | Successor [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (5,000,000) |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,643,000,000 |  |  | 4,679,000,000 |  |  |  |  |  |  |
Business Combination, Integration Related Costs | [6] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 69,000,000 | 0 |  | (18,000,000) | [1] |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,008,000,000 |  |  |  |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | DC PLUG charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 159,000,000 |  |  |  | 190,000,000 |  |  |  | 190,000,000 |  |  | 159,000,000 |  | 190,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | Fair value of long-term debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 569,000,000 |  |  |  | 619,000,000 |  |  |  | 619,000,000 |  |  | 569,000,000 |  | 619,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 120,000,000 |  |  |  | 134,000,000 |  |  |  | 134,000,000 |  |  | 120,000,000 |  | 134,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | Electric Energy and Natural Gas Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 93,000,000 |  |  |  | 30,000,000 |  |  |  | 30,000,000 |  |  | 93,000,000 |  | 30,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | Merger integration costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 39,000,000 |  |  |  | 39,000,000 |  |  |  | 39,000,000 |  |  | 39,000,000 |  | 39,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | Energy efficiency and demand response programs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 255,000,000 |  |  |  | 310,000,000 |  |  |  | 310,000,000 |  |  | 255,000,000 |  | 310,000,000 |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | Pepco Holdings LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 320,000,000 |  |  |  |  |  |  |  |  |  |  | 320,000,000 |  |  |  |  |  |  |  |  |
Potomac Electric Power Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,000,000 |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | [4] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 8,000,000 |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage | [5] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.50% |  |  |  |  |  |  |  |  |
Projected Capital Expenditures |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 500,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 891,000,000 |  |  |  | 891,000,000 |  |  |  |  | 891,000,000 |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 14,000,000 |  | (17,000,000) |  | (12,000,000) |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 14,000,000 |  |  |  | 14,000,000 |  |  |  |  | 14,000,000 |  |  |  |  |  |  |
Regulatory Liability, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,000,000 |  |  |  | 3,000,000 |  |  |  | 3,000,000 |  |  | 7,000,000 |  | 3,000,000 |  |  |  |  |  |  |
Regulatory liabilities, noncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 822,000,000 |  |  |  | 829,000,000 |  |  |  | 829,000,000 |  |  | 822,000,000 |  | 829,000,000 |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 531,000,000 | 628,000,000 | 523,000,000 | 557,000,000 | 510,000,000 | 604,000,000 | 514,000,000 | 530,000,000 |  |  |  | 2,239,000,000 |  | 2,158,000,000 |  | 2,186,000,000 |  |  |  |  |
Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 829,000,000 |  |  |  | 832,000,000 |  |  |  | 832,000,000 |  |  | 829,000,000 |  | 832,000,000 |  |  |  |  |  |  |
Alternative Net Capital Requirement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 250,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Capital ProjectFundedByBonds |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 187,500,000 |  |  |  |  |  | 30,000,000 |  |  |  |  |  |  | $ 127,000,000 |  |
CapitalProjectFundedByAgency |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 62,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Prior Year Revenue Adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,000,000 |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 214,000,000 |  |  |  | 139,000,000 |  |  |  | 139,000,000 |  |  | 214,000,000 |  | 139,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 656,000,000 |  | 628,000,000 |  | 586,000,000 |  |  |  |  |
Potomac Electric Power Company [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  | $ 30,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 66,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount |  |  |  |  |  |  | $ 4,000,000 |  |  |  |  | $ (15,000,000) | $ (24,000,000) |  |  | $ 3,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 39,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 13,000,000 |  |  |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 84,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | DC PLUG charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 159,000,000 |  |  |  | 190,000,000 |  |  |  | 190,000,000 |  |  | 159,000,000 |  | 190,000,000 |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | MergerIntegrationCostsToBeRecoveredInDCServiceTerritory [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,000,000 |  |  |  | 9,000,000 |  |  |  | 9,000,000 |  |  | 9,000,000 |  | 9,000,000 |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | Fair value of long-term debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  | 0 |  | 0 |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | MergerIntegrationCostsToBeRecoveredInMarylandServiceTerritory [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,000,000 |  |  |  | 11,000,000 |  |  |  | 11,000,000 |  |  | 9,000,000 |  | 11,000,000 |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 90,000,000 |  |  |  | 100,000,000 |  |  |  | 100,000,000 |  |  | 90,000,000 |  | 100,000,000 |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | Electric Energy and Natural Gas Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 84,000,000 |  |  |  | 8,000,000 |  |  |  | 8,000,000 |  |  | 84,000,000 |  | 8,000,000 |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | Merger integration costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 18,000,000 |  |  |  | 20,000,000 |  |  |  | 20,000,000 |  |  | 18,000,000 |  | 20,000,000 |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | Energy efficiency and demand response programs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 188,000,000 |  |  |  | 229,000,000 |  |  |  | 229,000,000 |  |  | 188,000,000 |  | 229,000,000 |  |  |  |  |  |  |
Potomac Electric Power Company [Member] | Pepco Holdings LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 120,000,000 |  |  |  |  |  |  |  |  |  |  | 120,000,000 |  |  |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 14,000,000 |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | [4] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 27,000,000 |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage | [5] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.50% |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 314,000,000 |  |  |  | 314,000,000 |  |  |  |  | 314,000,000 |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  | 0 |  | 2,000,000 |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,000,000 |  |  |  | 6,000,000 |  |  |  |  | 6,000,000 |  |  |  |  |  |  |
Regulatory Liability, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 59,000,000 |  |  |  | 42,000,000 |  |  |  | 42,000,000 |  |  | 59,000,000 |  | 42,000,000 |  |  |  |  |  |  |
Regulatory liabilities, noncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 606,000,000 |  |  |  | 593,000,000 |  |  |  | 593,000,000 |  |  | 606,000,000 |  | 593,000,000 |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 331,000,000 | 328,000,000 | 289,000,000 | 384,000,000 | 330,000,000 | 327,000,000 | 282,000,000 | 362,000,000 |  |  |  | 1,332,000,000 |  | 1,300,000,000 |  | 1,277,000,000 |  |  |  |  |
Business Combination, Integration Related Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | [1],[6] | (7,000,000) | [1],[6] | 20,000,000 |  |  |  |  |
Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 665,000,000 |  |  |  | 635,000,000 |  |  |  | 635,000,000 |  |  | 665,000,000 |  | 635,000,000 |  |  |  |  |  |  |
Prior Year Revenue Adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 13,000,000 |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 111,000,000 |  |  |  | 82,000,000 |  |  |  | 82,000,000 |  |  | 111,000,000 |  | 82,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 364,000,000 |  | 428,000,000 |  | 349,000,000 |  |  |  |  |
Delmarva Power & Light Company [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | [7] |  |  |  |  |  |  |  |  | $ (7,000,000) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Rate Increase (Decrease), Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 13,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12,000,000 | [7] |  |  |  |  |  | $ 19,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 19,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | Gas Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | [7] |  |  |  |  |  | $ (4,000,000) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | [7] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12,000,000 |  |  |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | DC PLUG charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  | 0 |  | 0 |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | Fair value of long-term debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  | 0 |  | 0 |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 30,000,000 |  |  |  | 34,000,000 |  |  |  | 34,000,000 |  |  | 30,000,000 |  | 34,000,000 |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | Electric Energy and Natural Gas Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 7,000,000 |  |  |  | 7,000,000 |  |  | 0 |  | 7,000,000 |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | Merger integration costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,000,000 |  |  |  | 10,000,000 |  |  |  | 10,000,000 |  |  | 11,000,000 |  | 10,000,000 |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | Energy efficiency and demand response programs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 67,000,000 |  |  |  | 81,000,000 |  |  |  | 81,000,000 |  |  | 67,000,000 |  | 81,000,000 |  |  |  |  |  |  |
Delmarva Power & Light Company [Member] | Pepco Holdings LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 89,000,000 |  |  |  |  |  |  |  |  |  |  | 89,000,000 |  |  |  |  |  |  |  |  |
Atlantic City Electric Company [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  | $ 40,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,000,000 |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount | [4] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  |  |  |  |  |  |  |  |
Public Utilities, Approved Return on Equity, Percentage | [5] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.50% |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 430,000,000 |  |  |  | 430,000,000 |  |  |  |  | 430,000,000 |  |  |  |  |  |  |
Amortization Rate Stabilization Deferral |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  | 0 |  | 0 |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,000,000 |  |  |  | 7,000,000 |  |  |  |  | 7,000,000 |  |  |  |  |  |  |
Regulatory Liability, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 18,000,000 |  |  |  | 11,000,000 |  |  |  | 11,000,000 |  |  | 18,000,000 |  | 11,000,000 |  |  |  |  |  |  |
Regulatory liabilities, noncurrent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 402,000,000 |  |  |  | 411,000,000 |  |  |  | 411,000,000 |  |  | 402,000,000 |  | 411,000,000 |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 254,000,000 | 406,000,000 | 265,000,000 | $ 310,000,000 | 271,000,000 | $ 370,000,000 | $ 270,000,000 | $ 275,000,000 |  |  |  | 1,236,000,000 |  | 1,186,000,000 |  | 1,257,000,000 |  |  |  |  |
Business Combination, Integration Related Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | [1],[6] | (6,000,000) | [1],[6] | 19,000,000 |  |  |  |  |
Regulatory Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 420,000,000 |  |  |  | 422,000,000 |  |  |  | 422,000,000 |  |  | 420,000,000 |  | 422,000,000 |  |  |  |  |  |  |
Prior Year Revenue Adjustment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (4,000,000) |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 23,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 154,000,000 |  |  |  | 118,000,000 |  |  |  | 118,000,000 |  |  | 154,000,000 |  | 118,000,000 |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 335,000,000 |  | 312,000,000 |  | $ 311,000,000 |  |  |  |  |
Atlantic City Electric Company [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Property, Plant, and Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 338,000,000 |  |  |  |
Atlantic City Electric Company [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | [9] |  |  |  |  | $ 122,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | Electric Transmission [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax Savings From Tax Cuts and Jobs Act |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 11,000,000 |  |  |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | PJM Transmission Rate Design Settlement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounts Payable, Current |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | DC PLUG charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  | 0 |  | 0 |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | Fair value of long-term debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  | 0 |  | 0 |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | Advanced Metering Infrastructure Legacy Meter Costs [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | 0 |  |  |  | 0 |  |  | 0 |  | 0 |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | Electric Energy and Natural Gas Costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 9,000,000 |  |  |  | 15,000,000 |  |  |  | 15,000,000 |  |  | 9,000,000 |  | 15,000,000 |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | Merger integration costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000 |  |  |  | 9,000,000 |  |  |  | 9,000,000 |  |  | 10,000,000 |  | 9,000,000 |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | Energy efficiency and demand response programs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  | $ 0 |  |  |  | $ 0 |  |  | 0 |  | $ 0 |  |  |  |  |  |  |
Atlantic City Electric Company [Member] | Pepco Holdings LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other Commitment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 111,000,000 |  |  |  |  |  |  |  |  |  |  | $ 111,000,000 |  |  |  |  |  |  |  |  |
One-Time Revenue Adjustment [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 76,000,000 |  |  |  |  |  |  |  | 76,000,000 |  |  |  |  |  |  |  |  |  |  |
One-Time Revenue Adjustment [Member] | Commonwealth Edison Co [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 51,000,000 |  |  |  |  |  |  |  | 51,000,000 |  |  |  |  |  |  |  |  |  |  |
One-Time Revenue Adjustment [Member] | Baltimore Gas and Electric Company [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 15,000,000 |  |  |  |  |  |  |  | 15,000,000 |  |  |  |  |  |  |  |  |  |  |
One-Time Revenue Adjustment [Member] | Pepco Holdings LLC [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000 |  |  |  |  |  |  |  | 10,000,000 |  |  |  |  |  |  |  |  |  |  |
One-Time Revenue Adjustment [Member] | Potomac Electric Power Company [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,000,000 |  |  |  |  |  |  |  | 3,000,000 |  |  |  |  |  |  |  |  |  |  |
One-Time Revenue Adjustment [Member] | Delmarva Power & Light Company [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5,000,000 |  |  |  |  |  |  |  | 5,000,000 |  |  |  |  |  |  |  |  |  |  |
One-Time Revenue Adjustment [Member] | Atlantic City Electric Company [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory Matters Additional Narrative Information [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of Impairment to Carrying Amount of Regulatory Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 2,000,000 |  |  |  |  |  |  |  | $ 2,000,000 |  |  |  |  |  |  |  |  |  |  |
[1] | The costs incurred are classified primarily within Operating and maintenance expense in the Registrants’ respective Consolidated Statements of Operations and Comprehensive Income, with the exception of the financing costs, which are included within Interest expense. Costs do not include merger commitments discussed above.
[2] | Does not include an offsetting receivable from New Jersey Utilities of $16 million as of December 31, 2018.
[3] | The time period for any formal challenges to the annual transmission formula rate update filings expired with no formal challenges submitted.
[4] | {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmVlYzRiNDIxOTkxNDRkN2ViNWYzYTRhOTVmMjFkNDYzfFRleHRTZWxlY3Rpb246MzY0MUFFQzNGNTE3Mzk3OTI2RjIxNTRFRUQyNkYyMzMM}
[5] | As part of the FERC-approved settlement of ComEd’s 2007 transmission rate case, the rate of return on common equity is 11.50%, inclusive of a 50-basis-point incentive adder for being a member of a RTO, and the common equity component of the ratio used to calculate the weighted average debt and equity return for the transmission formula rate is currently capped at 55%. As part of the FERC-approved settlement of the ROE complaint against BGE, Pepco, DPL and ACE, the rate of return on common equity is 10.50%, inclusive of a 50-basis-point incentive adder for being a member of a RTO.
[6] | (b)For the year ended December 31, 2017, includes deferrals of previously incurred integration costs as regulatory assets of $24 million, $8 million, $8 million, and $8 million at PHI, Pepco, DPL and ACE, respectively. For the year ended December 31, 2016, includes deferrals of previously incurred integration costs as regulatory assets of $8 million, $6 million, $11 million and $4 million at ComEd, BGE, Pepco and DPL, respectively. For the Successor period March 24, 2016 to December 31, 2016, includes deferrals of previously incurred integration costs as regulatory assets of $16 million at PHI. See Note 4 - Regulatory Matters for additional information.
[7] | Includes the annual ongoing TCJA tax savings further discussed below.
[8] | BGE's transmission revenue requirement includes a FERC approved dedicated facilities charge of $12 million to recover the costs of providing transmission service to specifically designated load by BGE.
[9] | {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmVlYzRiNDIxOTkxNDRkN2ViNWYzYTRhOTVmMjFkNDYzfFRleHRTZWxlY3Rpb246NUYyM0EwMDI1MDhGQUUyMUZEMzExNTNGOUY0NjExNDUM}

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