XML 249 R131.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Debt and Credit Agreements - Summary of Outstanding Long-term Debt (Details) - USD ($) $ in Millions | 1 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Feb. 08, 2019 | Sep. 30, 2018 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Jun. 30, 2014
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | $ 1,349 |  |  |  |
Long-term Debt, Gross |  |  |  | 34,911 |  | $ 33,657 |  |
Unamortized debt discount and premium, net |  |  |  | (66) |  | (57) |  |
Unamortized Debt Issuance Expense |  |  |  | (216) |  | (201) |  |
Fair value adjustment |  |  |  | 795 |  | 865 |  |
Long-term debt due within one year |  |  |  | (1,349) | [1] | (2,088) |  |
Long-term debt |  |  |  | 34,075 |  | 32,176 |  |
Long-term debt to financing trusts |  |  |  | 390 |  | 389 |  |
2020 |  |  |  | 3,528 |  |  |  |
2021 |  |  |  | 1,511 |  |  |  |
Repayments of Long-term Debt |  |  |  | 1,786 |  | 2,490 | $ 1,936 |
ComEd Financing III Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts |  |  |  | 206 |  | 205 |  |
PECO Trust III Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts |  |  |  | 81 |  | 81 |  |
PECO Trust IV Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts |  |  |  | 103 |  | 103 |  |
Secured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [2] |  |  | $ 16,496 |  | 15,197 |  |
Secured Debt [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [2] |  |  | 1.70% |  |  |  |
Secured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [2] |  |  | 7.90% |  |  |  |
Senior Notes [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 11,285 |  | 11,285 |  |
Senior Notes [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.45% |  |  |  |
Senior Notes [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.60% |  |  |  |
Unsecured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 2,900 |  | 2,600 |  |
Unsecured Debt [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.40% |  |  |  |
Unsecured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 6.35% |  |  |  |
Pollution Control Notes [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 435 |  | 435 |  |
Pollution Control Notes [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.50% |  |  |  |
Pollution Control Notes [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.70% |  |  |  |
Notes Payable to Banks [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 39 |  | 82 |  |
Notes Payable to Banks [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 3.15% |  |  |  |
Notes Payable, Other Payables [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [3],[4] |  |  | $ 188 |  | 405 |  |
Unamortized Debt Issuance Expense |  |  |  | $ 0 |  | $ (1) |  |
Notes Payable, Other Payables [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [3],[4] |  |  | 2.85% |  |  |  |
Notes Payable, Other Payables [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [3],[4] |  |  | 8.88% |  |  |  |
Junior Subordinated Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  |  |  | 3.497% |  | 2.50%
Long-term Debt, Gross |  |  |  | $ 1,150 |  | $ 1,150 |  |
Junior Subordinated Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 3.50% |  |  |  |
Software License Arrangement [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 73 |  | 79 |  |
Software License Arrangement [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 3.95% |  |  |  |
Tax-exempt Money Market Funds [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 112 |  | 112 |  |
Tax-exempt Money Market Funds [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 1.74% |  |  |  |
Tax-exempt Money Market Funds [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 5.40% |  |  |  |
Medium-term Notes [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 22 |  | 26 |  |
Medium-term Notes [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.61% |  |  |  |
Medium-term Notes [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.72% |  |  |  |
Transition Bonds [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 59 |  | 90 |  |
Transition Bonds [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 5.55% |  |  |  |
Loans Payable [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 50 |  | 0 |  |
Loans Payable [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.00% |  |  |  |
Non Recourse Fixed Rate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 1,253 |  | 1,331 |  |
Non Recourse Fixed Rate [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.29% |  |  |  |
Non Recourse Fixed Rate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 6.00% |  |  |  |
Non Recourse Variable Rate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [5] |  |  | $ 849 |  | 865 |  |
Non Recourse Variable Rate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [5] |  |  | 5.81% |  |  |  |
Capital Lease Obligations [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Capital lease obligations, noncurrent |  |  |  | $ 36 |  | 53 |  |
Due in 2019 |  |  |  | 21 |  |  |  |
Due in 2020 |  |  |  | 5 |  |  |  |
Due in 2021 |  |  |  | 1 |  |  |  |
Due in 2022 |  |  |  | 1 |  |  |  |
Due in 2023 |  |  |  | 0 |  |  |  |
Thereafter |  |  |  | 8 |  |  |  |
Long-term Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts |  |  |  | 390 |  | 390 |  |
Long-term Debt [Member] | ComEd Financing III Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts | [6] |  |  | $ 206 |  | 206 |  |
Long-term Debt [Member] | ComEd Financing III Affiliate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [6] |  |  | 6.35% |  |  |  |
Long-term Debt [Member] | PECO Trust III Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts | [6] |  |  | $ 81 |  | 81 |  |
Long-term Debt [Member] | PECO Trust III Affiliate [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [6] |  |  | 7.38% |  |  |  |
Long-term Debt [Member] | PECO Trust III Affiliate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [6] |  |  | 7.50% |  |  |  |
Long-term Debt [Member] | PECO Trust IV Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts | [6] |  |  | $ 103 |  | 103 |  |
Long-term Debt [Member] | PECO Trust IV Affiliate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [6] |  |  | 5.75% |  |  |  |
Exelon Generation Co L L C [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | $ 906 |  |  |  |
Long-term Debt, Gross |  |  |  | 8,759 |  | 8,955 |  |
Unamortized debt discount and premium, net |  |  |  | (6) |  | (8) |  |
Unamortized Debt Issuance Expense |  |  |  | (51) |  | (60) |  |
Fair value adjustment |  |  |  | 91 |  | 103 |  |
Long-term debt due within one year |  |  |  | (906) |  | (346) |  |
Long-term debt |  |  |  | 6,989 |  | 7,734 |  |
Debt and Capital Lease Obligations |  |  |  | 7,887 |  | 8,644 |  |
2020 |  |  |  | 2,108 |  |  |  |
2021 |  |  |  | 1 |  |  |  |
Repayments of Long-term Debt |  |  |  | 141 |  | 1,261 | 202 |
Exelon Generation Co L L C [Member] | Senior Notes [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 6,019 |  | 6,019 |  |
Exelon Generation Co L L C [Member] | Senior Notes [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.95% |  |  |  |
Exelon Generation Co L L C [Member] | Senior Notes [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.60% |  |  |  |
Exelon Generation Co L L C [Member] | Pollution Control Notes [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 435 |  | 435 |  |
Exelon Generation Co L L C [Member] | Pollution Control Notes [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.50% |  |  |  |
Exelon Generation Co L L C [Member] | Pollution Control Notes [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.70% |  |  |  |
Exelon Generation Co L L C [Member] | Notes Payable to Banks [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 39 |  | 82 |  |
Exelon Generation Co L L C [Member] | Notes Payable to Banks [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 3.15% |  |  |  |
Exelon Generation Co L L C [Member] | Notes Payable, Other Payables [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [7],[8] |  |  | $ 164 |  | 223 |  |
Exelon Generation Co L L C [Member] | Notes Payable, Other Payables [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [7],[8] |  |  | 2.85% |  |  |  |
Exelon Generation Co L L C [Member] | Notes Payable, Other Payables [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [7],[8] |  |  | 7.83% |  |  |  |
Exelon Generation Co L L C [Member] | Non Recourse Fixed Rate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 1,253 |  | 1,331 |  |
Exelon Generation Co L L C [Member] | Non Recourse Fixed Rate [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.29% |  |  |  |
Exelon Generation Co L L C [Member] | Non Recourse Fixed Rate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 6.00% |  |  |  |
Exelon Generation Co L L C [Member] | Non Recourse Variable Rate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [9] |  |  | $ 849 |  | 865 |  |
Exelon Generation Co L L C [Member] | Non Recourse Variable Rate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [9] |  |  | 5.81% |  |  |  |
Exelon Generation Co L L C [Member] | Capital Lease Obligations [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Capital lease obligations, noncurrent |  |  |  | $ 14 |  | 18 |  |
Due in 2019 |  |  |  | 7 |  |  |  |
Due in 2020 |  |  |  | 5 |  |  |  |
Due in 2021 |  |  |  | 1 |  |  |  |
Due in 2022 |  |  |  | 1 |  |  |  |
Due in 2023 |  |  |  | 0 |  |  |  |
Commonwealth Edison Co [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | 300 |  |  |  |
Long-term Debt, Gross |  |  |  | 8,187 |  | 7,676 |  |
Unamortized debt discount and premium, net |  |  |  | (23) |  | (23) |  |
Unamortized Debt Issuance Expense |  |  |  | (63) |  | (52) |  |
Long-term debt due within one year |  |  |  | (300) | [10] | (840) |  |
Long-term debt |  |  |  | 7,801 |  | 6,761 |  |
Long-term debt to financing trusts |  |  |  | 205 |  | 205 |  |
Debt and Capital Lease Obligations |  |  |  | 7,801 |  | 6,761 |  |
2020 |  |  |  | 500 |  |  |  |
2021 |  |  |  | 350 |  |  |  |
Repayments of Long-term Debt |  |  |  | 840 |  | 425 | 665 |
Commonwealth Edison Co [Member] | ComEd Financing III Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Unamortized Debt Issuance Expense |  |  |  | (1) |  | (1) |  |
Long-term debt to financing trusts |  |  |  | 205 |  | 205 |  |
Commonwealth Edison Co [Member] | Secured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [11] |  |  | $ 8,179 |  | 7,529 |  |
Commonwealth Edison Co [Member] | Secured Debt [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [11] |  |  | 2.15% |  |  |  |
Commonwealth Edison Co [Member] | Secured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [11] |  |  | 6.45% |  |  |  |
Commonwealth Edison Co [Member] | Notes Payable, Other Payables [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [12] |  |  | $ 8 |  | 147 |  |
Commonwealth Edison Co [Member] | Notes Payable, Other Payables [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [12] |  |  |  |  |  |  |
Commonwealth Edison Co [Member] | Notes Payable, Other Payables [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [12] |  |  | 7.49% |  |  |  |
Commonwealth Edison Co [Member] | Capital Lease Obligations [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Capital lease obligations, noncurrent |  |  |  | $ 8 |  |  |  |
Thereafter |  |  |  | 1 |  |  |  |
Commonwealth Edison Co [Member] | Long-term Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts |  |  |  | 206 |  | 206 |  |
Commonwealth Edison Co [Member] | Long-term Debt [Member] | ComEd Financing III Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts | [13] |  |  | $ 206 |  | 206 |  |
Commonwealth Edison Co [Member] | Long-term Debt [Member] | ComEd Financing III Affiliate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [13] |  |  | 6.35% |  |  |  |
PECO Energy Co [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | $ 0 |  |  |  |
Long-term Debt, Gross |  |  |  | 3,125 |  | 2,925 |  |
Unamortized debt discount and premium, net |  |  |  | (18) |  | (5) |  |
Unamortized Debt Issuance Expense |  |  |  | (23) |  | (17) |  |
Long-term debt |  |  |  | 3,084 |  | 2,403 |  |
Long-term debt to financing trusts | [14] |  |  | 184 |  | 184 |  |
Long-term debt due within one year |  |  |  | 0 |  | (500) |  |
Debt and Capital Lease Obligations |  |  |  | 3,084 |  | 2,403 |  |
2020 |  |  |  | 0 |  |  |  |
2021 |  |  |  | 300 |  |  |  |
Repayments of Long-term Debt |  |  |  | 500 |  | 0 | 300 |
PECO Energy Co [Member] | PECO Trust III Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts |  |  |  | 81 |  | 81 |  |
PECO Energy Co [Member] | PECO Trust IV Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts |  |  |  | 103 |  | 103 |  |
PECO Energy Co [Member] | Secured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [15] |  |  | $ 3,075 |  | 2,925 |  |
PECO Energy Co [Member] | Secured Debt [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [15] |  |  | 1.70% |  |  |  |
PECO Energy Co [Member] | Secured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [15] |  |  | 5.95% |  |  |  |
PECO Energy Co [Member] | Loans Payable [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 50 |  | 0 |  |
PECO Energy Co [Member] | Loans Payable [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.00% |  |  |  |
PECO Energy Co [Member] | Long-term Debt [Member] | PECO Trust III Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts | [14] |  |  | $ 81 |  | 81 |  |
PECO Energy Co [Member] | Long-term Debt [Member] | PECO Trust III Affiliate [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [14] |  |  | 7.38% |  |  |  |
PECO Energy Co [Member] | Long-term Debt [Member] | PECO Trust III Affiliate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [14] |  |  | 7.50% |  |  |  |
PECO Energy Co [Member] | Long-term Debt [Member] | PECO Trust IV Affiliate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term debt to financing trusts | [14] |  |  | $ 103 |  | 103 |  |
PECO Energy Co [Member] | Long-term Debt [Member] | PECO Trust IV Affiliate [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [14] |  |  | 5.75% |  |  |  |
Baltimore Gas and Electric Company [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | $ 0 |  |  |  |
Long-term Debt, Gross |  |  |  | 2,900 |  | 2,600 |  |
Unamortized debt discount and premium, net |  |  |  | (6) |  | (6) |  |
Unamortized Debt Issuance Expense |  |  |  | (18) |  | (17) |  |
Long-term debt |  |  |  | 2,876 |  | 2,577 |  |
Long-term debt |  |  |  | 2,876 |  | 2,577 |  |
2020 |  |  |  | 0 |  |  |  |
2021 |  |  |  | 300 |  |  |  |
Repayments of Long-term Debt |  |  |  | 0 |  | 41 | 379 |
Baltimore Gas and Electric Company [Member] | Senior Notes [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 2,900 |  | 2,600 |  |
Baltimore Gas and Electric Company [Member] | Senior Notes [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 2.40% |  |  |  |
Baltimore Gas and Electric Company [Member] | Senior Notes [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 6.35% |  |  |  |
Pepco Holdings LLC [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | $ 125 |  |  |  |
Long-term Debt, Gross |  |  |  | 5,636 |  | 5,189 |  |
Unamortized debt discount and premium, net |  |  |  | 4 |  | 5 |  |
Unamortized Debt Issuance Expense |  |  |  | (14) |  | (6) |  |
Fair value adjustment |  |  |  | 633 |  | 686 |  |
Long-term debt |  |  |  | 6,134 |  | 5,478 |  |
Long-term debt due within one year |  |  |  | (125) |  | (396) |  |
Long-term debt |  |  |  | 6,134 |  | 5,478 |  |
2020 |  |  |  | 20 |  |  |  |
2021 |  |  |  | 261 |  |  |  |
Repayments of Long-term Debt |  |  |  | 299 |  | 169 |  |
Pepco Holdings LLC [Member] | Secured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [16] |  |  | $ 5,242 |  | 4,743 |  |
Pepco Holdings LLC [Member] | Secured Debt [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [16] |  |  | 1.81% |  |  |  |
Pepco Holdings LLC [Member] | Secured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [16] |  |  | 7.90% |  |  |  |
Pepco Holdings LLC [Member] | Unsecured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 185 |  | 185 |  |
Pepco Holdings LLC [Member] | Unsecured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.45% |  |  |  |
Pepco Holdings LLC [Member] | Notes Payable, Other Payables [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [17] |  |  | $ 16 |  | 33 |  |
Pepco Holdings LLC [Member] | Notes Payable, Other Payables [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [17] |  |  | 7.28% |  |  |  |
Pepco Holdings LLC [Member] | Notes Payable, Other Payables [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [17] |  |  | 8.88% |  |  |  |
Pepco Holdings LLC [Member] | Tax-exempt Money Market Funds [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 112 |  | 112 |  |
Pepco Holdings LLC [Member] | Tax-exempt Money Market Funds [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 1.74% |  |  |  |
Pepco Holdings LLC [Member] | Tax-exempt Money Market Funds [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 5.40% |  |  |  |
Pepco Holdings LLC [Member] | Medium-term Notes [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 22 |  | 26 |  |
Pepco Holdings LLC [Member] | Medium-term Notes [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.61% |  |  |  |
Pepco Holdings LLC [Member] | Medium-term Notes [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.72% |  |  |  |
Pepco Holdings LLC [Member] | Transition Bonds [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [18] |  |  | $ 59 |  | 90 |  |
Pepco Holdings LLC [Member] | Transition Bonds [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [18] |  |  |  |  |  |  |
Pepco Holdings LLC [Member] | Transition Bonds [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [18] |  |  | 5.55% |  |  |  |
Pepco Holdings LLC [Member] | Capital Lease Obligations [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Capital lease obligations, current |  |  |  | $ 14 |  |  |  |
Capital lease obligations, noncurrent |  |  |  |  |  | 27 |  |
Potomac Electric Power Company [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | 15 |  |  |  |
Long-term Debt, Gross |  |  |  | 2,751 |  | 2,570 |  |
Unamortized debt discount and premium, net |  |  |  | 2 |  | 2 |  |
Unamortized Debt Issuance Expense |  |  |  | (34) |  | (32) |  |
Long-term debt |  |  |  | 2,704 |  | 2,521 |  |
Long-term debt due within one year |  |  |  | (15) |  | (19) |  |
Long-term debt |  |  |  | 2,704 |  | 2,521 |  |
Due in 2019 |  |  |  | 14 |  |  |  |
2020 |  |  |  | 0 |  |  |  |
2021 |  |  |  | 1 |  |  |  |
Repayments of Long-term Debt |  |  |  | 14 |  | 13 | 11 |
Potomac Electric Power Company [Member] | Secured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [19] |  |  | $ 2,735 |  | 2,535 |  |
Potomac Electric Power Company [Member] | Secured Debt [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [19] |  |  | 3.05% |  |  |  |
Potomac Electric Power Company [Member] | Secured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [19] |  |  | 7.90% |  |  |  |
Potomac Electric Power Company [Member] | Notes Payable, Other Payables [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [20] |  |  | $ 16 |  | 35 |  |
Potomac Electric Power Company [Member] | Notes Payable, Other Payables [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [20] |  |  | 7.28% |  |  |  |
Potomac Electric Power Company [Member] | Notes Payable, Other Payables [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [20] |  |  | 8.88% |  |  |  |
Delmarva Power & Light Company [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | $ 91 |  |  |  |
Long-term Debt, Gross |  |  |  | 1,504 |  | 1,309 |  |
Unamortized debt discount and premium, net |  |  |  | 2 |  | 2 |  |
Unamortized Debt Issuance Expense |  |  |  | (12) |  | (11) |  |
Long-term debt due within one year |  |  |  | (79) |  | (79) |  |
Long-term debt |  |  |  | 1,403 |  | 1,217 |  |
Long-term debt due within one year |  |  |  | (91) |  | (83) |  |
Long-term debt |  |  |  | 1,403 |  | 1,217 |  |
2020 |  |  |  | 0 |  |  |  |
2021 |  |  |  | 0 |  |  |  |
Repayments of Long-term Debt |  |  |  | 4 |  | 40 | 100 |
Delmarva Power & Light Company [Member] | Secured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [21] |  |  | $ 1,370 |  | 1,171 |  |
Delmarva Power & Light Company [Member] | Secured Debt [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [21] |  |  | 1.81% |  |  |  |
Delmarva Power & Light Company [Member] | Secured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [21] |  |  | 4.27% |  |  |  |
Delmarva Power & Light Company [Member] | Tax-exempt Money Market Funds [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 112 |  | 112 |  |
Delmarva Power & Light Company [Member] | Tax-exempt Money Market Funds [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 1.74% |  |  |  |
Delmarva Power & Light Company [Member] | Tax-exempt Money Market Funds [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 5.40% |  |  |  |
Delmarva Power & Light Company [Member] | Medium-term Notes [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  | $ 22 |  | 26 |  |
Delmarva Power & Light Company [Member] | Medium-term Notes [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.61% |  |  |  |
Delmarva Power & Light Company [Member] | Medium-term Notes [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  | 7.72% |  |  |  |
Atlantic City Electric Company [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | $ 18 |  |  |  |
Long-term Debt, Gross |  |  |  | 1,196 |  | 1,127 |  |
Unamortized debt discount and premium, net |  |  |  | (1) |  | (1) |  |
Unamortized Debt Issuance Expense |  |  |  | (7) |  | (5) |  |
Long-term debt |  |  |  | 1,170 |  | 840 |  |
Long-term debt due within one year |  |  |  | (18) |  | (281) |  |
Long-term debt |  |  |  | 1,170 |  | 840 |  |
2020 |  |  |  | 20 |  |  |  |
2021 |  |  |  | 260 |  |  |  |
Repayments of Long-term Debt |  |  |  | 281 |  | 35 | $ 48 |
Atlantic City Electric Company [Member] | Secured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Gross | [22] |  |  | $ 1,137 |  | 1,037 |  |
Atlantic City Electric Company [Member] | Secured Debt [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [22] |  |  | 3.38% |  |  |  |
Atlantic City Electric Company [Member] | Secured Debt [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [22] |  |  | 6.80% |  |  |  |
Atlantic City Electric Company [Member] | Transition Bonds [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months |  |  |  | $ 18 |  |  |  |
Long-term Debt, Gross | [23] |  |  | 59 |  | $ 90 |  |
2020 |  |  |  | 20 |  |  |  |
2021 |  |  |  | $ 21 |  |  |  |
Atlantic City Electric Company [Member] | Transition Bonds [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | [23] |  |  | 5.55% |  |  |  |
AGEPFNotesNov2017 [Member] | AGE Biomass project [Member] | Long-term Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Repayments of Long-term Debt |  |  | $ 228 |  |  |  |  |
Subsequent Event [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Repayments of Debt |  | $ 300 |  |  |  |  |  |
Subsequent Event [Member] | Commonwealth Edison Co [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Repayments of Debt |  | $ 300 |  |  |  |  |  |
[1] | In January 2019, $300 million of ComEd long-term debt due within one year was paid in full.
[2] | Substantially all of ComEd’s assets other than expressly excepted property and substantially all of PECO’s, Pepco's, DPL's and ACE's assets are subject to the liens of their respective mortgage indentures.
[3] | Includes capital lease obligations of $36 million and $53 million at December 31, 2018 and 2017, respectively. Lease payments of $21 million, $5 million, $1 million, $1 million, less than $1 million, and $8 million will be made in 2019, 2020, 2021, 2022, 2023, and thereafter, respectively.
[4] | Includes financing related to Albany Green Energy, LLC (AGE). During the third quarter of 2017, Generation retired $228 million of its outstanding debt balance.
[5] | Excludes interest on CEU Upstream nonrecourse debt, see discussion below.
[6] | Amounts owed to these financing trusts are recorded as Long-term debt to financing trusts within Exelon’s Consolidated Balance Sheets.
[7] | Includes Generation’s capital lease obligations of $14 million and $18 million at December 31, 2018 and 2017, respectively. Generation will make lease payments of $7 million, $5 million, $1 million, and $1 million in 2019, 2020, 2021, and 2022, respectively. Lease payments of less than $1 million annually will be made from 2023 through expiration of the final capital lease in 2024.
[8] | Includes financing related to Albany Green Energy, LLC (AGE). During the third quarter of 2017, Generation retired $228 million of its outstanding debt balance.
[9] | Excludes interest on CEU Upstream nonrecourse debt, see discussion below.
[10] | In January 2019, the $300 million balance was paid in full.
[11] | Substantially all of ComEd’s assets, other than expressly excepted property, are subject to the lien of its mortgage indenture.
[12] | Includes ComEd’s capital lease obligations of $8 million at both December 31, 2018 and 2017, respectively. Lease payments of less than $1 million annually will be made from 2019 through expiration at 2053.
[13] | Amount owed to this financing trust is recorded as Long-term debt to financing trust within ComEd’s Consolidated Balance Sheets.
[14] | Amounts owed to this financing trust are recorded as Long-term debt to financing trusts within PECO’s Consolidated Balance Sheets.
[15] | Substantially all of PECO’s assets are subject to the lien of its mortgage indenture.
[16] | Substantially all of Pepco's, DPL's, and ACE's assets are subject to the lien of its respective mortgage indenture.
[17] | Includes Pepco's capital lease obligations of $14 million and $27 million at December 31, 2018 and 2017, respectively.
[18] | Transition bonds are recorded as part of Long-term debt within ACE's Consolidated Balance Sheets.
[19] | Substantially all of Pepco's assets are subject to the lien of its respective mortgage indenture.
[20] | Includes capital lease obligations of $14 million and $27 million at December 31, 2018 and 2017, respectively. Lease payments of $14 million will be made in 2019.
[21] | Substantially all of DPL's assets are subject to the lien of its respective mortgage indenture.
[22] | Substantially all of ACE's assets are subject to the lien of its respective mortgage indenture.
[23] | Maturities of ACE's Transition Bonds outstanding at December 31, 2018 are $18 million in 2019, $20 million in 2020 and $21 million in 2021.

X
- Definition Including current and noncurrent portions, and adjustments for fair value, swaps, and discounts and premiums. + References No definition available. + Details
Name: | exc_TotalLongTermDebtWithAdjustments
Namespace Prefix: | exc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of capital lease obligation due within one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84164758&loc=d3e45023-112735 + Details
Name: | us-gaap_CapitalLeaseObligationsCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid more than one year (or one operating cycle, if longer) after the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84164758&loc=d3e45023-112735 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_CapitalLeaseObligationsNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of minimum lease payments for capital leases due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 + Details
Name: | us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of minimum lease payments for capital leases due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 + Details
Name: | us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of minimum lease payments for capital leases due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 + Details
Name: | us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of minimum lease payments for capital leases due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 + Details
Name: | us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of minimum lease payments for capital leases due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 + Details
Name: | us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of minimum lease payments for capital leases due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737 + Details
Name: | us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.13,16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_DebtAndCapitalLeaseObligations
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13476-108611 + Details
Name: | us-gaap_DebtInstrumentFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after accumulated amortization, of debt discount (premium). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28567-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399 + Details
Name: | us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of receivables owed to an entity that is affiliated with the reporting entity by means of direct or indirect ownership, which are usually due after one year (or one business cycle, if longer). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(12)(b)(3)) -URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(k)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(23)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DueToAffiliateNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19,20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebtCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04.(a)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690 + Details
Name: | us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebtNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt classified as other, payable within one year or the operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(20)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_OtherLongTermDebtCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations. + References No definition available. + Details
Name: | us-gaap_RepaymentsOfDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585 + Details
Name: | us-gaap_RepaymentsOfLongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=exc_ComedFinancingThreeAffiliateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=exc_PecoTrustThreeAffiliateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=exc_PecoTrustFourAffiliateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=exc_PollutionControlNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_NotesPayableToBanksMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_NotesPayableOtherPayablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_JuniorSubordinatedDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SoftwareLicenseArrangementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_TaxexemptMoneyMarketFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_MediumTermNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=exc_TransitionBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=exc_NonRecourseFixedRateMemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=exc_NonRecourseVariableRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_CapitalLeaseObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_LongTermDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_ExelonGenerationCoLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_CommonwealthEdisonCoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_PecoEnergyCoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_BaltimoreGasAndElectricCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_PepcoHoldingsLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_PotomacElectricPowerCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_DelmarvaPowerandLightCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_AtlanticCityElectricCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=exc_AGEPFNotesNov2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=exc_AGEBiomassprojectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |