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Significant Accounting Policies Expected Right of Use Assets and Lease Obligations (Details) | 12 Months Ended
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Dec. 31, 2018
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $1,400-$1,500
Estimated Operating Lease, Lease Liability | $1,600-$1,700
Exelon Generation Co L L C [Member] |
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $1,000-$1,100
Estimated Operating Lease, Lease Liability | $1,200-$1,300
Commonwealth Edison Co [Member] |
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $5-$10
Estimated Operating Lease, Lease Liability | $5-$10
PECO Energy Co [Member] |
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $1-$5
Estimated Operating Lease, Lease Liability | $1-$5
Baltimore Gas and Electric Company [Member] |
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $100-$120
Estimated Operating Lease, Lease Liability | $100-$120
Pepco Holdings LLC [Member] |
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $250-$270
Estimated Operating Lease, Lease Liability | $300-$320
Potomac Electric Power Company [Member] |
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $60-$65
Estimated Operating Lease, Lease Liability | $60-$65
Delmarva Power & Light Company [Member] |
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $70-$75
Estimated Operating Lease, Lease Liability | $75-$80
Atlantic City Electric Company [Member] |
Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Line Items] |
Estimated Operating Lease, Right-of-Use Asset | $20-$25
Estimated Operating Lease, Lease Liability | $20-$25

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- Definition [Line Items] for Estimated Right of Use Assets and Lease Liabilities from Operating Leases [Table] + References No definition available. + Details
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- Definition Operating Lease, Estimated Lease Liabilities The lease liabilities that are expected to appear on the balance sheet during Q1 2019 reporting of the 10-Q. + References No definition available. + Details
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- Definition Operating Lease, Estimated Right-of-Use Assets The right of use assets that are expected to appear on the balance sheet during Q1 2019 reporting of the 10-Q. + References No definition available. + Details
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