Lessor - Operating Lease, Payments, Fiscal Year Maturity (Details) $ in Millions	Dec. 31, 2020 USD ($)
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	$ 51
2022	50
2023	49
2024	49
2025	48
Remaining years	217
Total Lessor, Operating Lease, Payments to be Received	464
Exelon Generation Co L L C [Member]
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	45
2022	45
2023	45
2024	45
2025	45
Remaining years	182
Total Lessor, Operating Lease, Payments to be Received	407
Commonwealth Edison Co [Member]
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	0
2022	0
2023	0
2024	0
2025	0
Remaining years	1
Total Lessor, Operating Lease, Payments to be Received	1
PECO Energy Co [Member]
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	0
2022	0
2023	0
2024	0
2025	0
Remaining years	4
Total Lessor, Operating Lease, Payments to be Received	4
Baltimore Gas and Electric Company [Member]
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	0
2022	0
2023	0
2024	0
2025	0
Remaining years	1
Total Lessor, Operating Lease, Payments to be Received	1
Pepco Holdings LLC [Member]
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	4
2022	4
2023	4
2024	3
2025	4
Remaining years	31
Total Lessor, Operating Lease, Payments to be Received	50
Potomac Electric Power Company [Member]
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	1
2022	0
2023	0
2024	0
2025	0
Remaining years	0
Total Lessor, Operating Lease, Payments to be Received	1
Delmarva Power & Light Company [Member]
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	3
2022	3
2023	4
2024	3
2025	4
Remaining years	31
Total Lessor, Operating Lease, Payments to be Received	48
Atlantic City Electric Company [Member]
Schedule of Lessor, Operating Lease, Payments to be Received, Maturity [Line Items]
2021	0
2022	0
2023	0
2024	0
2025	0
Remaining years	0
Total Lessor, Operating Lease, Payments to be Received	$ 0

[Line Items] for Schedule of Lessor, Operating Lease, Payments to be Received, Maturity

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- Definition

Amount of lease payments to be received by lessor for operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919396-209981

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- Definition

Amount of lease payment to be received by lessor for operating lease in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lease payment to be received by lessor for operating lease in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lease payment to be received by lessor for operating lease in remainder of current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919396-209981

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- Definition

Amount of lease payment to be received by lessor for operating lease after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of lease payment to be received by lessor for operating lease in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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- Definition

Amount of lease payment to be received by lessor for operating lease in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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