Cash Remitted To VIE

No definition available.

Name:	exc_CashRemittedToVIE
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of variable interest entities (VIEs) consolidated.

+ References

No definition available.

+ Details

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Namespace Prefix:	exc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of variable interest entities (VIEs) not consolidated.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

For an unclassified balance sheet, amount of receivables due from an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

+ References

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Data Type:	num:percentItemType
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Period Type:	instant

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Balance Type:	credit
Period Type:	instant

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

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Balance Type:	credit
Period Type:	instant

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- 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

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- Definition

Net carrying amount of the assets and liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), when the reporting entity is not the VIE's primary beneficiary.

+ References

No definition available.

+ Details

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- Details

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Variable Interest Entities - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) VIE	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) VIE	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) VIE	Apr. 01, 2014 USD ($)
Variable Interest Entity [Line Items]
Number Of Variable Interest Entities Consolidated \| VIE	5		5		5
Number of Variable Interest Entities not consolidated by equity holders \| VIE	8		8		7
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 68		$ 68
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	16		16		$ 15
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 16		$ 16		$ 15
Payment Guarantee [Member] \| CENG [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted						$ 245
Financial Guarantee [Member] \| CENG [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted						165
Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Number Of Variable Interest Entities Consolidated \| VIE	3		3		3
Number of Variable Interest Entities not consolidated by equity holders \| VIE	8		8		7
Guarantor Obligations, Current Carrying Value	$ 6		$ 6		$ 34
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	12		12		13
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	12		12		$ 13
Exelon Generation Co L L C [Member] \| CENG [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Current Carrying Value	$ 688		$ 688
Equity Method Investment, Ownership Percentage	50.01%		50.01%
Due from Affiliates						$ 400
Atlantic City Electric Company [Member]
Variable Interest Entity [Line Items]
Number Of Variable Interest Entities Consolidated \| VIE	1		1		1
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 17		$ 17
Atlantic City Electric Company [Member] \| ATF [Member]
Variable Interest Entity [Line Items]
Cash Remitted To VIE	$ 3	$ 6	$ 7	$ 14
Pepco Holdings LLC [Member]
Variable Interest Entity [Line Items]
Number Of Variable Interest Entities Consolidated \| VIE	1		1		1
Investments [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 203		$ 203		$ 223
Investments [Member] \| Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	203		203		223
Finite-Lived Intangible Assets [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	7		7		7
Finite-Lived Intangible Assets [Member] \| Exelon Generation Co L L C [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 7		$ 7		$ 7