Represents the reimbursable smart grid investment grant project expenditures included in capital expenditures.

No definition available.

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

- Definition

DOE Smart Grid Investment Grant Reimbursement

+ References

No definition available.

+ Details

Name:	exc_SmartGridGrantReimbursements
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Supplemental Financial Information.

+ References

No definition available.

+ Details

Name:	exc_SupplementalFinancialInformationTablesLineItems
Namespace Prefix:	exc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953423-111524

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ 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 210.5-02.3)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_NotesReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=exc_PecoEnergyCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=exc_LowToMediumRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_RiskLevelMediumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_RiskLevelHighMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Supplemental Financial Information - Narrative (Details) - PECO Energy Co [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2015	Dec. 31, 2014
Supplemental Financial Information Tables [Line Items]
Smart Grid Grant Project Capital Expenditures	$ 2
Smart Grid Grant Reimbursements	$ 5
Financing Receivable, Net		$ 15
Financing Receivable, Allowance for Credit Losses		17	$ 15
Low To Medium Risk [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Allowance for Credit Losses		1	1
Risk Level, Medium [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Allowance for Credit Losses		4	3
Risk Level, High [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Allowance for Credit Losses		$ 12	$ 11