XML 272 R154.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Retirement Benefits Retirement Benefits - Gross Accumulated Other Comprehensive Loss and Regulatory Assets (Liabilities) not Recognized as Components of Periodic Benefit Cost (Details) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Pension Plan, Defined Benefit [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prior service (credit) cost | $ (29) | $ (24)
Actuarial loss | 7,558 | 7,556
Total | 7,529 | 7,532
Benefits included in accumulated other comprehensive income | 3,899 | 3,896
Benefits included in regulatory assets | 3,630 | 3,636
Other Postretirement Benefit Plan, Defined Benefit [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prior service (credit) cost | (337) | (522)
Actuarial loss | 531 | 829
Total | 194 | 307
Benefits included in accumulated other comprehensive income | 70 | 125
Benefits included in regulatory assets | $ 124 | $ 182

X
- Definition The pretax total of net (gain) loss, prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income and regulatory assets associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost. + References No definition available. + Details
Name: | exc_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeAndRegulatoryAssetsBeforeTaxNotYetRecognized
Namespace Prefix: | exc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan. + References No definition available. + Details
Name: | exc_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeAndRegulatoryAssetsGainsLossesBeforeTax
Namespace Prefix: | exc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount related to the pretax cost of benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost. + References No definition available. + Details
Name: | exc_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeAndRegulatoryAssetsPriorServiceCostCreditBeforeTax
Namespace Prefix: | exc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The pretax total of net (gain) loss, prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in regulatory assets associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost. + References No definition available. + Details
Name: | exc_DefinedBenefitPlanRegulatoryAssetsBeforeTax
Namespace Prefix: | exc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669686-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (i-k) -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580 + Details
Name: | us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |