XML 152 R135.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Employee Benefit Plans (Accumulated Benefit Obligation (ABO)) (Details) - Pension Plan [Member] - CAD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
ABO | $ 1,608 | $ 2,462
Fair Value of Plan Assets | 1,409 | 2,171
Funded Status | $ (199) | $ (291)

X
- Definition If aggregate disclosures are presented, the aggregate funded status of plan assets for plans with benefit obligations in excess of plan assets which are measured as the difference between the fair value of plan assets and the benefit obligation. + References No definition available. + Details
Name: | ema_DefinedBenefitPlanPlansWithBenefitObligationsInExcessOfPlanAssetsAggregateFundedStatusOfPlans
Namespace Prefix: | ema_
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
- Definition Amount of benefit obligation for defined benefit plan with benefit obligation in excess of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920 + Details
Name: | us-gaap_DefinedBenefitPlanPlansWithBenefitObligationsInExcessOfPlanAssetsAggregateBenefitObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value of plan assets for defined benefit plan with benefit obligation in excess of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2417-114920 + Details
Name: | us-gaap_DefinedBenefitPlanPlansWithBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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