XML 114 R97.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Accumulated Other Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - CAD CAD in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | CAD 137 | CAD (348)
Other comprehensive income (loss) before reclassifications | 0 | 371
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 19 | (114)
Other equity method reclassification adjustment | (46) | 0
Net current period other comprehensive income (loss) | (27) | 485
Other | (4) | 0
Ending Balance | 106 | 137
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | (35) | (8)
Other comprehensive income (loss) before reclassifications | 11 | (34)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 11 | (7)
Other equity method reclassification adjustment | (8) |
Net current period other comprehensive income (loss) | 14 | (27)
Other | 0 | 0
Ending Balance | (21) | (35)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | (318) | (425)
Other comprehensive income (loss) before reclassifications | 0 | 0
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 12 | (107)
Other equity method reclassification adjustment | (3) |
Net current period other comprehensive income (loss) | 9 | 107
Other | 0 | 0
Ending Balance | (309) | (318)
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 0 | 0
Other comprehensive income (loss) before reclassifications | (49) | 0
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 0 | 0
Other equity method reclassification adjustment | 0 |
Net current period other comprehensive income (loss) | (49) | 0
Other | 0 | 0
Ending Balance | (49) | 0
Accumulated Net Available For Sale Securities Gain (Loss) [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 0 | 3
Other comprehensive income (loss) before reclassifications | 3 | (3)
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | (4) | 0
Other equity method reclassification adjustment | 0 |
Net current period other comprehensive income (loss) | (1) | (3)
Other | 0 | 0
Ending Balance | (1) | 0
Accumulated Foreign Currency Adjustment Attributable to Parent [Member] |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Beginning Balance | 490 | 82
Other comprehensive income (loss) before reclassifications | 35 | 408
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent | 0 | 0
Other equity method reclassification adjustment | (35) |
Net current period other comprehensive income (loss) | 0 | 408
Other | (4) | 0
Ending Balance | CAD 486 | CAD 490

X
- Definition Amount reclassified out of comprehensive income net of tax due to other equity method adjustment. + References No definition available. + Details
Name: | ema_OtherComprehensiveIncomeEquityMethodReclassificationNetOfTax
Namespace Prefix: | ema_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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_AccumulatedOtherComprehensiveIncomeLossLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount before tax of increase (decrease) in accumulated equity from transactions and other events and circumstances from non-owner sources, attributable to parent. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners). + References No definition available. + Details
Name: | us-gaap_AociBeforeTaxAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=66004921&loc=d3e1436-108581 Reference 2: 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=66004124&loc=SL7669686-108580 + Details
Name: | us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of tax expense (benefit) allocated to other comprehensive income (loss) attributable to parent entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=64809438&loc=SL4573702-111684 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=68079674&loc=SL4569616-111683 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=68079674&loc=SL4569643-111683 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase (decrease) in other comprehensive income, after tax, from changes classified as other. + References No definition available. + Details
Name: | us-gaap_OtherComprehensiveIncomeOtherNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount before tax of reclassification adjustments of other comprehensive income (loss) attributable to parent. + 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=66004124&loc=SL7669686-108580 + Details
Name: | us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=ema_AccumulatedNetAvailableForSaleSecuritiesGainLossMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedTranslationAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |