XML 130 R113.htm IDEA: XBRL DOCUMENT v3.19.1

Regulatory Assets and Liabilities (ROE of New Mexico Gas Company) (Details) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018 CAD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 CAD ($)
Public Utilities, General Disclosures [Line Items]
Regulatory Liabilities	$ 2,610		$ 2,468
New Mexico Gas Company [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Return on Equity, Percentage	10.00%
Public Utilities, Approved Equity Capital Structure, Percentage	52.00%
Regulatory Liabilities		$ 8

X

- Definition

Percentage of public utility's approved equity to capital, including debt and equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedEquityCapitalStructurePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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_PublicUtilitiesGeneralDisclosuresLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 405
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394

+ Details

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

X

- Details

Name:	us-gaap_ConsolidatedEntitiesAxis=ema_NewMexicoGasCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: