XML 167 R150.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Short Term Debt (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Nov. 02, 2017 | Mar. 22, 2017 | Mar. 08, 2017
Revolving Credit Facility [Member] | New Mexico Gas Company [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  | $ 125 |
Line of Credit Facility, Expiration Date | Mar. 22, 2022 | Dec. 17, 2018 |  |  |
Revolving Credit Facility [Member] | TECO Energy Inc. and TECO Finance Inc. [Member] |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  | 300 |
Revolving Credit Facility [Member] | TECO Energy Inc. and TECO Finance Inc. [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Line of Credit Facility, Expiration Date | Mar. 22, 2022 | Dec. 17, 2018 |  |  |
Letter of Credit [Member] | Tampa Electric Division [Member] |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  | 50 |
Finance Term Credit Facility [Member] | Tampa Electric Division [Member] |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  | $ 325 |
Line of Credit Facility, Expiration Date | Mar. 22, 2022 | Dec. 17, 2018 |  |  |
Finance Term Credit Facility [Member] | Tampa Electric Division [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  | $ 300 |  |
Line of Credit Facility, Expiration Date | Nov. 01, 2018 |  |  |  |
Finance Term Credit Facility [Member] | TECO Energy Inc. and TECO Finance Inc. [Member] |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |
Line of Credit Facility, Maximum Borrowing Capacity |  |  |  |  | $ 400
Line of Credit Facility, Expiration Date | Mar. 08, 2018 | Mar. 14, 2017 |  |  |

X
- Definition Date the credit facility terminates, in CCYY-MM-DD format. + 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 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
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_LineOfCreditFacilityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + 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 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ema_NewMexicoGasCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ema_TecoEnergyIncAndTecoFinanceIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ema_TampaElectricDivisionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=ema_FinanceTermCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |