XML 80 R65.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Revenue Recognition (Disaggregation of Revenue) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues |  | $ 4,991.1 | [1] | $ 4,730.2 | $ 4,392.5
Other revenues |  | 123.4 |  | 144.4 | 100.0
Total Operating Revenues |  | 5,114.5 |  | $ 4,874.6 | $ 4,492.5
Gas Distribution Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 3,372.0 |  |  |
Other revenues |  | 34.4 |  |  |
Total Operating Revenues |  | 3,406.4 |  |  |
Electric Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 1,618.4 |  |  |
Other revenues |  | 89.0 |  |  |
Total Operating Revenues |  | 1,707.4 |  |  |
Corporate and Other |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 0.7 |  |  |
Other revenues |  | 0.0 |  |  |
Total Operating Revenues |  | 0.7 |  |  |
Residential | Gas Distribution Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 2,250.0 |  |  |
Residential | Electric Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 494.7 |  |  |
Residential | Corporate and Other |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 0.0 |  |  |
Commercial | Gas Distribution Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 751.9 |  |  |
Commercial | Electric Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 492.7 |  |  |
Commercial | Corporate and Other |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 0.0 |  |  |
Industrial | Gas Distribution Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 228.0 |  |  |
Industrial | Electric Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 613.6 |  |  |
Industrial | Corporate and Other |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 0.0 |  |  |
Off-system | Gas Distribution Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 92.4 |  |  |
Off-system | Electric Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 0.0 |  |  |
Off-system | Corporate and Other |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 0.0 |  |  |
Miscellaneous | Gas Distribution Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 49.7 |  |  |
Miscellaneous | Electric Operations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 17.4 |  |  |
Miscellaneous | Corporate and Other |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 0.7 |  |  |
Residential |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 2,744.7 |  |  |
Commercial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 1,244.6 |  |  |
Industrial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 841.6 |  |  |
Off-system |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | 92.4 |  |  |
Miscellaneous |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Customer revenues | [1] | $ 67.8 |  |  |
[1] | Customer revenue amounts exclude intersegment revenues. See Note 22, "Segments of Business," for discussion of intersegment revenues.

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

X
- Definition The total amount of regulated operating revenues recognized during the period. + References No definition available. + Details
Name: | us-gaap_RegulatedOperatingRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of regulated other operating revenues recognized during the period. + References No definition available. + Details
Name: | us-gaap_RegulatedOperatingRevenueOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045 + Details
Name: | us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=nix_GasDistributionOperationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=nix_ElectricOperationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=us-gaap_CorporateAndOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=nix_ResidentialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=nix_CommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=nix_IndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=nix_OffsystemMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=nix_Misc.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=nix_ResidentialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=nix_CommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=nix_IndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=nix_OffsystemMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=nix_Misc.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |