Liability for Estimated Remediation Costs

No definition available.

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Namespace Prefix:	nix_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Number of waste disposal sites identified by program.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Other Commitments And Contingencies [Line Items]

+ References

No definition available.

+ Details

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Namespace Prefix:	nix_
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- References

No definition available.

+ Details

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Namespace Prefix:	nix_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Wind Power Purchase Agreement, Purchase Percentage

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 410
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481931/410-30-50-10

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 410
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-Name Accounting Standards Codification
-Section 50
-Paragraph 10
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481931/410-30-50-10

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 410
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481899/410-30-55-16

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.Y.Q1)
-Publisher FASB
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 410
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481931/410-30-50-7

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

This item represents a non-contingent liability for the fair value of an obligation to stand ready to perform over the term of a guaranty issued in the event that specified triggering events or conditions occur.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 25
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482050/460-10-25-4

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-SubTopic 10
-Topic 210
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-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Aggregate cash payments for a combination of transactions that are classified as investing activities in which assets, which may include securities, other types of investments, or productive assets, are purchased from third-party sellers. This element can be used by entities to aggregate payments for all asset purchases that are classified as investing activities.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-13

+ Details

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- Details

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- Details

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Other Commitments And Contingencies (Narrative) (Details) $ in Thousands	Mar. 18, 2024 USD ($)	Mar. 31, 2024 USD ($) Rate	Dec. 31, 2023 USD ($)
Other Commitments And Contingencies [Line Items]
Guaranty Liabilities		$ 672,300	$ 646,100
Recorded reserves to cover environmental remediation at various sites		$ 77,800	80,000
Wind Power Purchase Agreement, Purchase Percentage \| Rate		100.00%
Payments to Acquire Assets, Investing Activities	$ 110,600
MGP Sites
Other Commitments And Contingencies [Line Items]
Number of waste disposal sites identified by program		53
Liability for Estimated Remediation Costs		$ 72,800	$ 73,700
Reasonably possible remediation costs variance from reserve		15,100
Standby Letters of Credit
Other Commitments And Contingencies [Line Items]
Long-term Line of Credit		$ 9,900