Accrued Property Taxes

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- Definition

Gas Pipe Materials And Operating Supplies

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- Definition

Significant Accounting Policies [Line Items]

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Software, Cloud-Based

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- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

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-Topic 740
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-Paragraph 231
-Publisher FASB
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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
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-Name Accounting Standards Codification
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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
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-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-13

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- Definition

The total amount of regulated operating revenues recognized during the period.

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- Definition

The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

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-Topic 980
-SubTopic 340
-Name Accounting Standards Codification
-Section 50
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- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

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No definition available.

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Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands			1 Months Ended		3 Months Ended		6 Months Ended
	Aug. 11, 2025 shares	May 22, 2025 shares	Sep. 30, 2025 segment	Aug. 31, 2025 segment	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($) segment	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)
Significant Accounting Policies [Line Items]
Capital expenditures					$ 320,400	$ 199,300	$ 529,116	$ 362,457
Number of reportable segments \| segment			1	2			1
Gas pipe materials and operating supplies					80,600		$ 80,600		$ 78,100
Regulated operations revenues					358,154	$ 396,318	943,273	$ 1,142,734
Cloud-based software					42,700		42,700		33,900
Accrued property taxes					$ 30,700		$ 30,700		27,100
Effective income tax rate					18.30%	102.50%	23.60%	32.40%
Decoupling Mechanism
Significant Accounting Policies [Line Items]
Regulatory asset					$ 125,200		$ 125,200		91,100
Margin Tracker for Southern Nevada
Significant Accounting Policies [Line Items]
Regulatory asset					46,100		46,100		28,500
Accrued Pension And Other Postretirement Benefit Costs
Significant Accounting Policies [Line Items]
Regulatory asset					266,200		266,200		246,400
Public Offering And Private Placement
Significant Accounting Policies [Line Items]
Sale of stock, number of shares (in shares) \| shares	18,823,500	13,207,142
Southwest Gas Corporation
Significant Accounting Policies [Line Items]
Capital expenditures							$ 529,116	$ 362,457
Number of reportable segments \| segment							1
Gas pipe materials and operating supplies					80,600		$ 80,600		78,100
Regulated operations revenues					358,154	$ 396,318	943,273	$ 1,144,834
Cloud-based software					42,700		42,700		33,900
Accrued property taxes					$ 30,700		$ 30,700		27,100
Effective income tax rate					18.10%	(18.80%)	22.60%	14.50%
Southwest Gas Corporation \| California General Rate Case
Significant Accounting Policies [Line Items]
Regulated operations revenues					$ 20,200
Southwest Gas Corporation \| Decoupling Mechanism
Significant Accounting Policies [Line Items]
Regulatory asset					125,200		$ 125,200		91,100
Southwest Gas Corporation \| Margin Tracker for Southern Nevada
Significant Accounting Policies [Line Items]
Regulatory asset					46,100		46,100		28,500
Southwest Gas Corporation \| Accrued Pension And Other Postretirement Benefit Costs
Significant Accounting Policies [Line Items]
Regulatory asset					$ 266,200		$ 266,200		$ 246,400