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Impairment of assets and other charges Impairment Of Assets And Other Charges Impairment Of Assets And Other Charges Cover [Abstract] Cover [Abstract] Fixed price contracts Fixed-Price Contract [Member] Change in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Other current liabilities Other current liabilities Other Liabilities, Current Deferred offering costs Deferred Offering Costs Medium-term notes, $7.92% series, due 2027 Debentures Medium Term Notes, 7.92% series, Due 2027 [Member] Debentures Medium Term Notes, 7.92% series, Due 2027 Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Trading Symbol Trading Symbol Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Current partial redemption transpired Redeemable Noncontrolling Interest, Equity, Redemption Value Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest All Trading Arrangements All Trading Arrangements [Member] Billed on completed contracts and contracts in progress Billed On Completed Contracts And Contracts In Progress [Member] Billed on completed contracts and contracts in progress. 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SERP Supplemental Employee Retirement Plan [Member] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Net cash surrender value of COLI policies Cash Surrender Value of Life Insurance Other comprehensive income (loss), before tax Other Comprehensive Income (Loss), before Tax Award Timing Disclosures [Line Items] Investment, Name [Domain] Investment, Name [Domain] Other Performance Measure, Amount Other Performance Measure, Amount Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Other components of net periodic benefit cost Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit Goodwill [Line Items] Goodwill [Line Items] Utility infrastructure services revenues Regulated Operating Revenue, Utility Infrastructure Services Regulated Operating Revenue, Utility Infrastructure Services Common stock, outstanding (in shares) Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding Deferred gas cost, net Deferred Gas Cost, Net Deferred Gas Cost, Net Debt Instrument, Covenant, Period [Domain] Debt Instrument, Covenant, Period [Domain] Debt Instrument, Covenant, Period [Domain] Redemption of equity interest from noncontrolling party Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Change in long-term credit facility and commercial paper Proceeds From Repayments Of Lines Of Credit And Commercial Paper The net cash inflow or cash outflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with either short term or long term maturity that is collateralized (backed by pledge, mortgage or other lien in the entity's assets) and issuing (borrowing) and repaying commercial paper Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Customer deposits Contract with Customer, Liability, Current Sale of stock, price per share (in USD per share) Sale of Stock, Price Per Share Plan Name [Domain] Plan Name [Domain] Other deferred credits and other long-term liabilities Other deferred credits and other long-term liabilities Deferred Credits and Other Liabilities, Noncurrent Service cost Defined Benefit Plan, Service Cost Deferred charges and other assets Deferred charges and other assets Other Assets, Noncurrent Entity Tax Identification Number Entity Tax Identification Number Equity ownership, percentage purchased Equity Ownership, Percentage Purchased During Period Equity Ownership, Percentage Purchased During Period Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt Schedule of Long-Term Debt Instruments [Table Text Block] Retirement Plan Type [Axis] Retirement Plan Type [Axis] AOCI Including Portion Attributable to Noncontrolling Interest AOCI Including Portion Attributable to Noncontrolling Interest [Member] Money Market Funds Money Market Funds [Member] Changes in customer advances Changes In Customer Advances, Investing Activities Changes In Customer Advances, Investing Activities Operating Segments Operating Segments [Member] Line of credit designated for working capital purposes Line Of Credit Facility Working Capital Purposes Line Of Credit Facility, Working Capital Purposes Receivable Type [Axis] Receivable Type [Axis] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Net proceeds from sale of stock Sale of Stock, Consideration Received on Transaction CASH FLOW FROM OPERATING ACTIVITIES: CASH FLOW FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Schedule of Rollforward of Accumulated Other Comprehensive Income Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Intersegment Eliminations Intersegment Eliminations [Member] Secured Debt Secured Debt [Member] Plan Name [Axis] Plan Name [Axis] Equity Components [Axis] Equity Components [Axis] Regulatory adjustment Accumulated Defined Benefit Plans Adjustment, Regulartory Adjustment, Attributable to Parent [Member] Accumulated Defined Benefit Plans Adjustment, Regulartory Adjustment, Attributable to Parent [Member] Non-regulated property, equipment, and intangibles Property Plant Equipment And Intangible Assets Gross Property plant equipment and intangible assets gross. Award Timing Method Award Timing Method [Text Block] Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Capital expenditures incurred but not yet paid, increase (decrease) Capital Expenditures Incurred But Not Yet Paid, Increase (Decrease) Capital Expenditures Incurred But Not Yet Paid, Increase (Decrease) Transportation Transportation [Member] Transportation. Drum Drum [Member] Drum Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding $400 Million Credit Facility $400 Million Credit Facility [Member] $400 Million Credit Facility [Member] Insider Trading Policies and Procedures [Line Items] Proceeds from the sale of business, net of cash sold Proceeds from Divestiture of Businesses Total operating expenses Costs and Expenses Net actuarial loss Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Debt secured by assets Debt Instrument, Collateral Amount Schedule of Significant Items Included in Other Income (Deductions) Schedule of Other Nonoperating Income, by Component [Table Text Block] Receivable [Domain] Receivable [Domain] Adjustment to Compensation, Amount Adjustment to Compensation Amount Additional paid-in capital Additional Paid in Capital, Common Stock Compensation Amount Outstanding Recovery Compensation Amount Disposal Group Classification [Axis] Disposal Group Classification [Axis] Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Entity Small Business Entity Small Business Less: accumulated depreciation Less: accumulated depreciation Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Company Selected Measure Amount Company Selected Measure Amount Tabular List, Table Tabular List [Table Text Block] Period of option to purchase for underwriters Sale Of Stock, Period Of Option To Purchase Sale Of Stock, Period Of Option To Purchase Foreign currency exchange translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Components of Net Periodic Benefit Cost Compensation and Employee Benefit Plans [Text Block] Impairment of asset held for sale adjustment Impairment of Long-Lived Assets to be Disposed of Prior service cost Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Credit Facility [Domain] Credit Facility [Domain] Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Amortization of net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Taxes other than income taxes Taxes, Miscellaneous Notes, $3.18%, due 2051 Debentures Notes, 3.18%, Due 2051 [Member] Debentures Notes, 3.18%, Due 2051 Centuri secured term loan facility Centuri Secured Term Loan Facility [Member] Centuri Secured Term Loan Facility Current assets: Current assets: Assets, Current [Abstract] Goodwill Goodwill Goodwill, beginning balance Goodwill, ending balance Goodwill Consolidation Items [Axis] Consolidation Items [Axis] Gas infrastructure services Gas Infrastructure Services [Member] Gas Infrastructure Services Withholding remittance - share-based compensation Withholding remittance - share-based compensation Payment, Tax Withholding, Share-Based Payment Arrangement Accrued utility revenue Accrued Utility Revenue Accrued utility revenue. Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Promissory Note Promissory Note [Member] Promissory Note Product and Service [Domain] Product and Service [Domain] Entity Information [Line Items] Entity Information [Line Items] Employee Stock Option Share-Based Payment Arrangement, Option [Member] Schedule of Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) Schedule Of Related Tax Effects Allocated To Components Of Other Comprehensive Income (Loss) [Table Text Block] Related tax effects of defined benefit pension plans and designated hedging activities reclassifications and amounts arising during the period included in other comprehensive income (loss). Goodwill [Roll Forward] Goodwill [Roll Forward] Accrued purchased gas cost Accrued Purchased Gas Costs Accrued Purchased Gas Costs Schedule of Information about Receivables, Revenue Earned on Contracts in Progress in Excess of Billings, Which are Included Within Accounts Receivable, Net of Allowances, and Amounts Billed in Excess of Revenue Earned on Contracts Schedule Of Information About Receivables Revenue Earned On Contracts In Progress In Excess Of Billings And Amounts Billed In Excess Of Revenue Earned On Contracts [Table Text Block] Schedule Of Information About Receivables Revenue Earned On Contracts In Progress In Excess Of Billings And Amounts Billed In Excess Of Revenue Earned On Contracts Other, including principal payments on finance leases Other Proceeds from (Payments for) Other Financing Activities Revenue earned on contracts in progress in excess of billings Revenue Earned On Contracts In Progress In Excess Of Billings Revenue Earned On Contracts In Progress In Excess Of Billings Comprehensive income attributable to Southwest Gas Holdings, Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent Fiscal quarter ending March 31, 2024 Debt Instrument, Covenant, Period One [Member] Debt Instrument, Covenant, Period One Security Exchange Name Security Exchange Name Debt, basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Award Type Award Type [Axis] Foreign currency translation adjustment Goodwill, Foreign Currency Translation Gain (Loss) Total other comprehensive income (loss) - noncontrolling interest, net-of- tax amount Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Accumulated removal costs Other Accrued Liabilities, Noncurrent Repayments of debt Repayments of Debt Noncontrolling interest Equity, Attributable to Noncontrolling Interest Short-term debt Short-term debt Short-Term Debt Residential Residential [Member] Residential. Common stock, par (in USD per share) Common Stock, Par or Stated Value Per Share Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Revolving Credit Facility Revolving Credit Facility [Member] Expiration Date Trading Arrangement Expiration Date CASH FLOW FROM INVESTING ACTIVITIES: CASH FLOW FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Total other comprehensive income (loss), net-of- tax amount Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Total Shareholder Return Amount Total Shareholder Return Amount Common stock, issued (in shares) Common Stock, Shares, Issued Entity [Domain] Entity [Domain] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Credit facility maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Notes, $2.2%, due 2030 Debentures Notes, 2.2%, Due 2030 [Member] Debentures Notes, 2.2%, Due 2030 Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Other Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Other Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Non-regulated accumulated provision for depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Percentage of redeemable noncontrolling interest redeemed Redeemable Noncontrolling Interest, Percentage Redeemed Redeemable Noncontrolling Interest, Percentage Redeemed Debt Instrument [Line Items] Debt Instrument [Line Items] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Common stock, authorized (in shares) Common Stock, Shares Authorized Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Diluted (in shares) Weighted average diluted shares (in shares) Weighted Average Number of Shares Outstanding, Diluted Contract with Customer, Basis of Pricing [Axis] Contract with Customer, Basis of Pricing [Axis] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Gas plant Public Utilities, Property, Plant and Equipment, Gas Plant Public Utilities, Property, Plant and Equipment, Gas Plant AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Movement In Redeemable Noncontrolling Interest [Roll Forward] Movement In Redeemable Noncontrolling Interest [Roll Forward] Movement In Redeemable Noncontrolling Interest [Roll Forward] Total equity Beginning balance, attributable to parent Ending balance, attributable to parent Equity, Attributable to Parent Held for sale Disposal Group, Held For Sale [Policy Text Block] Disposal Group, Held For Sale [Policy Text Block] Related Party Related Party [Member] Amortization of net actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Net interest deductions Interest Expense, Nonoperating Notes, $4.875%, due 2043 Debentures Notes, 4.875%, Due 2043 [Member] Debentures Notes, 4.875%, Due 2043 Schedule of Goodwill Schedule of Goodwill [Table Text Block] Ichan Partners LP & Ichan Partners Master Fund LP Ichan Partners LP & Ichan Partners Master Fund LP [Member] Ichan Partners LP & Ichan Partners Master Fund LP Notes, $3.7%, due 2028 Debentures Notes, 3.7%, Due 2028 [Member] Debentures Notes, 3.7%, Due 2028 Total other comprehensive income (loss), tax (expense) or benefit Total other comprehensive income (loss), tax (expense) or benefit Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Accounts receivable, net of allowance Centuri accounts receivable for services provided to Southwest Accounts Receivable, after Allowance for Credit Loss, Current Beginning balance, attributable to parent, before tax Ending balance, attributable to parent, before tax Stockholders' Equity Attributable To Parent, Before Tax Stockholders' Equity Attributable To Parent, Before Tax Ownership percentage by parent Subsidiary, Ownership Percentage, Parent Sale of Stock [Domain] Sale of Stock [Domain] Changes in other liabilities and deferred credits Increase (Decrease) in Other Operating Liabilities Current assets held for sale Asset, Held-for-Sale, Not Part of Disposal Group, Current Long-term debt Long-term debt outstanding Long-Term Debt Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Document Fiscal Period Focus Document Fiscal Period Focus All Executive Categories All Executive Categories [Member] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] ASSETS ASSETS Assets [Abstract] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Total other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Revolving credit facility and commercial paper Revolving Credit Facility And Commercial Paper [Member] Revolving Credit Facility And Commercial Paper [Member] Amortization of prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax Document Type Document Type Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Schedule of Segment Reporting Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Statutory income tax rate Statutory Income Tax Rate, Percent Statutory Income Tax Rate, Percent Nonrelated Party Nonrelated Party [Member] Total other comprehensive income (loss) - noncontrolling interest, tax (expense) or benefit Less current period other comprehensive income (loss) attributable to noncontrolling interest , tax (expense) or benefit Other Comprehensive Income (Loss), Tax, Portion Attributable to Noncontrolling Interest Decrease in net cost of gas sold Increase (Decrease) In Net Cost Of Gas Sold Increase (Decrease) In Net Cost Of Gas Sold Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Regulatory adjustment Accumulated Defined Benefit Plans Adjustment, Regulatory Adjustment, Attributable to Parent [Member] Accumulated Defined Benefit Plans Adjustment, Regulatory Adjustment, Attributable to Parent [Member] Other property and investments Property, Plant and Equipment, Other, Net Schedule of Utility Infrastructure Services Contracts Receivable Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Parent Parent [Member] Maximum Maximum [Member] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Beginning balance, attributable to parent, tax (expense) benefit Ending balance, attributable to parent, tax (expense) benefit Stockholders' Equity Attributable To Parent, Tax Stockholders' Equity Attributable To Parent, Tax Cash and cash equivalents included in current assets held for sale at beginning of period Cash And Cash Equivalents Included In Current Assets Held For Sale Cash And Cash Equivalents Included In Current Assets Held For Sale Contract assets increase (decrease) Contract with Customer, Receivable, Allowance for Credit Loss, Noncurrent Accounts payable Accounts Payable, Current Operating revenues: Revenues [Abstract] Net income (loss) attributable to redeemable noncontrolling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Current Fiscal Year End Date Current Fiscal Year End Date Noncurrent assets: Noncurrent assets: Assets, Noncurrent [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] PEO Name PEO Name Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Payments to noncontrolling interests Payments to Noncontrolling Interests Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Common stock issued (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period All Award Types Award Type [Domain] Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Other comprehensive income, net of tax Other comprehensive income, net of tax Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract] Name Outstanding Recovery, Individual Name Beginning balance, before tax Ending balance, before tax Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Before Tax Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Before 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Items] Class of Stock [Line Items] Restricted stock units (in shares) Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends Investment, Name [Axis] Investment, Name [Axis] Recent Accounting Standards Updates New Accounting Pronouncements, Policy [Policy Text Block] Amortization of prior service costs Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Diluted (in USD per share) Earnings Per Share, Diluted Class of Stock [Axis] Class of Stock [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Centuri IPO, tax (expense) benefit Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, IPO Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, IPO Notes, $4.15%, due 2049 Debentures Notes, 4.15%, Due 2049 [Member] Debentures Notes, 4.15%, Due 2049 Name Measure Name Entity Interactive Data Current Entity Interactive Data Current Decrease of contract liability Increase (Decrease) in Contract with Customer, Liability Schedule of Accounts Receivable for Services Accounts Receivable For Services [Table Text Block] Accounts Receivable For Services Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Ownership [Axis] Ownership [Axis] Other Current Liabilities Other Current Liabilities Policy [Policy Text Block] Other Current Liabilities Policy Retirement Benefits [Abstract] Retirement Benefits [Abstract] Customer [Axis] Customer [Axis] Centuri, MountainWest And Southwest Gas Holdings, Inc. Centuri, MountainWest And Southwest Gas Holdings, Inc. [Member] Centuri, MountainWest And Southwest Gas Holdings, Inc. Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Changes in undistributed stock compensation Share-Based Payment Arrangement, Noncash Expense Net income Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Defined Benefit Plans Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Loss on disposal adjustment Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal Proceeds from the sale of property Proceeds from the sale of property Proceeds from Sale of Property, Plant, and Equipment Income tax expense Income tax expense (benefit) Income Tax Expense (Benefit) Centuri IPO, After-Tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, IPO Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment,, Centuri IPO Interest cost Defined Benefit Plan, Interest Cost Other income and (expenses): Nonoperating Income (Expense) [Abstract] Debt instrument interest rate Debt Instrument, Interest Rate, Stated Percentage Corporate and administrative Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] SUPPLEMENTAL INFORMATION: SUPPLEMENTAL INFORMATION: Supplemental Cash Flow Information [Abstract] Revenue from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Total other (expenses) Nonoperating Income (Expense) Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] 2008 Series A, due 2038 Variable Rate Bonds 2008 Series A- Due 2038 [Member] Variable Rate Bonds 2008 Series A- Due 2038 Nature of Operations Nature Of Operations [Policy Text Block] Nature Of Operations [Policy Text Block] Defined benefit pension plans: Defined benefit pension plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification 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Purchase Plan [Member] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest [Table Text Block] Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest Spinoff transaction costs Spinoff Transaction Costs Spinoff Transaction Costs Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Legal Entity [Axis] Legal Entity [Axis] Master services agreement Master Services Agreement [Member] Master Services Agreement [Member] Regulated operations plant: Regulated operations plant: Public Utilities, Property, Plant and Equipment, Net [Abstract] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Individual: Individual [Axis] Construction work in progress Public Utilities, Property, Plant and Equipment, Construction Work in Progress Accumulated other comprehensive loss Accumulated other comprehensive loss AOCI AOCI Attributable to Parent [Member] Transaction price allocated to unsatisfied performance obligations of contracts, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Product and Service [Axis] Product and Service [Axis] Entity Address, State or Province Entity Address, State or Province $550 Million Term Loan Credit Agreement Due July 31, 2025 Term Loan Credit Agreement Due July 31, 2025 [Member] Term Loan Credit Agreement Due July 31, 2025 Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Redemption value adjustments Redemption value adjustments Noncontrolling Interest, Change in Redemption Value Statement [Line Items] Statement [Line Items] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Disposal consideration Disposal Group, Including Discontinued Operation, Consideration Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Linetec Linetec Services, LLC [Member] Linetec Services, LLC [Member] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Percentage of equity interest exchanged with debt forgiveness Percentage Of Equity Interest Exchanged With Debt Forgiveness Percentage Of Equity Interest Exchanged With Debt Forgiveness IPO IPO [Member] CAPITALIZATION AND LIABILITIES CAPITALIZATION AND LIABILITIES Liabilities and Equity [Abstract] Schedule of Net Periodic Benefit Costs Schedule of Net Benefit Costs [Table Text Block] Unamortized discount and debt issuance costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Medium-term notes, $6.76% series, due 2027 Debentures Medium Term Notes, 6.76% series, Due 2027 [Member] Debentures Medium Term Notes, 6.76% series, Due 2027 Minimum Minimum [Member] Restatement Determination Date Restatement Determination Date Fair Value Estimate of Fair Value Measurement [Member] Adoption Date Trading Arrangement Adoption Date Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Omnibus Incentive Plan Omnibus Incentive Plan [Member] Omnibus Incentive Plan Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Previous Owner Of Linetec Previous Owner Of Linetec [Member] Previous Owner Of Linetec Segments [Axis] Segments [Axis] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Long-term debt, gross Long-Term Debt, Gross Exercise Price Award Exercise Price Dividends declared but not yet paid Dividends Payable, Current Amortization of prior service cost Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Miscellaneous income and (expense) Miscellaneous Income (Expense) Miscellaneous Income (Expense) Total operating revenues Regulated operations revenues Regulated and Unregulated Operating Revenue Arrangement Duration Trading Arrangement Duration Subsequent Event Subsequent Event [Member] Revision of Prior Period, Error Correction, Adjustment Revision of Prior Period, Error Correction, Adjustment [Member] Contracts receivable, gross Contract with Customer, Asset, before Allowance for Credit Loss Operating expenses: Costs and Expenses [Abstract] Change from net income attributable to Southwest Gas Holdings, Inc. and transfers from noncontrolling interest Change From Net Income (Loss) Transfers From Noncontrolling Interest Change From Net Income (Loss) Transfers From Noncontrolling Interest Centuri Centuri Centuri Group, Inc. [Member] Centuri Group, Inc. [Member] Other receivables Other Receivables [Member] Other Receivables Income Taxes Income Tax, Policy [Policy Text Block] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Other debt obligations Other Debt Obligations [Member] Segments [Domain] Segments [Domain] Other comprehensive income (loss), tax Other Comprehensive Income (Loss), Tax Deferred purchased gas costs Deferred Gas Purchases, Current Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] All Individuals All Individuals [Member] Tax-exempt Series A, due 2028 Variable Rate Bonds Tax Exempt Series A- Due 2028 [Member] Variable Rate Bonds Tax Exempt Series Due 2028 Other property and investments, net Other Property And Investments Aggregate carrying amount, as of the balance sheet date, of other property and investments not separately presented elsewhere in the balance sheet. Centuri distribution to redeemable noncontrolling interest Distribution To Redeemable Noncontrolling Interest Distribution To Redeemable Noncontrolling Interest PEO PEO [Member] Variable Rate [Axis] Variable Rate [Axis] Entities [Table] Entities [Table] Name Trading Arrangement, Individual Name Other income Other income Total other income (deductions) Other Nonoperating Income (Expense) PBOP Other Postretirement Benefits Plan [Member] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Recognized in AOCI Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Utility Infrastructure Services Utility Infrastructure Services Segment [Member] Utility Infrastructure Services Segment [Member] Disposal Group Name [Axis] Disposal Group Name [Axis] Notes, $4.05%, due 2032 Debentures Notes, 4.05%, Due 2032 [Member] Debentures Notes, 4.05%, Due 2032 Schedule of Amount Recognized Before Income Tax in Accumulated Other Comprehensive Income Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Equity in earnings (loss) of unconsolidated investments Income (Loss) from Equity Method Investments CORRA CORRA [Member] CORRA Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Common Stock Common Stock Disclosure [Text Block] Common Stock Disclosure [Text Block] Operations and maintenance Utilities Operating Expense, Maintenance and Operations Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Other income (deductions) Other Nonoperating Income (Expense) [Abstract] Equity AFUDC Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Related Party [Domain] Related and Nonrelated Parties [Domain] Money market fund investments Cash and Cash Equivalents, Fair Value Disclosure Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Local Phone Number Local Phone Number Change in short-term portion of credit facility Proceeds from (Repayments of) Lines of Credit prime rate Variable Rate Component Three [Member] Variable Rate Component Three Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Deferred purchased gas costs Deferred purchased gas costs Increase in deferred purchased gas costs Increase (Decrease) in Deferred Gas Cost Allowance for doubtful accounts Contract with Customer, Asset, Allowance for Credit Loss Large commercial Large Commercial [Member] Large commercial. Fiscal quarter ending June 30, 2024 Debt Instrument, Covenant, Period Two [Member] Debt Instrument, Covenant, Period Two Amounts billed in excess of revenue earned on contracts Contract with Customer, Receivable, after Allowance for Credit Loss Variable Rate Component [Domain] Variable Rate Component [Domain] Variable Rate Component [Domain] Changes in deferred charges and other assets Changes in deferred charges and other assets Increase (Decrease) in Other Operating Assets Changes in current assets and liabilities: Changes in current assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Secured Overnight Financing Rate (SOFR) Secured Overnight Financing Rate (SOFR) [Member] PEO Total Compensation Amount PEO Total Compensation Amount Net defined benefit pension plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Less: amount recognized in regulatory assets Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Amount Recognized Regulatory Assets, Before Tax Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Amount Recognized Regulatory Assets, Before Tax Deferred purchased gas costs Deferred Gas Cost Total other comprehensive income (loss), before- tax amount Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent Accrued interest Interest Payable, Current Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] No Trading Symbol - Preferred Stock Purchase Rights No Trading Symbol Flag Stock issuance costs Payments of Stock Issuance Costs Debt Disclosure [Abstract] Debt Disclosure [Abstract] Southwest Gas Holdings, Inc. Common Stock, $1 Par Value Common stock shares Common stock shares Common Stock [Member] Measure: Measure [Axis] Debt Instrument, Covenant, Period [Axis] Debt Instrument, Covenant, Period [Axis] Debt Instrument, Covenant, Period Share-based compensation Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Long-Lived Assets Held-for-Sale by Asset Type [Axis] Long-Lived Asset, Held-for-Sale, Type [Axis] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Common stock issuances (in shares) Stock Issued During Period, Shares, New Issues Line of Credit Line of Credit [Member] Entity Emerging Growth Company Entity Emerging Growth Company Segment Reporting [Abstract] Segment Reporting [Abstract] Entity Central Index Key Entity Central Index Key Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Foreign currency translation adjustment Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Discontinued Operations and Disposal Groups [Abstract] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Reclassification from AOCI, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Equity Component [Domain] Equity Component [Domain] Segment Information Segment Reporting Disclosure [Text Block] Current maturities of long-term debt Less: current maturities Long-Term Debt, Current Maturities Small commercial Small Commercial [Member] Small commercial. Amortization of net actuarial (gain)/loss Amortization of net actuarial loss Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Reclassification from AOCI, net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Entity Shell Company Entity Shell Company Measurement Basis [Axis] Measurement Basis [Axis] $8% Series, due 2026 Debentures 8% Series Due 2026 [Member] Debentures 8% Series Due 2026 Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Title Trading Arrangement, Individual Title Other current assets and liabilities Other current assets and liabilities Increase (Decrease) in Other Current Assets and Liabilities, Net Statement [Table] Statement [Table] Foreign Currency Items Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Counterparty Name [Axis] Counterparty Name [Axis] Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Consolidation Items [Domain] Consolidation Items [Domain] City Area Code City Area Code Current liabilities: Current liabilities: Liabilities, Current [Abstract] Net regulated operations plant Public Utilities, Property, Plant and Equipment, Net Interest paid, net of amounts capitalized Interest paid, net of amounts capitalized Interest Paid, Excluding Capitalized Interest, Operating Activities SWH term loan facility $550 Million Term Loan Credit Agreement Due October 2024 [Member] $550 Million Term Loan Credit Agreement Due October 2024 Notes, $5.45%, due 2028 Debentures Notes, 5.45%, Due 2028 [Member] Debentures Notes, 5.45%, Due 2028 Disposal Group Classification [Domain] Disposal Group Classification [Domain] Centuri secured revolving credit facility Centuri Secured Revolving Credit Facility [Member] Centuri secured revolving credit facility. Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Gas pipe materials and operating supplies Materials, Supplies, and Other Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Estimated loss on disposition of assets Gain (Loss) on Disposition of Assets Total current assets Assets, Current Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Southwest Gas Corporation Southwest Gas Corporation [Member] Southwest gas corporation. Capitalization: Capitalization: Capitalization, Long-Term Debt and Equity [Abstract] Revision of Prior Period [Domain] Revision of Prior Period [Domain] Accrued taxes Increase (Decrease) in Accrued Taxes Payable Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Centuri secured term loan facility Centuri Term Loan Facility [Member] Centuri term loan facility. Long-term debt, less current maturities Long-term debt, less current maturities Long-Term Debt, Excluding Current Maturities Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Notes, $3.8%, due 2046 Debentures Notes, 3.8%, Due 2046 [Member] Debentures Notes, 3.8%, Due 2046 Subsequent Event Type [Axis] Subsequent Event Type [Axis] Background, Organization, and Summary of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Earnings per share attributable to Southwest Gas Holdings, Inc.: Earnings Per Share [Abstract] Equity [Abstract] Equity [Abstract] Accrued general taxes Accrual for Taxes Other than Income Taxes, Current Retained earnings Retained Earnings (Accumulated Deficit) Class of Stock [Domain] Class of Stock [Domain] Net income Net income Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest 2009 Series A, due 2039 Variable Rate Bonds 2009 Series A- Due 2039 [Member] Variable Rate Bonds 2009 Series A- Due 2039 Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Equity Awards Adjustments Equity Awards Adjustments [Member] Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Alternative revenue program revenues (deferrals) Alternative Revenue Program Revenues (Deferrals) Alternative revenue program revenues (deferrals). Underlying Securities Award Underlying Securities Amount Credit Facility [Axis] Credit Facility [Axis] Fiscal quarter ending September 30, 2024 Debt Instrument, Covenant, Period Three [Member] Debt Instrument, Covenant, Period Three Interest income Interest Income, Other Amendment Flag Amendment Flag Carrying Amount Reported Value Measurement [Member] Entity Registrant Name Entity Registrant Name Gains on sale of property and equipment Gain (Loss) on Disposition of Property Plant Equipment Other Other Infrastructure Services [Member] Other Infrastructure Services Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Fair Value as of Grant Date Award Grant Date Fair Value Other comprehensive income (loss) before reclassifications, net of tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Sale of stock, number of shares (in shares) Sale of Stock, Number of Shares Issued in Transaction Debt Debt Disclosure [Text Block] Condensed Income Statement [Table] Condensed Income Statement [Table] Certain Members Of Riggs Distler Management Certain Members Of Riggs Distler Management [Member] Certain Members Of Riggs Distler Management $300 Million Credit Facility $300 Million Credit Facility [Member] $300 Million Credit Facility Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Debt instrument face amount Debt Instrument, Face Amount Schedule of Revenue Disaggregated by Service Type and Contract Type Disaggregation of Revenue [Table Text Block] Common stock issuances and Centuri IPO Common stock issued, amount Increase in additional paid-in capital as a result of Centuri IPO Stock Issued During Period, Value, New Issues Issuance of short-term debt Proceeds from Short-Term Debt Entity Address, Postal Zip Code Entity Address, Postal Zip Code Redeemable Noncontrolling Interests Consolidation, Policy [Policy Text Block] 2003 Series A, due 2038 Variable Rate Bonds 2003 Series A- Due 2038 [Member] Variable Rate Bonds 2003 Series A- Due 2038 Restatement Determination Date: Restatement Determination Date [Axis] Change in COLI policies Life Insurance, Corporate or Bank Owned, Change in Value Title of 12(b) Security Title of 12(b) Security Deferred income taxes and other credits: Deferred income taxes and other credits: Other Liabilities, Noncurrent [Abstract] Common stock, $1 par (authorized - 120,000,000 shares; issued and outstanding - 71,709,298 and 71,563,750 shares) Common stock Common Stock, Value, Issued MountainWest MountainWest [Member] MountainWest Natural Gas Distribution Natural Gas Distribution Segment [Member] Natural Gas Distribution Segment Regulatory adjustment Regulatory adjustment Other Comprehensive Income Defined Benefit Plans Regulatory Adjustment Net of Tax The portion of the pension, PBOP, and SERP liability that is recoverable in rates net-of-tax. Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Other comprehensive income (loss) before reclassifications, before tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Payments for (Proceeds from) Other Investing Activities Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Reclassification from AOCI, tax Reclassification from AOCI, Current Period, Tax Line of credit facility, maximum commitment amount Line Of Credit Facility, Maximum Commitment Amount Line Of Credit Facility, Maximum Commitment Amount Schedule of Other Property and Investments Investment [Table Text Block] CASH FLOW FROM FINANCING ACTIVITIES: CASH FLOW FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Bid contract Bid Contract [Member] Bid contract. Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Debt covenant, net leverage ratio Line Of Credit Facility, Covenants, Net Leverage Ratio Line Of Credit Facility, Covenants, Net Leverage Ratio Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Fair Value Measurement [Domain] Fair Value Measurement [Domain] Basic (in USD per share) Earnings Per Share, Basic Accounts payable Increase (Decrease) in Accounts Payable Issuance of common stock, net Proceeds from Issuance of Common Stock Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Foreign transaction gain (loss) Realized Gain (Loss), Foreign Currency Transaction, before Tax Ownership [Domain] Ownership [Domain] Net cost of gas sold Net cost of gas sold Utilities Operating Expense, Gas and Petroleum Purchased Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Schedule of Goodwill [Table] Goodwill [Table] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Schedule of Stock by Class [Table] Stock, Class of Stock [Table] Total current liabilities Liabilities, Current Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Notes, $5.8%, due 2027 Debentures Notes, 5.8%, Due 2027 [Member] Debentures Notes, 5.8%, Due 2027 Previously Reported Previously Reported [Member] Total assets Assets Certain Assets Associated With Previous Corporate Headquarters Certain Assets Associated With Previous Corporate Headquarters [Member] Certain Assets Associated With Previous Corporate Headquarters Utility infrastructure services expenses Cost of Goods and Services Sold Borrowings outstanding under facility Long-Term Line of Credit Long-Lived Assets Held-for-Sale, Name [Domain] Long-Lived Assets Held-for-Sale, Name [Domain] Income taxes receivable, net Income Taxes Receivable, Current Over-Allotment Option Over-Allotment Option [Member] Construction expenditures and property additions Construction expenditures and property additions Payments to Acquire Property, Plant, and Equipment Total deferred income taxes and other credits Other Liabilities, Noncurrent Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Total other comprehensive income (loss) - noncontrolling interest, before- tax amount Less current period other comprehensive income (loss) attributable to noncontrolling interest , before- tax amount Other Comprehensive Income (Loss), before Tax, Portion Attributable to Noncontrolling Interest Termination Date Trading Arrangement Termination Date Beginning balance, tax (expense) benefit Ending balance, tax (expense) benefit Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Tax Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Tax Deferred income taxes and investment tax credits, net Deferred Income Taxes And Unamortized Investment Tax Credits Represents deferred tax liabilities, which result from applying the applicable tax rate to net taxable temporary differences pertaining to each jurisdiction to which the entity is obligated to pay income tax. Additionally, this element includes the future effects on income taxes attributable to investment tax credits. Revenues Revenues Repayment of short-term debt Repayments of Short-Term Debt Entity Address, City or Town Entity Address, City or Town Issuance of long-term debt, net Proceeds from Issuance of Long-Term Debt Debt Instrument [Axis] Debt Instrument [Axis] Pipeline and Storage Pipeline And Storage Segment [Member] Pipeline And Storage Segment Number of performance share units granted (in shares) Number Of Performance Share Units Granted Number Of Performance Share Units Granted. Centuri Separation Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Net income attributable to Southwest Gas Holdings, Inc. Segment net income (loss) Net income attributable to Southwest Gas Holdings, Inc. Net Income (Loss) Attributable to Parent Trading Arrangement: Trading Arrangement [Axis] Electric power infrastructure services Electric Power Infrastructure Services [Member] Electric Power Infrastructure Services Other Comprehensive Income and Accumulated Other Comprehensive Income Comprehensive Income (Loss) Note [Text Block] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Entity File Number Entity File Number Centuri Secured Term Loan Facility And Revolving Credit Facility Centuri Secured Term Loan Facility And Revolving Credit Facility [Member] Centuri Secured Term Loan Facility And Revolving Credit Facility Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Centuri IPO, before- tax amount Other Comprehensive (Income) Loss, Defined Benefit Plan, before Tax, after Reclassification Adjustment, IPO Other Comprehensive (Income) Loss, Defined Benefit Plan, before Tax, after Reclassification Adjustment, Centuri IPO Revenue Revenue from Contract with Customer [Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Noncontrolling interest Noncontrolling Interest [Member] Income Statement [Abstract] Income Statement [Abstract] Entity Address, Address Line One Entity Address, Address Line One Line of credit designated as long term debt Line Of Credit Facility Amount Classified As Long Term Debt Line Of Credit Facility, Amount Classified As Long-Term Debt Weighted average shares: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Entity Address, Address Line Two Entity Address, Address Line Two Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Effects of currency translation on cash and cash equivalents Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Continuing Operations Dividends declared Dividends declared to Southwest Gas Holdings, Inc. Dividends, Common Stock Name Forgone Recovery, Individual Name Document Period End Date Document Period End Date Debentures Debentures [Member] Debentures [Member] Contract with Customer, Basis of Pricing [Domain] Contract with Customer, Basis of Pricing [Domain] Sale of Stock [Axis] Sale of Stock [Axis] Deferred income taxes Deferred income taxes Increase (Decrease) in Deferred Income Taxes Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Alternative base rate Base Rate [Member] Total noncurrent assets Assets, Noncurrent, Other than Noncurrent Investments and Property, Plant and Equipment Insider Trading Arrangements [Line Items] Contracts receivable, net Contracts receivable, net Contract with Customer, Asset, after Allowance for Credit Loss Regulated operations revenues Total Regulated operations revenues Regulated Operating Revenue, Gas Other Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment [Member] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Industrial development revenue bonds Industrial Development Revenue Bonds [Member] Industrial Development Revenue Bonds [Member] Discontinued Operations, Disposed of by Sale Discontinued Operations, Disposed of by Sale [Member] Effect of dilutive securities: Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] Notes, $6.1%, due 2041 Debentures Notes, 6.1%, Due 2041 [Member] Debentures Notes, 6.1%, Due 2041 Adjustment to Compensation: Adjustment to Compensation [Axis] Prepaid and other current assets Prepaid and other current assets Prepaid Expense and Other Assets, Current Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Document Transition Report Document Transition Report Document Quarterly Report Document Quarterly Report Other revenues Other Revenue Other Revenue Schedule of Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest [Table Text Block] Goodwill impairment and loss on sale Goodwill Impairment And Loss On Sale Goodwill Impairment And Loss On Sale Prepaid and other current assets Prepaid And Other Current Assets Policy [Policy Text Block] Prepaid And Other Current Assets Policy Customer [Domain] Customer [Domain] Variable Rate Component [Axis] Variable Rate Component [Axis] Variable Rate Component Accumulated other comprehensive loss, net Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Current Reporting Status Entity Current Reporting Status Retained earnings Retained earnings Retained Earnings [Member] Ownership percentage by noncontrolling owners Subsidiary, Ownership Percentage, Noncontrolling Owner Proceeds from Centuri initial public offering, net Proceeds from Issuance Initial Public Offering Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Related Party [Axis] Related and Nonrelated Parties [Axis] Basic (in shares) Weighted average basic shares (in shares) Weighted Average Number of Shares Outstanding, Basic Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Income taxes payable, net Income Taxes Payable, Net Income Taxes Payable, Net Total equity Beginning balance Ending balance Total equity ending balances Equity, Including Portion Attributable to Noncontrolling Interest Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Executive Category: Executive Category [Axis] Name Awards Close in Time to MNPI Disclosures, Individual Name Entity Filer Category Entity Filer Category Time and materials contracts Time-and-Materials Contract [Member] Transaction price allocated to unsatisfied performance obligations of contracts Revenue, Remaining Performance Obligation, Amount Contributions from Southwest Gas Holdings, Inc. Adjustments To Additional Paid In Capital Contributions From Parent Adjustments to additional paid in capital contributions from parent. Company Selected Measure Name Company Selected Measure Name