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Line of Credit Line of Credit [Member] Transmission Gas Transmission [Member] Annual utility depreciation and amortization expense percentage Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service Segment Reporting [Abstract] Segment Reporting [Abstract] Debt Instrument, Covenant, Period Three Debt Instrument, Covenant, Period Three [Member] Debt Instrument, Covenant, Period Three Entity Central Index Key Entity Central Index Key Other segment items Segment Reporting, Other Segment Item, Amount Changes in customer advances Changes in customer advances Changes In Customer Advances, Investing Activities Changes In Customer Advances, Investing Activities Deferred compensation plan, payment term, option three Deferred Compensation Plan, Payment Term, Option Three Deferred Compensation Plan, Payment Term, Option Three Foreign currency translation adjustments 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 Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Segment Information Segment Reporting Disclosure [Text Block] Current maturities of long-term debt Less: current maturities Long-Term Debt, Current Maturities Fair Value, Inputs, Level 1 and 2 Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Net actuarial gain/(loss) Amortization of net actuarial loss Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Regulatory assets, margin, interest and property tax-tracking, recovery period Regulatory Assets, Margin, Interest And Property Tax-Tracking, Recovery Period Regulatory Assets, Margin, Interest And Property Tax-Tracking, Recovery Period Deferred tax liabilities: Deferred Tax Liabilities, Net [Abstract] Measurement Basis [Axis] Measurement Basis [Axis] MountainWest sale/goodwill impairment MountainWest Sale/Goodwill Impairment [Member] MountainWest Sale/Goodwill Impairment Impairment of assets and other charges Impairment Of Assets And Other Charges Impairment Of Assets And Other Charges Title Trading Arrangement, Individual Title Other current assets and liabilities Other current assets and liabilities Increase (Decrease) in Other Current Assets and Liabilities, Net Environmental compliance programs Environmental Compliance Programs [Member] Environmental compliance programs. Foreign Currency and Centuri IPO Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] Summary of Income (Loss) Before Taxes and Noncontrolling Interest for Domestic and Foreign Operations Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Geographic Concentration Risk Geographic Concentration Risk [Member] Unrecognized tax benefits at beginning of year Unrecognized tax benefits at end of year Unrecognized Tax Benefits Increase of weighted-average rate of compensation Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase, Increase (Decrease) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase, Increase (Decrease) Comprehensive income attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest City Area Code City Area Code Current liabilities: Current liabilities: Liabilities, Current [Abstract] Auditor Location Auditor Location Net regulated operations plant Public Utilities, Property, Plant and Equipment, Net Disposal Group Classification [Domain] Disposal Group Classification [Domain] Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Estimated loss on disposition of assets Gain (Loss) on Disposition of Assets Accrued taxes Accrued taxes Increase (Decrease) in Accrued Taxes Payable Debt-related costs Deferred Tax Liabilities, Debt-Related Costs Deferred Tax Liabilities, Debt-Related Costs Equity ownership, percentage purchased Equity Ownership, Percentage Purchased During Period Equity Ownership, Percentage Purchased During Period 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] Weighted-average grant date fair value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Background, Organization, and Summary of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Earnings (loss) per share attributable to Southwest Gas Holdings, Inc.: Earnings Per Share [Abstract] 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 Equity [Abstract] Equity [Abstract] Change in long-term credit facility and commercial paper 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 Retained earnings Retained earnings Retained Earnings (Accumulated Deficit) Schedule of Nonvested Performance and Restricted Stock Unit Plans Schedule of Nonvested Share Activity [Table Text Block] Class of Stock [Domain] Class of Stock [Domain] Net (loss) income Net income Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Transportation Transportation [Member] Transportation. 2026 Long-Term Debt, Maturity, Year Two Schedule of Accounts Receivable for Services Accounts Receivable For Services [Table Text Block] Accounts Receivable For Services Table Text Block. Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Equity Awards Adjustments Equity Awards Adjustments [Member] Total operating lease liabilities Total Operating Lease, Liability Underlying Securities Award Underlying Securities Amount Performance Stock Units Performance Shares [Member] Regulatory Assets And Liabilities [Line Items] Regulatory Assets And Liabilities [Line Items] Regulatory Assets And Liabilities [Line Items] Weighted-average assumptions (net benefit cost) Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] 2029 Finance Lease, Liability, to be Paid, Year Five Interest income Interest income Interest Income, Other Amendment Flag Amendment Flag Carrying Amount Reported Value Measurement [Member] Gains on sale of property and equipment Gain on sale of property Gain (Loss) on Disposition of Property Plant Equipment Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Amortization of ROU assets Finance Lease, Right-of-Use Asset, Amortization Deferred compensation, percentage of multiple interest rate Floating Interest Rate Index Floating Interest Rate Index Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) 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] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Condensed Income Statement [Table] Condensed Income Statement [Table] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Debt instrument face amount Debt Instrument, Face Amount Issuance of short-term debt Issuance of short-term debt Proceeds from Short-Term Debt Entity Address, Postal Zip Code Entity Address, Postal Zip Code Self-insured retention amount associated with general liability claims Self Insured Retention Amount Associated With General Liability Claims Amount of risk retained by the entity per incident before the insurance arrangement begins to provide coverage. Change in COLI policies Life Insurance, Corporate or Bank Owned, Change in Value Electric power infrastructure services Electric Power Infrastructure Services [Member] Electric Power Infrastructure Services [Member] Industrial/other Industrial/other [Member] Industrial/other. Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Other Other Payments for (Proceeds from) Other Investing Activities Large commercial Large Commercial [Member] Large commercial. Number of performance share units granted (in shares) Number Of Performance Share Units Granted Number Of Performance Share Units Granted. 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] Auditor Name Auditor Name Reclassification from AOCI, tax Reclassification from AOCI, Current Period, Tax Forfeited or expired (in USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Schedule of Other Property and Investments Investment [Table Text Block] Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Other current liabilities Other Current Liabilities [Member] 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] Redeemable Noncontrolling Interests Noncontrolling Interest Disclosure [Text Block] Depreciation and amortization Depreciation and amortization expense Depreciation, Depletion and Amortization, Nonproduction Fair Value Measurement [Domain] Fair Value Measurement [Domain] Accrued pension and other postretirement benefit costs Accrued Pension And Other Postretirement Benefit Costs [Member] Accrued Pension And Other Postretirement Benefit Costs [Member] Accounts payable Accounts payable Increase (Decrease) in Accounts Payable 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 Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Foreign transaction gain (loss) Realized Gain (Loss), Foreign Currency Transaction, before Tax Net cost of gas sold Net cost of gas sold Utilities Operating Expense, Gas and Petroleum Purchased Financing cash flows from finance leases Finance Lease, Principal Payments 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] 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] Total assets Segment assets Assets Other Current Liabilities Other Current Liabilities [Policy Text Block] Other Current Liabilities [Policy Text Block] Utility infrastructure services expenses Cost of Goods and Services Sold Auditor [Line Items] Auditor [Line Items] Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss Defined Benefit Plan, Amount Recognized in Net Periodic Benefit Cost (Credit) and Other Comprehensive (Income) Loss, before Tax Income taxes receivable, net Income Taxes Receivable, Current 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 Commitments and contingencies (Note 10) Commitments and contingencies (Note 10) Commitments and Contingencies Deferred compensation plan, matching percentage Deferred Compensation Arrangement With Individual, Matching Percentage Deferred Compensation Arrangement With Individual, Matching Percentage Income Tax [Table] Income Tax [Table] Income Tax [Table] Summary of Reconciliation of U.S Federal Statutory Rate to Consolidated Effective Tax Rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] 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 Gross-up related to contributions in aid of construction Gross-Up Related To Contributions In Aid Of Construction [Member] Gross-Up Related To Contributions In Aid Of Construction [Member] Termination Date Trading Arrangement Termination Date EIP, percent of compensation deferred with match Employees' Investment Plan, Percent Of Compensation Deferred With Match Employees' Investment Plan, Percent Of Compensation Deferred With Match 2026 Lessee, Operating Lease, Liability, to be Paid, Year Two 2025 Long-Term Debt, Maturity, Year One Preferred stock purchase right, purchase price per one ten-thousandth of one preferred stock Preferred Stock Purchase Right, Purchase Price Per One Ten-Thousandth Of One Preferred Stock Preferred Stock Purchase Right, Purchase Price Per One Ten-Thousandth Of One Preferred Stock Schedule of Revenues by Geographic Area Revenue from External Customers by Geographic Areas [Table Text Block] Debt Instrument [Axis] Debt Instrument [Axis] Unit-price contracts Unit Priced Contracts [Member] Unit priced contracts. Unsold accounts receivable, held as collateral Accounts Receivable Securitization, Unsold Receivables Accounts Receivable Securitization, Unsold Receivables Noncontrolling Interest [Abstract] Noncontrolling Interest [Abstract] Net income (loss) attributable to Southwest Gas Holdings, Inc. Net income attributable to Southwest Gas Holdings, Inc. Net Income (Loss) Net Income (Loss) Attributable to Parent Trading Arrangement: Trading Arrangement [Axis] Distribution Gas Distribution [Member] Regulated Operations Plant and Leases Regulated Operations Plant And Leases Disclosure [Text Block] Regulated Operations Plant And Leases Disclosure 2030-2034 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Schedule of Fair Value of Plan Assets Schedule of Allocation of Plan Assets [Table Text Block] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Entity File Number Entity File Number Multiemployer plan, special surcharges Multiemployer Plan, Special Surcharges Multiemployer Plan, Special Surcharges Schedule of Assumptions Used Defined Benefit Plan, Assumptions [Table Text Block] Number of customers party to contracts with rate components subject to negotiation (less than) Number Of Customers Party To Contracts With Rate Components Subject To Negotiation Number Of Customers Party To Contracts With Rate Components Subject To Negotiation Noncontrolling Interest Noncontrolling Interest [Member] Income Statement [Abstract] Income Statement [Abstract] Entity Address, Address Line One Entity Address, Address Line One Capital Loss Carryforward Capital Loss Carryforward [Member] Federal Current Federal Tax Expense (Benefit) Weighted average shares: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Weighted average discount rate Leases, Weighted Average Discount Rate [Abstract] Leases, Weighted Average Discount Rate 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 ($2.48 per share) Dividends declared to Southwest Gas Holdings, Inc. Dividends, Common Stock Name Forgone Recovery, Individual Name Operating leases Operating Lease, Weighted Average Remaining Lease Term Contract with Customer, Basis of Pricing [Domain] Contract with Customer, Basis of Pricing [Domain] Repayments of accounts receivable securitization Repayments of Accounts Receivable Securitization Deferred income taxes Deferred income taxes Increase (Decrease) in Deferred Income Taxes Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Preferred Stock Purchase Rights Preferred Stock Purchase Rights [Member] Preferred Stock Purchase Rights Schedule of Expected Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] Gross decreases – tax positions in prior period Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Performance measurement period Share-based Compensation Arrangement by Share-based Payment Award, Performance Measurement Period Share-based Compensation Arrangement by Share-based Payment Award, Performance Measurement Period Contracts receivable, net Contracts receivable, net Contract with Customer, Asset, after Allowance for Credit Loss Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Public Utility [Axis] Public Utility [Axis] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Yield charge on securitization Yield Charge on Securitization Yield Charge on Securitization 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] Adjustment to Compensation: Adjustment to Compensation [Axis] Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Natural Gas Distribution Natural Gas Distribution Segment [Member] Natural Gas Distribution Segment Maximum loss exposure amount Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount Amended cooperation agreement term, period prior to expiration of advance notice deadline Amended Cooperation Agreement, Period Prior To Expiration Of Advance Notice Deadline Amended Cooperation Agreement, Period Prior To Expiration Of Advance Notice Deadline Amounts reclassified into net income FSIRS amounts reclassified to net income, net of tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax Accumulated other comprehensive loss, net Accumulated other comprehensive loss, net Accumulated Other Comprehensive Income (Loss), Net of Tax Linetec Linetec Services, LLC [Member] Linetec Services, LLC [Member] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Related Party, Type [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] Gas, Transmission and Distribution Plant Gas, Transmission and Distribution Equipment [Member] Accounts receivable securitization, maximum amount authorized Accounts Receivable Securitization, Maximum Amount Authorized Accounts Receivable Securitization, Maximum Amount Authorized Total equity Beginning balance Ending balance Total equity Equity, Including Portion Attributable to Noncontrolling Interest Defined benefit plan, plan assets, target allocation, percentage Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Other property and investments adjustment Other Property And Investments, Net Other Property And Investments, Net Property-related items Property Related Items [Member] Property-Related Items [Member] Name Awards Close in Time to MNPI Disclosures, Individual Name Nevada NEVADA Entity Filer Category Entity Filer Category Transaction price allocated to unsatisfied performance obligations of contracts Revenue, Remaining Performance Obligation, Amount Loss Contingencies [Line Items] Loss Contingencies [Line Items] Employee benefits Deferred Tax Liabilities, Employee benefits, Net Deferred Tax Liabilities, Employee benefits, Net Net Assets, Geographic Area Net Assets, Geographic Area [Member] Purchased gas cost adjustments Purchased Gas Cost Adjustments [Member] Purchased Gas Cost Adjustments [Member] QRP QRP Other Pension Plan [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] Significant Components of Deferred Income Tax Expense (Benefit) Schedule Of Deferred Income Tax Expense Benefit [Table Text Block] Schedule Of Deferred Income Tax Expense (Benefit) [Table Text Block] Capital expenditures Segment, Expenditure, Addition to Long-Lived Assets Schedule of Components of Lease Expense, and Supplemental Cash Flow Information Related to Leases Lease, Cost [Table Text Block] Significant Components Of Deferred Income Tax Expense [Table] Significant Components Of Deferred Income Tax Expense [Table] Significant Components Of Deferred Income Tax Expense [Table] Deferred charges and other assets Deferred Charges And Other Assets [Member] Deferred Charges And Other Assets [Member] Fixed-price contracts Fixed-Price Contract [Member] Employee benefits Employee Benefits [Member] Employee Benefits [Member] Mutual funds Mutual Fund [Member] Other current liabilities Other current liabilities Other Liabilities, Current Unrecognized tax benefits that, if recognized, would affect the effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Future estimated funding amount Future Estimated Funding Amount In Next Fiscal Year Future estimated funding amount in next fiscal year Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Redeemable noncontrolling interest, equity, redemption value Redeemable Noncontrolling Interest, Equity, Redemption Value All Trading Arrangements All Trading Arrangements [Member] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Tax credit carryforward Tax Credit Carryforward, Amount Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Previous Owner Of Linetec Previous Owner Of Linetec [Member] Previous Owner Of Linetec Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Income taxes paid, net Income taxes paid (received), net Income Taxes Paid, Net Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Pay vs Performance Disclosure [Line Items] Redeemable noncontrolling interest Beginning balance Ending balance Redeemable Noncontrolling Interest, Equity, Carrying Amount Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] SERP Supplemental Employee Retirement Plan [Member] Deferred: Deferred federal and state: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] W.S. Nicholls Western Construction LTD WS Nicholls Western Construction Ltd [Member] WS Nicholls Western Construction Ltd. Share-based compensation plan expense, net of related tax benefits Share-Based Payment Arrangement, Expense, after Tax Other Performance Measure, Amount Other Performance Measure, Amount Deferred Income Tax Expense (Benefit Components [Axis] Deferred Income Tax Expense (Benefit Components [Axis] Deferred Income Tax Expense (Benefit Components Weighted-average rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase 2027 Finite-Lived Intangible Asset, Expected Amortization, Year Three Non-service 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] Common stock, outstanding (in shares) Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Operating lease cost Operating Lease, Cost Other deferred credits and other long-term liabilities Operating Lease, Liability, Noncurrent Net operating loss Net Operating Loss [Member] Net Operating Loss Benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Debentures Debentures [Member] Debentures [Member] Schedule of Regulatory Liabilities [Table] Regulated Operation, Regulatory Liability [Table] Redemption of redeemable noncontrolling interest Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Interest on lease liabilities Finance Lease, Interest Expense Schedule of Regulatory Assets [Table] Regulated Operation, Regulatory Asset [Table] Customer deposits Customer deposits Contract with Customer, Liability, Current Schedule of Regulatory Liabilities Schedule of Regulatory Liabilities [Table Text Block] 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 Debt covenant, additional debt amount could be issued Debt Instrument, Covenant, Compliance Credit Risk Exposure Amount Debt instrument covenant compliance credit risk exposure amount. Entity Tax Identification Number Entity Tax Identification Number Equity Securities Defined Benefit Plan, Equity Securities [Member] Schedule of Finite-Lived Intangible Assets [Table] Intangible Asset, Finite-Lived [Table] Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt Schedule of Long-Term Debt Instruments [Table Text Block] Gross increases – tax positions in prior period Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Foreign Deferred Foreign Income Tax Expense (Benefit) Retirement Plan Type [Axis] Retirement Plan Type [Axis] Receivables and Related Allowances Loans, Notes, Trade and Other Receivables Disclosure [Text Block] AOCI Including Portion Attributable to Noncontrolling Interest AOCI Including Portion Attributable to Noncontrolling Interest [Member] Money Market Funds Money Market Funds [Member] Weighted-average rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Net proceeds from sale of stock Sale of Stock, Consideration Received on Transaction Deferred tax assets: Deferred Tax Assets, Net [Abstract] Intersegment sales Intersegment Eliminations [Member] Unamortized gain on reacquired debt Unamortized Gain On Reacquired Debt [Member] Unamortized Gain On Reacquired Debt [Member] Plan Name [Axis] Plan Name [Axis] Regulatory balancing accounts Deferred Tax Liabilities, Regulatory Assets and Liabilities Thereafter Finance Lease, Liability, to be Paid, after Year Five Equity Components [Axis] Equity Components [Axis] Total lease payments Finance Lease, Liability, to be Paid Receivables and Related Allowances Accounts Receivable [Policy Text Block] Notes, 3.18%, due 2051 Debentures Notes, 3.18%, Due 2051 [Member] Debentures Notes, 3.18%, Due 2051 Total operating expenses Costs and Expenses Net actuarial loss Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Southwest Gas Holdings, Inc. Southwest Gas Holdings, Inc. [Member] Southwest Gas Holdings, Inc. Receivable [Domain] Receivable [Domain] Revenues from external customers Operating Segments, Excluding Intersegment Elimination [Member] Operating Segments, Excluding Intersegment Elimination Geographical [Axis] Geographical [Axis] Certain Assets Associated With Previous Corporate Headquarters Certain Assets Associated With Previous Corporate Headquarters [Member] Certain Assets Associated With Previous Corporate Headquarters Percentage of equity interest exchanged with debt forgiveness Percentage Of Equity Interest Exchanged With Debt Forgiveness Percentage Of Equity Interest Exchanged With Debt Forgiveness Bid contract Bid Contract [Member] Bid contract. 2029 Lessee, Operating Lease, Liability, to be Paid, Year Five 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] Schedule of Allowance for Uncollectibles Accounts Receivable, Allowance for Credit Loss [Table Text Block] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] 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 Prior service cost Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Number of contracts with original duration more than one year Revenue Recognition, Number Of Contracts With Original Duration More Than One Year Revenue Recognition, Number Of Contracts With Original Duration More Than One Year Deferred compensation plan, percentage of contributions with matching Deferred Compensation Arrangement With Individual, Percentage Of Contributions With Matching Deferred Compensation Arrangement With Individual, Percentage Of Contributions With Matching 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 Weighted average interest rate Debt, Weighted Average Interest Rate Amortization of net actuarial loss Amortization of net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax FSIRS: FSIRS: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Compensation cost related to nonvested management incentive plan shares, performance shares, and restricted stock/units not yet recognized Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Foreign Current Foreign Tax Expense (Benefit) Net actuarial loss (gain) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Deferred income taxes and investment tax credits, net 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. Current assets: Current assets: Assets, Current [Abstract] Consolidation Items [Axis] Consolidation Items [Axis] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Product and Service [Domain] Product and Service [Domain] Short-term lease cost Short-Term Lease, Cost $300 Million Credit Facility $300 Million Credit Facility [Member] $300 Million Credit Facility Vested and issued (in USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Goodwill [Roll Forward] Goodwill [Roll Forward] Security Exchange Name Security Exchange Name Debt, basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Total other comprehensive income (loss) - noncontrolling interest, net-of- tax amount Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest Restricted Stock/ Units Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] State Current State and Local Tax Expense (Benefit) Short-term debt Short-Term Debt Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Notes, 3.7%, due 2028 Debentures Notes, 3.7%, Due 2028 [Member] Debentures Notes, 3.7%, Due 2028 Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Finance leases Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Revolving credit facility and commercial paper Revolving Credit Facility And Commercial Paper [Member] Revolving Credit Facility And Commercial Paper [Member] Total other comprehensive income (loss), net-of- tax amount Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Subsequent Events Subsequent Events, Policy [Policy Text Block] Common stock, issued (in shares) Common Stock, Shares, Issued Amortization of net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Entity [Domain] Entity [Domain] Concentration risk, percentage Concentration Risk, Percentage Credit facility maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Total income before income taxes Income (Loss), Including Portion Attributable to Noncontrolling Interest, before Tax Receivables And Related Allowances [Table] Receivables And Related Allowances [Table] Receivables And Related Allowances [Table] Dividends (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Dividends Share based compensation arrangement by share based payment award equity instruments other than options dividends 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 Public Utility, Property, Plant and Equipment [Line Items] Public Utility, Property, Plant and Equipment [Line Items] Total deferred federal and state Deferred Income Tax Expense (Benefit), Gross Deferred Income Tax Expense (Benefit), Gross Common stock, authorized (in shares) Common Stock, Shares Authorized General General [Member] General [Member] Acquisition of businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Change in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Continuing Operations Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Pipeline And Storage Pipeline And Storage Segment [Member] Pipeline And Storage Segment Accrued purchased gas costs Accrued Purchased Gas Costs [Member] Accrued Purchased Gas Costs [Member] Entity Voluntary Filers Entity Voluntary Filers Related Party Related Party [Member] Amortization of net actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Lease renewal term (up to) Lessee, Operating Lease, Renewal Term Balance Sheet Location [Axis] Statement of Financial Position Location, Balance [Axis] Net interest deductions Interest expense Interest Expense, Nonoperating Total deferred income tax expense (benefit) Deferred Income Tax Expense (Benefit) Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Contributions from Southwest Gas Holdings, Inc. Adjustments To Additional Paid In Capital Contributions From Parent Adjustments to additional paid in capital contributions from parent. Total other comprehensive income (loss), tax (expense) or benefit Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Income taxes payable, net Income Taxes Payable Net Income taxes payable net. Accounts receivable, net of allowances Customer accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Ownership percentage by parent Subsidiary, Ownership Percentage, Parent Schedule of Supplemental Information Related to Leases Included in Balance Sheet Assets And Liabilities, Lessee [Table Text Block] Assets And Liabilities, Lessee [Table Text Block] Accounts written off, less recoveries Accounts Receivable, Allowance For Credit Loss, Write Off, Net Of Recoveries Accounts Receivable, Allowance For Credit Loss, Write Off, Net Of Recoveries Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Changes in other liabilities and deferred credits 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 Total Long-term debt outstanding Long-Term Debt Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Market value of plan assets at beginning of year Market value of plan assets at end of year Defined benefit plan, plan assets, amount Defined Benefit Plan, Plan Assets, Amount Additional self-insured retention amount of general liability Additional Self Insured Retention Amount Of General Liability Additional self-insured retention amount of general liability Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Document Annual Report Document Annual Report 2027 Finance Lease, Liability, to be Paid, Year Three 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 Other Regulatory Liabilities, Other, Miscellaneous [Member] Regulatory Liabilities, Other, Miscellaneous Vested and issued (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Southwest Gas Holdings, Inc. Parent [Member] Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward] Equity, Attributable to Noncontrolling Interest [Roll Forward] Amortization of intangibles Amortization of Intangible Assets EIP, employer matching contribution, percent of match Employees' Investment Plan, Employer Matching Contribution, Percent Of Match Employees' Investment Plan, Employer Matching Contribution, Percent Of Match State mandated public purpose programs (including low income and conservation programs) State Mandated Public Purpose Programs [Member] State and mandated public purpose programs (including low income and conservation programs). Operating revenues: Revenues [Abstract] Net income attributable to redeemable noncontrolling interests Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Current Fiscal Year End Date Current Fiscal Year End Date Less imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Regulatory Asset [Domain] Regulatory Asset [Domain] PEO Name PEO Name AFUDC rate Public Utilities, Allowance for Funds Used During Construction, Rate Common stock issued (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period Vesting [Axis] Vesting [Axis] Award Type [Domain] Award Type [Domain] Master services agreement Master Services Agreement [Member] Master Services Agreement [Member] Industrial development revenue bonds Industrial Development Revenue Bonds [Member] Industrial Development Revenue Bonds [Member] Other comprehensive income (loss) before reclassifications, tax Other Comprehensive Income (Loss) before Reclassifications, Tax Promissory Note Promissory Note [Member] Promissory Note Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax 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 Accrued utility revenue Accrued utility revenue Accrued Utility Revenue Accrued utility revenue. Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Revision of Prior Period [Axis] Revision of Prior Period [Axis] Deferred income taxes Deferred Income Tax Assets, Net Non-PEO NEO Non-PEO NEO [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Other deferred credits and other long-term liabilities Finance Lease, Liability, Noncurrent Schedule of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Decrease in contract assets Increase (Decrease) in Contract with Customer, Asset Pension and Other Postretirement Benefits Retirement Benefits [Text Block] Dividends (in USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Dividends, Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Dividends, Weighted Average Grant Date Fair Value Class of Stock [Line Items] Class of Stock [Line Items] Regulatory Liability [Axis] Regulatory Liability [Axis] Recent Accounting Standards Updates New Accounting Pronouncements, Policy [Policy Text Block] Class of Stock [Axis] Class of Stock [Axis] Accounts receivable securitization term (in years) Accounts Receivable Securitization, Term Accounts Receivable Securitization, Term Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Centuri Centuri Group, Inc. [Member] Centuri Group, Inc. [Member] 2028 Finance Lease, Liability, to be Paid, Year Four Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Schedule of Defined Benefit Plans Disclosures Schedule of Defined Benefit Plans Disclosures [Table Text Block] Name Measure Name Entity Interactive Data Current Entity Interactive Data Current Canada CANADA 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 Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Changes in undistributed stock compensation Compensation expense Share-Based Payment Arrangement, Noncash Expense Deferred tax assets, total Deferred Tax Assets, Net of Valuation Allowance Insurance company general account contracts Fair Value Measured at Net Asset Value Per Share [Member] Vesting Tranche Two Share-Based Payment Arrangement, Tranche Two [Member] Pension plans other comprehensive income (loss) Defined Benefit Plans Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Debt instrument interest rate Debt instrument, stated interest rate Debt Instrument, Interest Rate, Stated Percentage Corporate and administrative Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] SUPPLEMENTAL INFORMATION: SUPPLEMENTAL INFORMATION: Supplemental Cash Flow Information [Abstract] 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 Total other income and (expenses) Nonoperating Income (Expense) Number of types of agreements with customers Number Of Types Of Agreements With Customers Number Of Types Of Agreements With Customers Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Auditor Firm ID Auditor Firm ID Consolidated effective income tax rate Effective Income Tax Rate Reconciliation, Percent Operating income (loss) Net impact Operating Income (Loss) Regulatory adjustments Regulatory Adjustments [Member] Regulatory Adjustments [Member] Gas plant Natural Gas Processing Plant [Member] Operations and Maintenance Expense Operations And Maintenance Expense [Policy Text Block] Operations And Maintenance Expense Policy Text Block Variable Rate [Domain] Variable Rate [Domain] Number of reportable segments Number of Reportable Segments Total capitalization and liabilities Liabilities and Equity Percentage of redeemable noncontrolling interest redeemed Redeemable Noncontrolling Interest, Percentage Redeemed Redeemable Noncontrolling Interest, Percentage Redeemed Defined benefit plan, plan assets, shares redeemed with notice, period Defined Benefit Plan, Plan Assets, Shares Redeemed With Notice, Period Defined Benefit Plan, Plan Assets, Shares Redeemed With Notice, Period Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Line of credit designated for working capital purposes Line Of Credit Facility Working Capital Purposes Line Of Credit Facility, Working Capital Purposes Defined Benefit Plan, Equity Securities, Non-US Defined Benefit Plan, Equity Securities, Non-US [Member] 2026 Finance Lease, Liability, to be Paid, Year Two Other deferred credits and other long-term liabilities Other Deferred Credits And Other Long-term Liabilities [Member] Other Deferred Credits And Other Long-term Liabilities [Member] Regulated Operations [Abstract] Regulated Operations [Abstract] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Estimated Maturities of Long-Term Debt Schedule of Maturities of Long-Term Debt [Table Text Block] Operating leases Right-of-Use Asset Obtained in Exchange for Operating Lease Liability 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 Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Individual: Individual [Axis] General Business Tax Credit Carryforward General Business Tax Credit Carryforward [Member] Construction work in progress Construction work in progress Public Utilities, Property, Plant and Equipment, Construction Work in Progress AOCI AOCI Attributable to Parent AOCI Attributable to Parent [Member] Schedule of Regulatory Assets Schedule of Regulatory Assets [Table Text Block] Accounts receivable, extending period Accounts Receivable, Extending Period Accounts Receivable, Extending Period Product and Service [Axis] Product and Service [Axis] Gas utility customer accounts receivable balance Gas Utility Customer Accounts Receivable Gas Utility Customer Accounts Receivable Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Statement [Line Items] Statement [Line Items] 2008 Series A, due 2038 Variable Rate Bonds 2008 Series A- Due 2038 [Member] Variable Rate Bonds 2008 Series A- Due 2038 Accumulated Removal Costs Accumulated Removal Costs [Policy Text Block] Accumulated Removal Costs Policy Text Block. Benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] IPO IPO [Member] Derivatives Derivatives, Policy [Policy Text Block] Centuri And MountainWest Centuri And MountainWest [Member] Centuri And MountainWest Unamortized discount and debt issuance costs Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Minimum Minimum [Member] Notes, 5.45%, due 2028 Debentures Notes, 5.45%, Due 2028 [Member] Debentures Notes, 5.45%, Due 2028 Adoption Date Trading Arrangement Adoption Date 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 Schedule of Capitalized and Debt Portion of AFUDC Schedule of Capitalization [Table Text Block] Additions charged to expense Accounts Receivable, Credit Loss Expense (Reversal) 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] U.S. federal statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Variable Rate Component [Axis] Variable Rate Component [Axis] Variable Rate Component Long-term debt, gross Long-Term Debt, Gross Exercise Price Award Exercise Price Summary of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Total operating revenues Regulated operations revenues Revenues Regulated and Unregulated Operating Revenue Per capita cost of covered health care benefits medical rate trend assumption Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Arrangement Duration Trading Arrangement Duration Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Revision of Prior Period, Error Correction, Adjustment Revision of Prior Period, Error Correction, Adjustment [Member] Operating loss carryforward Operating Loss Carryforwards EIP, employer matching contribution, percent of employees' eligible compensation Employees' Investment Plan, Employer Matching Contribution, Percent Of Employees' Eligible Compensation Employees' Investment Plan, Employer Matching Contribution, Percent Of Employees' Eligible Compensation Deferred compensation plan, maximum percentage of salary deferral Deferred Compensation Arrangement With Individual, Maximum Percentage Of Deferral Deferred Compensation Arrangement With Individual, Maximum Percentage Of Deferral Federal Domestic Tax Jurisdiction [Member] Deferred purchased gas costs Deferred purchased gas costs Deferred Gas Purchases, Current Southwest Gas Corporation Southwest Gas Corporation [Member] Southwest gas corporation. Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Notes, 4.05%, due 2032 Debentures Notes, 4.05%, Due 2032 [Member] Debentures Notes, 4.05%, Due 2032 Total finance lease liabilities Total Finance Lease, Liability 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Four All Individuals All Individuals [Member] Audit Information [Abstract] Audit Information [Abstract] Increase in discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Increase (Decrease) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Increase (Decrease) Variable Rate [Axis] Variable Rate [Axis] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Entities [Table] Entities [Table] Meals and entertainment expenses Effective Income Tax Rate Reconciliation, Nondeductible Expense, Meals and Entertainment, Percent Other income (deductions) Other income (deductions) Total other income (deductions) Other Nonoperating Income (Expense) Summary 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 Contracts Receivables And 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. PBOP Other Postretirement Benefits Plan [Member] Debt covenant, net leverage ratio Line Of Credit Facility, Covenants, Net Leverage Ratio Line Of Credit Facility, Covenants, Net Leverage Ratio Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Receivables [Abstract] Receivables [Abstract] Deferred compensation plan, payment term, option one Deferred Compensation Plan, Payment Term, Option One Deferred Compensation Plan, Payment Term, Option One Fixed Income Investments Fixed Income Investments [Member] Schedule of Amount Recognized Before Income Tax in Accumulated Other Comprehensive Income Schedule of Amounts Recognized in Other Comprehensive Income Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] MountainWest sale Effective Income Tax Rate Reconciliation, Disposition of Business, Percent Goodwill impairment and loss on sale Goodwill Impairment And Loss On Sale Goodwill Impairment And Loss On Sale Cumulative foreign earnings Undistributed Earnings of Foreign Subsidiaries 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] Change in plan assets: Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Operations and maintenance Operations and maintenance Operations and maintenance expense Utilities Operating Expense, Maintenance and Operations Equity portion 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] Related Party, Type [Domain] Related and Nonrelated Parties [Domain] Accounts receivable securitization, remaining amount authorized Accounts Receivable Securitization, Remaining Amount Authorized Accounts Receivable Securitization, Remaining Amount Authorized Debt covenant, ratio of funded debt to total capitalization Debt Instrument, Covenant, Ratio Of Funded Debt To Total Capitalization Debt Instrument, Covenant, Ratio Of Funded Debt To Total Capitalization Operating leases: Operating Lease, Assets And Liabilities, Lessee [Abstract] Operating Lease, Assets And Liabilities, Lessee Change in short-term portion of credit facility Proceeds from (Repayments of) Lines of Credit Schedule of Depreciation and Amortization Expense Schedule Of Depreciation And Amortization Expense [Table Text Block] Schedule Of Depreciation And Amortization Expense Table Text Block Deferred purchased gas costs Deferred purchased gas costs Increase (Decrease) in Deferred Gas Cost Allowance for doubtful accounts Contract with Customer, Asset, Allowance for Credit Loss Debt Instrument, Covenant, Period [Axis] Debt Instrument, Covenant, Period [Axis] Debt Instrument, Covenant, Period Net recovery claims Amounts billed in excess of revenue earned on contracts Contract with Customer, Receivable, after Allowance for Credit Loss Ownership percentage disposed Disposal Group, Including Discontinued Operation, Ownership Percentage in Disposed Asset Disposal Group, Including Discontinued Operation, Ownership Percentage in Disposed Asset Changes in deferred charges and other assets Changes in deferred charges and other assets Increase (Decrease) in Other Operating Assets Other revenues Other Revenue Other Revenue Net defined benefit pension plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Common stock, dividend, number of preferred stock purchase rights Common Stock, Dividends, Number Of Preferred Stock Purchase Rights Common Stock, Dividends, Number Of Preferred Stock Purchase Rights Federal Deferred Federal Income Tax Expense (Benefit) Deferred purchased gas costs Deferred purchased gas costs Deferred Gas Cost Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] No Trading Symbol Flag No Trading Symbol Flag Stock issuance costs Payments of Stock Issuance Costs Beginning balance, attributable to parent, tax Ending balance, attributable to parent, tax Stockholders' Equity Attributable To Parent, Tax Stockholders' Equity Attributable To Parent, Tax Employee benefits Deferred Tax Assets, Employee benefits, Net Deferred Tax Assets, Employee benefits, Net Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Deferred purchased gas costs Deferred Purchased Gas Costs, Assets [Member] Deferred Purchased Gas Costs, Assets Thereafter Finite-Lived Intangible Asset, Expected Amortization, after Year Five Change in benefit obligations: Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Measure: Measure [Axis] Accrued purchased gas costs Accrued Purchased Gas Costs Accrued Purchased Gas Costs Share-based compensation Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture Gross increases – current period tax positions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Long-Lived Assets Held-for-Sale by Asset Type [Axis] Long-Lived Asset, Held-for-Sale, Type [Axis] Regulatory adjustment Accumulated Defined Benefit Plans Adjustment, Regulatory Adjustment, Attributable to Parent [Member] Accumulated Defined Benefit Plans Adjustment, Regulatory Adjustment, Attributable to Parent [Member] Common stock issuances (in shares) Stock Issued During Period, Shares, New Issues 2025 Defined Benefit Plan, Expected Future Benefit Payment, Year One Total finance lease cost Finance Lease, Cost Finance Lease, Cost Entity Emerging Growth Company Entity Emerging Growth Company Deferred purchased gas costs, recovered or refunded period Deferred Purchased Gas Costs, Recovered Or Refunded Period Deferred Purchased Gas Costs, Recovered Or Refunded Period 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 2029 Long-Term Debt, Maturity, Year Five Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Schedule of Percent of Customers by State Schedule Of Percent Of Customers By State [Table Text Block] Schedule of percent of customers by state table text block. Reclassification from AOCI, before tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Other Other regulatory liabilities Regulatory Liabilities Other [Member] Regulatory Liabilities Other [Member] Other property and investments Finance Lease, Right-of-Use Asset, after Accumulated Amortization Equity Component [Domain] Equity Component [Domain] Regulatory adjustment Defined Benefit Plan Regulatory Adjustment Before Tax Net Defined benefit plan, regulatory adjustment before-tax net. Other Other regulatory assets Regulatory Assets Other [Member] Regulatory Assets Other [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 MountainWest MountainWest [Member] MountainWest Entity Shell Company Entity Shell Company Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code 2028 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Variable Rate Component Three Variable Rate Component Three [Member] Variable Rate Component Three Notes, 4.875%, due 2043 Debentures Notes, 4.875%, Due 2043 [Member] Debentures Notes, 4.875%, Due 2043 Statement [Table] Statement [Table] Other property and investments, net Other property and investments, net Other property and investments 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. Counterparty Name [Axis] Counterparty Name [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Debt covenant, dividend restriction calculation, period Debt Instrument, Covenant, Dividend Restriction Calculation, Period Debt Instrument, Covenant, Dividend Restriction Calculation, Period Interest paid, net of amounts capitalized Interest paid, net of amounts capitalized Interest Paid, Excluding Capitalized Interest, Operating Activities Regulatory excess deferred/other taxes and gross-up Regulatory Offsets To Deferred Tax Balances [Member] Regulatory offsets to deferred tax balances. 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