Number of shares, granted (in shares) Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Intangibles Deferred Tax Liabilities, Intangible Assets Significant Components Of Deferred Income Tax Expense [Line Items] Significant Components Of Deferred Income Tax Expense [Line Items] Significant Components Of Deferred Income Tax Expense [Line Items] Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Receivable Type [Axis] Receivable Type [Axis] Change in benefit obligations: Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Allowance for doubtful accounts Contract with Customer, Asset, Allowance for Credit Loss Change in plan assets: Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Noncontrolling Interest [Table] Noncontrolling Interest [Table] Prepaid and other current assets Regulatory Assets, Current Gas infrastructure services Gas Infrastructure Services [Member] Gas Infrastructure Services [Member] Condensed Income Statement [Table] Condensed Income Statement [Table] Total income before income taxes Income (Loss), Including Portion Attributable to Noncontrolling Interest, before Tax Statistical Measurement [Domain] Statistical Measurement [Domain] CAPITALIZATION AND LIABILITIES Liabilities and Equity [Abstract] Common Stock Common Stock Disclosure [Text Block] Common Stock Disclosure [Text Block] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Amortization of ROU assets Finance Lease, Right-of-Use Asset, Amortization Security Exchange Name Security Exchange Name Other Other Infrastructure Services [Member] Other Infrastructure Services [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 Issuance of long-term debt, net Proceeds from Issuance of Long-term Debt Total current liabilities Liabilities, Current Receivables and Related Allowances Accounts Receivable [Policy Text Block] Secured Revolving Credit Facility and Term Loan Secured Revolving Credit Facility Term Loan [Member] Secured Revolving Credit Facility Term Loan [Member] Regulatory assets, accrued absence time, lag period Regulatory Assets, Accrued Absence Time, Lag Period Regulatory Assets, Accrued Absence Time, Lag Period Performance Shares Performance Shares [Member] Prepaid and other current assets Prepaid Expense and Other Assets, Current Beginning balance (in USD per share) Ending balance (in USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Variable Rate [Domain] Variable Rate [Domain] 2025 Defined Benefit Plan, Expected Future Benefit Payment, Year Five Total lease payments Finance Lease, Liability, Payment, Due ASSETS Assets [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Investment, Name [Axis] Investment, Name [Axis] Alternative minimum tax credit Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax Share-based compensation Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture Operating cash flows from operating leases Operating Lease, Payments 2023 Long-Term Debt, Maturity, Year Three 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 Summary of Income Before Taxes for Continuing and Discontinued Operations Schedule Of Income Before Income Tax, Continuing And Discontinued Operations [Table Text Block] Schedule Of Income Before Income Tax, Continuing And Discontinued Operations [Table Text Block] Other Receivables [Member] Other Receivables [Member] Other Receivables Schedule Of Quarterly Financial Information [Table] Schedule Of Quarterly Financial Information [Table] Schedule Of Quarterly Financial Information [Table] 2021 Lessee, Operating Lease, Liability, to be Paid, Year One Accumulated removal costs Other Accrued Liabilities, Noncurrent 2024 Lessee, Operating Lease, Liability, to be Paid, Year Four Other deferred credits and other long-term liabilities Deferred Credits and Other Liabilities, Noncurrent 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 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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Lease renewal term (up to) Lessee, Operating Lease, Renewal Term Deferred compensation plan, vesting percentage of deferral Deferred Compensation Arrangement With Individual, Vesting Percentage Of Deferral Deferred Compensation Arrangement With Individual, Vesting Percentage Of Deferral Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] 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). Other revenue related to tax reform savings reserves/adjustments Other Revenue Related To Tax Reform Savings Reserves/Adjustments Other Revenue Related To Tax Reform Savings Reserves/Adjustments Emerging markets Emerging Markets [Member] Emerging markets. 2022 Lessee, Operating Lease, Liability, to be Paid, Year Two State State and Local Jurisdiction [Member] CASH FLOW FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Schedule of Components of Lease Expense, and Supplemental Cash Flow Information Related to Leases Lease, Cost [Table Text Block] Centuri term loan facility Centuri Term Loan Facility [Member] Centuri term loan facility. Reconciliation of Unrecognized Tax Benefits Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block] 2023 Lessee, Operating Lease, Liability, to be Paid, Year Three Deferred charges and other assets Other Assets, Noncurrent Plan Name [Axis] Plan Name [Axis] Money market fund investments Cash and Cash Equivalents, Fair Value Disclosure Total assets Segment assets Assets 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 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. Restricted Stock/Unit Plan and Management Incentive Plan Restricted Stock/Unit Plan, And Management Incentive Plan [Member] Restricted Stock/Unit Plan, And Management Incentive Plan [Member] Company-owned life insurance Effective Income Tax Rate Reconciliation Company Owned Life Insurance Effective income tax rate reconciliation, company owned life insurance. Nonvested/unissued at beginning of year (in shares) Nonvested/unissued at year end (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Contract with Customer, Basis of Pricing [Axis] Contract with Customer, Basis of Pricing [Axis] Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) 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 Tax Finance Leases Finance Lease, Liability, Payment, Due [Abstract] Financing cash flows from finance leases Finance Lease, Principal Payments, Leases Entered Or Modified During Period Finance Lease, Principal Payments, Leases Entered Or Modified During Period Subsequent Event Type [Axis] Subsequent Event Type [Axis] Intangible Assets Intangible Assets, Finite-Lived, Policy [Policy Text Block] Deferred purchased gas costs Deferred Gas Cost 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] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Line of credit facility, fair value Lines of Credit, Fair Value Disclosure Less imputed interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Summary of Redeemable Noncontrolling Interest Redeemable Noncontrolling Interest [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Other property Property, Plant and Equipment, Other, Net Level 1 – Quoted prices in active markets for identical financial assets Fair Value, Inputs, Level 1 [Member] Unrealized net loss on non-trading derivatives (Swaps) Unrealized Loss On Non Trading Derivatives, Assets [Member] Unrealized Loss On Non-Trading Derivatives, Assets Regulated Operations [Abstract] Regulated Operations [Abstract] Foreign currency exchange translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent Private commingled fixed income funds Defined Benefit Plan, Private Commingled Fixed Income Funds [Member] Defined Benefit Plan, Private Commingled Fixed Income Funds [Member] Weighted average interest rate Debt, Weighted Average Interest Rate Notes, 4.45%, due 2020 Debentures Notes Four Point Four Five Percentage Due Two Thousand And Twenty [Member] Debentures Notes Four Point Four Five Percentage Due Two Thousand And Twenty [Member] Number of states in which entity operates Number of States in which Entity Operates Number of nonvested/unissued shares Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Additional paid-in capital Additional Paid-in Capital [Member] Dividend Reinvestment and Stock Purchase Plan Dividend Reinvestment And Stock Purchase Plan [Member] Dividend Reinvestment And Stock Purchase Plan [Member] Interest on lease liabilities Finance Lease, Interest Expense Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Common stock, outstanding (in shares) Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding Deferred tax assets: Deferred Tax Assets, Net [Abstract] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Number of customers Number Of Customers Number Of Customers $100 Million Credit Facility $100 Million Credit Facility [Member] $100 Million Credit Facility [Member] All other differences Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Net actuarial gain/(loss) Amortization of net actuarial loss Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Pooled funds and mutual funds Pooled Funds And Mutual Funds [Member] Pooled funds and mutual funds. Acquisition of businesses, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Common stock, authorized (in shares) Common Stock, Shares Authorized Schedule of Revenues by Geographic Area Revenue from External Customers by Geographic Areas [Table Text Block] Federal Deferred Federal Income Tax Expense (Benefit) 2022 Defined Benefit Plan, Expected Future Benefit Payment, Year Two Schedule of Segment Reporting Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Funded status at year end Defined Benefit Plan, Funded (Unfunded) Status of Plan Defined benefit pension plans: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract] Gas pipe materials and operating supplies Materials, Supplies, and Other Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Income Statement [Abstract] Income Statement [Abstract] Accumulated other comprehensive loss AOCI Attributable to Parent AOCI Attributable to Parent [Member] Commercial Paper Program Commercial Paper Program [Member] Commercial Paper Program [Member] Summary of Effective Interest Rates on Variable-Rate IDRBs Schedule Of Effective Interest Rates On Long Term Debt [Table Text Block] Schedule Of Effective Interest Rates On Long-Term Debt [Table Text Block] Income Tax Disclosure [Table] Income Tax Disclosure [Table] Income Tax Disclosure [Table] Notes, 4.15%, due 2049 Debentures Notes Four Point Fifteen Percentage, Due Two Thousand And Forty Nine [Member] Debentures Notes Four Point Fifteen Percentage, Due Two Thousand And Forty Nine Number of types of services provided to customers Number Of Types Of Services Provided To Customers Number Of Types Of Services Provided To Customers Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Equity cushion relating to minimum fixed charge ratio coverage requirement Equity Cushion Relating To Minimum Fixed Charge Ratio Coverage Requirement Equity cushion relating to minimum fixed charge ratio coverage requirement. Schedule of Regulatory Liabilities [Table] Schedule of Regulatory Liabilities [Table] Significant increases or decreases in unrecognized tax benefit within the next 12 months Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit AOCI Including Portion Attributable to Noncontrolling Interest AOCI Including Portion Attributable to Noncontrolling Interest [Member] Income Tax Authority [Domain] Income Tax Authority [Domain] Schedule of Assumptions Used Defined Benefit Plan, Assumptions [Table Text Block] Regulatory Assets [Line Items] Regulatory Assets [Line Items] Construction expenditures and property additions Capital expenditures Payments to Acquire Property, Plant, and Equipment Consolidation Items [Domain] Consolidation Items [Domain] Accounts receivable for Centuri services Due from Related Parties, Current Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Shares registered and available for issuance (in shares) Common Stock, Capital Shares Reserved for Future Issuance Public Utility, Property, Plant and Equipment [Table] Public Utility, Property, Plant and Equipment [Table] Equity in earnings of unconsolidated investment – Western Income (Loss) from Equity Method Investments Total income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Unamortized premium on reacquired debt Unamortized Premium On Reacquired Debt [Member] Unamortized Premium On Reacquired Debt [Member] Global Global [Member] Global [Member] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] 2026-2030 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Omnibus Incentive Plan Omnibus Incentive Plan [Member] Omnibus Incentive Plan Other comprehensive income (loss) before reclassifications, tax Other Comprehensive Income (Loss) before Reclassifications, Tax Annual utility depreciation and amortization expense percentage Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service Entity [Domain] Entity [Domain] Withholding remittance – share-based compensation Payment, Tax Withholding, Share-based Payment Arrangement Goodwill from acquisition Goodwill, Acquired During Period Debt-related costs Deferred Tax Liabilities, Deferred Expense, Debt Issuance Costs Quarterly Financial Data (Unaudited) Quarterly Financial Information [Text Block] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] Centuri property, equipment, and intangibles Property Plant Equipment And Intangible Assets Gross Property plant equipment and intangible assets gross. Goodwill [Line Items] Goodwill [Line Items] Receivables And Related Allowances [Line Items] Receivables And Related Allowances [Line Items] Receivables And Related Allowances [Line Items] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Contributions from parent Proceeds from Contributions from Parent 2003 Series A, due 2038 Variable Rate Bonds Two Thousand And Three Series A- Due Two Thousand And Thirty Eight [Member] Variable Rate Bonds Two Thousand and Three Series A Due Two Thousand and Thirty Eight [Member] Lease-related item Deferred Tax Liabilities, Lease-Related Item Deferred Tax Liabilities, Lease-Related Item Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Equity cushion relating to minimum net worth requirement Equity Cushion Relating To Minimum Net Worth Requirement Equity cushion relating to minimum net worth requirement. Schedule of Allowance for Uncollectibles Accounts Receivable, Allowance for Credit Loss [Table Text Block] Operating lease liabilities, current Operating Lease, Liability, Current Increments of change to the discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Increments Of Change Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Increments Of Change Finance leases Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Notes, 6.1%, due 2041 Debentures Notes Six Point One Percentage Due Two Thousand And Forty One [Member] Debentures Notes Six Point One Percentage Due Two Thousand And Forty One [Member] 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 Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] VIR ownership percentage Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Interest Rate Swap Interest Rate Swap [Member] Customer [Domain] Customer [Domain] Residential Residential [Member] Residential. Deferred compensation plan, payment term, option two Deferred Compensation Plan, Payment Term, Option Two Deferred Compensation Plan, Payment Term, Option Two Maximum current borrowing usage Line of Credit Facility, Maximum Amount Outstanding During Period Additional paid-in capital Additional Paid in Capital, Common Stock Entity Registrant Name Entity Registrant Name Other Other Miscellaneous Regulatory Asset [Member] Other Miscellaneous Regulatory Asset [Member] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Finance lease, weighted average discount rate Operating Lease, Weighted Average Discount Rate, Percent Changes in other liabilities and deferred credits Increase (Decrease) in Other Operating Liabilities 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. Equity AFUDC Increase (Decrease) in Allowance for Equity Funds Used During Construction Regulatory assets Regulatory Assets Less imputed interest Finance Lease, Liability, Undiscounted Excess Amount Dividends paid Payments of Ordinary Dividends, Common Stock Regulatory adjustment Accumulated Defined Benefit Plans Adjustment, Regulartory Adjustment, Attributable to Parent [Member] Accumulated Defined Benefit Plans Adjustment, Regulartory Adjustment, Attributable to Parent [Member] Equipment loans Equipment Loans [Member] Equipment Loans Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Natural Gas Operations Natural Gas Operations [Member] Natural Gas Operations [Member] Depreciation and amortization Depreciation and amortization expense Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Short-term lease total future lease payments Short-term Lease Commitment, Amount Centuri secured revolving credit facility Centuri Secured Revolving Credit Facility [Member] Centuri secured revolving credit facility. Net Assets, Geographic Area Net Assets, Geographic Area [Member] Lease remaining lease term (up to) Lessee, Operating Lease, Remaining Lease Term Sale of Stock [Axis] Sale of Stock [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Notes, 4.875%, due 2043 Debentures Notes Four Point Eight Seven Five Percentage Due Two Thousand And Forty Three [Member] Debentures Notes Four Point Eight Seven Five Percentage Due Two Thousand And Forty Three [Member] Deferred tax assets, total Deferred Tax Assets, Net of Valuation Allowance Goodwill Goodwill, Beginning balance Goodwill, Ending balance Goodwill Federal net operating losses Deferred Tax Assets, Operating Loss Carryforwards All other deferred All Other Deferred [Member] All Other Deferred [Member] Movement In Redeemable Noncontrolling Interest [Roll Forward] Movement In Redeemable Noncontrolling Interest [Roll Forward] Movement In Redeemable Noncontrolling Interest [Roll Forward] Dividends declared per share (in USD per share) Common Stock, Dividends, Per Share, Declared Debt instrument face amount Debt Instrument, Face Amount Storage Storage [Member] Storage [Member] Miscellaneous income and (expense) Miscellaneous Income Expense Miscellaneous income (expense). Schedule of Goodwill Schedule of Goodwill [Table Text Block] Equity [Abstract] Equity [Abstract] Deferred ITC, net Deferred Investment Tax Credit, Net Deferred Investment Tax Credit, Net Regulatory balancing accounts Deferred Tax Liabilities, Regulatory Assets and Liabilities Customer deposits Contract with Customer, Liability, Current Notes, 3.875%, due 2022 Debentures Notes Three Point Eight Seven Five Percentage Due Two Thousand And Twenty Two [Member] Debentures Notes Three Point Eight Seven Five Percentage Due Two Thousand And Twenty Two [Member] Entities [Table] Entities [Table] Schedule of Estimated Future Amortization of Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Diluted (in shares) Average diluted shares (in shares) Weighted Average Number of Shares Outstanding, Diluted International International [Member] International. Forfeited or expired (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Debt Disclosure [Abstract] Debt Disclosure [Abstract] Management Incentive Plan Management Incentive Plan [Member] Management incentive plan. Restricted Stock/Unit Plan Restricted Stock/Unit Plan [Member] Restricted Stock/Unit Plan [Member] Gross proceeds Proceeds From Issuance Of Common Stock, Gross Proceeds From Issuance Of Common Stock, Gross Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities Retirement of long-term debt Repayments of Long-term Debt 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 Transaction price allocated to unsatisfied performance obligations of contracts Revenue, Remaining Performance Obligation, Amount Medium-term notes, 7.78% series, due 2022 Debentures Medium Term Notes Seven Point Seven Eight Percentage Series Due Two Thousand And Twenty Two [Member] Debentures Medium Term Notes Seven Point Seven Eight Percentage Series Due Two Thousand and Twenty Two [Member] Tax Credit Carryforward, Name [Domain] Tax Credit Carryforward, Name [Domain] Unrecognized tax benefits at beginning of year Unrecognized tax benefits at end of year Unrecognized Tax Benefits Gas plant Natural Gas Processing Plant [Member] Common stock Common Stock, Value, Issued 2024 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Document Fiscal Year Focus Document Fiscal Year Focus 2022 Finite-Lived Intangible Asset, Expected Amortization, Year Two 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 Noncurrent assets: Assets, Noncurrent [Abstract] Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Axis] Current maturities of long-term debt Less: current maturities Long-term Debt, Current Maturities Settlements Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO) Benefit obligation at end of year (PBO/PBO/APBO) Defined Benefit Plan, Benefit Obligation Entity Current Reporting Status Entity Current Reporting Status Medium-term notes, 6.76% series, due 2027 Debentures Medium Term Notes Six Point Seven Six Percentage Series Due Two Thousand And Twenty Seven [Member] Debentures Medium Term Notes Six Point Seven Six Percentage Series Due Two Thousand and Twenty Seven [Member] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Environmental compliance programs Environmental Compliance Programs [Member] Environmental compliance programs. Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Award vesting percentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Common stock, issued (in shares) Common Stock, Shares, Issued Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Decrease in weighted-average rate of compensation Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Rate Of Compensation, Increase (Decrease) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Rate Of Compensation, Increase (Decrease) Total Operating lease liabilities Operating Lease, Liability Net deferred tax liabilities Deferred Tax Liabilities, Net Long-term debt, less current maturities Long-term debt, less current maturities Long-term debt, less current maturities Long-term Debt, Excluding Current Maturities Segment Reporting [Abstract] Segment Reporting [Abstract] Contract with Customer, Basis of Pricing [Domain] Contract with Customer, Basis of Pricing [Domain] Other components of net periodic benefit cost Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract] Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract] Debt Instrument [Line Items] Debt Instrument [Line Items] Total Southwest Gas Holdings, Inc. equity Beginning balance, attributable to parent Ending balance, attributable to parent Stockholders' Equity Attributable to Parent Entity Address, City or Town Entity Address, City or Town Notes payable Notes Payable Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Per capita cost of covered health care benefits medical rate trend assumption Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Southwest Gas Holdings, Inc. Parent [Member] 2025 Lessee, Operating Lease, Liability, to be Paid, Year Five Prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Tax Schedule of Regulatory Liabilities Schedule of Regulatory Liabilities [Table Text Block] Short-term lease cost Short-term Lease, Cost Gains on sale of equipment Gain (Loss) on Disposition of Property Plant Equipment Transportation Transportation [Member] Transportation. Schedule of Accounts Receivable for Services Accounts Receivable For Services [Table Text Block] Accounts Receivable For Services Table Text Block. Valuation allowance Deferred Tax Assets, Valuation Allowance 2023 Finite-Lived Intangible Asset, Expected Amortization, Year Three Southwest Gas Credit Facility Southwest Gas Credit Facility [Member] Southwest Gas Credit Facility [Member] Gas Operating Revenues Revenue from Contract with Customer [Policy Text Block] Percentage of interest retained by noncontrolling party subject to election Noncontrolling Interest, Percentage Of Interest Retained By Noncontrolling Party Subject To Election Noncontrolling Interest, Percentage Of Interest Retained By Noncontrolling Party Subject To Election Regulatory Assets And Liabilities [Line Items] Regulatory Assets And Liabilities [Line Items] Regulatory Assets And Liabilities [Line Items] Finance lease liabilities, noncurrent Finance Lease, Liability, Noncurrent Other current liabilities Other Liabilities, Current FSIRS AOCI, Derivative Qualifying as Hedge, Excluded Component, Parent [Member] Investment, Name [Domain] Investment, Name [Domain] Total other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax Regulatory Asset [Axis] Regulatory Asset [Axis] Leases [Abstract] Leases [Abstract] Taxes other than income taxes Taxes, Miscellaneous Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Transmission Gas Transmission [Member] Total current assets Assets, Current Deferred compensation, percentage of multiple interest rate Floating Interest Rate Index Floating Interest Rate Index Comprehensive income (loss) attributable to noncontrolling interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Operating loss carryforward Operating Loss Carryforwards Earnings per share: Earnings Per Share [Abstract] Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Amortization of prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Insurance company general account contracts Fair Value Measured at Net Asset Value Per Share [Member] Net state taxes Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent 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. Defined Benefit Plans Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Change in ownership of noncontrolling interest Noncontrolling Interest, Increase from Subsidiary Equity Issuance 2025 Finite-Lived Intangible Asset, Expected Amortization, Year Five Document Fiscal Period Focus Document Fiscal Period Focus Regulatory Assets and Liabilities Schedule of Regulatory Assets and Liabilities [Text Block] Subsequent Events Subsequent Events, Policy [Policy Text Block] Electric power infrastructure services Electric Power Infrastructure Services [Member] Electric Power Infrastructure Services [Member] Amortization of net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Industrial/other Industrial/other [Member] Industrial/other. 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. Employer contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Fair Value, Inputs, Level 1 and 2 Fair Value, Inputs, Level 1, 2 and 3 [Member] Debt redemption price, percentage Debt Instrument, Redemption Price, Percentage Entity Filer Category Entity Filer Category Schedule of Share-Based Plan Compensation Expense, Including Cash Award Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Common Stock Common Stock [Member] Foreign currency items Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Product and Service [Domain] Product and Service [Domain] Schedule of Net Utility Plant Public Utility Property, Plant, and Equipment [Table Text Block] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Schedule of Regulatory Assets Schedule of Regulatory Assets [Table Text Block] Accrued pension and other postretirement benefit costs Accrued Pension And Other Postretirement Benefit Costs [Member] Accrued Pension And Other Postretirement Benefit Costs [Member] Geographic Concentration Risk Geographic Concentration Risk [Member] 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 Finance lease, weighted average discount rate Finance Lease, Weighted Average Discount Rate, Percent Distribution Gas Distribution [Member] Percentage of maximum dividend payout restriction Percentage Of Maximum Dividend Payout Restriction Percentage of maximum dividend payout restriction. Debt instrument, stated interest rate Debt Instrument, Interest Rate, Stated Percentage Dividends declared Dividends Payable, Current Revenue, remaining performance obligation, expected timing of satisfaction, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Other Current Liabilities Other Current Liabilities [Policy Text Block] Other Current Liabilities [Policy Text Block] Change in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Total other income and (expenses) Nonoperating Income (Expense) 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] 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] Foreign Currency Items Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member] 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 Public Utility [Axis] Public Utility [Axis] Operating expenses: Costs and Expenses [Abstract] Foreign currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Sale of Stock [Domain] Sale of Stock [Domain] State Deferred State and Local Income Tax Expense (Benefit) 2025 Long-Term Debt, Maturity, Year Five Ownership [Domain] Ownership [Domain] U.S. Income (Loss) from Continuing Operations before Income Taxes, Domestic Asset return assumption Expected return on plan assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Interest paid, net of amounts capitalized Interest Paid, Excluding Capitalized Interest, Operating Activities Unit price contracts Unit Priced Contracts [Member] Unit priced contracts. Beginning balance Ending balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Schedule of Other Property and Investments Investment [Table Text Block] Revenues Revenues 2021 Finite-Lived Intangible Asset, Expected Amortization, Year One Income taxes paid (received), net Income Taxes Paid, Net Defined contribution plans, employer contribution amount Defined Contribution Plan, Employer Discretionary Contribution Amount Diluted (in USD per share) Diluted earnings per common share (in USD per share) Earnings Per Share, Diluted Multiemployer plan, special surcharges Multiemployer Plan, Special Surcharges Multiemployer Plan, Special Surcharges 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 Deferred tax liabilities: Deferred Tax Liabilities, Net [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Operating loss carryforwards, net of federal benefit Operating Loss Carryforwards, Net Of Federal Benefit Operating Loss Carryforwards, Net Of Federal Benefit Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt Schedule of Long-term Debt Instruments [Table Text Block] Entity Address, Address Line One Entity Address, Address Line One Noncompete agreements Noncompete Agreements [Member] Entity Address, Address Line Two Entity Address, Address Line Two Entity Emerging Growth Company Entity Emerging Growth Company Total deferred income tax expense Deferred Income Tax Expense (Benefit) Multiemployer plan, contributions by employer Multiemployer Plan, Employer Contribution, Cost 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 Utility Plant [Domain] Utility Plant [Domain] Income Taxes [Line Items] Income Taxes [Line Items] Income Taxes [Line Items] Net income (loss) Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Maximum Maximum [Member] Noncontrolling interest Noncontrolling Interest [Member] Effective income tax rate Consolidated effective income tax rate Effective Income Tax Rate Reconciliation, Percent Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Beginning Balance Ending Balance Accounts Receivable, Allowance for Credit Loss PBOP Other Postretirement Benefits Plan [Member] Trading Symbol Trading Symbol Linetec Linetec Services, LLC [Member] Linetec Services, LLC [Member] Weighted average shares: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Regulatory Liability [Axis] Regulatory Liability [Axis] Contracts receivable, net Contracts receivable, net Contract with Customer, Asset, after Allowance for Credit Loss Notes payable, fair value disclosure Notes Payable, Fair Value Disclosure Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Property-related items Property Related Items [Member] Property-Related Items [Member] Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Entity Shell Company Entity Shell Company Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] 2022 Finance Lease, Liability, to be Paid, Year Two Entity Public Float Entity Public Float Notes, 3.7%, due 2028 Debentures Notes Three Point Seven Percentage Due Two Thousand And Twenty Eight [Member] Debentures notes three point seven percentage due two thousand and twenty eight. Document Type Document Type ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Other income (deductions) Total other income (deductions) Other Nonoperating Income (Expense) Purchased gas cost adjustments Purchased Gas Cost Adjustments [Member] Purchased Gas Cost Adjustments [Member] 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] 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] Employee benefits Employee Benefits [Member] Employee Benefits [Member] Segments [Axis] Segments [Axis] Pension and Other Postretirement Benefits Retirement Benefits [Text Block] 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 Schedule of Rollforward of Accumulated Other Comprehensive Income Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Contracts receivable, gross Contract with Customer, Asset, before Allowance for Credit Loss Future estimated funding amount Future Estimated Funding Amount In Next Fiscal Year Future estimated funding amount in next fiscal year Net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Maximum value of common stock issuance Maximum Aggregate Market Value Of Potential Stock Issuance The amount of maximum aggregate market value of potential stock issuance under the program. Line of Credit Line of Credit [Member] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies [Table] Proceeds from debt Proceeds from Issuance of Debt Trade names and trademarks Trademarks and Trade Names [Member] Operating income Operating income Operating Income (Loss) Debt instrument discount rate Debt Instrument, Discount Rate Debt Instrument, Discount Rate Redeemable Noncontrolling Interest Noncontrolling Interest Disclosure [Text Block] W.S. Nicholls Western Construction LTD WS Nicholls Western Construction Ltd [Member] WS Nicholls Western Construction Ltd. Schedule of Utility Infrastructure Services Contracts Receivable Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] Variable Rate [Axis] Variable Rate [Axis] Commitments and contingencies (Note 10) Commitments and Contingencies Vesting Tranche Two Share-based Payment Arrangement, Tranche Two [Member] Schedule of Other Income (Deductions) Schedule of Other Nonoperating Income, by Component [Table Text Block] Award vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Entity Address, State or Province Entity Address, State or Province Schedule of Defined Benefit Plans Disclosures Schedule of Defined Benefit Plans Disclosures [Table Text Block] Vested and issued (in shares) Vested and issued (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Other comprehensive income (loss), before tax Other Comprehensive Income (Loss), before Tax Accounts payable Accounts Payable, Current Debentures Debentures [Member] Debentures [Member] Foreign currency translation adjustment Goodwill, Foreign Currency Translation Gain (Loss) Centuri term loan/secured revolving credit facility Secured Debt Retained earnings Retained Earnings (Accumulated Deficit) Operating lease ROU assets Operating Lease, Right-of-Use Asset Issuance of additional debt Debt Instrument Covenant Compliance Credit Risk Exposure Amount Debt instrument covenant compliance credit risk exposure amount. Property-related items, including accelerated depreciation Deferred Tax Liabilities, Property, Plant and Equipment 2021 Finance Lease, Liability, to be Paid, Year One Unamortized gain on reacquired debt Unamortized Gain On Reacquired Debt [Member] Unamortized Gain On Reacquired Debt [Member] Customer [Axis] Customer [Axis] Income Taxes Income Tax, Policy [Policy Text Block] Total lease cost - Southwest Gas Holdings, Inc. Lease, Cost Other Payments for (Proceeds from) Other Investing Activities Allowance for Funds Used During Construction ("AFUDC") Allowance for Funds Used During Construction, Policy [Policy Text Block] Revenue from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Regulatory Liability [Domain] Regulatory Liability [Domain] Bid contract Bid Contract [Member] Bid contract. Business Acquisition [Axis] Business Acquisition [Axis] Geographical [Domain] Geographical [Domain] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Foreign Deferred Foreign Income Tax Expense (Benefit) Deferred income taxes Increase (Decrease) in Deferred Income Taxes 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 Accrued interest Interest Payable, Current Entity Voluntary Filers Entity Voluntary Filers Tax Credit Carryforward [Axis] Tax Credit Carryforward [Axis] 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 Thereafter Finite-Lived Intangible Asset, Expected Amortization, after Year Five Credit Facility [Axis] Credit Facility [Axis] Weighted-average assumptions (benefit obligation): Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract] 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. Foreign Foreign Tax Authority [Member] Utility plant: Public Utilities, Property, Plant and Equipment, Net [Abstract] Capital Loss Carryforward Capital Loss Carryforward [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Unamortized debt issuance costs Unamortized Debt Issuance Expense Issuance of common stock, net Net proceeds Proceeds from Issuance of Common Stock Goodwill [Roll Forward] Goodwill [Roll Forward] Derivative, number of instruments held Derivative, Number of Instruments Held Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Effect of dilutive securities: Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] Line of credit facility Borrowings outstanding under facility Long-term Line of Credit Margin, interest - and property tax-tracking Margin, Interest - and Property Tax-Tracking [Member] Margin, Interest - and Property Tax-Tracking Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Deferred income taxes and other credits: Other Liabilities, Noncurrent [Abstract] Entity Central Index Key Entity Central Index Key Software and software-related intangibles Computer Software, Intangible Asset [Member] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Summary of Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Revolving credit facility and commercial paper Revolving Credit Facility And Commercial Paper [Member] Revolving Credit Facility And Commercial Paper [Member] Net cost of gas sold Utilities Operating Expense, Gas and Petroleum Purchased Income taxes receivable, net Income Taxes Receivable, Current Geographical [Axis] Geographical [Axis] Reclassification from AOCI, tax Reclassification from AOCI, Current Period, Tax Forward-starting interest rate swaps (“FSIRS”): Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Receivables And Related Allowances [Table] Receivables And Related Allowances [Table] Receivables And Related Allowances [Table] Segments [Domain] Segments [Domain] 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 Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] 2024 Long-Term Debt, Maturity, Year Four Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding General General [Member] General [Member] Amount of FSIRS existing AOCI losses expected to reclassified income in next twelve months Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Federal Current Federal Tax Expense (Benefit) Amortization expenses Amortization of intangibles Amortization of Intangible Assets Net regulatory liabilities Net Regulatory Liabilities Net Regulatory Liabilities Accrued purchased gas costs Accrued Purchased Gas Costs [Member] Accrued Purchased Gas Costs [Member] AFUDC rate Public Utilities, Allowance for Funds Used During Construction, Rate Segment Information Segment Reporting Disclosure [Text Block] Common stock issuances Stock Issued During Period, Value, New Issues Tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent Operating cash flows from finance leases Finance Lease, Interest Payment on Liability Contributions from Southwest Gas Holdings, Inc. Adjustments To Additional Paid In Capital Contributions From Parent Adjustments to additional paid in capital contributions from parent. Reclassification of excess deferred taxes Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect 2009 Series A, due 2039 Variable Rate Bonds Two Thousand And Nine Series A- Due Two Thousand And Thirty Nine [Member] Variable Rate Bonds Two Thousand and Nine Series A Due Two Thousand and Thirty Nine [Member] Total noncurrent assets Assets, Noncurrent, Other than Noncurrent Investments and Property, Plant and Equipment Title of 12(b) Security Title of 12(b) Security Income taxes payable, net Income Taxes Payable Net Income taxes payable net. 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 Schedule Of Quarterly Financial Information [Line Items] Schedule Of Quarterly Financial Information [Line Items] Schedule Of Quarterly Financial Information [Line Items] Net Carrying Amount Finite-Lived Intangible Assets, Net Additional self-insured retention amount of general liability Additional Self Insured Retention Amount Of General Liability Additional self-insured retention amount of general liability Total operating revenues Revenues Operating revenues Regulated and Unregulated Operating Revenue Vesting [Domain] Vesting [Domain] Schedule of Maturities of Finance Lease Liabilities Finance Lease, Liability, Fiscal Year Maturity [Table Text Block] Net interest deductions Interest expense Interest Expense Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Summary of Income Tax Expense (Benefit) Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Ownership percentage by noncontrolling owners Ownership percentage by noncontrolling owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Product and Service [Axis] Product and Service [Axis] Income Taxes [Table] Income Taxes [Table] Income Taxes [Table] Amortization of prior service cost Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Compensation cost not yet recognized, period for recognition Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition 2025 Finance Lease, Liability, to be Paid, Year Five Centuri other debt obligations Other Long-term Debt 2022 Long-Term Debt, Maturity, Year Two 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 Change in contract liability, revenue recognized Contract with Customer, Liability, Revenue Recognized 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). Accounts payable Increase (Decrease) in Accounts Payable Debt Instrument [Axis] Debt Instrument [Axis] Schedule of Quarterly Financial Data Quarterly Financial Information [Table Text Block] Master services agreement Master Services Agreement [Member] Master Services Agreement [Member] Operating Segments Operating Segments [Member] IDRBs Industrial Development Revenue Bonds [Member] Industrial Development Revenue Bonds [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Class of Stock [Line Items] Class of Stock [Line Items] Net actuarial gain (loss) 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. Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Less: accumulated depreciation Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Entity Information [Line Items] Entity Information [Line Items] Subsequent Event Subsequent Event [Member] Centuri Centuri Group, Inc. [Member] Centuri Group, Inc. [Member] Alternative minimum tax Alternative Minimum Tax [Member] Alternative Minimum Tax Federal Domestic Tax Authority [Member] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Natural Gas Operations Southwest [Member] Southwest [Member] Deferred purchased gas costs, estimated incremental costs Deferred Purchased Gas Costs, Estimated Incremental Costs Deferred Purchased Gas Costs, Estimated Incremental Costs Nevada NEVADA Fair Value Estimate of Fair Value Measurement [Member] Operating lease liabilities, noncurrent Operating Lease, Liability, Noncurrent 2024 Finite-Lived Intangible Asset, Expected Amortization, Year Four Change in COLI policies Life Insurance, Corporate or Bank Owned, Change in Value Net defined benefit pension plans Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Schedule of Common Stock Activity Schedule Of Common Stock Activity [Table Text Block] Schedule Of Common Stock Activity [Table Text Block] Current assets: Assets, Current [Abstract] 8% Series, due 2026 Debentures Eight Percentage Series Due Two Thousand And Twenty Six [Member] Debentures Eight Percentage Series Due Two Thousand And Twenty Six [Member] Number of types of agreements with customers Number Of Types Of Agreements With Customers Number Of Types Of Agreements With Customers Comprehensive income attributable to Southwest Gas Holdings, Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent 2023 Finance Lease, Liability, to be Paid, Year Three Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Regulatory adjustments Regulatory Adjustments [Member] Regulatory Adjustments [Member] Reconciliation of U.S Federal Statutory Rate to Consolidated Effective Tax Rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] 2021 Long-Term Debt, Maturity, Year One Weighted-average rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Operations and Maintenance Expense Operations And Maintenance Expense [Policy Text Block] Operations And Maintenance Expense Policy Text Block City Area Code City Area Code Legal Entity [Axis] Legal Entity [Axis] Line of credit designated for working capital purposes Line Of Credit Facility Working Capital Purposes Line Of Credit Facility, Working Capital Purposes Schedule of Accumulated Benefit Obligation Schedule of Accumulated and Projected Benefit Obligations [Table Text Block] Income Tax Authority [Axis] Income Tax Authority [Axis] Document Period End Date Document Period End Date Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] 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] Net income Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Summary of Revenue Disaggregated by Service Type and Contract Type Disaggregation of Revenue [Table Text Block] Reclassification from AOCI, net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Quarterly Financial Information Disclosure [Abstract] Quarterly Financial Information Disclosure [Abstract] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Other comprehensive income (loss) before reclassifications, before tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Accounts receivable, extending period Accounts Receivable, Extending Period Accounts Receivable, Extending Period Changes in undistributed stock compensation Compensation expense Share-based Payment Arrangement, Noncash Expense Change in short-term debt Proceeds from (Repayments of) Short-term Debt Gas utility customer accounts receivable balance Gas Utility Customer Accounts Receivable Gas Utility Customer Accounts Receivable Other Proceeds from (Payments for) Other Financing Activities Unsecured debt Unsecured Debt Cover [Abstract] Legacy Restricted Stock/Unit Plan Legacy Restricted Stock/Unit Plan [Member] Legacy Restricted Stock/Unit Plan Alternative Base Rate Base Rate [Member] Accumulated Removal Costs Accumulated Removal Costs [Policy Text Block] Accumulated Removal Costs Policy Text Block. Regulatory Asset [Domain] Regulatory Asset [Domain] Other comprehensive income (loss) before reclassifications, net of tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Gross decreases – current period tax positions Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions Prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Tax Common stock available for sale under the program Maximum Amount Of Common Stock Available For Sale Maximum amount of common stock available for sale. Summary of Income Before Taxes and Noncontrolling Interest for Domestic and Foreign Operations Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Long-term debt Long-term debt Long-term Debt Notes, 2.2%, due 2030 Debentures Notes Two Point Two Percentage, Due Two Thousand And Thirty [Member] Debentures Notes Two Point Two Percentage, Due Two Thousand And Thirty Service cost Defined Benefit Plan, Service Cost Accrued taxes Increase (Decrease) in Accrued Taxes Payable Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Customer relationships Customer Relationships [Member] Utility infrastructure services expenses Cost of Goods and Services Sold California CALIFORNIA Total operating expenses Costs and Expenses Equity Components [Axis] Equity Components [Axis] Net forward-starting interest rate swaps Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Decrease of asset return assumption Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets, Increase (Decrease) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets, Increase (Decrease) Construction work in progress Public Utilities, Property, Plant and Equipment, Construction Work in Progress Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Receivables [Abstract] Receivables [Abstract] Minimum Minimum [Member] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Equity Securities Defined Benefit Plan, Equity Securities [Member] Net income (loss) attributable to noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Notes, 3.8%, due 2046 Debentures Notes Three Point Eight Percentage Due Two Thousand And Forty Six [Member] Debentures notes three point eight percentage due two thousand and forty six. Government fixed income and mortgage backed securities Asset-backed Securities [Member] Amortization of net actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Entity Interactive Data Current Entity Interactive Data Current United States UNITED STATES Net periodic benefit cost Net periodic benefit costs recognized in net income Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Deferred payroll taxes Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Compensation Schedule of Fair Value of Plan Assets Schedule of Allocation of Plan Assets [Table Text Block] Arizona ARIZONA Operating revenues: Revenues [Abstract] CASH FLOW FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") Stockholders' Equity Note Disclosure [Text Block] 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 Commitment fee percentage Line of Credit Facility, Commitment Fee Percentage Southwest Gas Corporation Southwest Gas Corporation Southwest Gas Corporation [Member] Southwest gas corporation. Foreign Current Foreign Tax Expense (Benefit) Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Decrease of 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) Deferred tax liabilities, gross Deferred Tax Liabilities, Gross 2021 Defined Benefit Plan, Expected Future Benefit Payment, Year One Accounts Receivable, Allowance for Credit Loss [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Number of reportable segments Number of Reportable Segments Retirement Plan Type [Domain] Retirement Plan Type [Domain] Other income (deductions) Other Nonoperating Income (Expense) [Abstract] Debt instrument percentage Debt Instrument, Percentage Of Total With Interest Rates Reference To LIBOR And Due After 2021 Debt Instrument, Percentage Of Total With Interest Rates Reference To LIBOR And Due After 2021 Condensed Income Statements, Captions [Line Items] Condensed Income Statements, Captions [Line Items] Effective interest rates Debt Instrument, Interest Rate, Effective Percentage Deferred compensation plan, payment term, option one Deferred Compensation Plan, Payment Term, Option One Deferred Compensation Plan, Payment Term, Option One Consolidation Items [Axis] Consolidation Items [Axis] Net utility plant Public Utilities, Property, Plant and Equipment, Net Net actuarial loss (gain) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Goodwill impairment charges Goodwill, Impairment Loss Accounts receivable, net of allowances Customer accounts receivable Accounts Receivable, after Allowance for Credit Loss, Current Total lease payments Lessee, Operating Lease, Liability, to be Paid Other Deferred Tax Assets, Other Noncontrolling Interest [Abstract] Noncontrolling Interest [Abstract] Regulatory Liabilities [Line Items] Regulatory Liabilities [Line Items] Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] 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 Payable to parent Due to Affiliate, Current Document Transition Report Document Transition Report 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: Deferred federal and state: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Equity Shelf Program Equity Shelf Program [Member] Equity Shelf Program [Member] Other income and (expenses): Nonoperating Income (Expense) [Abstract] Schedule of Regulatory Assets [Table] Schedule of Regulatory Assets [Table] Amortization of prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax Level 2 – Significant other observable inputs Fair Value, Inputs, Level 2 [Member] Vesting [Axis] Vesting [Axis] Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Other revenues Other Revenue Other Revenue Beginning balance, attributable to parent, tax Ending balance, attributable to parent, tax Stockholders' Equity Attributable To Parent, Tax Stockholders' Equity Attributable To Parent, Tax Deferred purchased gas costs Deferred Purchased Gas Costs, Assets [Member] Deferred Purchased Gas Costs, Assets Credit Facility [Domain] Credit Facility [Domain] Mutual funds Mutual Fund [Member] Basic (in USD per share) Basic earnings per common share (in USD per share) Earnings Per Share, Basic Unrecognized tax benefits that, if recognized, would affect the effective tax rate Unrecognized Tax Benefits that Would Impact Effective Tax Rate Entity File Number Entity File Number Other current liabilities Other Current Liabilities [Member] Total finance lease cost Finance Lease, Cost Finance Lease, Cost Accrued general taxes Accrual for Taxes Other than Income Taxes, Current Weighted-average rate of compensation increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Operating lease, weighted average remaining lease term (in years) Operating Lease, Weighted Average Remaining Lease Term SERP Supplemental Employee Retirement Plan [Member] 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 Dividends declared Dividends, Common Stock Prior service cost Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Assets amount securing the facility Debt Instrument, Collateral Amount 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. Other regulatory liabilities Regulatory Liabilities Other [Member] Regulatory Liabilities Other [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Utility infrastructure services revenues Revenue from Contract with Customer, Including Assessed Tax Document Annual Report Document Annual Report Regulatory adjustment Defined Benefit Plan Regulatory Adjustment Before Tax Net Defined benefit plan, regulatory adjustment before-tax net. Share-based compensation plan related tax benefits Share-based Payment Arrangement, Expense, Tax Benefit Other regulatory assets Regulatory Assets Other [Member] Regulatory Assets Other [Member] Schedule of Accounts Receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] 2024 Finance Lease, Liability, to be Paid, Year Four Retirement Benefits [Abstract] Retirement Benefits [Abstract] Receivable [Domain] Receivable [Domain] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Accrued utility revenue Increase (Decrease) in Contract with Customer, Asset Other property and investments Total 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. Weighted average grant date fair value (in USD per share) Granted (in USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Long-term Debt, Current and Noncurrent Abstract Long-term Debt, Current and Noncurrent [Abstract] Short-term debt Short term borrowings outstanding Short-term Debt CASH FLOW FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Gas Pipe Materials and Supplies Gas Pipe Inventory And Operating Supplies [Member] Gas pipe inventory and operating supplies. Unamortized discount and debt issuance costs Debt Instrument Unamortized Discount And Debt Issuance Costs Debt instrument unamortized discount and debt issuance costs. Other Deferred Tax Liabilities, Other Operations and maintenance Utilities Operating Expense, Maintenance and Operations Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Regulatory excess deferred/other taxes and gross-up Regulatory Offsets To Deferred Tax Balances [Member] Regulatory offsets to deferred tax balances. Prepaids and Other Current Assets Prepaid And Other Current Assets Policy [Policy Text Block] Prepaid And Other Current Assets Policy [Policy Text Block] Multiemployer pension plans, number of critical plans Multiemployer Plan, Pension, Significant, Number Of Plans Multiemployer Plan, Pension, Significant, Number Of Plans Regulatory liabilities Regulatory Liabilities Schedule Of Regulatory Assets And Liabilities [Table] Schedule Of Regulatory Assets And Liabilities [Table] Schedule Of Regulatory Assets And Liabilities [Table] Accounts receivable, net of allowances Increase (Decrease) in Accounts Receivable Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Less: agent commissions Payments of Stock Issuance Costs Concentration Risk Type [Domain] Concentration Risk Type [Domain] Plan amendments Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Total capitalization and liabilities Liabilities and Equity Deferred purchased gas costs Deferred Gas Purchases, Current Loss Contingencies [Line Items] Loss Contingencies [Line Items] Accumulated other comprehensive loss, net Accumulated Other Comprehensive Income (Loss), Net of Tax Income Taxes Income Tax Disclosure [Text Block] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Lease termination period Lessee, Operating Lease, Termination Period Lessee, Operating Lease, Termination Period Fixed price contracts Fixed-price Contract [Member] Lapse in statute of limitations Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations Operating lease cost Operating Lease, Cost Cumulative foreign earnings Undistributed Earnings of Foreign Subsidiaries Total current income tax expense Current Income Tax Expense (Benefit) Finance lease, weighted average remaining lease term (in years) Finance Lease, Weighted Average Remaining Lease Term 2008 Series A, due 2038 Variable Rate Bonds Two Thousand And Eight Series A- Due Two Thousand And Thirty Eight [Member] Variable Rate Bonds Two Thousand and Eight Series A Due Two Thousand and Thirty Eight [Member] Gross increases – current period tax positions Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Gross increases – tax positions in prior period Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Capitalization: Capitalization, Long-term Debt and Equity [Abstract] Equity Component [Domain] Equity Component [Domain] Schedule of Expected Benefit Payments Schedule of Expected Benefit Payments [Table Text Block] Tax-exempt Series A, due 2028 Variable Rate Bonds Tax Exempt Series A- Due Two Thousand And Twenty Eight [Member] Variable Rate Bonds Tax Exempt Series Due Two Thousand and Twenty Eight [Member] Entity Tax Identification Number Entity Tax Identification Number Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Share-Based Compensation Share-based Payment Arrangement [Text Block] Net income attributable to Southwest Gas Holdings, Inc. Segment net income Net income attributable to Southwest Gas Holdings, Inc. Net Income (Loss) Attributable to Parent Minimum current borrowing usage Line Of Credit Facility Minimum Amount Outstanding During Period Line Of Credit Facility Minimum Amount Outstanding During Period Changes in current assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] LIBOR London Interbank Offered Rate (LIBOR) [Member] Other current assets and liabilities Increase (Decrease) in Other Current Assets and Liabilities, Net Percent of customers by state: Percent Of Customers By State Percent Of Customers By State Background, Organization, and Summary of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Accumulated removal costs Accumulated Removal Costs [Member] Accumulated Removal Costs [Member] Amortization of excess deferred taxes Effective Income Tax Rate Reconciliation, Amortization Of Excess Deferred Taxes, Percent Effective Income Tax Rate Reconciliation, Amortization Of Excess Deferred Taxes, Percent Current Fiscal Year End Date Current Fiscal Year End Date Finance lease liabilities Finance lease liabilities Finance Lease, Liability Other Other Plant in Service [Member] AFUDC capitalized as part of utility plant Public Utilities, Allowance for Funds Used During Construction, Additions Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Deferred Purchased Gas Costs Deferred Purchased Costs [Policy Text Block] Deferred Purchased Costs Policy Text Block. Deferred income taxes for future amortization of ITC and excess deferred taxes Deferred Tax Assets, Tax Credit Carryforwards Income Tax Disclosure [Line Items] Income Tax Disclosure [Line Items] Income Tax Disclosure [Line Items] Deferred purchased gas costs Increase (Decrease) in Deferred Gas Cost Thereafter Finance Lease, Liability, to be Paid, after Year Five Pension tracking mechanism Pension Tracking Mechanism [Member] Regulatory accounts for differences related to pension funding. SUPPLEMENTAL INFORMATION: Supplemental Cash Flow Information [Abstract] Utility Infrastructure Services Utility Infrastructure Services Utility Infrastructure Services Segment [Member] Utility Infrastructure Services Segment [Member] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Nature of Operations Nature Of Operations [Policy Text Block] Nature Of Operations [Policy Text Block] U.S. equity securities Defined Benefit Plan, Equity Securities, US [Member] Net income attributable to redeemable noncontrolling interest Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Gas, Transmission and Distribution Plant Gas, Transmission and Distribution Equipment [Member] Benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Customer contracts backlog Customer Contracts [Member] Inventory [Domain] Inventory [Domain] Debt portion Public Utilities, Allowance for Funds Used During Construction, Capitalized, Debt Portion Public Utilities, Allowance for Funds Used During Construction, Capitalized, Debt Portion 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 Lease-related item Deferred Tax Assets, Lease-Related Item Deferred Tax Assets, Lease-Related Item Beginning balance, tax Ending balance, tax Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Tax Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Tax Other comprehensive income (loss), tax Other Comprehensive Income (Loss), Tax Common stock issuances (in shares) Number of shares sold (in shares) Stock Issued During Period, Shares, New Issues Gross Carrying Amount Finite-Lived Intangible Assets, Gross Schedule of Capitalized and Debt Portion of AFUDC Schedule of Capitalization [Table Text Block] Recognized in AOCI Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Additions charged to expense Accounts Receivable, Credit Loss Expense (Reversal) Money Market Funds Money Market Funds [Member] Employee investment plan cost Employees' Investment Plan, Cost Employees' Investment Plan, Cost Centuri accumulated provision for depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Net actuarial loss Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Schedule of Nonvested Performance and Restricted Stock Unit Plans Schedule of Nonvested Share Activity [Table Text Block] Restricted stock units (in shares) Incremental Common Shares Attributable to Dilutive Effect of Nonvested Shares with Forfeitable Dividends Finance lease ROU assets Finance Lease, Right-of-Use Asset, after Accumulated Amortization Schedule of Maturities of Operating Lease Liabilities Lessee, Operating Lease, Liability, Maturity [Table Text Block] Gas plant Public Utilities, Property, Plant and Equipment, Gas Plant Public Utilities, Property, Plant and Equipment, Gas Plant Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Basic (in shares) Weighted average basic shares (in shares) Weighted Average Number of Shares Outstanding, Basic Applicable margin Debt Instrument, Basis Spread on Variable Rate Weighted average price per share (USD per share) Common Stock Weighted Average Issue Price Per Share Common stock weighted average issue price per share. Ownership [Axis] Ownership [Axis] Loss Contingencies [Table] Loss Contingencies [Table] Carrying Amount Reported Value Measurement [Member] Tax-related interest income Income Tax Examination, Interest Expense Plan Name [Domain] Plan Name [Domain] Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Revenue Revenue from Contract with Customer [Text Block] Deferred Compensation Plan, percent of amount deferred with match Deferred Compensation Plan, Percent Of Amount Deferred With Match Deferred Compensation Plan, Percent Of Amount Deferred With Match Amortization of net actuarial loss Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Operating leases Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Actuarial loss (gain) Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Unsecured debt, fair value Long-term Debt, Fair Value Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Income tax expense Total income tax expense Income tax expense Income Tax Expense (Benefit) 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 Net Utility Plant Property, Plant and Equipment, Policy [Policy Text Block] Redemption value adjustment Noncontrolling Interest, Change in Redemption Value Estimated Maturities of Long-Term Debt Schedule of Maturities of Long-term Debt [Table Text Block] Medium-term notes, 7.92% series, due 2027 Debentures Medium Term Notes Seven Point Nine Two Percentage Series Due Two Thousand And Twenty Seven [Member] Debentures Medium Term Notes Seven Point Nine Two Percentage Series Due Two Thousand and Twenty Seven [Member] Finance lease liabilities, current Finance Lease, Liability, Current Local Phone Number Local Phone Number Reclassification from AOCI, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Vesting Tranche One Share-based Payment Arrangement, Tranche One [Member] Gross decreases – tax positions in prior period Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Deferred payroll taxes Deferred Payroll Taxes [Member] Deferred Payroll Taxes Amounts billed in excess of revenue earned on contracts Contract with Customer, Liability Changes in deferred charges and other assets Increase (Decrease) in Other Operating Assets Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Gas operating revenues Total Gas operating revenues Regulated Operating Revenue, Gas Share-based compensation plan expense, net of related tax benefits Share-based Payment Arrangement, Expense, after Tax Threshold period after inactivation for write-off of accounts receivable Threshold Period Past Due for Write-off of Trade Accounts Receivable Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Credit facility maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Weighted-average assumptions (net benefit cost) Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract] Award Type [Axis] Award Type [Axis] 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] Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Prepaids and other current assets Prepaid Expenses and Other Current Assets [Member] Retained earnings Retained Earnings [Member] Measurement Basis [Axis] Measurement Basis [Axis] Management Incentive Plan shares (in shares) Incremental Common Shares Attributable to Dilutive Effect of Equity Forward Agreements Public Utility, Property, Plant and Equipment [Line Items] Public Utility, Property, Plant and Equipment [Line Items] Schedule of Net Benefit Cost Schedule of Net Benefit Costs [Table Text Block] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Total deferred federal and state Deferred Federal And State Income Tax Expense Benefit Deferred federal and state income tax expense benefit Award Type [Domain] Award Type [Domain] Accrued pension and other postretirement benefit costs, recovery period Regulatory Assets, Accrued Pension And Other Postretirement Benefit Costs, Recovery Period Regulatory Assets, Accrued Pension And Other Postretirement Benefit Costs, Recovery Period Utility Plant and Leases Utility Plant And Leases Disclosure [Text Block] Utility Plant And Leases Disclosure [Text Block] Net cash surrender value of COLI policies Cash Surrender Value of Life Insurance Infrastructure replacement programs and similar Infrastructure Replacement Programs and Similar [Member] Infrastructure replacement programs and similar. Equity portion Equity AFUDC Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Pension Pension Plan [Member] Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Current liabilities: Liabilities, Current [Abstract] Redeemable noncontrolling interest Balance, Beginning Balance, Ending Redeemable Noncontrolling Interest, Equity, Carrying Amount U.S. federal statutory income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Recently Accounting Standards Updates New Accounting Pronouncements, Policy [Policy Text Block] Accrued absence time Accrued Absence Time [Member] Accrued absence time. Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Depreciation and Amortization Regulatory Depreciation and Amortization, Policy [Policy Text Block]