Leases [Abstract]
Lessee, Lease, Description [Table]
Lessee, Lease, Description [Table]
Legal Entity [Axis]
Legal Entity [Axis]
Entity [Domain]
Entity [Domain]
Southwest Gas Corporation
Southwest Gas Corporation [Member]
Southwest gas corporation.
Centuri
Centuri Group, Inc. [Member]
Centuri Group, Inc. [Member]
Lessee, Lease, Description [Line Items]
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases
Operating Lease, Payments
Operating cash flows from finance leases
Finance Lease, Interest Payment on Liability
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
ROU assets obtained in exchange for operating leases obligations
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability
ROU assets obtained in exchange for finance leases obligations
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition [Table]
Schedule of Business Acquisitions, by Acquisition [Table]
Business Acquisition [Axis]
Business Acquisition [Axis]
Business Acquisition, Acquiree [Domain]
Business Acquisition, Acquiree [Domain]
Linetec
Linetec Services, LLC [Member]
Linetec Services, LLC [Member]
Business Acquisition [Line Items]
Business Acquisition [Line Items]
Fair Values of Assets Acquired and Liabilities Assumed
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Cash and cash equivalents
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents
Accounts receivable
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables
Revenue earned on contracts in progress in excess of billings
Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Assets Other Receivables
Business combination recognized identifiable assets acquired and liabilities assumed current assets other receivables.
Prepaid expenses and other current assets
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets
Property and equipment
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment
Intangible assets
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill
Goodwill
Goodwill
Total assets acquired
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets
Accounts payable
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable
Accrued liabilities
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Liabilities
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Liabilities
Deferred compensation and related accrued taxes
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Compensation And Related Accrued Taxes
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Compensation And Related Accrued Taxes
Redeemable noncontrolling interest
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other
Total liabilities assumed and noncontrolling interest
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities
Net assets acquired
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net
Measurement Period Adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Accounts receivable, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accounts Receivable
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accounts Receivable
Revenue earned on contracts in progress in excess of billings, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Revenue Earned On Contracts In Progress In Excess Of Billings
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Revenue Earned On Contracts In Progress In Excess Of Billings
Prepaid expenses and other current assets, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Prepaid Expenses And Other Current Assets
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Prepaid Expenses And Other Current Assets
Property and equipment, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment
Intangible assets, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles
Goodwill, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Goodwill
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Goodwill
Total assets acquired, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Assets
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Assets
Accrued liabilities, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accrued Liabilities
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accrued Liabilities
Total liabilities assumed and noncontrolling interest, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Liabilities
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Liabilities
Net assets acquired, measurement period adjustments
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Assets Acquired, Goodwill And Liabilities Assumed, Net
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Assets Acquired, Goodwill And Liabilities Assumed, Net
Debt Disclosure [Abstract]
Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt
Schedule of Long-term Debt Instruments [Table Text Block]
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment [Table]
Schedule of Segment Reporting Information, by Segment [Table]
Segments [Axis]
Segments [Axis]
Segments [Domain]
Segments [Domain]
Natural Gas Operations
Natural Gas Operations [Member]
Natural Gas Operations [Member]
Utility Infrastructure Services
Utility Infrastructure Services Segment [Member]
Utility Infrastructure Services Segment [Member]
Consolidation Items [Axis]
Consolidation Items [Axis]
Consolidation Items [Domain]
Consolidation Items [Domain]
Operating Segments
Operating Segments [Member]
Intersegment Eliminations
Intersegment Eliminations [Member]
Segment Reconciling Items
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information [Line Items]
Revenues
Revenues
Segment net income (loss)
Net Income (Loss) Attributable to Parent
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Contract notional amounts
Derivative, Nonmonetary Notional Amount
Retirement Benefits [Abstract]
Schedule of Net Periodic Benefit Costs
Schedule of Net Benefit Costs [Table Text Block]
Ownership [Axis]
Ownership [Axis]
Ownership [Domain]
Ownership [Domain]
Percentage of voting interests acquired
Business Acquisition, Percentage of Voting Interests Acquired
Ownership percentage by noncontrolling owners
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners
Reduction to purchase price
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred
Payments to acquisition
Payments to Acquire Businesses, Gross
Remaining unpaid consideration
Business Acquisition, Consideration Unpaid
Business Acquisition, Consideration Unpaid
Acquisition costs
Acquisition Costs, Period Cost
Adjustments for New Accounting Pronouncements [Axis]
Adjustments for New Accounting Pronouncements [Axis]
Type of Adoption [Domain]
Type of Adoption [Domain]
Accounting Standards Update 2016-02
Accounting Standards Update 2016-02 [Member]
Statistical Measurement [Axis]
Statistical Measurement [Axis]
Statistical Measurement [Domain]
Statistical Measurement [Domain]
Minimum
Minimum [Member]
Maximum
Maximum [Member]
Operating lease ROU assets
Operating Lease, Right-of-Use Asset
Lease liabilities
Operating Lease, Liability
Lease remaining lease term
Lessee, Operating Lease, Remaining Lease Term
Lessee, Operating Lease, Remaining Lease Term
Lease renewal term (up to)
Lessee, Operating Lease, Renewal Term
Lease termination period
Lessee, Operating Lease, Termination Period
Lessee, Operating Lease, Termination Period
Short-term lease cost
Short-term Lease, Cost
2019
Operating Leases, Future Minimum Payments, Remainder of Fiscal Year
2020
Operating Leases, Future Minimum Payments, Due in Two Years
2021
Operating Leases, Future Minimum Payments, Due in Three Years
2022
Operating Leases, Future Minimum Payments, Due in Four Years
2023
Operating Leases, Future Minimum Payments, Due in Five Years
Thereafter
Operating Leases, Future Minimum Payments, Due Thereafter
Total minimum lease payments
Operating Leases, Future Minimum Payments Due
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue [Table]
Disaggregation of Revenue [Table]
Customer [Axis]
Customer [Axis]
Customer [Domain]
Customer [Domain]
Residential
Residential [Member]
Residential.
Small commercial
Small Commercial [Member]
Small commercial.
Large commercial
Large Commercial [Member]
Large commercial.
Industrial/other
Industrial/other [Member]
Industrial/other.
Transportation
Transportation [Member]
Transportation.
Income Statement Location [Axis]
Income Statement Location [Axis]
Income Statement Location [Domain]
Income Statement Location [Domain]
Tax Reform Savings Revenue Adjustments
Tax Reform Savings Revenue Adjustments [Member]
Tax reform savings revenue adjustments.
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers
Revenue from Contract with Customer, Excluding Assessed Tax
Alternative revenue program revenues (deferrals)
Alternative Revenue Program Revenues (Deferrals)
Alternative revenue program revenues (deferrals).
Other revenues
Other Revenue
Other Revenue
Total Gas operating revenues
Regulated Operating Revenue, Gas
Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table]
Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table]
Derivative Instrument [Axis]
Derivative Instrument [Axis]
Derivative Contract [Domain]
Derivative Contract [Domain]
Swaps
Swap [Member]
Balance Sheet Location [Axis]
Balance Sheet Location [Axis]
Balance Sheet Location [Domain]
Balance Sheet Location [Domain]
Deferred charges and other assets
Deferred Charges And Other Assets [Member]
Deferred Charges And Other Assets [Member]
Prepaid and other current assets
Prepaid Expenses and Other Current Assets [Member]
Other current liabilities
Other Current Liabilities [Member]
Other deferred credits
Other Deferred Credits [Member]
Other Deferred Credits [Member]
Derivatives, Fair Value [Line Items]
Derivatives, Fair Value [Line Items]
Asset derivatives not designated as hedging instruments
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value
Liability derivatives not designated as hedging instruments
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value
Net total not designated as hedging instruments
Other Derivatives Not Designated as Hedging Instruments at Fair Value, Net
Cover page.
Entities [Table]
Entities [Table]
Entity Information [Line Items]
Entity Information [Line Items]
Document Type
Document Type
Document Quarterly Report
Document Quarterly Report
Document Period End Date
Document Period End Date
Document Transition Report
Document Transition Report
Entity File Number
Entity File Number
Entity Registrant Name
Entity Registrant Name
Entity Incorporation, State or Country Code
Entity Incorporation, State or Country Code
Entity Tax Identification Number
Entity Tax Identification Number
Entity Address, Address Line One
Entity Address, Address Line One
Entity Address, Address Line Two
Entity Address, Address Line Two
Entity Address, City or Town
Entity Address, City or Town
Entity Address, State or Province
Entity Address, State or Province
Entity Address, Postal Zip Code
Entity Address, Postal Zip Code
City Area Code
City Area Code
Local Phone Number
Local Phone Number
Title of 12(b) Security
Title of 12(b) Security
Trading Symbol
Trading Symbol
Security Exchange Name
Security Exchange Name
Entity Current Reporting Status
Entity Current Reporting Status
Entity Interactive Data Current
Entity Interactive Data Current
Entity Filer Category
Entity Filer Category
Entity Small Business
Entity Small Business
Entity Emerging Growth Company
Entity Emerging Growth Company
Entity Shell Company
Entity Shell Company
Entity Common Stock, Shares Outstanding
Entity Common Stock, Shares Outstanding
Entity Central Index Key
Entity Central Index Key
Current Fiscal Year End Date
Current Fiscal Year End Date
Document Fiscal Year Focus
Document Fiscal Year Focus
Document Fiscal Period Focus
Document Fiscal Period Focus
Amendment Flag
Amendment Flag
Equity [Abstract]
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
Schedule of Short-term Debt [Table]
Schedule of Short-term Debt [Table]
Credit Facility [Axis]
Credit Facility [Axis]
Credit Facility [Domain]
Credit Facility [Domain]
$100 Million Credit Facility
$100 Million Credit Facility [Member]
$100 Million Credit Facility [Member]
$400 Million Credit Facility
$400 Million Credit Facility [Member]
$400 Million Credit Facility [Member]
Short-term Debt [Line Items]
Short-term Debt [Line Items]
Credit facility maximum borrowing capacity
Line of Credit Facility, Maximum Borrowing Capacity
Short term borrowings outstanding
Short-term Debt
Line of credit designated for working capital purposes
Line Of Credit Facility Working Capital Purposes
Line Of Credit Facility, Working Capital Purposes
Operating lease liabilities, current
Operating Lease, Liability, Current
Operating lease liabilities, noncurrent
Operating Lease, Liability, Noncurrent
Operating lease liabilities
Operating lease, weighted average remaining lease term (in years)
Operating Lease, Weighted Average Remaining Lease Term
Operating lease, weighted average discount rate
Operating Lease, Weighted Average Discount Rate, Percent
Finance lease ROU assets
Finance Lease, Right-of-Use Asset
Finance lease liabilities, current
Finance Lease, Liability, Current
Finance lease liabilities, noncurrent
Finance Lease, Liability, Noncurrent
Finance lease liabilities
Finance Lease, Liability
Finance lease, weighted average remaining lease term (in years)
Finance Lease, Weighted Average Remaining Lease Term
Finance lease, weighted average discount rate
Finance Lease, Weighted Average Discount Rate, Percent
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Other Property and Investments
Investment [Table Text Block]
Accounts Receivable for Services
Accounts Receivable For Services [Table Text Block]
Accounts Receivable For Services Table Text Block.
Schedule of Goodwill
Schedule of Goodwill [Table Text Block]
Other Income (Deductions)
Schedule of Other Nonoperating Income, by Component [Table Text Block]
Contracts receivable, net
Accounts Receivable, after Allowance for Credit Loss
Revenue earned on contracts in progress in excess of billings
Revenue earned on contracts in progress in excess of billings
Revenue earned on contracts in progress in excess of billings.
Amounts billed in excess of revenue earned on contracts
Amounts billed in excess of revenue earned on contracts
Amounts billed in excess of revenue earned on contracts.
Components of Net Periodic Benefit Cost
Compensation and Employee Benefit Plans [Text Block]
Derivative [Table]
Derivative [Table]
Geographical [Axis]
Geographical [Axis]
Geographical [Domain]
Geographical [Domain]
Arizona
ARIZONA
California
CALIFORNIA
Derivative [Line Items]
Derivative [Line Items]
Natural gas portfolios, maximum % rate
Natural Gas Portfolios Percentage Rate Range Maximum
The maximum percentage of the natural gas portfolio that is fixed
Derivative collateral outstanding
Derivative, Collateral Outstanding
Derivative, Collateral Outstanding
Revenue
Revenue from Contract with Customer [Text Block]
Schedule of Long-term Debt Instruments [Table]
Schedule of Long-term Debt Instruments [Table]
Measurement Basis [Axis]
Measurement Basis [Axis]
Fair Value Measurement [Domain]
Fair Value Measurement [Domain]
Portion at Fair Value Measurement [Member]
Portion at Fair Value Measurement [Member]
Carrying Amount
Reported Value Measurement [Member]
Market Value
Estimate of Fair Value Measurement [Member]
Debt Instrument [Axis]
Debt Instrument [Axis]
Debt Instrument, Name [Domain]
Debt Instrument, Name [Domain]
Debentures
Debentures [Member]
Debentures [Member]
Industrial development revenue bonds
Industrial Development Revenue Bonds [Member]
Industrial Development Revenue Bonds [Member]
Long-term Debt, Type [Axis]
Long-term Debt, Type [Axis]
Long-term Debt, Type [Domain]
Long-term Debt, Type [Domain]
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]
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]
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]
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]
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.
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.
Notes, 4.15%, due 2049
Debentures Notes 4.15%, Due 2049 [Member]
Debentures Notes 4.15%, Due 2049 [Member]
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]
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]
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]
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]
Revolving credit facility and commercial paper
Revolving Credit Facility And Commercial Paper [Member]
Revolving Credit Facility And Commercial Paper [Member]
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]
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]
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]
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]
Centuri term loan facility
Centuri Term Loan Facility [Member]
Centuri term loan facility.
Centuri other debt obligations
Centuri Other Debt Obligations [Member]
Centuri Other Debt Obligations [Member]
Centuri secured revolving credit facility
Centuri Secured Revolving Credit Facility [Member]
Centuri secured revolving credit facility.
Debt Instrument [Line Items]
Debt Instrument [Line Items]
Notes payable
Notes Payable
Notes payable, fair value disclosure
Notes Payable, Fair Value Disclosure
Unamortized discount and debt issuance costs
Debt Instrument Unamortized Discount And Debt Issuance Costs
Debt instrument unamortized discount and debt issuance costs.
Line of credit facility
Long-term Line of Credit
Line of credit facility, fair value
Lines of Credit, Fair Value Disclosure
Unsecured debt
Unsecured Debt
Unsecured debt, fair value
Long-term Debt, Fair Value
Less: current maturities
Long-term Debt, Current Maturities
Long-term debt, less current maturities
Long-term Debt, Excluding Current Maturities
Unamortized debt issuance costs
Unamortized Debt Issuance Expense
Long-term Debt, Current and Noncurrent Abstract
Long-term Debt, Current and Noncurrent [Abstract]
Long-term debt
Long-term Debt
Long-term debt, less current maturities
Centuri secured revolving credit facility
Secured Debt
Centuri other debt obligations
Other Long-term Debt
Debt instrument interest rate
Debt Instrument, Interest Rate, Stated Percentage
Investment [Table]
Investment [Table]
Investment [Line Items]
Investment [Line Items]
Net cash surrender value of COLI policies
Cash Surrender Value of Life Insurance
Other property
Property, Plant and Equipment, Other, Net
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.
Centuri property, equipment, and intangibles
Property Plant Equipment And Intangible Assets Gross
Property plant equipment and intangible assets gross.
Centuri accumulated depreciation/amortization
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment
Operating lease cost
Operating Lease, Cost
Amortization of ROU assets
Finance Lease, Right-of-Use Asset, Amortization
Interest on lease liabilities
Finance Lease, Interest Expense
Total finance lease cost
Finance Lease, Cost
Finance Lease, Cost
Total lease cost
Lease, Cost
Number of operating segment
Number of Operating Segments
Change in contract liability, revenue recognized
Contract with Customer, Liability, Revenue Recognized
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
Condensed Income Statement [Table]
Condensed Income Statement [Table]
Corporate and administrative
Corporate, Non-Segment [Member]
Condensed Income Statements, Captions [Line Items]
Condensed Income Statements, Captions [Line Items]
Other income (deductions)
Other Nonoperating Income (Expense) [Abstract]
Change in COLI policies
Life Insurance, Corporate or Bank Owned, Change in Value
Interest income
Interest Income, Other
Equity AFUDC
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity
Foreign transaction gain (loss)
Foreign Currency Transaction Gain (Loss), Realized
Other components of net periodic benefit cost
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit
Miscellaneous income and (expense)
Miscellaneous Income Expense
Miscellaneous income (expense).
Total other income (deductions)
Other Nonoperating Income (Expense)
Summary of Fair Values of Assets Acquired and Liabilities Assumed
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]
Components of Lease Expense, and Supplemental Cash Flow Information Related to Leases
Lease, Cost [Table Text Block]
Supplemental Information Related to Leases Included in Balance Sheet
Assets And Liabilities, Lessee [Table Text Block]
Assets And Liabilities, Lessee [Table Text Block]
Schedule of Maturities of Operating Lease Liabilities
Lessee, Operating Lease, Liability, Maturity [Table Text Block]
Schedule of Maturities of Finance Lease Liabilities
Finance Lease, Liability, Maturity [Table Text Block]
Schedule of Rental and Lease Payments
Schedule of Rent Expense [Table Text Block]
Schedule of Future Minimum Rental Payments for Operating Leases
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]
Net actuarial (loss) gain
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax
Prior service cost
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax
Less: amount recognized in regulatory assets
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Amount Recognized Regulatory Assets, Before Tax
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Amount Recognized Regulatory Assets, Before Tax
Recognized in AOCI
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax
Accumulated Other Comprehensive Income (Loss) [Table]
Accumulated Other Comprehensive Income (Loss) [Table]
Equity Components [Axis]
Equity Components [Axis]
Equity Component [Domain]
Equity Component [Domain]
Defined Benefit Plans
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Amortization of prior service cost
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Amortization of net actuarial loss
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Regulatory adjustment
Accumulated Defined Benefit Plans Adjustment, Regulartory Adjustment, Attributable to Parent [Member]
Accumulated Defined Benefit Plans Adjustment, Regulartory Adjustment, Attributable to Parent [Member]
FSIRS
AOCI, Derivative Qualifying as Hedge, Excluded Component, Parent [Member]
Foreign Currency Items
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss) [Line Items]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax
Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Before Tax
Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Before Tax
Beginning balance, tax
Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Tax
Stockholders' Equity, Including Portion Attributable To Noncontrolling Interest, Tax
Beginning balance
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest
Beginning balance, attributable to parent, before tax
Stockholders' Equity Attributable To Parent, Before Tax
Stockholders' Equity Attributable To Parent, Before Tax
Beginning balance, attributable to parent, tax
Stockholders' Equity Attributable To Parent, Tax
Stockholders' Equity Attributable To Parent, Tax
Beginning balance, attributable to parent
Stockholders' Equity Attributable to Parent
Other comprehensive income (loss) before reclassifications, before tax
Other Comprehensive Income (Loss), before Reclassifications, before Tax
Other comprehensive income (loss) before reclassifications, net of tax
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax
Reclassification from AOCI, before Tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax
Reclassification from AOCI, tax
Reclassification from AOCI, Current Period, Tax
Reclassification from AOCI, net of tax
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax
Other comprehensive income (loss), before tax
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss), tax
Other Comprehensive Income (Loss), Tax
Total other comprehensive income (loss), net of tax
Other Comprehensive Income (Loss), Net of Tax
Ending balance, attributable to parent, before tax
Ending balance, attributable to parent, tax
Ending balance, attributable to parent
Ending balance, before tax
Ending balance, tax
Ending balance
Effective income tax rate
Effective Income Tax Rate Reconciliation, Percent
Noncontrolling Interest [Abstract]
Summary of Redeemable Noncontrolling Interest
Redeemable Noncontrolling Interest [Table Text Block]
Net actuarial gain/(loss)
Other comprehensive income (loss) before reclassifications, tax
Other Comprehensive Income (Loss) before Reclassifications, Tax
Long-Term Debt
Long-term Debt [Text Block]
Redeemable Noncontrolling Interests
Noncontrolling Interest Disclosure [Text Block]
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).
Rollforward of Accumulated Other Comprehensive Income
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]
Amount Recognized Before Income Tax in Accumulated Other Comprehensive Income
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]
Schedule of Common Stock Activity
Schedule Of Common Stock Activity [Table Text Block]
Schedule Of Common Stock Activity [Table Text Block]
Other Comprehensive Income and Accumulated Other Comprehensive Income
Comprehensive Income (Loss) Note [Text Block]
Statement of Comprehensive Income [Abstract]
Statement [Table]
Statement [Table]
Statement [Line Items]
Statement [Line Items]
Net income
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest
Other comprehensive income (loss), net of tax
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Defined benefit pension plans:
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax [Abstract]
Net actuarial gain (loss)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax
Amortization of prior service cost
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax
Amortization of net actuarial loss
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax
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.
Net defined benefit pension plans
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax
Forward-starting interest rate swaps (“FSIRS”):
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract]
Amounts reclassified into net income
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax
Net forward-starting interest rate swaps
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax
Foreign currency translation adjustments
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax
Comprehensive income
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest
Comprehensive income (loss) attributable to noncontrolling interests
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest
Comprehensive income attributable to Southwest Gas Holdings, Inc.
Comprehensive Income (Loss), Net of Tax, Attributable to Parent
Income Statement [Abstract]
Operating revenues:
Revenues [Abstract]
Gas operating revenues
Utility infrastructure services revenues
Revenue from Contract with Customer, Including Assessed Tax
Total operating revenues
Regulated and Unregulated Operating Revenue
Operating expenses:
Costs and Expenses [Abstract]
Net cost of gas sold
Utilities Operating Expense, Gas and Petroleum Purchased
Operations and maintenance
Utilities Operating Expense, Maintenance and Operations
Depreciation and amortization
Depreciation, Depletion and Amortization, Nonproduction
Taxes other than income taxes
Taxes, Miscellaneous
Utility infrastructure services expenses
Cost of Goods and Services Sold
Total operating expenses
Costs and Expenses
Operating income
Operating Income (Loss)
Other income and (expenses):
Nonoperating Income (Expense) [Abstract]
Net interest deductions
Interest Expense
Other income (deductions)
Total other income and (expenses)
Nonoperating Income (Expense)
Income tax expense (benefit)
Income Tax Expense (Benefit)
Net income
Net income (loss) attributable to noncontrolling interests
Net Income (Loss) Attributable to Noncontrolling Interest
Net income attributable to Southwest Gas Holdings, Inc.
Basic earnings per share (in USD per share)
Earnings Per Share, Basic
Diluted earnings per share (in USD per share)
Earnings Per Share, Diluted
Average number of common shares (in shares)
Weighted Average Number of Shares Outstanding, Basic
Average shares (assuming dilution) (in shares)
Weighted Average Number of Shares Outstanding, Diluted
Statement of Financial Position [Abstract]
Common stock, par (in USD per share)
Common Stock, Par or Stated Value Per Share
Common stock, authorized (in shares)
Common Stock, Shares Authorized
Common stock, issued (in shares)
Common Stock, Shares, Issued
Common stock, outstanding (in shares)
Common Stock, Shares, Outstanding
Statement of Cash Flows [Abstract]
CASH FLOW FROM OPERATING ACTIVITIES:
Net Cash Provided by (Used in) Operating Activities [Abstract]
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]
Deferred income taxes
Increase (Decrease) in Deferred Income Taxes
Changes in current assets and liabilities:
Increase (Decrease) in Operating Capital [Abstract]
Accounts receivable, net of allowances
Increase (Decrease) in Accounts Receivable
Accrued utility revenue
Increase (Decrease) in Unbilled Receivables
Deferred purchased gas costs
Increase (Decrease) in Deferred Gas Cost
Accounts payable
Increase (Decrease) in Accounts Payable
Accrued taxes
Increase (Decrease) in Accrued Taxes Payable
Other current assets and liabilities
Increase (Decrease) in Other Current Assets and Liabilities, Net
Gains on sale
Gain (Loss) on Disposition of Property Plant Equipment
Changes in undistributed stock compensation
Share-based Payment Arrangement, Noncash Expense
Equity AFUDC
Increase (Decrease) in Allowance for Equity Funds Used During Construction
Changes in other assets and deferred charges
Increase (Decrease) in Other Operating Assets
Changes in other liabilities and deferred credits
Increase (Decrease) in Other Operating Liabilities
Net cash provided by operating activities
Net Cash Provided by (Used in) Operating Activities
CASH FLOW FROM INVESTING ACTIVITIES:
Net Cash Provided by (Used in) Investing Activities [Abstract]
Construction expenditures and property additions
Payments to Acquire Property, Plant, and Equipment
Acquisition of businesses, net of cash acquired
Payments to Acquire Businesses, Net of Cash Acquired
Changes in customer advances
Increase (Decrease) in Customer Advances
Miscellaneous inflows
Payments for (Proceeds from) Other Investing Activities
Net cash used in investing activities
Net Cash Provided by (Used in) Investing Activities
CASH FLOW FROM FINANCING ACTIVITIES:
Net Cash Provided by (Used in) Financing Activities [Abstract]
Issuance of common stock, net
Proceeds from Issuance of Common Stock
Contributions from parent
Proceeds from Contributions from Parent
Dividends paid
Payments of Ordinary Dividends, Common Stock
Issuance of long-term debt, net
Proceeds from Issuance of Long-term Debt
Retirement of long-term debt
Repayments of Long-term Debt
Change in 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
Change in short-term debt
Proceeds from (Repayments of) Short-term Debt
Principal payments on finance lease obligations
Finance Lease, Principal Payments
Redemption of Centuri shares from noncontrolling parties
Payments for Repurchase of Redeemable Noncontrolling Interest
Withholding remittance - share-based compensation
Payment, Tax Withholding, Share-based Payment Arrangement
Other
Proceeds from (Payments for) Other Financing Activities
Net cash provided by financing activities
Net Cash Provided by (Used in) Financing Activities
Effects of currency translation on cash and cash equivalents
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents
Change in cash and cash equivalents
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect
Cash and cash equivalents at beginning of period
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents
Cash and cash equivalents at end of period
Supplemental information:
Supplemental Cash Flow Information [Abstract]
Interest paid, net of amounts capitalized
Interest Paid, Excluding Capitalized Interest, Operating Activities
Income taxes paid (received)
Income Taxes Paid, Net
Schedule of Goodwill [Table]
Schedule of Goodwill [Table]
Goodwill [Line Items]
Goodwill [Line Items]
Goodwill [Roll Forward]
Goodwill [Roll Forward]
Goodwill, beginning balance
Measurement-period adjustments - Linetec acquisition (a)
Goodwill, Acquired During Period
Foreign currency translation adjustment
Goodwill, Foreign Currency Translation Gain (Loss)
Goodwill, ending balance
Schedule of Defined Benefit Plans Disclosures [Table]
Schedule of Defined Benefit Plans Disclosures [Table]
Retirement Plan Type [Axis]
Retirement Plan Type [Axis]
Retirement Plan Type [Domain]
Retirement Plan Type [Domain]
Qualified Retirement Plan
Other Pension Plan [Member]
SERP
Supplemental Employee Retirement Plan [Member]
PBOP
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Disclosure [Line Items]
Service cost
Defined Benefit Plan, Service Cost
Interest cost
Defined Benefit Plan, Interest Cost
Expected return on plan assets
Defined Benefit Plan, Expected Return (Loss) on Plan Assets
Amortization of prior service costs
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)
Amortization of net actuarial loss
Defined Benefit Plan, Amortization of Gain (Loss)
Net periodic benefit cost
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Statement of Stockholders' Equity [Abstract]
Common Stock
Common Stock [Member]
Additional paid-in capital
Additional Paid-in Capital [Member]
Accumulated other comprehensive income (loss)
Retained Earnings
Retained Earnings [Member]
Southwest Gas Holdings, Inc.
Parent [Member]
Non-controlling Interest
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)
Common stock issuances (in shares)
Stock Issued During Period, Shares, New Issues
Common stock issuances
Stock Issued During Period, Value, New Issues
Net income (loss)
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest
Change in ownership of noncontrolling interest
Noncontrolling Interest, Increase from Subsidiary Equity Issuance
Foreign currency exchange translation adjustment
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Portion Attributable to Parent
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
FSIRS amounts reclassified to net income, net of tax
Reclassification of excess deferred taxes
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect
Share-based compensation
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture
Dividends declared
Dividends, Common Stock
Contributions from Southwest Gas Holdings, Inc.
Adjustments To Additional Paid In Capital Contributions From Parent
Adjustments to additional paid in capital contributions from parent.
Ending balance (in shares)
Dividends declared per share (in USD per share)
Common Stock, Dividends, Per Share, Declared
Common Stock
Common Stock Disclosure [Text Block]
Common Stock Disclosure [Text Block]
Centuri accounts receivable for services provided to Southwest
Due from Related Parties, Current
Short-Term Debt
Short-term Debt [Text Block]
Nature of Operations
Nature Of Operations [Policy Text Block]
Nature Of Operations [Policy Text Block]
Basis of Presentation
Basis of Accounting, Policy [Policy Text Block]
Fair Value Measurements
Fair Value Measurement, Policy [Policy Text Block]
Cash and Cash Equivalents
Cash and Cash Equivalents, Policy [Policy Text Block]
Income Taxes
Income Tax, Policy [Policy Text Block]
Goodwill
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]
Recent Accounting Standards Updates
New Accounting Pronouncements, Policy [Policy Text Block]
Noncontrolling Interest [Table]
Noncontrolling Interest [Table]
Noncontrolling Interest [Line Items]
Noncontrolling Interest [Line Items]
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
Leases
Lessee, Finance Leases [Text Block]
Leases
Lessee, Operating Leases [Text Block]
Billed on completed contracts and contracts in progress
Billed on completed contracts and contracts in progress
Billed on completed contracts and contracts in progress.
Other receivables
Other Receivables
Contracts receivable, gross
Accounts Receivable, before Allowance for Credit Loss
Allowance for doubtful accounts
Accounts Receivable, Allowance for Credit Loss
Contracts receivable, net
Number of segments
Number of Reportable Segments
Business Acquisitions
Business Combination Disclosure [Text Block]
Paid to counterparties
Payments For Derivative Instrument Operating Activities
The cash outflow for derivative instruments during the period, which are classified as operating activities, excluding those designated as hedging instruments.
Received from counterparties
Proceeds from Derivative Instrument, Investing Activities
Movement In Redeemable Noncontrolling Interest [Roll Forward]
Movement In Redeemable Noncontrolling Interest [Roll Forward]
Movement In Redeemable Noncontrolling Interest [Roll Forward]
Balance, December 31, 2018
Redeemable Noncontrolling Interest, Equity, Carrying Amount
Net income attributable to redeemable noncontrolling interest
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest
Balance, June 30, 2019
Product and Service [Axis]
Product and Service [Axis]
Product and Service [Domain]
Product and Service [Domain]
Gas infrastructure services
Replacement Gas Construction [Member]
Replacement gas construction.
Electric power infrastructure services
New Gas Construction [Member]
New Gas Construction [Member]
Other
Other Construction [Member]
Other construction.
Contract with Customer, Basis of Pricing [Axis]
Contract with Customer, Basis of Pricing [Axis]
Contract with Customer, Basis of Pricing [Domain]
Contract with Customer, Basis of Pricing [Domain]
Master services agreement
Master Services Agreement [Member]
Master Services Agreement [Member]
Bid contract
Bid Contract [Member]
Bid contract.
Unit priced contracts
Unit Priced Contracts [Member]
Unit priced contracts.
Fixed priced contracts
Fixed-price Contract [Member]
Time and materials contracts
Time-and-materials Contract [Member]
Revenue from contracts with customers
Schedule of Stock by Class [Table]
Schedule of Stock by Class [Table]
Sale of Stock [Axis]
Sale of Stock [Axis]
Sale of Stock [Domain]
Sale of Stock [Domain]
Equity Shelf Program
Equity Shelf Program [Member]
Equity Shelf Program [Member]
Plan Name [Axis]
Plan Name [Axis]
Plan Name [Domain]
Plan Name [Domain]
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]
Dividend Reinvestment and Stock Purchase Plan
Dividend Reinvestment And Stock Purchase Plan [Member]
Dividend Reinvestment And Stock Purchase Plan [Member]
Class of Stock [Line Items]
Class of Stock [Line Items]
Sale of stock, maximum amount of stock allowed to be offered
Sale Of Stock, Maxumum Amount Of Stock Allowed To Be Offered
Sale Of Stock, Maxumum Amount Of Stock Allowed To Be Offered
Sale of stock, common stock available for sale
Sale Of Stock, Common Stock Available For Sale
Sale Of Stock, Common Stock Available For Sale
Sale of stock, number of shares sold (in shares)
Sale of Stock, Number of Shares Issued in Transaction
Gross proceeds
Proceeds From Issuance Of Common Stock, Gross
Proceeds From Issuance Of Common Stock, Gross
Agent commissions
Payments of Stock Issuance Costs
Net proceeds to company
Number of shares sold (in shares)
Weighted average price per share
Common Stock Weighted Average Issue Price Per Share
Common stock weighted average issue price per share.
Common stock issued (in shares)
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period
Common stock issued, amount
Common stock available for issuance (in shares)
Common Stock, Capital Shares Reserved for Future Issuance
Summary of Revenue Disaggregated by Service Type and Contract Type
Disaggregation of Revenue [Table Text Block]
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.
Schedule of Construction Services Contracts Receivable
Schedule of Construction Services Contracts Receivable [Table Text Block]
Schedule of Construction Services Contracts Receivable [Table Text Block]
Notional Amounts under Swaps Contracts
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]
Paid to and Received from Counterparties for Settlements of Matured Swaps
Paid And Received From Counterparties For Settlements Of Matured Swaps [Table Text Block]
Paid and Received From Counterparties for Settlements of Matured Swaps [Table Text Block]
Fair Values of Swaps in Consolidated Balance Sheets
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]
Southwest Gas Credit Facility
Southwest Gas Credit Facility [Member]
Southwest Gas Credit Facility [Member]
Commercial Paper Program
Commercial Paper Program [Member]
Commercial Paper Program [Member]
Secured Revolving Credit Facility and Term Loan
Secured Revolving Credit Facility Term Loan [Member]
Secured Revolving Credit Facility Term Loan [Member]
Line of Credit
Line of Credit [Member]
Variable Rate [Axis]
Variable Rate [Axis]
Variable Rate [Domain]
Variable Rate [Domain]
LIBOR
London Interbank Offered Rate (LIBOR) [Member]
Alternative Base Rate
Alternative Base Rate [Member]
Alternative Base Rate [Member]
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
Applicable margin
Debt Instrument, Basis Spread on Variable Rate
Long-term debt
Borrowings outstanding under facility
Debt face amount
Debt Instrument, Face Amount
Debt discount rate
Debt Instrument, Discount Rate
Debt Instrument, Discount Rate
Debt secured by assets
Debt Instrument, Collateral Amount
Percentage of total debt 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
Debt Instrument, Percentage Of Total With Interest Rates Reference To LIBOR And Due After 2021
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to unsatisfied performance obligations of contracts
Revenue, Remaining Performance Obligation, Amount
Revenue, remaining performance obligation, expected timing of satisfaction, period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
ASSETS
Assets [Abstract]
Utility plant:
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Gas plant
Public Utilities, Property, Plant and Equipment, Plant in Service
Less: accumulated depreciation
Public Utilities, Property, Plant and Equipment, Accumulated Depreciation
Construction work in progress
Public Utilities, Property, Plant and Equipment, Construction Work in Progress
Net utility plant
Public Utilities, Property, Plant and Equipment, Net
Other property and investments
Current assets:
Assets, Current [Abstract]
Cash and cash equivalents
Cash and Cash Equivalents, at Carrying Value
Accounts receivable, net of allowances
Accounts Receivable, after Allowance for Credit Loss, Current
Accrued utility revenue
Accrued Utility Revenue
Accrued utility revenue.
Income taxes receivable
Income Taxes Receivable, Current
Deferred purchased gas costs
Deferred Gas Cost
Prepaid and other current assets
Prepaid Expense and Other Assets, Current
Total current assets
Assets, Current
Noncurrent assets:
Assets, Noncurrent [Abstract]
Deferred income taxes
Deferred Income Tax Assets, Net
Deferred charges and other assets
Other Assets, Noncurrent
Total noncurrent assets
Assets, Noncurrent, Other than Noncurrent Investments and Property, Plant and Equipment
Total assets
Assets
CAPITALIZATION AND LIABILITIES
Liabilities and Equity [Abstract]
Capitalization:
Capitalization, Long-term Debt and Equity [Abstract]
Common stock, $1 par (authorized - 60,000,000 shares; issued and outstanding - 54,321,217 and 53,026,848 shares)
Common Stock, Value, Issued
Additional paid-in capital
Additional Paid in Capital, Common Stock
Accumulated other comprehensive income (loss), net
Accumulated Other Comprehensive Income (Loss), Net of Tax
Retained earnings
Retained Earnings (Accumulated Deficit)
Total Southwest Gas Holdings, Inc. equity
Noncontrolling interest
Stockholders' Equity Attributable to Noncontrolling Interest
Total equity
Redeemable noncontrolling interest
Total capitalization
Capitalization, Long-term Debt and Equity
Current liabilities:
Liabilities, Current [Abstract]
Current maturities of long-term debt
Short-term debt
Accounts payable
Accounts Payable, Current
Customer deposits
Customer Deposits, Current
Income taxes payable
Taxes Payable, Current
Accrued general taxes
Accrual for Taxes Other than Income Taxes, Current
Accrued interest
Interest Payable, Current
Deferred purchased gas costs
Deferred Gas Purchases, Current
Payable to parent
Due to Affiliate, Current
Other current liabilities
Other Liabilities, Current
Total current liabilities
Liabilities, Current
Deferred income taxes and other credits:
Other Liabilities, Noncurrent [Abstract]
Deferred income taxes and investment tax credits
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.
Accumulated removal costs
Other Accrued Liabilities, Noncurrent
Other deferred credits and other long-term liabilities
Deferred Credits and Other Liabilities, Noncurrent
Total deferred income taxes and other credits
Other Liabilities, Noncurrent
Total capitalization and liabilities
Liabilities and Equity
Derivatives
Derivative Instruments and Hedging Activities Disclosure [Text Block]
Significant Accounting Policies [Table]
Significant Accounting Policies [Table]
Significant Accounting Policies [Table]
Intellichoice Energy LLC
Intellichoice Energy LLC [Member]
Intellichoice Energy LLC [Member]
NPL
NPL [Member]
NPL [Member]
Cash and Cash Equivalents [Axis]
Cash and Cash Equivalents [Axis]
Cash and Cash Equivalents [Domain]
Cash and Cash Equivalents [Domain]
Pooled Funds and Mutual Funds
Money Market Funds [Member]
Fair Value Hierarchy and NAV [Axis]
Fair Value Hierarchy and NAV [Axis]
Fair Value Hierarchy and NAV [Domain]
Fair Value Hierarchy and NAV [Domain]
Level 2 - Significant Other Observable Inputs
Fair Value, Inputs, Level 2 [Member]
Inventory [Axis]
Inventory [Axis]
Inventory [Domain]
Inventory [Domain]
Gas Pipe Materials and Supplies
Gas Pipe Inventory And Operating Supplies [Member]
Gas pipe inventory and operating supplies.
Significant Accounting Policies [Line Items]
Significant Accounting Policies [Line Items]
Significant Accounting Policies [Line Items]
Ownership percentage by parent
Noncontrolling Interest, Ownership Percentage by Parent
Additional capital contributed
Proceeds from Contributed Capital
Money market fund investments
Cash and Cash Equivalents, Fair Value Disclosure
Purchase consideration
Business Combination, Consideration Transferred
Gas pipe materials and operating supplies
Materials, Supplies, and Other
Prepaid and other current assets
Regulatory Assets, Current
Goodwill impairment
Goodwill, Impairment Loss
Dividends declared but not yet paid
Dividends Payable, Current
Background, Organization, and Summary of Significant Accounting Policies
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]
Rental payments/lease expense
Operating Leases, Rent Expense, Net
Schedule of Segment Reporting Information
Schedule of Segment Reporting Information, by Segment [Table Text Block]
Segment Information
Segment Reporting Disclosure [Text Block]
Operating leases
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months
2021
Lessee, Operating Lease, Liability, Payments, Due Year Two
2022
Lessee, Operating Lease, Liability, Payments, Due Year Three
2023
Lessee, Operating Lease, Liability, Payments, Due Year Four
2024
Lessee, Operating Lease, Liability, Payments, Due Year Five
Thereafter
Lessee, Operating Lease, Liability, Payments, Due after Year Five
Total lease payments
Lessee, Operating Lease, Liability, Payments, Due
Less imputed interest
Lessee, Operating Lease, Liability, Undiscounted Excess Amount
Total
Finance leases
Finance Lease, Liability, Payment, Due [Abstract]
2020
Finance Lease, Liability, Payments, Due Next Twelve Months
2021
Finance Lease, Liability, Payments, Due Year Two
2022
Finance Lease, Liability, Payments, Due Year Three
2023
Finance Lease, Liability, Payments, Due Year Four
2024
Finance Lease, Liability, Payments, Due Year Five
Thereafter
Finance Lease, Liability, Payments, Due after Year Five
Total lease payments
Finance Lease, Liability, Payment, Due
Less imputed interest
Finance Lease, Liability, Undiscounted Excess Amount
Total