101 - Document - Document and Entity Information link:calculationLink link:presentationLink link:definitionLink 103 - Statement - Condensed Consolidated Balance Sheets link:calculationLink link:presentationLink link:definitionLink 104 - Statement - Condensed Consolidated Balance Sheets (Parenthetical) link:calculationLink link:presentationLink link:definitionLink 105 - Statement - Condensed Consolidated Statements of Income link:calculationLink link:presentationLink link:definitionLink 106 - Statement - Condensed Consolidated Statements of Comprehensive Income link:calculationLink link:presentationLink link:definitionLink 107 - Statement - Condensed Consolidated Statements of Cash Flows link:calculationLink link:presentationLink link:definitionLink 108 - Disclosure - Nature of Operations and Basis of Presentation link:calculationLink link:presentationLink link:definitionLink 109 - Disclosure - Components of Net Periodic Benefit Cost link:calculationLink link:presentationLink link:definitionLink 110 - Disclosure - Segment Information link:calculationLink link:presentationLink link:definitionLink 111 - Disclosure - Derivatives and Fair Value Measurements link:calculationLink link:presentationLink link:definitionLink 112 - Disclosure - Common Stock link:calculationLink link:presentationLink link:definitionLink 113 - Disclosure - Long-Term Debt link:calculationLink link:presentationLink link:definitionLink 114 - Disclosure - Short-Term Debt link:calculationLink link:presentationLink link:definitionLink 115 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income link:calculationLink link:presentationLink link:definitionLink 116 - Disclosure - Construction Services Redeemable Noncontrolling Interest link:calculationLink link:presentationLink link:definitionLink 117 - Disclosure - Reorganization Impacts - Discontinued Operations Solely Related to Southwest Gas Corporation link:calculationLink link:presentationLink link:definitionLink 118 - Disclosure - Nature of Operations and Basis of Presentation (Policies) link:calculationLink link:presentationLink link:definitionLink 119 - Disclosure - Nature of Operations and Basis of Presentation (Tables) link:calculationLink link:presentationLink link:definitionLink 120 - Disclosure - Components of Net Periodic Benefit Cost (Tables) link:calculationLink link:presentationLink link:definitionLink 121 - Disclosure - Segment Information (Tables) link:calculationLink link:presentationLink link:definitionLink 122 - Disclosure - Derivatives and Fair Value Measurements (Tables) link:calculationLink link:presentationLink link:definitionLink 123 - Disclosure - Long-Term Debt (Tables) link:calculationLink link:presentationLink link:definitionLink 124 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income (Tables) link:calculationLink link:presentationLink link:definitionLink 125 - Disclosure - Construction Services Redeemable Noncontrolling Interest (Tables) link:calculationLink link:presentationLink link:definitionLink 126 - Disclosure - Reorganization Impacts - Discontinued Operations Solely Related to Southwest Gas Corporation (Tables) link:calculationLink link:presentationLink link:definitionLink 127 - Disclosure - Nature of Operations and Basis of Presentation - Additional Information (Detail) link:calculationLink link:presentationLink link:definitionLink 128 - Disclosure - Nature of Operations and Basis of Presentation - Schedule of Goodwill (Detail) link:calculationLink link:presentationLink link:definitionLink 129 - Disclosure - Nature of Operations and Basis of Presentation - Accounts Receivable for Services (Detail) link:calculationLink link:presentationLink link:definitionLink 130 - Disclosure - Nature of Operations and Basis of Presentation - Schedule of Other Property and Investments (Detail) link:calculationLink link:presentationLink link:definitionLink 131 - Disclosure - Nature of Operations and Basis of Presentation - Other Income (Deductions) (Detail) link:calculationLink link:presentationLink link:definitionLink 132 - Disclosure - Components of Net Periodic Benefit Cost - Schedule of Net Periodic Benefit Costs (Detail) link:calculationLink link:presentationLink link:definitionLink 133 - Disclosure - Segment Information - Additional Information (Detail) link:calculationLink link:presentationLink link:definitionLink 134 - Disclosure - Segment Information - Schedule of Segment Reporting Information (Detail) link:calculationLink link:presentationLink link:definitionLink 135 - Disclosure - Derivatives and Fair Value Measurements - Additional Information (Detail) link:calculationLink link:presentationLink link:definitionLink 136 - Disclosure - Derivatives and Fair Value Measurements - Notional Amounts under Swaps Contracts (Detail) link:calculationLink link:presentationLink link:definitionLink 137 - Disclosure - Derivatives and Fair Value Measurements - Amount of Gain or Losses Recognized in Income on Derivatives (Detail) link:calculationLink link:presentationLink link:definitionLink 138 - Disclosure - Derivatives and Fair Value Measurements - Fair Values of Swaps in Consolidated Balance Sheets (Detail) link:calculationLink link:presentationLink link:definitionLink 139 - Disclosure - Derivatives and Fair Value Measurements - Paid to and Received from Counterparties for Settlements of Matured Swaps (Detail) link:calculationLink link:presentationLink link:definitionLink 140 - Disclosure - Derivatives and Fair Value Measurements - Regulatory Assets/Liabilities Offsetting Derivatives at Fair Value in Condensed Consolidated Balance Sheets (Detail) link:calculationLink link:presentationLink link:definitionLink 141 - Disclosure - Derivatives and Fair Value Measurements - Significant Other Observable Inputs (Detail) link:calculationLink link:presentationLink link:definitionLink 142 - Disclosure - Common Stock - Additional Information (Detail) link:calculationLink link:presentationLink link:definitionLink 143 - Disclosure - Long-Term Debt - Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Detail) link:calculationLink link:presentationLink link:definitionLink 144 - Disclosure - Long-Term Debt - Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Parenthetical) (Detail) link:calculationLink link:presentationLink link:definitionLink 145 - Disclosure - Long-Term Debt - Additional Information (Detail) link:calculationLink link:presentationLink link:definitionLink 146 - Disclosure - Short-Term Debt - Additional Information (Detail) link:calculationLink link:presentationLink link:definitionLink 147 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Detailed Activities of Equity and Redeemable Noncontrolling Interest (Detail) link:calculationLink link:presentationLink link:definitionLink 148 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Detailed Activities of Equity and Redeemable Noncontrolling Interest (Parenthetical) (Detail) link:calculationLink link:presentationLink link:definitionLink 149 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) (Detail) link:calculationLink link:presentationLink link:definitionLink 150 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) (Parenthetical) (Detail) link:calculationLink link:presentationLink link:definitionLink 151 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Additional Information (Detail) link:calculationLink link:presentationLink link:definitionLink 152 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Rollforward of Accumulated Other Comprehensive Income (Detail) link:calculationLink link:presentationLink link:definitionLink 153 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Rollforward of Accumulated Other Comprehensive Income (Parenthetical) (Detail) link:calculationLink link:presentationLink link:definitionLink 154 - Disclosure - Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Amount Recognized Before Income Tax Associated with Defined Benefit Plans in Accumulated Other Comprehensive Income (Detail) link:calculationLink link:presentationLink link:definitionLink 155 - Disclosure - Construction Services Redeemable Noncontrolling Interest - Additional Information (Detail) link:calculationLink link:presentationLink link:definitionLink 156 - Disclosure - Construction Services Redeemable Noncontrolling Interest - Summary of Redeemable Noncontrolling Interest (Detail) link:calculationLink link:presentationLink link:definitionLink 157 - Disclosure - Reorganization Impacts - Discontinued Operations Solely Related to Southwest Gas Corporation - Summary of Assets and Liabilities within Amounts Reported as Discontinued Operations - Construction Services in Condensed Consolidated Balance Sheet (Detail) link:calculationLink link:presentationLink link:definitionLink 158 - Disclosure - Reorganization Impacts - Discontinued Operations Solely Related to Southwest Gas Corporation - Components of Discontinued Operations - Construction Services Non-Owner Equity Amount in Condensed Consolidated Balance Sheet (Detail) link:calculationLink link:presentationLink link:definitionLink 159 - Disclosure - Reorganization Impacts - Discontinued Operations Solely Related to Southwest Gas Corporation - Summary of Income Statement Components of Discontinued Operations - Construction Services in Condensed Consolidated Income Statements (Detail) link:calculationLink link:presentationLink link:definitionLink