Significant Accounting Policies [Line Items]

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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- Definition

Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
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- Definition

The carrying amount of capitalized costs of materials, supplies, and other assets, which are not included in inventory but used in production.

+ References

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- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

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- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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- Definition

Threshold period past due for trade accounts receivable to write off as uncollectible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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Background, Organization, and Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2020 USD ($) state	Dec. 31, 2019 USD ($)	Nov. 30, 2018
Significant Accounting Policies [Line Items]
Number of states in which entity operates \| state	3
Threshold period after inactivation for write-off of accounts receivable	2 months
Goodwill impairment	$ 0
Linetec
Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners			20.00%
Gas Pipe Materials and Supplies \| Prepaid and other current assets
Significant Accounting Policies [Line Items]
Gas pipe materials and operating supplies	53,000,000	$ 57,000,000
Prepaid and other current assets	3,000,000	33,000,000
Pooled Funds and Mutual Funds
Significant Accounting Policies [Line Items]
Money market fund investments	49,000	26,700,000
Southwest Gas Corporation
Significant Accounting Policies [Line Items]
Dividends declared but not yet paid	25,900,000	25,200,000
Southwest Gas Corporation \| Pooled Funds and Mutual Funds
Significant Accounting Policies [Line Items]
Money market fund investments	$ 40,000	$ 23,500,000