Southwest Gas 10-Q 8 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	SWX
Entity Registrant Name	Southwest Gas Holdings, Inc.
Entity Central Index Key	0001692115
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		53,396,583
Southwest Gas Corporation
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	SWX
Entity Registrant Name	Southwest Gas Corporation
Entity Central Index Key	0000092416
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Utility plant:
Gas plant	$ 7,268,255	$ 7,134,239
Less: accumulated depreciation	(2,257,017)	(2,234,029)
Construction work in progress	204,370	193,028
Net utility plant	5,215,608	5,093,238
Other property and investments	716,722	623,551
Current assets:
Cash and cash equivalents	97,037	85,361
Accounts receivable, net of allowances	429,248	413,926
Accrued utility revenue	47,000	77,200
Income taxes receivable	14,069	14,653
Deferred purchased gas costs	65,242	4,928
Prepaid and other current assets	177,784	243,701
Total current assets	830,380	839,769
Noncurrent assets:
Goodwill	364,482	359,045
Deferred income taxes	1,074	1,264
Deferred charges and other assets	441,166	440,862
Total noncurrent assets	806,722	801,171
Total assets	7,569,432	7,357,729
Capitalization:
Common stock, $1 par (authorized - 60,000,000 shares; issued and outstanding - 53,391,731 and 53,026,848 shares)	55,021	54,656
Additional paid-in capital	1,332,793	1,305,769
Accumulated other comprehensive income (loss), net	(50,623)	(52,668)
Retained earnings	1,009,809	944,285
Total Southwest Gas Holdings, Inc. equity	2,347,000	2,252,042
Noncontrolling interest	(452)	(452)
Total equity	2,346,548	2,251,590
Redeemable noncontrolling interest	82,406	81,831
Long-term debt, less current maturities	2,106,274	2,107,258
Total capitalization	4,535,228	4,440,679
Current liabilities:
Current maturities of long-term debt	34,915	33,060
Short-term debt	188,000	152,000
Accounts payable	231,343	248,993
Customer deposits	68,593	67,940
Income taxes payable	0	1,083
Accrued general taxes	69,423	43,560
Accrued interest	31,439	21,369
Deferred purchased gas costs	72,213	79,762
Other current liabilities	278,552	290,878
Total current liabilities	974,478	938,645
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits	556,063	529,201
Accumulated removal costs	385,000	383,000
Other deferred credits and other long-term liabilities	1,118,663	1,066,204
Total deferred income taxes and other credits	2,059,726	1,978,405
Total capitalization and liabilities	7,569,432	7,357,729
Southwest Gas Corporation
Utility plant:
Gas plant	7,268,255	7,134,239
Less: accumulated depreciation	(2,257,017)	(2,234,029)
Construction work in progress	204,370	193,028
Net utility plant	5,215,608	5,093,238
Other property and investments	123,783	116,146
Current assets:
Cash and cash equivalents	75,148	31,962
Accounts receivable, net of allowances	170,471	140,057
Accrued utility revenue	47,000	77,200
Income taxes receivable	10,602	13,444
Deferred purchased gas costs	65,242	4,928
Prepaid and other current assets	165,382	229,562
Total current assets	533,845	497,153
Noncurrent assets:
Goodwill	10,095	10,095
Deferred charges and other assets	423,495	424,952
Total noncurrent assets	433,590	435,047
Total assets	6,306,826	6,141,584
Capitalization:
Common stock, $1 par (authorized - 60,000,000 shares; issued and outstanding - 53,391,731 and 53,026,848 shares)	49,112	49,112
Additional paid-in capital	1,089,002	1,065,242
Accumulated other comprehensive income (loss), net	(47,795)	(49,049)
Retained earnings	797,584	717,155
Total Southwest Gas Holdings, Inc. equity	1,887,903	1,782,460
Total equity	1,887,903	1,782,460
Long-term debt, less current maturities	1,818,959	1,818,669
Total capitalization	3,706,862	3,601,129
Current liabilities:
Short-term debt	188,000	152,000
Accounts payable	148,309	184,982
Customer deposits	68,593	67,940
Accrued general taxes	69,423	43,560
Accrued interest	30,398	20,243
Deferred purchased gas costs	72,213	79,762
Payable to parent	1,038	472
Other current liabilities	100,556	94,136
Total current liabilities	678,530	643,095
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits	517,124	490,458
Accumulated removal costs	385,000	383,000
Other deferred credits and other long-term liabilities	1,019,310	1,023,902
Total deferred income taxes and other credits	1,921,434	1,897,360
Total capitalization and liabilities	$ 6,306,826	$ 6,141,584

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par (in USD per share)	$ 1	$ 1
Common stock, authorized (in shares)	60,000,000	60,000,000
Common stock, issued (in shares)	53,391,731	53,026,848
Common stock, outstanding (in shares)	53,391,731	53,026,848

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Operating revenues:
Gas operating revenues	$ 520,677	$ 494,313	$ 1,384,092	$ 1,334,019
Utility infrastructure services revenues	312,862	260,017	1,575,130	1,314,366
Total operating revenues	833,539	754,330	2,959,222	2,648,385
Operating expenses:
Net cost of gas sold	192,604	185,732	426,260	393,898
Operations and maintenance	106,245	102,351	410,287	390,819
Depreciation and amortization	77,539	62,478	264,273	240,951
Taxes other than income taxes	16,206	15,257	60,847	58,421
Utility infrastructure services expenses	300,465	258,952	1,429,202	1,215,959
Total operating expenses	693,059	624,770	2,590,869	2,300,048
Operating income	140,480	129,560	368,353	348,337
Other income and (expenses):
Net interest deductions	(26,397)	(22,631)	(100,437)	(81,981)
Other income (deductions)	6,839	(4,334)	(6,253)	(9,374)
Total other income and (expenses)	(19,558)	(26,965)	(106,690)	(91,355)
Income before income taxes	120,922	102,595	261,663	256,982
Income tax expense	25,538	24,301	62,921	53,751
Net income	95,384	78,294	198,742	203,231
Net income (loss) attributable to noncontrolling interests	575	(797)	747	(393)
Net income attributable to Southwest Gas Holdings, Inc.	$ 94,809	$ 79,091	$ 197,995	$ 203,624
Basic earnings per share (in USD per share)	$ 1.78	$ 1.63	$ 3.91	$ 4.23
Diluted earnings per share (in USD per share)	$ 1.77	$ 1.63	$ 3.91	$ 4.23
Average number of common shares (in shares)	53,369	48,416	50,640	48,105
Average shares (assuming dilution) (in shares)	53,424	48,459	50,701	48,139
Southwest Gas Corporation
Operating revenues:
Gas operating revenues	$ 520,677	$ 494,313	$ 1,384,092	$ 1,334,019
Operating expenses:
Net cost of gas sold	192,604	185,732	426,260	393,898
Operations and maintenance	105,542	102,190	408,165	389,687
Depreciation and amortization	57,612	49,961	199,467	190,688
Taxes other than income taxes	16,206	15,257	60,847	58,421
Total operating expenses	371,964	353,140	1,094,739	1,032,694
Operating income	148,713	141,173	289,353	301,325
Other income and (expenses):
Net interest deductions	(23,099)	(19,255)	(85,584)	(71,778)
Other income (deductions)	5,946	(4,603)	(6,691)	(9,747)
Total other income and (expenses)	(17,153)	(23,858)	(92,275)	(81,525)
Income before income taxes	131,560	117,315	197,078	219,800
Income tax expense	28,171	26,966	45,196	49,571
Net income	103,389	90,349	151,882	170,229
Net income attributable to Southwest Gas Holdings, Inc.	$ 103,389	$ 90,349	$ 151,882	$ 170,229

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Net income	$ 95,384	$ 78,294	$ 198,742	$ 203,231
Defined benefit pension plans:
Net actuarial gain (loss)	0	0	(15,524)	(32,701)
Amortization of prior service cost	241	254	1,002	875
Amortization of net actuarial loss	4,441	6,387	23,603	18,219
Regulatory adjustment	(4,063)	(5,746)	(4,574)	10,400
Net defined benefit pension plans	619	895	4,507	(3,207)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	635	635	2,541	2,190
Net forward-starting interest rate swaps	635	635	2,541	2,190
Foreign currency translation adjustments	791	(911)	(1,308)	640
Total other comprehensive income (loss), net of tax	2,045	619	5,740	(377)
Comprehensive income	97,429	78,913	204,482	202,854
Comprehensive income (loss) attributable to noncontrolling interests	575	(797)	747	(389)
Comprehensive income attributable to Southwest Gas Holdings, Inc.	96,854	79,710	203,735	203,243
Southwest Gas Corporation
Net income	103,389	90,349	151,882	170,229
Defined benefit pension plans:
Net actuarial gain (loss)	0	0	(15,524)	(32,701)
Amortization of prior service cost	241	254	1,002	875
Amortization of net actuarial loss	4,441	6,387	23,603	18,219
Regulatory adjustment	(4,063)	(5,746)	(4,574)	10,400
Net defined benefit pension plans	619	895	4,507	(3,207)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	635	635	2,541	2,190
Net forward-starting interest rate swaps	635	635	2,541	2,190
Total other comprehensive income (loss), net of tax	1,254	1,530	7,048	(1,017)
Comprehensive income	$ 104,643	$ 91,879	$ 158,930	$ 169,212

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$ 95,384	$ 78,294	$ 198,742	$ 203,231
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	77,539	62,478	264,273	240,951
Deferred income taxes	24,923	23,228	52,736	49,372
Changes in current assets and liabilities:
Accounts receivable, net of allowances	(15,562)	8,858	(40,282)	(68,978)
Accrued utility revenue	30,200	30,900	300	(1,400)
Deferred purchased gas costs	(67,863)	(10,628)	25,339	(36,330)
Accounts payable	(12,643)	(48,497)	47,632	26,762
Accrued taxes	25,400	18,776	(5,331)	491
Other current assets and liabilities	47,848	(643)	(5,582)	(29,945)
Gains on sale	(233)	(230)	(1,706)	(4,087)
Changes in undistributed stock compensation	3,188	1,861	7,438	6,638
AFUDC	(960)	(229)	(4,358)	(2,050)
Changes in other assets and deferred charges	(16,328)	(1,845)	(20,221)	(16,941)
Changes in other liabilities and deferred credits	(2,782)	18,244	17,420	20,965
Net cash provided by operating activities	188,111	180,567	536,400	388,679
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(210,662)	(154,542)	(822,034)	(662,401)
Acquisition of businesses, net of cash acquired	0	(4,209)	(247,164)	(98,413)
Changes in customer advances	3,078	3,038	13,503	2,304
Miscellaneous inflows	262	1,505	3,200	13,429
Net cash used in investing activities	(207,322)	(154,208)	(1,052,495)	(745,081)
CASH FLOW FROM FINANCING ACTIVITIES:
Issuance of common stock, net	25,879	11,220	369,061	52,375
Dividends paid	(27,602)	(23,839)	(104,003)	(94,572)
Centuri distribution to redeemable noncontrolling interest	0	(102)	0	(204)
Issuance of long-term debt, net	29,666	335,382	259,456	716,165
Retirement of long-term debt	(31,160)	(21,102)	(247,816)	(312,308)
Change in credit facility and commercial paper	0	(111,000)	111,000	24,000
Change in short-term debt	36,000	(192,000)	165,500	22,500
Principal payments on finance lease obligations	(70)	(165)	(553)	(946)
Redemption of Centuri shares from noncontrolling parties	0	0	0	(23,000)
Withholding remittance - share-based compensation	(1,838)	(2,852)	(2,096)	(3,510)
Other	(53)	(337)	(2,460)	(2,498)
Net cash provided by (used in) financing activities	30,822	(4,795)	548,089	378,002
Effects of currency translation on cash and cash equivalents	65	(71)	(72)	114
Change in cash and cash equivalents	11,676	21,493	31,922	21,714
Cash and cash equivalents at beginning of period	85,361	43,622	65,115	43,401
Cash and cash equivalents at end of period	97,037	65,115	97,037	65,115
Supplemental information:
Interest paid, net of amounts capitalized	15,850	13,294	89,118	74,949
Income taxes paid (received)	454	4,418	(2,743)	8,264
Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	103,389	90,349	151,882	170,229
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	57,612	49,961	199,467	190,688
Deferred income taxes	26,270	18,676	50,593	46,622
Changes in current assets and liabilities:
Accounts receivable, net of allowances	(30,414)	(28,201)	(22,522)	(29,031)
Accrued utility revenue	30,200	30,900	300	(1,400)
Deferred purchased gas costs	(67,863)	(10,628)	25,339	(36,330)
Accounts payable	(39,574)	(34,564)	18,398	14,717
Accrued taxes	28,704	27,476	(17,504)	12,683
Other current assets and liabilities	81,625	3,163	(12,982)	(47,905)
Changes in undistributed stock compensation	2,597	2,118	5,834	5,695
AFUDC	(960)	(229)	(4,358)	(2,050)
Changes in other assets and deferred charges	(18,238)	(1,998)	(23,289)	(17,655)
Changes in other liabilities and deferred credits	(2,977)	17,887	16,805	20,230
Net cash provided by operating activities	170,371	164,910	387,963	326,493
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(163,636)	(131,743)	(714,762)	(591,184)
Changes in customer advances	3,078	3,038	13,503	2,304
Miscellaneous inflows	(78)	293	(357)	2,250
Net cash used in investing activities	(160,636)	(128,412)	(701,616)	(586,630)
CASH FLOW FROM FINANCING ACTIVITIES:
Issuance of common stock, net	0	0	0	41,359
Contributions from parent	22,842	0	136,391	0
Dividends paid	(23,500)	(21,000)	(89,500)	(83,997)
Issuance of long-term debt, net	0	297,495	0	297,495
Change in credit facility and commercial paper	0	(111,000)	111,000	24,000
Change in short-term debt	36,000	(191,000)	188,000	0
Withholding remittance - share-based compensation	(1,838)	(2,852)	(2,096)	(3,510)
Other	(53)	(298)	(783)	(371)
Net cash provided by (used in) financing activities	33,451	(28,655)	343,012	274,976
Change in cash and cash equivalents	43,186	7,843	29,359	14,839
Cash and cash equivalents at beginning of period	31,962	37,946	45,789	30,950
Cash and cash equivalents at end of period	75,148	45,789	75,148	45,789
Supplemental information:
Interest paid, net of amounts capitalized	11,585	10,296	75,094	66,097
Income taxes paid (received)	$ (22)	$ 0	$ (5,878)	$ (7,816)

Background, Organization, and S

Background, Organization, and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Background, Organization, and Summary of Significant Accounting Policies	Note 1 – Background, Organization, and Summary of Significant Accounting Policies Nature of Operations. Southwest Gas Holdings, Inc. is a holding company, owning all of the shares of common stock of Southwest Gas Corporation (“Southwest” or the “natural gas operations segment”) and all of the shares of common stock of Centuri Group, Inc. (“Centuri,” or the “utility infrastructure services” segment). At the annual meeting of shareholders of Southwest Gas Holdings, Inc., held on May 2, 2019, shareholders voted to approve changing the state of incorporation for Southwest Gas Holdings, Inc. from California to Delaware. The reincorporation is expected to be effective during the second or third quarter of 2019. However, the reincorporation remains subject to certain regulatory approvals, which are currently pending. Southwest is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Public utility rates, practices, facilities, and service territories of Southwest are subject to regulatory oversight. The timing and amount of rate relief can materially impact results of operations. Natural gas purchases and the timing of related recoveries can materially impact liquidity. Results for the natural gas operations segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures. Centuri is a comprehensive utility infrastructure services enterprise dedicated to delivering a diverse array of solutions to North America’s gas and electric providers. Centuri derives revenue from installation, replacement, repair, and maintenance of energy distribution systems, and developing industrial construction solutions. Centuri operations are generally conducted under the business names of NPL Construction Co. (“NPL”), NPL Canada Ltd. (“NPL Canada”), New England Utility Constructors, Inc. (“Neuco”) and Linetec Services, LLC (“Linetec”). Utility infrastructure services activity is seasonal in most of Centuri’s operating areas. Peak periods are the summer and fall months in colder climate areas, such as the northeastern and midwestern United States (“U.S”) and in Canada. In warmer climate areas, such as the southwestern and southeastern U.S., utility infrastructure services activity continues year round. In November 2017, Centuri acquired Neuco, thereby expanding its core services in the northeast region of the U.S. Additionally, in November 2018, Centuri expanded its operations in the southeast region of the U.S. through the acquisition of an 80% interest in Linetec. See Note 12 – Business Acquisitions for more information. Basis of Presentation. The condensed consolidated financial statements for Southwest Gas Holdings, Inc. and subsidiaries (the “Company”) and Southwest included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The year-end condensed balance sheet data was derived from audited financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. No substantive change has occurred with regard to the Company’s business segments on the whole, or in the primary businesses comprising those segments as a result of the foregoing acquisitions of Neuco and Linetec. The preparation of the condensed consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. In the opinion of management, all adjustments, consisting of normal recurring items and estimates necessary for a fair statement of results for the interim periods, have been made. It is suggested that these condensed consolidated financial statements be read in conjunction with the consolidated financial statements and the notes thereto included in the 2018 Annual Report to Shareholders, which is incorporated by reference into the 2018 Form 10-K. Fair Value Measurements . Certain assets and liabilities are reported at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. U.S. GAAP states that a fair value measurement should be based on the assumptions that market participants would use in pricing the asset or liability and establishes a fair value hierarchy that ranks the inputs used to measure fair value by their reliability. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to fair values derived from unobservable inputs (Level 3 measurements). Financial assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The three levels of the fair value hierarchy are as follows: Level 1 – quoted prices (unadjusted) in active markets for identical assets or liabilities that a company has the ability to access at the measurement date. Level 2 – inputs other than quoted prices included within Level 1 that are observable for similar assets or liabilities, either directly or indirectly. Level 3 – unobservable inputs for the asset or liability. Unobservable inputs are used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. The Company primarily used quoted market prices and other observable market pricing information in valuing cash and cash equivalents, derivatives, long-term debt outstanding, and assets of the qualified pension plan and postretirement benefit plans required to be disclosed at fair value. Other Property and Investments. Other property and investments on the Condensed Consolidated Balance Sheets includes (thousands of dollars): March 31, 2019 December 31, 2018 Southwest Gas Corporation: Net cash surrender value of COLI policies $ 122,048 $ 114,405 Other property 1,735 1,741 Total Southwest Gas Corporation 123,783 116,146 Centuri property, equipment, and intangibles 894,739 792,191 Centuri accumulated depreciation/amortization (316,832 ) (298,939 ) Other property 15,032 14,153 Total Southwest Gas Holdings, Inc. $ 716,722 $ 623,551 Cash and Cash Equivalents. For purposes of reporting consolidated cash flows, cash and cash equivalents include cash on hand and financial instruments with maturities of three months or less. Such investments are carried at cost, which approximates market value. Cash and cash equivalents for Southwest and the Company also include money market fund investments totaling approximately $41 million and $54.4 million , respectively, at March 31, 2019 , and $18 million and $59.9 million , respectively, at December 31, 2018 , which fall within Level 2 of the fair value hierarchy, due to the asset valuation methods used by money market funds. Typical non-cash investing activities for Southwest include customer advances applied as contributions toward utility construction activity and capital expenditures that were not paid as of quarter end that are included in accounts payable. Amounts related to such activities were immaterial for the periods presented herein. Non-cash investing activities for the three months and twelve months ended March 31, 2019 included $73.5 million of purchase consideration related to the Linetec acquisition by Centuri, in the form of liabilities incurred that remained unpaid as of March 31, 2019 ; such amounts are included in Other current liabilities on the Condensed Consolidated Balance Sheets of the Company. Also, see Recent Accounting Standards Updates and Note 4 – Leases for information related to right-of-use assets obtained in exchange for lease liabilities, which are non-cash investing and financing activities. Intercompany Transactions . Centuri recognizes revenues generated from contracts with Southwest (see Note 10 – Segment Information ). Centuri’s accounts receivable for these services are presented in the table below (thousands of dollars): March 31, 2019 December 31, 2018 Centuri accounts receivable for services provided to Southwest $ 16,837 $ 18,830 The accounts receivable balance, revenues, and associated profits are included in the condensed consolidated financial statements of the Company and Southwest and were not eliminated during consolidation in accordance with accounting treatment for rate-regulated entities. Income Taxes. In 2017, the Tax Cuts and Jobs Act (the “TCJA”) was enacted. The TCJA had significant impacts on the taxation of business entities, including specific provisions related to regulated public utilities. The more significant changes that impacted the Company and Southwest include the reduction in the corporate federal income tax rate from 35% to 21%, and limiting the utilization of net operating losses (“NOLs”) to 80% of taxable income, with the ability to indefinitely carryforward unutilized NOLs to reduce future taxable income. Prepaid and Other Current Assets. Prepaid and other current assets includes gas pipe materials and operating supplies of $55 million at March 31, 2019 and $56 million at December 31, 2018 (carried at weighted average cost), as well as $55 million at March 31, 2019 and $74 million at December 31, 2018 related to a regulatory asset associated with the Arizona decoupling mechanism (an alternative revenue program). Goodwill. Goodwill is assessed as of October 1 st each year for impairment, or more frequently, if circumstances indicate an impairment to the carrying value of goodwill may have occurred. Management of the Company and Southwest considered its reporting units and segments and determined that its segments and reporting units remain consistent between periods presented below, and that no change was necessary with regard to the level at which goodwill is assessed for impairment. No impairment was deemed to have occurred in the first three months of 2019 . (Thousands of dollars) Natural Gas Operations Utility Infrastructure Services Total Company December 31, 2018 $ 10,095 $ 348,950 $ 359,045 Measurement Period Adjustment - Linetec acquisition — 3,303 3,303 Foreign currency translation adjustment — 2,134 2,134 March 31, 2019 $ 10,095 $ 354,387 $ 364,482 Other Current Liabilities . Other current liabilities for Southwest include $22.8 million of dividends declared by Southwest Gas Corporation, but not yet paid to Southwest Gas Holdings, Inc. at March 31, 2019 . Other Income (Deductions). The following table provides the composition of significant items included in Other income (deductions) in the Condensed Consolidated Statements of Income (thousands of dollars): Three Months Ended Twelve Months Ended March 31, March 31, 2019 2018 2019 2018 Southwest Gas Corporation - natural gas operations segment: Change in COLI policies $ 7,600 $ (700 ) $ 5,100 $ 6,800 Interest income 1,597 1,418 6,199 3,638 Equity AFUDC 960 229 4,358 2,049 Other components of net periodic benefit cost (3,765 ) (5,265 ) (19,560 ) (19,834 ) Miscellaneous income and (expense) (446 ) (285 ) (2,788 ) (2,400 ) Southwest Gas Corporation - total other income (deductions) 5,946 (4,603 ) (6,691 ) (9,747 ) Utility infrastructure services segment: Interest income — 1 87 4 Foreign transaction gain (loss) 531 147 162 (606 ) Miscellaneous income and (expense) 344 115 125 956 Centuri - total other income (deductions) 875 263 374 354 Corporate and administrative 18 6 64 19 Consolidated Southwest Gas Holdings, Inc. - total other income (deductions) $ 6,839 $ (4,334 ) $ (6,253 ) $ (9,374 ) Included in the table above is the change in cash surrender values of company-owned life insurance (“COLI”) policies (including net death benefits recognized). These life insurance policies on members of management and other key employees are used by Southwest to indemnify itself against the loss of talent, expertise, and knowledge, as well as to provide indirect funding for certain nonqualified benefit plans. Current tax regulations provide for tax-free treatment of life insurance (death benefit) proceeds. Therefore, changes in the cash surrender values of COLI policies, as they progress towards the ultimate death benefits, are also recorded without tax consequences. Refer also to Note 2 – Components of Net Periodic Benefit Cost . Recent Accounting Standards Updates. Accounting pronouncements adopted in 2019: In February 2016, the FASB issued the update “Leases (Topic 842).” Under the update, lessees were required to recognize a lease liability for the obligation to make lease payments, measured on a discounted basis; and a right-of-use asset for the right to use, or control the use of, a specified asset for the lease term. The Company and Southwest adopted Topic 842 in the first quarter of 2019 through an optional transition method, which was elected, permitting the application of the provisions of the standard at the adoption date, rather than to earlier comparative periods. As a result, the Company and Southwest have not recast prior periods to reflect the adoption of this standard. See Note 4 – Leases . Accounting pronouncements that will be effective after 2019: In June 2016, the FASB issued ASU 2016-13 update “Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The update requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. The inputs currently used to estimate credit losses will still be used; however, they may be adapted to reflect the full amount of expected losses. The update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. All entities may adopt the amendments in this update earlier as of fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Management is evaluating what impact, if any, this update might have on the Company’s and Southwest’s consolidated financial statements and disclosures. In January 2017, the FASB issued ASU 2017-04 “Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” Currently, unless meeting the criteria for qualitative assessment only, an entity is required to perform a two-step test to determine the amount, if any, of goodwill impairment. In Step 1, an entity compares the fair value of a reporting unit with its carrying amount, including goodwill. If the carrying amount of the reporting unit exceeds its fair value, the entity performs Step 2 and compares the implied fair value of goodwill with the carrying amount of that goodwill for that reporting unit, requiring a hypothetical purchase price allocation to measure the amount of a goodwill impairment. An impairment charge equal to the amount by which the carrying amount of goodwill for the reporting unit exceeds the implied fair value of that goodwill is recorded, limited to the amount of goodwill allocated to that reporting unit. Under the update, an entity will apply a one-step quantitative test and record the amount of goodwill impairment as the excess of a reporting unit's carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. The new guidance does not amend the optional qualitative assessment. The amount of any goodwill impairment calculated under the update could vary from the calculation under existing guidance, largely due to the consideration to be given to unrecognized differences between the fair value and carrying values of the other assets and liabilities in the reporting unit under the new guidance. The amendments should be applied on a prospective basis. The update is effective for fiscal and interim periods beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. Management is evaluating the impacts this update might have on the Company’s and Southwest’s consolidated financial statements and disclosures. In August 2018, the FASB issued ASU 2018-15 “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract.” The update generally aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement (that is a service contract) with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The update also requires the entity to expense the capitalized implementation costs of such hosting arrangements over the term of the hosting arrangement, including reasonably certain renewal periods. The update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption of the amendments in this update is permitted for interim and related annual fiscal periods after December 15, 2018. Management is evaluating the impacts this update might have on the Company’s and Southwest’s consolidated financial statements and disclosures. In August 2018, the FASB issued ASU 2018-14 “Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans.” This update removes disclosures that are no longer considered cost-beneficial, clarifies the specific requirements of disclosures, and adds disclosure requirements identified as relevant. The update applies to all employers that sponsor defined benefit pension or other postretirement plans. The update is effective for fiscal years ending after December 15, 2020. Upon adoption, the Company and Southwest will modify their disclosures to conform to the requirements of the update.

Components of Net Periodic Bene

Components of Net Periodic Benefit Cost	3 Months Ended
	Mar. 31, 2019
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost	Note 2 – Components of Net Periodic Benefit Cost Southwest has a noncontributory qualified retirement plan with defined benefits covering substantially all employees and a separate unfunded supplemental retirement plan (“SERP”) which is limited to officers. Southwest also provides postretirement benefits other than pensions (“PBOP”) to its qualified retirees for health care, dental, and life insurance. The service cost component of net periodic benefit costs included in the table below are components of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of that portion of overall net periodic benefit costs to the same accounts to which productive labor is charged. As a result, service costs become components of various accounts, primarily operations and maintenance expense, net utility plant, and deferred charges and other assets for both the Company and Southwest. The other components of net periodic benefit cost are reflected in Other income (deductions) on the Condensed Consolidated Statements of Income of the Company and Southwest. Qualified Retirement Plan Period Ended March 31, Three Months Twelve Months 2019 2018 2019 2018 (Thousands of dollars) Service cost $ 6,466 $ 7,139 $ 27,882 $ 24,683 Interest cost 12,252 11,043 45,383 45,606 Expected return on plan assets (15,061 ) (14,689 ) (59,127 ) (56,086 ) Amortization of net actuarial loss 5,589 8,029 29,675 26,032 Net periodic benefit cost $ 9,246 $ 11,522 $ 43,813 $ 40,235 SERP Period Ended March 31, Three Months Twelve Months 2019 2018 2019 2018 (Thousands of dollars) Service cost $ 66 $ 61 $ 250 $ 292 Interest cost 440 415 1,683 1,827 Amortization of net actuarial loss 255 375 1,382 1,456 Net periodic benefit cost $ 761 $ 851 $ 3,315 $ 3,575 PBOP Period Ended March 31, Three Months Twelve Months 2019 2018 2019 2018 (Thousands of dollars) Service cost $ 319 $ 368 $ 1,424 $ 1,469 Interest cost 762 687 2,823 3,111 Expected return on plan assets (789 ) (930 ) (3,577 ) (3,448 ) Amortization of prior service costs 317 334 1,318 1,335 Net periodic benefit cost $ 609 $ 459 $ 1,988 $ 2,467

Revenue

Revenue	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue	Note 3 – Revenue The following information about the Company’s revenues is presented by segment. Southwest encompasses one segment – natural gas operations. Natural Gas Operations Segment : Gas operating revenues on the Condensed Consolidated Statements of Income of both the Company and Southwest include revenue from contracts with customers, which is shown below, disaggregated by customer type, and various categories of revenue: Three Months Ended Twelve Months Ended March 31, March 31, (Thousands of dollars) 2019 2018 2019 2018 Residential $ 417,228 $ 344,611 $ 959,837 $ 859,078 Small commercial 89,610 87,943 256,750 250,331 Large commercial 13,962 15,440 51,714 54,224 Industrial/other 6,478 6,510 23,457 23,085 Transportation 24,902 24,054 87,838 89,081 Revenue from contracts with customers 552,180 478,558 1,379,596 1,275,799 Alternative revenue program revenues (deferrals) (34,545 ) 27,209 (15,775 ) 66,788 Other revenues (a) 3,042 (11,454 ) 20,271 (8,568 ) Total Gas operating revenues $ 520,677 $ 494,313 $ 1,384,092 $ 1,334,019 (a) Includes various other revenues which, in the periods presented ending March 31, 2018, were offset by a $14 million reserve against revenue associated with a tax reform savings adjustment. Utility Infrastructure Services Segment : The following tables display Centuri’s revenue, reflected as Utility infrastructure services revenues on the Condensed Consolidated Statements of Income of the Company, representing revenue from contracts with customers disaggregated by service and contract types: (Thousands of dollars) Three Months Ended Twelve Months Ended March 31, March 31, 2019 2018 2019 2018 Service Types: Gas infrastructure services $ 197,893 $ 193,527 $ 1,128,048 $ 938,342 Electric power infrastructure services 52,301 5,402 79,528 19,893 Other 62,668 61,088 367,554 356,131 Total Utility infrastructure services revenues $ 312,862 $ 260,017 $ 1,575,130 $ 1,314,366 (Thousands of dollars) Three Months Ended Twelve Months Ended March 31, March 31, 2019 2018 2019 2018 Contract Types: Master services agreement $ 235,655 $ 194,464 $ 1,143,603 $ 932,804 Bid contract 77,207 65,553 431,527 381,562 Total Utility infrastructure services revenues $ 312,862 $ 260,017 $ 1,575,130 $ 1,314,366 Unit priced contracts $ 235,686 $ 197,322 $ 1,296,783 $ 1,013,642 Fixed priced contracts 38,538 25,541 130,295 137,724 Time and materials contracts 38,638 37,154 148,052 163,000 Total Utility infrastructure services revenues $ 312,862 $ 260,017 $ 1,575,130 $ 1,314,366 The following table provides information about contracts receivable and revenue earned on contracts in progress in excess of billings (contract asset), which are both included within Accounts receivable, net of allowances, as well as amounts billed in excess of revenue earned on contracts (contract liability), which are included in Other current liabilities as of March 31, 2019 and December 31, 2018 on the Company’s Condensed Consolidated Balance Sheets: (Thousands of dollars) March 31, 2019 December 31, 2018 Contracts receivable, net $ 160,973 $ 186,249 Revenue earned on contracts in progress in excess of billings 97,642 87,520 Amounts billed in excess of revenue earned on contracts 4,588 4,211 The revenue earned on contracts in progress in excess of billings (contract asset) primarily relates to Centuri’s rights to consideration for work completed but not billed and/or approved at the reporting date. These contract assets are transferred to contracts receivable when the rights become unconditional. The amounts billed in excess of revenue earned (contract liability) primarily relates to the advance consideration received from customers for which work has not yet been completed. The change in this contract liability balance from December 31, 2018 to March 31, 2019 is due to revenue recognized of $4.2 million that was included in this item as of January 1, 2019, after which time it became earned and the balance was reduced, and to increases due to cash received, net of revenue recognized during the period related to contracts that commenced during the period. For contracts that have an original duration of one year or less, Centuri uses the practical expedient applicable to such contracts and does not consider/compute an interest component based on the time value of money. Further, because of the short duration of these contracts, Centuri has not disclosed the transaction price for the remaining performance obligations as of the end of each reporting period or when the Company expects to recognize the revenue. As of March 31, 2019 , Centuri has seventeen contracts that had an original duration of more than one year. The aggregate amount of the transaction price allocated to the unsatisfied performance obligations of these contracts as of March 31, 2019 is $60.7 million . Centuri expects to recognize the remaining performance obligations over the next three years ; however, the timing of that recognition is largely within the control of the customer, including when the necessary equipment and materials required to complete the work are provided by the customer. Utility infrastructure services contracts receivable consists of the following: (Thousands of dollars) March 31, 2019 December 31, 2018 Billed on completed contracts and contracts in progress $ 159,829 $ 184,100 Other receivables 1,527 2,588 Contracts receivable, gross 161,356 186,688 Allowance for doubtful accounts (383 ) (439 ) Contracts receivable, net $ 160,973 $ 186,249

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Note 4 – Leases The Company and Southwest adopted Topic 842 as of January 1, 2019. In association with the adoption, the Company recorded adjustments to its Condensed Consolidated Balance Sheet to record right-of-use (“ROU”) assets and lease liabilities of $58.4 million and $60.8 million , respectively. Included in those amounts, Southwest recorded $1.9 million related to both its ROU assets and lease liabilities. Neither the Company nor Southwest experienced a material impact to the Condensed Consolidated Statements of Income from the adoption and no cumulative-effect adjustment to the opening balance of retained earnings was recognized. Management elected to adopt the standard under the optional transition method (refer to Recent Accounting Standards Updates in Note 1 – Background, Organization, and Summary of Significant Accounting Policies ), and elected the following Topic 842 practical expedients and accounting policy elections: • To use the “package”, which is a set of three practical expedients that must be elected as a package and applied consistently to all of Southwest’s and Centuri’s leases. These include: not reassessing whether any expired or existing contracts are or contain leases; not reassessing the lease classification for expired or existing leases (that is, existing operating and capital leases in accordance with current lease guidance will in each case be classified as operating and finance leases, respectively, under the updated guidance); and not reassessing initial direct costs for any existing leases. • To utilize the practical expedient to exclude all easements in place prior to January 1, 2019 from treatment under Topic 842. However, Southwest will evaluate new easements entered into after the effective date of the standard to determine if the arrangements should be accounted for as leases. • To make an accounting policy election by asset class to include both the lease and non-lease components (as defined in the guidance) as a single component. • To make an accounting policy election to not apply Topic 842 to short-term leases, as permitted. • To not elect to use hindsight in determining the lease term and in assessing impairment of ROU assets. • To utilize a portfolio approach to effectively account for the operating lease ROU assets and liabilities with regard to certain equipment leases at Centuri. Southwest and Centuri determine if an arrangement is a lease at inception. ROU assets represent the right to use an underlying asset for the lease term; lease liabilities represent obligations to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. As most of Southwest’s and Centuri’s leases do not provide an implicit interest rate, an incremental borrowing rate based on information available at commencement is used in determining the present value of lease payments; an implicit rate, if readily determinable, is used. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Southwest’s leases are comprised primarily of operating leases of buildings, land, and equipment. Southwest has no finance leases and no significant short-term leases. Southwest’s leases have a remaining term of 1 to 10 years , some of which include options to extend the lease up to 3 years . Southwest is currently not a lessor in any significant lease arrangements. Southwest’s ROU assets are included in Gas plant, and its lease liabilities are included in, depending upon maturity, Other current liabilities or Other deferred credits and other long-term liabilities on the Company’s and Southwest’s Condensed Consolidated Balance Sheet as of March 31, 2019. Centuri has operating and finance leases for corporate and field offices, construction equipment, and transportation vehicles. Centuri is currently not a lessor in any significant lease arrangements. Centuri’s leases have remaining lease terms of 1 to 14 years . Some of these include options to extend the leases, generally for optional terms of up to 5 years , and some include options to terminate the leases within 1 year . Centuri’s equipment leases may include variable payment terms in addition to the fixed lease payments if machinery is used in excess of the standard work periods. These variable payments are not probable of occurring under the current operating environment and have not been included in consideration of lease payments. Expense for short-term leases of Centuri during the quarter ended March 31, 2019 was $2.6 million , and such leases were not accounted for under the provisions of Topic 842, as permitted. Due to the seasonality of Centuri’s business, expense for short-term leases will fluctuate throughout the year with higher expense incurred during the warmer months. Centuri’s ROU assets are included in Other property and investments, and its lease liabilities for operating and finance leases are included, depending upon maturity, in Other current liabilities or Other deferred credits and other long-term liabilities on the Company’s Condensed Consolidated Balance Sheet as of March 31, 2019 . The components of lease expense were as follows: (Thousands of dollars) Three Months Ended March 31, 2019 Southwest: Operating lease cost $ 406 Centuri: Operating lease cost $ 2,805 Finance lease cost: Amortization of ROU assets $ 35 Interest on lease liabilities 7 Total finance lease cost 42 Short-term lease cost 2,575 Total lease cost $ 5,828 Supplemental cash flow information related to leases for the three months ended March 31, 2019 was as follows: (Thousands of dollars) Southwest Centuri Consolidated Total Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 396 $ 2,555 $ 2,951 Operating cash flows from finance leases — 7 7 Financing cash flows from finance leases — 51 51 ROU assets obtained in exchange for lease obligations: Operating leases $ 523 $ 2,321 $ 2,844 Finance leases — 84 84 Supplemental information related to leases, including location in the Condensed Consolidated Balance Sheets, is as follows: (Thousands of dollars) March 31, 2019 Southwest: Operating leases: Net Utility Plant $ 1,977 Other current liabilities $ 745 Other deferred credits and other long-term liabilities 1,253 Total operating lease liabilities $ 1,998 Weighted average remaining lease term (in years) 4.22 Weighted average discount rate 3.39 % Centuri: Operating leases: Other property and investments $ 57,267 Other current liabilities 7,178 Other deferred credits and other long-term liabilities 52,647 Total operating lease liabilities $ 59,825 Finance leases: Other property and investments $ 639 Other current liabilities 256 Other deferred credits and other long-term liabilities 239 Total finance lease liabilities $ 495 Weighted average remaining lease term (in years) Operating leases 9.33 Finance leases 1.63 Weighted average discount rate Operating leases 4.08 % Finance leases 5.84 % The following is a schedule of maturities of lease liabilities as of March 31, 2019 : (Thousands of dollars) Operating leases Southwest: 2020 $ 800 2021 556 2022 295 2023 124 2024 78 Thereafter 307 Total lease payments 2,160 Less imputed interest 162 Total $ 1,998 (Thousands of dollars) Operating leases Finance leases Centuri: 2020 $ 10,394 $ 281 2021 9,327 128 2022 8,328 67 2023 7,645 38 2024 5,710 25 Thereafter 31,303 — Total lease payments 72,707 539 Less imputed interest 12,882 44 Total $ 59,825 $ 495 As the Company and Southwest adopted Topic 842 using the optional transition method referred to in Note 1 – Background, Organization, and Summary of Significant Accounting Policies , the recent annual disclosure of rental and lease payments as of December 31, 2018 in accordance with Topic 840 is presented in the table below: 2018 2017 Southwest Gas Corporation $ 4,556 $ 4,926 Centuri 59,491 62,310 Consolidated rental payments/lease expense $ 64,047 $ 67,236 The following is a schedule of future minimum lease payments for operating leases (with initial or remaining terms in excess of one year) as of December 31, 2018 (thousands of dollars): Southwest Centuri Consolidated Total 2019 $ 898 $ 10,053 $ 10,951 2020 363 7,656 8,019 2021 299 5,760 6,059 2022 163 5,163 5,326 2023 79 3,681 3,760 Thereafter 177 10,511 10,688 Total minimum lease payments $ 1,979 $ 42,824 $ 44,803
Leases	Note 4 – Leases The Company and Southwest adopted Topic 842 as of January 1, 2019. In association with the adoption, the Company recorded adjustments to its Condensed Consolidated Balance Sheet to record right-of-use (“ROU”) assets and lease liabilities of $58.4 million and $60.8 million , respectively. Included in those amounts, Southwest recorded $1.9 million related to both its ROU assets and lease liabilities. Neither the Company nor Southwest experienced a material impact to the Condensed Consolidated Statements of Income from the adoption and no cumulative-effect adjustment to the opening balance of retained earnings was recognized. Management elected to adopt the standard under the optional transition method (refer to Recent Accounting Standards Updates in Note 1 – Background, Organization, and Summary of Significant Accounting Policies ), and elected the following Topic 842 practical expedients and accounting policy elections: • To use the “package”, which is a set of three practical expedients that must be elected as a package and applied consistently to all of Southwest’s and Centuri’s leases. These include: not reassessing whether any expired or existing contracts are or contain leases; not reassessing the lease classification for expired or existing leases (that is, existing operating and capital leases in accordance with current lease guidance will in each case be classified as operating and finance leases, respectively, under the updated guidance); and not reassessing initial direct costs for any existing leases. • To utilize the practical expedient to exclude all easements in place prior to January 1, 2019 from treatment under Topic 842. However, Southwest will evaluate new easements entered into after the effective date of the standard to determine if the arrangements should be accounted for as leases. • To make an accounting policy election by asset class to include both the lease and non-lease components (as defined in the guidance) as a single component. • To make an accounting policy election to not apply Topic 842 to short-term leases, as permitted. • To not elect to use hindsight in determining the lease term and in assessing impairment of ROU assets. • To utilize a portfolio approach to effectively account for the operating lease ROU assets and liabilities with regard to certain equipment leases at Centuri. Southwest and Centuri determine if an arrangement is a lease at inception. ROU assets represent the right to use an underlying asset for the lease term; lease liabilities represent obligations to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. As most of Southwest’s and Centuri’s leases do not provide an implicit interest rate, an incremental borrowing rate based on information available at commencement is used in determining the present value of lease payments; an implicit rate, if readily determinable, is used. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Southwest’s leases are comprised primarily of operating leases of buildings, land, and equipment. Southwest has no finance leases and no significant short-term leases. Southwest’s leases have a remaining term of 1 to 10 years , some of which include options to extend the lease up to 3 years . Southwest is currently not a lessor in any significant lease arrangements. Southwest’s ROU assets are included in Gas plant, and its lease liabilities are included in, depending upon maturity, Other current liabilities or Other deferred credits and other long-term liabilities on the Company’s and Southwest’s Condensed Consolidated Balance Sheet as of March 31, 2019. Centuri has operating and finance leases for corporate and field offices, construction equipment, and transportation vehicles. Centuri is currently not a lessor in any significant lease arrangements. Centuri’s leases have remaining lease terms of 1 to 14 years . Some of these include options to extend the leases, generally for optional terms of up to 5 years , and some include options to terminate the leases within 1 year . Centuri’s equipment leases may include variable payment terms in addition to the fixed lease payments if machinery is used in excess of the standard work periods. These variable payments are not probable of occurring under the current operating environment and have not been included in consideration of lease payments. Expense for short-term leases of Centuri during the quarter ended March 31, 2019 was $2.6 million , and such leases were not accounted for under the provisions of Topic 842, as permitted. Due to the seasonality of Centuri’s business, expense for short-term leases will fluctuate throughout the year with higher expense incurred during the warmer months. Centuri’s ROU assets are included in Other property and investments, and its lease liabilities for operating and finance leases are included, depending upon maturity, in Other current liabilities or Other deferred credits and other long-term liabilities on the Company’s Condensed Consolidated Balance Sheet as of March 31, 2019 . The components of lease expense were as follows: (Thousands of dollars) Three Months Ended March 31, 2019 Southwest: Operating lease cost $ 406 Centuri: Operating lease cost $ 2,805 Finance lease cost: Amortization of ROU assets $ 35 Interest on lease liabilities 7 Total finance lease cost 42 Short-term lease cost 2,575 Total lease cost $ 5,828 Supplemental cash flow information related to leases for the three months ended March 31, 2019 was as follows: (Thousands of dollars) Southwest Centuri Consolidated Total Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 396 $ 2,555 $ 2,951 Operating cash flows from finance leases — 7 7 Financing cash flows from finance leases — 51 51 ROU assets obtained in exchange for lease obligations: Operating leases $ 523 $ 2,321 $ 2,844 Finance leases — 84 84 Supplemental information related to leases, including location in the Condensed Consolidated Balance Sheets, is as follows: (Thousands of dollars) March 31, 2019 Southwest: Operating leases: Net Utility Plant $ 1,977 Other current liabilities $ 745 Other deferred credits and other long-term liabilities 1,253 Total operating lease liabilities $ 1,998 Weighted average remaining lease term (in years) 4.22 Weighted average discount rate 3.39 % Centuri: Operating leases: Other property and investments $ 57,267 Other current liabilities 7,178 Other deferred credits and other long-term liabilities 52,647 Total operating lease liabilities $ 59,825 Finance leases: Other property and investments $ 639 Other current liabilities 256 Other deferred credits and other long-term liabilities 239 Total finance lease liabilities $ 495 Weighted average remaining lease term (in years) Operating leases 9.33 Finance leases 1.63 Weighted average discount rate Operating leases 4.08 % Finance leases 5.84 % The following is a schedule of maturities of lease liabilities as of March 31, 2019 : (Thousands of dollars) Operating leases Southwest: 2020 $ 800 2021 556 2022 295 2023 124 2024 78 Thereafter 307 Total lease payments 2,160 Less imputed interest 162 Total $ 1,998 (Thousands of dollars) Operating leases Finance leases Centuri: 2020 $ 10,394 $ 281 2021 9,327 128 2022 8,328 67 2023 7,645 38 2024 5,710 25 Thereafter 31,303 — Total lease payments 72,707 539 Less imputed interest 12,882 44 Total $ 59,825 $ 495 As the Company and Southwest adopted Topic 842 using the optional transition method referred to in Note 1 – Background, Organization, and Summary of Significant Accounting Policies , the recent annual disclosure of rental and lease payments as of December 31, 2018 in accordance with Topic 840 is presented in the table below: 2018 2017 Southwest Gas Corporation $ 4,556 $ 4,926 Centuri 59,491 62,310 Consolidated rental payments/lease expense $ 64,047 $ 67,236 The following is a schedule of future minimum lease payments for operating leases (with initial or remaining terms in excess of one year) as of December 31, 2018 (thousands of dollars): Southwest Centuri Consolidated Total 2019 $ 898 $ 10,053 $ 10,951 2020 363 7,656 8,019 2021 299 5,760 6,059 2022 163 5,163 5,326 2023 79 3,681 3,760 Thereafter 177 10,511 10,688 Total minimum lease payments $ 1,979 $ 42,824 $ 44,803

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Note 5 – Derivatives In managing its natural gas supply portfolios, Southwest has historically entered into fixed- and variable-price contracts, which qualify as derivatives. Additionally, Southwest utilizes fixed-for-floating swap contracts (“Swaps”) to supplement its fixed-price contracts. The fixed-price contracts, firm commitments to purchase a fixed amount of gas in the future at a fixed price, qualify for the normal purchases and normal sales exception that is allowed for contracts that are probable of delivery in the normal course of business, and are exempt from fair value reporting. The variable-price contracts qualify as derivative instruments; however, because the contract price is the prevailing price at the future transaction date, the contract has no determinable fair value. The Swaps’ contract prices are determined at the beginning of each month to reflect that month’s published first of month index price and are recorded at fair value. Southwest does not utilize derivative financial instruments for speculative purposes, nor does it have trading operations. The fixed-price contracts and Swaps are utilized by Southwest under its volatility mitigation programs to effectively fix the price on a portion (up to 25% in the Arizona and California jurisdictions) of its natural gas supply portfolios. The maturities of the Swaps highly correlate to forecasted purchases of natural gas, during time frames ranging from April 30, 2019 through October 31, 2020 . Under such contracts, Southwest pays the counterparty a fixed rate and receives from the counterparty a floating rate per MMBtu (“dekatherm”) of natural gas. Only the net differential is actually paid or received. The differential is calculated based on the notional amounts under the contracts, which are detailed in the table below (thousands of dekatherms): March 31, 2019 December 31, 2018 Contract notional amounts 14,757 13,387 The following table sets forth the gains and (losses) recognized on the Swaps (derivatives) for the three- and twelve-month periods ended March 31, 2019 and 2018 and their location in the Condensed Consolidated Statements of Income for both the Company and Southwest: Gains (losses) recognized in income for derivatives not designated as hedging instruments: (Thousands of dollars) Three Months Ended Twelve Months Ended Location of Gain or (Loss) Recognized in Income on Derivatives March 31, March 31, Instrument 2019 2018 2019 2018 Swaps Net cost of gas sold $ (3,533 ) $ (5,196 ) $ (450 ) $ (11,631 ) Swaps Net cost of gas sold 3,533 * 5,196 * 450 * 11,631 * Total $ — $ — $ — $ — * Represents the impact of regulatory deferral accounting treatment under U.S. GAAP for rate-regulated entities. No gains (losses) were recognized in net income or other comprehensive income during the periods presented for derivatives designated as cash flow hedging instruments. Previously, Southwest entered into two forward-starting interest rate swaps (“FSIRS”), both of which were designated cash flow hedges, to partially hedge the risk of interest rate variability during the period leading up to the planned issuance of debt. The first FSIRS terminated in December 2010. The second FSIRS terminated in March 2012. Losses on both FSIRS are being amortized over ten -year periods from Accumulated other comprehensive income (loss) into interest expense. The following table sets forth the fair values of the Swaps and their location in the Condensed Consolidated Balance Sheets for both the Company and Southwest (thousands of dollars): Fair values of derivatives not designated as hedging instruments: March 31, 2019 Asset Liability Instrument Balance Sheet Location Derivatives Derivatives Net Total Swaps Other current liabilities $ 805 $ (4,472 ) $ (3,667 ) Swaps Other deferred credits 60 (809 ) (749 ) Total $ 865 $ (5,281 ) $ (4,416 ) December 31, 2018 Asset Liability Instrument Balance Sheet Location Derivatives Derivatives Net Total Swaps Prepaid and other current assets $ 243 $ (99 ) $ 144 Swaps Other current liabilities 1,595 (3,347 ) (1,752 ) Swaps Other deferred credits 141 (251 ) (110 ) Total $ 1,979 $ (3,697 ) $ (1,718 ) The estimated fair values of the natural gas derivatives were determined using future natural gas index prices (as more fully described below). Master netting arrangements exist with each counterparty that provide for the net settlement (in the settlement month) of all contracts through a single payment. As applicable, management has elected to reflect the net amounts in its balance sheets. There was no outstanding collateral associated with the Swaps during either period shown in the above table. Pursuant to regulatory deferral accounting treatment for rate-regulated entities, unrealized gains and losses in fair value of the Swaps are recorded as a regulatory asset and/or liability. When the Swaps mature, any prior positions held are reversed and the settled position is recorded as an increase or decrease of purchased gas under the related purchase gas adjustment (“PGA”) mechanism in determining the deferred PGA balances. Neither changes in fair value nor settled amounts of Swaps have a direct effect on earnings or other comprehensive income. The following table shows the amounts Southwest paid to and received from counterparties for settlements of matured Swaps. Three Months Ended Twelve Months Ended (Thousands of dollars) March 31, 2019 March 31, 2019 Paid to counterparties $ 1,882 $ 5,948 Received from counterparties $ 1,047 $ 1,653 The following table details the regulatory assets/(liabilities) offsetting the derivatives at fair value in the Condensed Consolidated Balance Sheets for both the Company and Southwest (thousands of dollars). March 31, 2019 Instrument Balance Sheet Location Net Total Swaps Prepaid and other current assets $ 3,667 Swaps Deferred charges and other assets 749 December 31, 2018 Instrument Balance Sheet Location Net Total Swaps Other current liabilities $ (144 ) Swaps Prepaid and other current assets 1,752 Swaps Deferred charges and other assets 110 The estimated fair values of Southwest’s Swaps were determined at March 31, 2019 and December 31, 2018 using futures settlement prices for the delivery of natural gas at Henry Hub adjusted by the price of future settlement bases, which reflect the difference between the price of natural gas at a given delivery basin and the Henry Hub pricing points. These Level 2 inputs are observable in the marketplace throughout the full term of the Swaps, but have been credit-risk adjusted with no significant impact to the overall fair value measurement. The following table sets forth, by level within the three-level fair value hierarchy that ranks the inputs used to measure fair value by their reliability, the financial assets and liabilities that were accounted for at fair value by both the Company and Southwest: Level 2 - Significant other observable inputs (Thousands of dollars) March 31, 2019 December 31, 2018 Assets at fair value: Prepaid and other current assets - Swaps $ — $ 144 Liabilities at fair value: Other current liabilities - Swaps (3,667 ) (1,752 ) Other deferred credits - Swaps (749 ) (110 ) Net Assets (Liabilities) $ (4,416 ) $ (1,718 )

Common Stock

Common Stock	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Common Stock	Note 6 – Common Stock On March 29, 2017, the Company filed with the SEC an automatic shelf registration statement on Form S-3 (File No. 333-217018), which became effective upon filing, for the offer and sale of up to $150 million of common stock from time to time in at-the-market offerings under the prospectus included therein and in accordance with the Sales Agency Agreement, dated March 29, 2017, between the Company and BNY Mellon Capital Markets, LLC (the “Equity Shelf Program”). The following table provides activity in the Equity Shelf Program for the three and twelve months ended March 31, 2019 : Three Months Ended Twelve Months Ended March 31, March 31, 2019 2018 2019 2018 Gross proceeds $ 23,073,149 $ 9,199,661 $ 99,023,464 $ 50,976,456 Less: agent commissions (230,731 ) (91,997 ) (990,234 ) (509,765 ) Net proceeds $ 22,842,418 $ 9,107,664 $ 98,033,230 $ 50,466,691 Number of shares sold 277,829 137,300 1,286,234 643,007 Weighted average price per share $ 83.05 $ 67.00 $ 76.99 $ 79.28 During the quarter ended March 31, 2019 , the Company sold all of the remaining common stock available for sale under the program. Net proceeds from the sales of shares of common stock under the Equity Shelf Program are intended for general corporate purposes, including the acquisition of property for the construction, completion, extension or improvement of pipeline systems and facilities located in and around the communities served by Southwest. Net proceeds during the three months ended March 31, 2019 were contributed to, and reflected in the records of, Southwest (as a capital contribution from Southwest Gas Holdings, Inc.). During the three months ended March 31, 2019 , the Company issued approximately 53,000 shares of common stock through the Restricted Stock/Unit Plan and Management Incentive Plan. Also during the three months ended March 31, 2019 , the Company issued 34,000 shares of common stock through the Dividend Reinvestment and Stock Purchase Plan (“DRSPP”), raising approximately $2.8 million . On May 2, 2019, at the Company’s annual meeting of shareholders, the Company’s shareholders approved an amendment to the Company’s Articles of Incorporation to increase the number of shares of common stock available for issuance from 60,000,000 to 120,000,000

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Long-Term Debt	Note 7 – Long-Term Debt Carrying amounts of long-term debt and related estimated fair values as of March 31, 2019 and December 31, 2018 are disclosed in the following table. Southwest’s revolving credit facility (including commercial paper) and the variable-rate Industrial Development Revenue Bonds (“IDRBs”) approximate their carrying values, as they are repaid quickly (in the case of credit facility borrowings) and have interest rates that reset frequently. These are categorized as Level 1 due to Southwest’s ability to access similar debt arrangements at measurement dates with comparable terms, including variable/market rates. The fair values of Southwest’s debentures, senior notes, and fixed-rate IDRBs were determined utilizing a market-based valuation approach, where fair values are determined based on evaluated pricing data, such as broker quotes and yields for similar securities adjusted for observable differences. Significant inputs used in the valuation generally include benchmark yield curves, credit ratings and issuer spreads. The external credit rating, coupon rate, and maturity of each security are considered in the valuation, as applicable. The fair values of debentures and fixed-rate IDRBs are categorized as Level 2 (observable market inputs based on market prices of similar securities). The Centuri secured revolving credit and term loan facility and Centuri other debt obligations (not actively traded) are categorized as Level 3, based on significant unobservable inputs to their fair values. Because Centuri’s debt is not publicly traded, fair values for the secured revolving credit and term loan facility and other debt obligations were based on a conventional discounted cash flow methodology and utilized current market pricing yield curves, across Centuri’s debt maturity spectrum, of other industrial bonds with an assumed credit rating comparable to the Company’s. March 31, 2019 December 31, 2018 Carrying Amount Market Value Carrying Amount Market Value (Thousands of dollars) Southwest Gas Corporation: Debentures: Notes, 4.45%, due 2020 $ 125,000 $ 126,990 $ 125,000 $ 126,213 Notes, 6.1%, due 2041 125,000 154,294 125,000 150,728 Notes, 3.875%, due 2022 250,000 255,015 250,000 254,195 Notes, 4.875%, due 2043 250,000 277,683 250,000 268,985 Notes, 3.8%, due 2046 300,000 283,635 300,000 267,030 Notes, 3.7%, due 2028 300,000 306,465 300,000 298,926 8% Series, due 2026 75,000 95,128 75,000 93,827 Medium-term notes, 7.78% series, due 2022 25,000 27,715 25,000 27,497 Medium-term notes, 7.92% series, due 2027 25,000 30,824 25,000 30,016 Medium-term notes, 6.76% series, due 2027 7,500 8,845 7,500 8,651 Unamortized discount and debt issuance costs (11,641 ) (11,807 ) 1,470,859 1,470,693 Revolving credit facility and commercial paper 150,000 150,000 150,000 150,000 Industrial development revenue bonds: Variable-rate bonds: Tax-exempt Series A, due 2028 50,000 50,000 50,000 50,000 2003 Series A, due 2038 50,000 50,000 50,000 50,000 2008 Series A, due 2038 50,000 50,000 50,000 50,000 2009 Series A, due 2039 50,000 50,000 50,000 50,000 Unamortized discount and debt issuance costs (1,900 ) (2,024 ) 198,100 197,976 Less: current maturities — — Long-term debt, less current maturities - Southwest Gas Corporation $ 1,818,959 $ 1,818,669 Centuri: Centuri term loan facility $ 254,534 $ 257,579 $ 255,959 $ 260,135 Unamortized debt issuance costs (1,343 ) (1,414 ) 253,191 254,545 Centuri secured revolving credit facility 6,361 6,363 — — Centuri other debt obligations 62,678 63,365 67,104 67,053 Less: current maturities (34,915 ) (33,060 ) Long-term debt, less current maturities - Centuri $ 287,315 $ 288,589 Consolidated Southwest Gas Holdings, Inc.: Southwest Gas Corporation long-term debt $ 1,818,959 $ 1,818,669 Centuri long-term debt 322,230 321,649 Less: current maturities (34,915 ) (33,060 ) Long-term debt, less current maturities - Southwest Gas Holdings, Inc. $ 2,106,274 $ 2,107,258 Southwest has a $400 million credit facility that is scheduled to expire in March 2022 . Southwest designates $150 million of capacity related to the facility as long-term debt and has designated the remaining $250 million for working capital purposes. Interest rates for the credit facility are calculated at either the London Interbank Offered Rate (“LIBOR”) or an “alternate base rate,” plus in each case an applicable margin that is determined based on Southwest’s senior unsecured debt rating. At March 31, 2019 , the applicable margin is 1% for loans bearing interest with reference to LIBOR and 0% for loans bearing interest with reference to the alternative base rate. At March 31, 2019 , $150 million was outstanding on the long-term portion (including the commercial paper program, discussed below) and $188 million was outstanding on the short-term portion of this credit facility (see Note 8 – Short-Term Debt ). Southwest has a $50 million commercial paper program. Any issuance under the commercial paper program is supported by Southwest’s current revolving credit facility and, therefore, does not represent additional borrowing capacity under the credit facility. Borrowings under the commercial paper program are designated as long-term debt. Interest rates for the program are calculated at the then current commercial paper rate. At March 31, 2019 , as noted above, $50 million was outstanding under the commercial paper program. In November 2018, Centuri, in association with the acquisition of Linetec, amended and restated its senior secured revolving credit and term loan facility, increasing the capacity from $450 million to $590 million ; the amended facility is scheduled to expire in November 2023 . This facility includes a revolving credit facility and a term loan facility. The line of credit portion of the facility is $325 million ; amounts borrowed and repaid under the revolving credit facility are available to be re-borrowed. The term loan facility portion has a limit of approximately $265 million . The $590 million revolving credit and term loan facility is secured by substantially all of Centuri’s assets except those explicitly excluded under the terms of the agreement (including owned real estate and certain certificated vehicles). Centuri assets securing the facility at March 31, 2019 totaled $1.1 billion . At March 31, 2019 , $261 million

Short-Term Debt

Short-Term Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Short-Term Debt	Note 8 – Short-Term Debt The Company has a $100 million credit facility that is scheduled to expire in March 2022 . The Company had no short-term borrowings outstanding at March 31, 2019 under this facility. As discussed in Note 7 – Long-Term Debt , Southwest has a $ 400 million credit facility that is scheduled to expire in March 2022 , of which $ 250 million has been designated by management for working capital purposes. Southwest had $ 188 million in short-term borrowings outstanding at March 31, 2019

Equity, Other Comprehensive Inc

Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income	Note 9 – Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income The tables below provide details of activity in equity, the noncontrolling interest, and the redeemable noncontrolling interest for the Company on a consolidated basis for the three-month periods ended March 31, 2019 and March 31, 2018. Southwest Gas Holdings, Inc. Equity (In thousands, except per share amounts) Common Stock Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings Non-controlling Interest Redeemable Noncontrolling Interest (Temporary Equity) Shares Amount Total December 31, 2018 53,026 $ 54,656 $ 1,305,769 $ (52,668 ) $ 944,285 $ (452 ) $ 2,251,590 $ 81,831 Common stock issuances 365 365 27,024 27,389 Net income (loss) 94,809 94,809 575 Foreign currency exchange translation adjustment 791 791 Other comprehensive income (loss): Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax 619 619 FSIRS amounts reclassified to net income, net of tax 635 635 Dividends declared Common: $0.545 per share (29,285 ) (29,285 ) March 31, 2019 53,391 $ 55,021 $ 1,332,793 $ (50,623 ) $ 1,009,809 $ (452 ) $ 2,346,548 $ 82,406 Southwest Gas Holdings, Inc. Equity Common Stock Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings Non-controlling Interest (In thousands, except per share amounts) Shares Amount Total December 31, 2017 48,090 $ 49,720 $ 955,332 $ (47,682 ) $ 857,398 $ (2,365 ) $ 1,812,403 Common stock issuances 247 247 10,148 10,395 Net income (loss) 79,091 (797 ) 78,294 Foreign currency exchange translation adjustment (911 ) (911 ) Other comprehensive income (loss): Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax 895 895 FSIRS amounts reclassified to net income, net of tax 635 635 Reclassification of excess deferred taxes (a) (9,300 ) 9,300 — Dividends declared Common: $0.52 per share (25,335 ) (25,335 ) March 31, 2018 48,337 $ 49,967 $ 965,480 $ (56,363 ) $ 920,454 $ (3,162 ) $ 1,876,376 (a) Reclassification for the release of excess deferred taxes as a result of the adoption of ASU No. 2018-02 “Income Statement—Reporting Comprehensive Income—Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” which permitted release of excess amounts created following the December 2017 enactment of U.S. tax reform. The tables below provide details of activity in equity for Southwest during the three-month periods ended March 31, 2019 and March 31, 2018. Only equity shares of the Company are publicly traded, under the ticker symbol “SWX.” Southwest Gas Corporation Equity Common Stock Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings (In thousands) Shares Amount Total December 31, 2018 47,482 $ 49,112 $ 1,065,242 $ (49,049 ) $ 717,155 $ 1,782,460 Net income 103,389 103,389 Other comprehensive income (loss): Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax 619 619 FSIRS amounts reclassified to net income, net of tax 635 635 Stock-based compensation (a) 918 (160 ) 758 Dividends declared to Southwest Gas Holdings, Inc. (22,800 ) (22,800 ) Contributions from Southwest Gas Holdings, Inc. 22,842 22,842 March 31, 2019 47,482 $ 49,112 $ 1,089,002 $ (47,795 ) $ 797,584 $ 1,887,903 Southwest Gas Corporation Equity Common Stock Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings (In thousands) Shares Amount Total December 31, 2017 47,482 $ 49,112 $ 948,767 $ (47,073 ) $ 659,193 $ 1,609,999 Net income 90,349 90,349 Other comprehensive income (loss): Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax 895 895 FSIRS amounts reclassified to net income, net of tax 635 635 Reclassification of excess deferred taxes (b) (9,300 ) 9,300 — Stock-based compensation (a) (568 ) (166 ) (734 ) Dividends declared to Southwest Gas Holdings, Inc. (22,000 ) (22,000 ) March 31, 2018 47,482 $ 49,112 $ 948,199 $ (54,843 ) $ 736,676 $ 1,679,144 (a) Stock-based compensation is based on stock awards of Southwest Gas Corporation to be issued in shares of Southwest Gas Holdings, Inc. (b) Reclassification for the release of excess deferred taxes as a result of the adoption of ASU No. 2018-02, which permitted release of excess amounts created following the December 2017 enactment of U.S. tax reform. The following information provides insight into amounts impacting the Company’s Other comprehensive income (loss), both before and after-tax impacts, within the Condensed Consolidated Statements of Comprehensive Income, which also impact Accumulated other comprehensive income in the Condensed Consolidated Balance Sheets and the associated column in the equity tables above. See Note 5 – Derivatives for additional information on the FSIRS. Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) (Thousands of dollars) Three Months Ended Three Months Ended March 31, 2019 March 31, 2018 Before- Tax Amount Tax (Expense) or Benefit (1) Net-of- Tax Amount Before- Tax Amount Tax (Expense) or Benefit (1) Net-of- Tax Amount Defined benefit pension plans: Amortization of prior service cost $ 317 $ (76 ) $ 241 $ 334 $ (80 ) $ 254 Amortization of net actuarial (gain)/loss 5,844 (1,403 ) 4,441 8,404 (2,017 ) 6,387 Regulatory adjustment (5,347 ) 1,284 (4,063 ) (7,560 ) 1,814 (5,746 ) Pension plans other comprehensive income 814 (195 ) 619 1,178 (283 ) 895 FSIRS (designated hedging activities): Amounts reclassified into net income 836 (201 ) 635 837 (202 ) 635 FSIRS other comprehensive income 836 (201 ) 635 837 (202 ) 635 Total other comprehensive income - Southwest Gas Corporation 1,650 (396 ) 1,254 2,015 (485 ) 1,530 Foreign currency translation adjustments: Translation adjustments 791 — 791 (911 ) — (911 ) Foreign currency other comprehensive income (loss) 791 — 791 (911 ) — (911 ) Total other comprehensive income - Southwest Gas Holdings, Inc. $ 2,441 $ (396 ) $ 2,045 $ 1,104 $ (485 ) $ 619 Twelve Months Ended Twelve Months Ended March 31, 2019 March 31, 2018 Before- Tax Amount Tax (Expense) or Benefit (1) Net-of- Tax Amount Before- Tax Amount Tax (Expense) or Benefit (1) Net-of- Tax Amount Defined benefit pension plans: Net actuarial gain/(loss) $ (20,426 ) $ 4,902 $ (15,524 ) $ (43,027 ) $ 10,326 $ (32,701 ) Amortization of prior service cost 1,318 (316 ) 1,002 1,335 (460 ) 875 Amortization of net actuarial (gain)/loss 31,057 (7,454 ) 23,603 27,488 (9,269 ) 18,219 Regulatory adjustment (6,020 ) 1,446 (4,574 ) 10,515 (115 ) 10,400 Pension plans other comprehensive income (loss) 5,929 (1,422 ) 4,507 (3,689 ) 482 (3,207 ) FSIRS (designated hedging activities): Amounts reclassified into net income 3,344 (803 ) 2,541 3,345 (1,155 ) 2,190 FSIRS other comprehensive income 3,344 (803 ) 2,541 3,345 (1,155 ) 2,190 Total other comprehensive income (loss) - Southwest Gas Corporation 9,273 (2,225 ) 7,048 (344 ) (673 ) (1,017 ) Foreign currency translation adjustments: Translation adjustments (1,308 ) — (1,308 ) 640 — 640 Foreign currency other comprehensive income (loss) (1,308 ) — (1,308 ) 640 — 640 Total other comprehensive income (loss) - Southwest Gas Holdings, Inc. $ 7,965 $ (2,225 ) $ 5,740 $ 296 $ (673 ) $ (377 ) (1) Tax amounts are calculated using a 24% rate following the December 22, 2017 enactment date of U.S. tax reform. For periods prior to the enactment date (and included in specific line items of the tables for the twelve months ended March 31, 2018 ), tax amounts were calculated using a 38% rate. The tax effect of before-tax amounts remaining in the balance of Accumulated other comprehensive income (loss) as of March 31, 2019 is effectively computed using a 24% tax rate overall. With regard to foreign currency translation adjustments, the Company has elected to indefinitely reinvest the earnings of Centuri’s Canadian subsidiaries in Canada, thus preventing deferred taxes on such earnings. As a result of this assertion, the Company is not recognizing any tax effect or presenting a tax expense or benefit for the currency translation adjustment amount reported in Other comprehensive income (loss), as repatriation of earnings is not anticipated. Approximately $2.5 million of realized losses (net of tax) related to the FSIRS, reported in Accumulated other comprehensive income (loss) at March 31, 2019 , will be reclassified into interest expense within the next 12 months as the related interest payments on long-term debt occur. The following table represents a rollforward of AOCI, presented on the Company’s Condensed Consolidated Balance Sheets: AOCI - Rollforward (Thousands of dollars) Defined Benefit Plans FSIRS Foreign Currency Items Before-Tax Tax (Expense) Benefit (4,5) After-Tax (5) Before-Tax Tax (Expense) Benefit (4,5) After-Tax (5) Before-Tax Tax (Expense) Benefit After-Tax AOCI Beginning Balance AOCI December 31, 2018 $ (55,227 ) $ 13,254 $ (41,973 ) $ (9,310 ) $ 2,234 $ (7,076 ) $ (3,619 ) $ — $ (3,619 ) $ (52,668 ) Translation adjustments — — — — — — 791 — 791 791 Other comprehensive income (loss) before reclassifications — — — — — — 791 — 791 791 FSIRS amounts reclassified from AOCI (1) — — — 836 (201 ) 635 — — — 635 Amortization of prior service cost (2) 317 (76 ) 241 — — — — — — 241 Amortization of net actuarial loss (2) 5,844 (1,403 ) 4,441 — — — — — — 4,441 Regulatory adjustment (3) (5,347 ) 1,284 (4,063 ) — — — — — — (4,063 ) Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc. 814 (195 ) 619 836 (201 ) 635 791 — 791 2,045 Ending Balance AOCI March 31, 2019 $ (54,413 ) $ 13,059 $ (41,354 ) $ (8,474 ) $ 2,033 $ (6,441 ) $ (2,828 ) $ — $ (2,828 ) $ (50,623 ) (1) The FSIRS reclassification amounts are included in Net interest deductions on the Company’s Condensed Consolidated Statements of Income. (2) These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details). (3) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on the Company’s Condensed Consolidated Balance Sheets). (4) Tax amounts are calculated using a 24% rate. (5) The beginning balances depict amounts attributable to the individual components of AOCI (Defined Benefit Plans and FSIRS) following the adoption of ASU No. 2018-02, with no impact to the total balance of AOCI resulting from the depiction. The following table represents a rollforward of AOCI, presented on Southwest’s Condensed Consolidated Balance Sheets: AOCI - Rollforward (Thousands of dollars) Defined Benefit Plans FSIRS Before-Tax Tax (Expense) Benefit (9,10) After-Tax (10) Before-Tax Tax (Expense) Benefit (9,10) After-Tax (10) AOCI Beginning Balance AOCI December 31, 2018 $ (55,227 ) $ 13,254 $ (41,973 ) $ (9,310 ) $ 2,234 $ (7,076 ) $ (49,049 ) FSIRS amounts reclassified from AOCI (6) — — — 836 (201 ) 635 635 Amortization of prior service cost (7) 317 (76 ) 241 — — — 241 Amortization of net actuarial loss (7) 5,844 (1,403 ) 4,441 — — — 4,441 Regulatory adjustment (8) (5,347 ) 1,284 (4,063 ) — — — (4,063 ) Net current period other comprehensive income attributable to Southwest Gas Corporation 814 (195 ) 619 836 (201 ) 635 1,254 Ending Balance AOCI March 31, 2019 $ (54,413 ) $ 13,059 $ (41,354 ) $ (8,474 ) $ 2,033 $ (6,441 ) $ (47,795 ) (6) The FSIRS reclassification amounts are included in Net interest deductions on Southwest’s Condensed Consolidated Statements of Income. (7) These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details). (8) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on Southwest’s Condensed Consolidated Balance Sheets). (9) Tax amounts are calculated using a 24% rate. (10) The beginning balances depict amounts attributable to the individual components of AOCI (Defined Benefit Plans and FSIRS) following the adoption of ASU No. 2018-02, with no impact to the total balance of AOCI resulting from the depiction. The following table represents amounts (before income tax impacts) included in AOCI (in the tables above), that have not yet been recognized in net periodic benefit cost: Amounts Recognized in AOCI (Before Tax) (Thousands of dollars) March 31, 2019 December 31, 2018 Net actuarial (loss) gain $ (429,520 ) $ (435,364 ) Prior service cost (2,716 ) (3,033 ) Less: amount recognized in regulatory assets 377,823 383,170 Recognized in AOCI $ (54,413 ) $ (55,227 )

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Segment Information	Note 10 – Segment Information The Company has two reportable segments: natural gas operations and utility infrastructure services. Southwest has a single reportable segment that is referred to herein as the natural gas operations segment of the Company. In order to reconcile to net income as disclosed in the Condensed Consolidated Statements of Income, an Other column is included associated with impacts related to corporate and administrative activities related to Southwest Gas Holdings, Inc. The following tables present revenues from external customers, intersegment revenues, and segment net income for the two reportable segments (thousands of dollars): Natural Gas Operations Utility Infrastructure Services Other Total Three Months Ended March 31, 2019 Revenues from external customers $ 520,677 $ 274,189 $ — $ 794,866 Intersegment revenues — 38,673 — 38,673 Total $ 520,677 $ 312,862 $ — $ 833,539 Segment net income (loss) $ 103,389 $ (8,031 ) $ (549 ) $ 94,809 Three Months Ended March 31, 2018 Revenues from external customers $ 494,313 $ 232,859 $ — $ 727,172 Intersegment revenues — 27,158 — 27,158 Total $ 494,313 $ 260,017 $ — $ 754,330 Segment net income (loss) $ 90,349 $ (11,001 ) $ (257 ) $ 79,091 Natural Gas Operations Utility Infrastructure Services Other Total Twelve Months Ended March 31, 2019 Revenues from external customers $ 1,384,092 $ 1,427,701 $ — $ 2,811,793 Intersegment revenues — 147,429 — 147,429 Total $ 1,384,092 $ 1,575,130 $ — $ 2,959,222 Segment net income (loss) $ 151,882 $ 47,947 $ (1,834 ) $ 197,995 Twelve Months Ended March 31, 2018 Revenues from external customers $ 1,334,019 $ 1,211,345 $ — $ 2,545,364 Intersegment revenues — 103,021 — 103,021 Total $ 1,334,019 $ 1,314,366 $ — $ 2,648,385 Segment net income (loss) $ 170,229 $ 34,693 $ (1,298 ) $ 203,624

Redeemable Noncontrolling Inter

Redeemable Noncontrolling Interests	3 Months Ended
	Mar. 31, 2019
Noncontrolling Interest [Abstract]
Redeemable Noncontrolling Interests	Note 11 – Redeemable Noncontrolling Interest In connection with the acquisition of Linetec in November 2018, the previous owner retained a 20% equity interest in Linetec, the reduction of which is subject to certain rights based on the passage of time or upon the occurrence of certain triggering events. Effective January 2022, the Company has the right, but not the obligation, to purchase at fair value (subject to a floor) a portion of the interest held by the noncontrolling party, and in incremental amounts each year thereafter. The shares subject to the election accumulate (if earlier elections are not made) such that 100% of the interest retained by the noncontrolling party is subject to the election beginning in 2024. If the Company does not exercise its rights at each or any of the specified intervals, the noncontrolling party has the ability, but not the obligation, to exit their investment retained by requiring Centuri to purchase a similar portion of their interest up to the maximum cumulative amounts specified at each interval discussed above. The Company has determined that this noncontrolling interest is a redeemable noncontrolling interest and, in accordance with SEC guidance, is classified as mezzanine equity (temporary equity) in the Company’s Condensed Consolidated Balance Sheets. Significant changes in the value of the redeemable noncontrolling interest, above a floor established at the acquisition date, are recognized as they occur, and the carrying value is adjusted as necessary at each reporting date. The fair value is estimated using a market approach that utilizes certain financial metrics from guideline public companies of similar industry and operating characteristics. However, the carrying value of the redeemable noncontrolling interest was greater than its fair value as of March 31, 2019 , and no previous upward redemption value adjustments were made following the acquisition date. SEC guidance indicates that a redemption value adjustment would not be made under these circumstances. The following depicts changes to the balance of the redeemable noncontrolling interest between the indicated periods. Redeemable (Thousands of dollars): Balance, December 31, 2018 $ 81,831 Net income attributable to redeemable noncontrolling interest 575 Balance, March 31, 2019 $ 82,406

Business Acquisitions

Business Acquisitions	3 Months Ended
	Mar. 31, 2019
Business Combinations [Abstract]
Business Acquisitions	Note 12 – Business Acquisitions In November 2018, the Company, through its subsidiaries, led principally by Centuri, completed the acquisition of an 80% interest in a privately held infrastructure services business, Linetec Services, LLC (“Linetec”) with the remaining 20% retained by the seller. See the Company’s 2018 Form 10-K for additional information about this acquisition. Assets acquired and liabilities assumed in the transaction were recorded, generally, at their acquisition date fair values. Transaction costs associated with the acquisition were expensed as incurred. The Company’s allocation of the purchase price was based on an evaluation of the appropriate fair values and represented management’s best estimate based on available data (including market data, data regarding customers of the acquired businesses, terms of acquisition-related agreements, analysis of historical and projected results, and other types of data). The analysis included consideration of types of intangibles that were acquired, including customer relationships, trade names, and customer contracts. Certain payments were estimated as of the acquisition date and will be adjusted when paid; the final purchase accounting has not yet been completed. Further refinement is expected to occur, including potential changes to income taxes and intangibles, as well as additional consideration payments held back. The preliminary estimated fair values of assets acquired and liabilities assumed as of November 30, 2018, are as follows (millions of dollars): Acquisition Date Measurement Period Adjustments Revised Acquisition Date Cash and cash equivalents $ 3.9 $ — $ 3.9 Accounts receivable 32.8 (0.5 ) 32.3 Revenue earned on contracts in progress in excess of billings 21.6 1.7 23.3 Prepaid expenses and other current assets 1.1 0.2 1.3 Property and equipment 89.4 (0.5 ) 88.9 Intangible assets 89.3 — 89.3 Goodwill 188.5 3.3 191.8 Total assets acquired 426.6 4.2 430.8 Accounts payable 8.0 — 8.0 Accrued liabilities 6.9 1.6 8.5 Deferred compensation and related accrued taxes 3.4 — 3.4 Redeemable noncontrolling interest 81.7 — 81.7 Total liabilities assumed and noncontrolling interest 100.0 1.6 101.6 Net assets acquired $ 326.6 $ 2.6 $ 329.2 The Company incurred and expensed acquisition costs of $ 6.9 million for the twelve months ended March 31, 2019 which are included in Utility infrastructure services expenses on the Company’s Condensed Consolidated Statement of Income. No acquisition-related costs were incurred during the three months ended March 31, 2019.

Background, Organization, and_2

Background, Organization, and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations. Southwest Gas Holdings, Inc. is a holding company, owning all of the shares of common stock of Southwest Gas Corporation (“Southwest” or the “natural gas operations segment”) and all of the shares of common stock of Centuri Group, Inc. (“Centuri,” or the “utility infrastructure services” segment). At the annual meeting of shareholders of Southwest Gas Holdings, Inc., held on May 2, 2019, shareholders voted to approve changing the state of incorporation for Southwest Gas Holdings, Inc. from California to Delaware. The reincorporation is expected to be effective during the second or third quarter of 2019. However, the reincorporation remains subject to certain regulatory approvals, which are currently pending. Southwest is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Public utility rates, practices, facilities, and service territories of Southwest are subject to regulatory oversight. The timing and amount of rate relief can materially impact results of operations. Natural gas purchases and the timing of related recoveries can materially impact liquidity. Results for the natural gas operations segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures. Centuri is a comprehensive utility infrastructure services enterprise dedicated to delivering a diverse array of solutions to North America’s gas and electric providers. Centuri derives revenue from installation, replacement, repair, and maintenance of energy distribution systems, and developing industrial construction solutions. Centuri operations are generally conducted under the business names of NPL Construction Co. (“NPL”), NPL Canada Ltd. (“NPL Canada”), New England Utility Constructors, Inc. (“Neuco”) and Linetec Services, LLC (“Linetec”). Utility infrastructure services activity is seasonal in most of Centuri’s operating areas. Peak periods are the summer and fall months in colder climate areas, such as the northeastern and midwestern United States (“U.S”) and in Canada. In warmer climate areas, such as the southwestern and southeastern U.S., utility infrastructure services activity continues year round. In November 2017, Centuri acquired Neuco, thereby expanding its core services in the northeast region of the U.S. Additionally, in November 2018, Centuri expanded its operations in the southeast region of the U.S. through the acquisition of an 80% interest in Linetec. See Note 12 – Business Acquisitions for more information.
Basis of Presentation	Basis of Presentation. The condensed consolidated financial statements for Southwest Gas Holdings, Inc. and subsidiaries (the “Company”) and Southwest included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The year-end condensed balance sheet data was derived from audited financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. No substantive change has occurred with regard to the Company’s business segments on the whole, or in the primary businesses comprising those segments as a result of the foregoing acquisitions of Neuco and Linetec.
Fair Value Measurements	Fair Value Measurements . Certain assets and liabilities are reported at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. U.S. GAAP states that a fair value measurement should be based on the assumptions that market participants would use in pricing the asset or liability and establishes a fair value hierarchy that ranks the inputs used to measure fair value by their reliability. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to fair values derived from unobservable inputs (Level 3 measurements). Financial assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The three levels of the fair value hierarchy are as follows: Level 1 – quoted prices (unadjusted) in active markets for identical assets or liabilities that a company has the ability to access at the measurement date. Level 2 – inputs other than quoted prices included within Level 1 that are observable for similar assets or liabilities, either directly or indirectly. Level 3 – unobservable inputs for the asset or liability. Unobservable inputs are used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date.
Cash and Cash Equivalents	Cash and Cash Equivalents. For purposes of reporting consolidated cash flows, cash and cash equivalents include cash on hand and financial instruments with maturities of three months or less. Such investments are carried at cost, which approximates market value. Cash and cash equivalents for Southwest and the Company also include money market fund investments totaling approximately $41 million and $54.4 million , respectively, at March 31, 2019 , and $18 million and $59.9 million , respectively, at December 31, 2018 , which fall within Level 2 of the fair value hierarchy, due to the asset valuation methods used by money market funds. Typical non-cash investing activities for Southwest include customer advances applied as contributions toward utility construction activity and capital expenditures that were not paid as of quarter end that are included in accounts payable. Amounts related to such activities were immaterial for the periods presented herein. Non-cash investing activities for the three months and twelve months ended March 31, 2019 included $73.5 million of purchase consideration related to the Linetec acquisition by Centuri, in the form of liabilities incurred that remained unpaid as of March 31, 2019
Income Taxes	Income Taxes. In 2017, the Tax Cuts and Jobs Act (the “TCJA”) was enacted. The TCJA had significant impacts on the taxation of business entities, including specific provisions related to regulated public utilities. The more significant changes that impacted the Company and Southwest include the reduction in the corporate federal income tax rate from 35% to 21%, and limiting the utilization of net operating losses (“NOLs”) to 80% of taxable income, with the ability to indefinitely carryforward unutilized NOLs to reduce future taxable income.
Goodwill	Goodwill. Goodwill is assessed as of October 1 st
Recent Accounting Standards Updates	Recent Accounting Standards Updates. Accounting pronouncements adopted in 2019: In February 2016, the FASB issued the update “Leases (Topic 842).” Under the update, lessees were required to recognize a lease liability for the obligation to make lease payments, measured on a discounted basis; and a right-of-use asset for the right to use, or control the use of, a specified asset for the lease term. The Company and Southwest adopted Topic 842 in the first quarter of 2019 through an optional transition method, which was elected, permitting the application of the provisions of the standard at the adoption date, rather than to earlier comparative periods. As a result, the Company and Southwest have not recast prior periods to reflect the adoption of this standard. See Note 4 – Leases . Accounting pronouncements that will be effective after 2019: In June 2016, the FASB issued ASU 2016-13 update “Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” The update requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. The inputs currently used to estimate credit losses will still be used; however, they may be adapted to reflect the full amount of expected losses. The update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. All entities may adopt the amendments in this update earlier as of fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Management is evaluating what impact, if any, this update might have on the Company’s and Southwest’s consolidated financial statements and disclosures. In January 2017, the FASB issued ASU 2017-04 “Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment.” Currently, unless meeting the criteria for qualitative assessment only, an entity is required to perform a two-step test to determine the amount, if any, of goodwill impairment. In Step 1, an entity compares the fair value of a reporting unit with its carrying amount, including goodwill. If the carrying amount of the reporting unit exceeds its fair value, the entity performs Step 2 and compares the implied fair value of goodwill with the carrying amount of that goodwill for that reporting unit, requiring a hypothetical purchase price allocation to measure the amount of a goodwill impairment. An impairment charge equal to the amount by which the carrying amount of goodwill for the reporting unit exceeds the implied fair value of that goodwill is recorded, limited to the amount of goodwill allocated to that reporting unit. Under the update, an entity will apply a one-step quantitative test and record the amount of goodwill impairment as the excess of a reporting unit's carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. The new guidance does not amend the optional qualitative assessment. The amount of any goodwill impairment calculated under the update could vary from the calculation under existing guidance, largely due to the consideration to be given to unrecognized differences between the fair value and carrying values of the other assets and liabilities in the reporting unit under the new guidance. The amendments should be applied on a prospective basis. The update is effective for fiscal and interim periods beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. Management is evaluating the impacts this update might have on the Company’s and Southwest’s consolidated financial statements and disclosures. In August 2018, the FASB issued ASU 2018-15 “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract.” The update generally aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement (that is a service contract) with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. The update also requires the entity to expense the capitalized implementation costs of such hosting arrangements over the term of the hosting arrangement, including reasonably certain renewal periods. The update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption of the amendments in this update is permitted for interim and related annual fiscal periods after December 15, 2018. Management is evaluating the impacts this update might have on the Company’s and Southwest’s consolidated financial statements and disclosures. In August 2018, the FASB issued ASU 2018-14 “Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans.” This update removes disclosures that are no longer considered cost-beneficial, clarifies the specific requirements of disclosures, and adds disclosure requirements identified as relevant. The update applies to all employers that sponsor defined benefit pension or other postretirement plans. The update is effective for fiscal years ending after December 15, 2020. Upon adoption, the Company and Southwest will modify their disclosures to conform to the requirements of the update.

Background, Organization, and_3

Background, Organization, and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Other Property and Investments	Other Property and Investments. Other property and investments on the Condensed Consolidated Balance Sheets includes (thousands of dollars): March 31, 2019 December 31, 2018 Southwest Gas Corporation: Net cash surrender value of COLI policies $ 122,048 $ 114,405 Other property 1,735 1,741 Total Southwest Gas Corporation 123,783 116,146 Centuri property, equipment, and intangibles 894,739 792,191 Centuri accumulated depreciation/amortization (316,832 ) (298,939 ) Other property 15,032 14,153 Total Southwest Gas Holdings, Inc. $ 716,722 $ 623,551
Accounts Receivable for Services	Centuri’s accounts receivable for these services are presented in the table below (thousands of dollars): March 31, 2019 December 31, 2018 Centuri accounts receivable for services provided to Southwest $ 16,837 $ 18,830
Schedule of Goodwill	(Thousands of dollars) Natural Gas Operations Utility Infrastructure Services Total Company December 31, 2018 $ 10,095 $ 348,950 $ 359,045 Measurement Period Adjustment - Linetec acquisition — 3,303 3,303 Foreign currency translation adjustment — 2,134 2,134 March 31, 2019 $ 10,095 $ 354,387 $ 364,482
Other Income (Deductions)	Other Income (Deductions). The following table provides the composition of significant items included in Other income (deductions) in the Condensed Consolidated Statements of Income (thousands of dollars): Three Months Ended Twelve Months Ended March 31, March 31, 2019 2018 2019 2018 Southwest Gas Corporation - natural gas operations segment: Change in COLI policies $ 7,600 $ (700 ) $ 5,100 $ 6,800 Interest income 1,597 1,418 6,199 3,638 Equity AFUDC 960 229 4,358 2,049 Other components of net periodic benefit cost (3,765 ) (5,265 ) (19,560 ) (19,834 ) Miscellaneous income and (expense) (446 ) (285 ) (2,788 ) (2,400 ) Southwest Gas Corporation - total other income (deductions) 5,946 (4,603 ) (6,691 ) (9,747 ) Utility infrastructure services segment: Interest income — 1 87 4 Foreign transaction gain (loss) 531 147 162 (606 ) Miscellaneous income and (expense) 344 115 125 956 Centuri - total other income (deductions) 875 263 374 354 Corporate and administrative 18 6 64 19 Consolidated Southwest Gas Holdings, Inc. - total other income (deductions) $ 6,839 $ (4,334 ) $ (6,253 ) $ (9,374 )

Components of Net Periodic Be_2

Components of Net Periodic Benefit Cost (Tables)	3 Months Ended
	Mar. 31, 2019
Retirement Benefits [Abstract]
Schedule of Net Periodic Benefit Costs	The service cost component of net periodic benefit costs included in the table below are components of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of that portion of overall net periodic benefit costs to the same accounts to which productive labor is charged. As a result, service costs become components of various accounts, primarily operations and maintenance expense, net utility plant, and deferred charges and other assets for both the Company and Southwest. The other components of net periodic benefit cost are reflected in Other income (deductions) on the Condensed Consolidated Statements of Income of the Company and Southwest. Qualified Retirement Plan Period Ended March 31, Three Months Twelve Months 2019 2018 2019 2018 (Thousands of dollars) Service cost $ 6,466 $ 7,139 $ 27,882 $ 24,683 Interest cost 12,252 11,043 45,383 45,606 Expected return on plan assets (15,061 ) (14,689 ) (59,127 ) (56,086 ) Amortization of net actuarial loss 5,589 8,029 29,675 26,032 Net periodic benefit cost $ 9,246 $ 11,522 $ 43,813 $ 40,235 SERP Period Ended March 31, Three Months Twelve Months 2019 2018 2019 2018 (Thousands of dollars) Service cost $ 66 $ 61 $ 250 $ 292 Interest cost 440 415 1,683 1,827 Amortization of net actuarial loss 255 375 1,382 1,456 Net periodic benefit cost $ 761 $ 851 $ 3,315 $ 3,575 PBOP Period Ended March 31, Three Months Twelve Months 2019 2018 2019 2018 (Thousands of dollars) Service cost $ 319 $ 368 $ 1,424 $ 1,469 Interest cost 762 687 2,823 3,111 Expected return on plan assets (789 ) (930 ) (3,577 ) (3,448 ) Amortization of prior service costs 317 334 1,318 1,335 Net periodic benefit cost $ 609 $ 459 $ 1,988 $ 2,467

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Summary of Revenue Disaggregated by Service Type and Contract Type	Gas operating revenues on the Condensed Consolidated Statements of Income of both the Company and Southwest include revenue from contracts with customers, which is shown below, disaggregated by customer type, and various categories of revenue: Three Months Ended Twelve Months Ended March 31, March 31, (Thousands of dollars) 2019 2018 2019 2018 Residential $ 417,228 $ 344,611 $ 959,837 $ 859,078 Small commercial 89,610 87,943 256,750 250,331 Large commercial 13,962 15,440 51,714 54,224 Industrial/other 6,478 6,510 23,457 23,085 Transportation 24,902 24,054 87,838 89,081 Revenue from contracts with customers 552,180 478,558 1,379,596 1,275,799 Alternative revenue program revenues (deferrals) (34,545 ) 27,209 (15,775 ) 66,788 Other revenues (a) 3,042 (11,454 ) 20,271 (8,568 ) Total Gas operating revenues $ 520,677 $ 494,313 $ 1,384,092 $ 1,334,019 (a) Includes various other revenues which, in the periods presented ending March 31, 2018, were offset by a $14 million (Thousands of dollars) Three Months Ended Twelve Months Ended March 31, March 31, 2019 2018 2019 2018 Service Types: Gas infrastructure services $ 197,893 $ 193,527 $ 1,128,048 $ 938,342 Electric power infrastructure services 52,301 5,402 79,528 19,893 Other 62,668 61,088 367,554 356,131 Total Utility infrastructure services revenues $ 312,862 $ 260,017 $ 1,575,130 $ 1,314,366 (Thousands of dollars) Three Months Ended Twelve Months Ended March 31, March 31, 2019 2018 2019 2018 Contract Types: Master services agreement $ 235,655 $ 194,464 $ 1,143,603 $ 932,804 Bid contract 77,207 65,553 431,527 381,562 Total Utility infrastructure services revenues $ 312,862 $ 260,017 $ 1,575,130 $ 1,314,366 Unit priced contracts $ 235,686 $ 197,322 $ 1,296,783 $ 1,013,642 Fixed priced contracts 38,538 25,541 130,295 137,724 Time and materials contracts 38,638 37,154 148,052 163,000 Total Utility infrastructure services revenues $ 312,862 $ 260,017 $ 1,575,130 $ 1,314,366
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	The following table provides information about contracts receivable and revenue earned on contracts in progress in excess of billings (contract asset), which are both included within Accounts receivable, net of allowances, as well as amounts billed in excess of revenue earned on contracts (contract liability), which are included in Other current liabilities as of March 31, 2019 and December 31, 2018 on the Company’s Condensed Consolidated Balance Sheets: (Thousands of dollars) March 31, 2019 December 31, 2018 Contracts receivable, net $ 160,973 $ 186,249 Revenue earned on contracts in progress in excess of billings 97,642 87,520 Amounts billed in excess of revenue earned on contracts 4,588 4,211
Schedule of Construction Services Contracts Receivable	Utility infrastructure services contracts receivable consists of the following: (Thousands of dollars) March 31, 2019 December 31, 2018 Billed on completed contracts and contracts in progress $ 159,829 $ 184,100 Other receivables 1,527 2,588 Contracts receivable, gross 161,356 186,688 Allowance for doubtful accounts (383 ) (439 ) Contracts receivable, net $ 160,973 $ 186,249

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Components of Lease Expense, and Supplemental Cash Flow Information Related to Leases	The components of lease expense were as follows: (Thousands of dollars) Three Months Ended March 31, 2019 Southwest: Operating lease cost $ 406 Centuri: Operating lease cost $ 2,805 Finance lease cost: Amortization of ROU assets $ 35 Interest on lease liabilities 7 Total finance lease cost 42 Short-term lease cost 2,575 Total lease cost $ 5,828 Supplemental cash flow information related to leases for the three months ended March 31, 2019 was as follows: (Thousands of dollars) Southwest Centuri Consolidated Total Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 396 $ 2,555 $ 2,951 Operating cash flows from finance leases — 7 7 Financing cash flows from finance leases — 51 51 ROU assets obtained in exchange for lease obligations: Operating leases $ 523 $ 2,321 $ 2,844 Finance leases — 84 84
Supplemental Information Related to Leases Included in Balance Sheet	Supplemental information related to leases, including location in the Condensed Consolidated Balance Sheets, is as follows: (Thousands of dollars) March 31, 2019 Southwest: Operating leases: Net Utility Plant $ 1,977 Other current liabilities $ 745 Other deferred credits and other long-term liabilities 1,253 Total operating lease liabilities $ 1,998 Weighted average remaining lease term (in years) 4.22 Weighted average discount rate 3.39 % Centuri: Operating leases: Other property and investments $ 57,267 Other current liabilities 7,178 Other deferred credits and other long-term liabilities 52,647 Total operating lease liabilities $ 59,825 Finance leases: Other property and investments $ 639 Other current liabilities 256 Other deferred credits and other long-term liabilities 239 Total finance lease liabilities $ 495 Weighted average remaining lease term (in years) Operating leases 9.33 Finance leases 1.63 Weighted average discount rate Operating leases 4.08 % Finance leases 5.84 %
Schedule of Maturities of Operating Lease Liabilities	The following is a schedule of maturities of lease liabilities as of March 31, 2019 : (Thousands of dollars) Operating leases Southwest: 2020 $ 800 2021 556 2022 295 2023 124 2024 78 Thereafter 307 Total lease payments 2,160 Less imputed interest 162 Total $ 1,998 (Thousands of dollars) Operating leases Finance leases Centuri: 2020 $ 10,394 $ 281 2021 9,327 128 2022 8,328 67 2023 7,645 38 2024 5,710 25 Thereafter 31,303 — Total lease payments 72,707 539 Less imputed interest 12,882 44 Total $ 59,825 $ 495
Schedule of Maturities of Finance Lease Liabilities	(Thousands of dollars) Operating leases Finance leases Centuri: 2020 $ 10,394 $ 281 2021 9,327 128 2022 8,328 67 2023 7,645 38 2024 5,710 25 Thereafter 31,303 — Total lease payments 72,707 539 Less imputed interest 12,882 44 Total $ 59,825 $ 495
Schedule of Rental and Lease Payments	As the Company and Southwest adopted Topic 842 using the optional transition method referred to in Note 1 – Background, Organization, and Summary of Significant Accounting Policies , the recent annual disclosure of rental and lease payments as of December 31, 2018 in accordance with Topic 840 is presented in the table below: 2018 2017 Southwest Gas Corporation $ 4,556 $ 4,926 Centuri 59,491 62,310 Consolidated rental payments/lease expense $ 64,047 $ 67,236
Schedule of Future Minimum Rental Payments for Operating Leases	The following is a schedule of future minimum lease payments for operating leases (with initial or remaining terms in excess of one year) as of December 31, 2018 (thousands of dollars): Southwest Centuri Consolidated Total 2019 $ 898 $ 10,053 $ 10,951 2020 363 7,656 8,019 2021 299 5,760 6,059 2022 163 5,163 5,326 2023 79 3,681 3,760 Thereafter 177 10,511 10,688 Total minimum lease payments $ 1,979 $ 42,824 $ 44,803

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional Amounts under Swaps Contracts	The differential is calculated based on the notional amounts under the contracts, which are detailed in the table below (thousands of dekatherms): March 31, 2019 December 31, 2018 Contract notional amounts 14,757 13,387
Amount of Gain or Losses Recognized in Income on Derivatives	The following table sets forth the gains and (losses) recognized on the Swaps (derivatives) for the three- and twelve-month periods ended March 31, 2019 and 2018 and their location in the Condensed Consolidated Statements of Income for both the Company and Southwest: Gains (losses) recognized in income for derivatives not designated as hedging instruments: (Thousands of dollars) Three Months Ended Twelve Months Ended Location of Gain or (Loss) Recognized in Income on Derivatives March 31, March 31, Instrument 2019 2018 2019 2018 Swaps Net cost of gas sold $ (3,533 ) $ (5,196 ) $ (450 ) $ (11,631 ) Swaps Net cost of gas sold 3,533 * 5,196 * 450 * 11,631 * Total $ — $ — $ — $ — * Represents the impact of regulatory deferral accounting treatment under U.S. GAAP for rate-regulated entities.
Fair Values of Swaps in Consolidated Balance Sheets	The following table sets forth the fair values of the Swaps and their location in the Condensed Consolidated Balance Sheets for both the Company and Southwest (thousands of dollars): Fair values of derivatives not designated as hedging instruments: March 31, 2019 Asset Liability Instrument Balance Sheet Location Derivatives Derivatives Net Total Swaps Other current liabilities $ 805 $ (4,472 ) $ (3,667 ) Swaps Other deferred credits 60 (809 ) (749 ) Total $ 865 $ (5,281 ) $ (4,416 ) December 31, 2018 Asset Liability Instrument Balance Sheet Location Derivatives Derivatives Net Total Swaps Prepaid and other current assets $ 243 $ (99 ) $ 144 Swaps Other current liabilities 1,595 (3,347 ) (1,752 ) Swaps Other deferred credits 141 (251 ) (110 ) Total $ 1,979 $ (3,697 ) $ (1,718 )
Paid to and Received from Counterparties for Settlements of Matured Swaps	The following table shows the amounts Southwest paid to and received from counterparties for settlements of matured Swaps. Three Months Ended Twelve Months Ended (Thousands of dollars) March 31, 2019 March 31, 2019 Paid to counterparties $ 1,882 $ 5,948 Received from counterparties $ 1,047 $ 1,653
Regulatory Assets/Liabilities Offsetting Derivatives at Fair Value in Condensed Consolidated Balance Sheets	The following table details the regulatory assets/(liabilities) offsetting the derivatives at fair value in the Condensed Consolidated Balance Sheets for both the Company and Southwest (thousands of dollars). March 31, 2019 Instrument Balance Sheet Location Net Total Swaps Prepaid and other current assets $ 3,667 Swaps Deferred charges and other assets 749 December 31, 2018 Instrument Balance Sheet Location Net Total Swaps Other current liabilities $ (144 ) Swaps Prepaid and other current assets 1,752 Swaps Deferred charges and other assets 110
Summary of Financial Assets and Liabilities at Fair Value	The following table sets forth, by level within the three-level fair value hierarchy that ranks the inputs used to measure fair value by their reliability, the financial assets and liabilities that were accounted for at fair value by both the Company and Southwest: Level 2 - Significant other observable inputs (Thousands of dollars) March 31, 2019 December 31, 2018 Assets at fair value: Prepaid and other current assets - Swaps $ — $ 144 Liabilities at fair value: Other current liabilities - Swaps (3,667 ) (1,752 ) Other deferred credits - Swaps (749 ) (110 ) Net Assets (Liabilities) $ (4,416 ) $ (1,718 )

Common Stock (Tables)

Common Stock (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Schedule of Common Stock Activity	The following table provides activity in the Equity Shelf Program for the three and twelve months ended March 31, 2019 : Three Months Ended Twelve Months Ended March 31, March 31, 2019 2018 2019 2018 Gross proceeds $ 23,073,149 $ 9,199,661 $ 99,023,464 $ 50,976,456 Less: agent commissions (230,731 ) (91,997 ) (990,234 ) (509,765 ) Net proceeds $ 22,842,418 $ 9,107,664 $ 98,033,230 $ 50,466,691 Number of shares sold 277,829 137,300 1,286,234 643,007 Weighted average price per share $ 83.05 $ 67.00 $ 76.99 $ 79.28

Long-Term Debt (Tables)

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt	The Centuri secured revolving credit and term loan facility and Centuri other debt obligations (not actively traded) are categorized as Level 3, based on significant unobservable inputs to their fair values. Because Centuri’s debt is not publicly traded, fair values for the secured revolving credit and term loan facility and other debt obligations were based on a conventional discounted cash flow methodology and utilized current market pricing yield curves, across Centuri’s debt maturity spectrum, of other industrial bonds with an assumed credit rating comparable to the Company’s. March 31, 2019 December 31, 2018 Carrying Amount Market Value Carrying Amount Market Value (Thousands of dollars) Southwest Gas Corporation: Debentures: Notes, 4.45%, due 2020 $ 125,000 $ 126,990 $ 125,000 $ 126,213 Notes, 6.1%, due 2041 125,000 154,294 125,000 150,728 Notes, 3.875%, due 2022 250,000 255,015 250,000 254,195 Notes, 4.875%, due 2043 250,000 277,683 250,000 268,985 Notes, 3.8%, due 2046 300,000 283,635 300,000 267,030 Notes, 3.7%, due 2028 300,000 306,465 300,000 298,926 8% Series, due 2026 75,000 95,128 75,000 93,827 Medium-term notes, 7.78% series, due 2022 25,000 27,715 25,000 27,497 Medium-term notes, 7.92% series, due 2027 25,000 30,824 25,000 30,016 Medium-term notes, 6.76% series, due 2027 7,500 8,845 7,500 8,651 Unamortized discount and debt issuance costs (11,641 ) (11,807 ) 1,470,859 1,470,693 Revolving credit facility and commercial paper 150,000 150,000 150,000 150,000 Industrial development revenue bonds: Variable-rate bonds: Tax-exempt Series A, due 2028 50,000 50,000 50,000 50,000 2003 Series A, due 2038 50,000 50,000 50,000 50,000 2008 Series A, due 2038 50,000 50,000 50,000 50,000 2009 Series A, due 2039 50,000 50,000 50,000 50,000 Unamortized discount and debt issuance costs (1,900 ) (2,024 ) 198,100 197,976 Less: current maturities — — Long-term debt, less current maturities - Southwest Gas Corporation $ 1,818,959 $ 1,818,669 Centuri: Centuri term loan facility $ 254,534 $ 257,579 $ 255,959 $ 260,135 Unamortized debt issuance costs (1,343 ) (1,414 ) 253,191 254,545 Centuri secured revolving credit facility 6,361 6,363 — — Centuri other debt obligations 62,678 63,365 67,104 67,053 Less: current maturities (34,915 ) (33,060 ) Long-term debt, less current maturities - Centuri $ 287,315 $ 288,589 Consolidated Southwest Gas Holdings, Inc.: Southwest Gas Corporation long-term debt $ 1,818,959 $ 1,818,669 Centuri long-term debt 322,230 321,649 Less: current maturities (34,915 ) (33,060 ) Long-term debt, less current maturities - Southwest Gas Holdings, Inc. $ 2,106,274 $ 2,107,258

Equity, Other Comprehensive I_2

Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Detailed Activities of Equity and Redeemable Noncontrolling Interest	The tables below provide details of activity in equity, the noncontrolling interest, and the redeemable noncontrolling interest for the Company on a consolidated basis for the three-month periods ended March 31, 2019 and March 31, 2018. Southwest Gas Holdings, Inc. Equity (In thousands, except per share amounts) Common Stock Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings Non-controlling Interest Redeemable Noncontrolling Interest (Temporary Equity) Shares Amount Total December 31, 2018 53,026 $ 54,656 $ 1,305,769 $ (52,668 ) $ 944,285 $ (452 ) $ 2,251,590 $ 81,831 Common stock issuances 365 365 27,024 27,389 Net income (loss) 94,809 94,809 575 Foreign currency exchange translation adjustment 791 791 Other comprehensive income (loss): Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax 619 619 FSIRS amounts reclassified to net income, net of tax 635 635 Dividends declared Common: $0.545 per share (29,285 ) (29,285 ) March 31, 2019 53,391 $ 55,021 $ 1,332,793 $ (50,623 ) $ 1,009,809 $ (452 ) $ 2,346,548 $ 82,406 Southwest Gas Holdings, Inc. Equity Common Stock Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings Non-controlling Interest (In thousands, except per share amounts) Shares Amount Total December 31, 2017 48,090 $ 49,720 $ 955,332 $ (47,682 ) $ 857,398 $ (2,365 ) $ 1,812,403 Common stock issuances 247 247 10,148 10,395 Net income (loss) 79,091 (797 ) 78,294 Foreign currency exchange translation adjustment (911 ) (911 ) Other comprehensive income (loss): Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax 895 895 FSIRS amounts reclassified to net income, net of tax 635 635 Reclassification of excess deferred taxes (a) (9,300 ) 9,300 — Dividends declared Common: $0.52 per share (25,335 ) (25,335 ) March 31, 2018 48,337 $ 49,967 $ 965,480 $ (56,363 ) $ 920,454 $ (3,162 ) $ 1,876,376 (a) Reclassification for the release of excess deferred taxes as a result of the adoption of ASU No. 2018-02 “Income Statement—Reporting Comprehensive Income—Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income,” which permitted release of excess amounts created following the December 2017 enactment of U.S. tax reform. The tables below provide details of activity in equity for Southwest during the three-month periods ended March 31, 2019 and March 31, 2018. Only equity shares of the Company are publicly traded, under the ticker symbol “SWX.” Southwest Gas Corporation Equity Common Stock Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings (In thousands) Shares Amount Total December 31, 2018 47,482 $ 49,112 $ 1,065,242 $ (49,049 ) $ 717,155 $ 1,782,460 Net income 103,389 103,389 Other comprehensive income (loss): Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax 619 619 FSIRS amounts reclassified to net income, net of tax 635 635 Stock-based compensation (a) 918 (160 ) 758 Dividends declared to Southwest Gas Holdings, Inc. (22,800 ) (22,800 ) Contributions from Southwest Gas Holdings, Inc. 22,842 22,842 March 31, 2019 47,482 $ 49,112 $ 1,089,002 $ (47,795 ) $ 797,584 $ 1,887,903 Southwest Gas Corporation Equity Common Stock Additional Paid-in Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings (In thousands) Shares Amount Total December 31, 2017 47,482 $ 49,112 $ 948,767 $ (47,073 ) $ 659,193 $ 1,609,999 Net income 90,349 90,349 Other comprehensive income (loss): Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax 895 895 FSIRS amounts reclassified to net income, net of tax 635 635 Reclassification of excess deferred taxes (b) (9,300 ) 9,300 — Stock-based compensation (a) (568 ) (166 ) (734 ) Dividends declared to Southwest Gas Holdings, Inc. (22,000 ) (22,000 ) March 31, 2018 47,482 $ 49,112 $ 948,199 $ (54,843 ) $ 736,676 $ 1,679,144 (a) Stock-based compensation is based on stock awards of Southwest Gas Corporation to be issued in shares of Southwest Gas Holdings, Inc. (b)
Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss)	Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) (Thousands of dollars) Three Months Ended Three Months Ended March 31, 2019 March 31, 2018 Before- Tax Amount Tax (Expense) or Benefit (1) Net-of- Tax Amount Before- Tax Amount Tax (Expense) or Benefit (1) Net-of- Tax Amount Defined benefit pension plans: Amortization of prior service cost $ 317 $ (76 ) $ 241 $ 334 $ (80 ) $ 254 Amortization of net actuarial (gain)/loss 5,844 (1,403 ) 4,441 8,404 (2,017 ) 6,387 Regulatory adjustment (5,347 ) 1,284 (4,063 ) (7,560 ) 1,814 (5,746 ) Pension plans other comprehensive income 814 (195 ) 619 1,178 (283 ) 895 FSIRS (designated hedging activities): Amounts reclassified into net income 836 (201 ) 635 837 (202 ) 635 FSIRS other comprehensive income 836 (201 ) 635 837 (202 ) 635 Total other comprehensive income - Southwest Gas Corporation 1,650 (396 ) 1,254 2,015 (485 ) 1,530 Foreign currency translation adjustments: Translation adjustments 791 — 791 (911 ) — (911 ) Foreign currency other comprehensive income (loss) 791 — 791 (911 ) — (911 ) Total other comprehensive income - Southwest Gas Holdings, Inc. $ 2,441 $ (396 ) $ 2,045 $ 1,104 $ (485 ) $ 619 Twelve Months Ended Twelve Months Ended March 31, 2019 March 31, 2018 Before- Tax Amount Tax (Expense) or Benefit (1) Net-of- Tax Amount Before- Tax Amount Tax (Expense) or Benefit (1) Net-of- Tax Amount Defined benefit pension plans: Net actuarial gain/(loss) $ (20,426 ) $ 4,902 $ (15,524 ) $ (43,027 ) $ 10,326 $ (32,701 ) Amortization of prior service cost 1,318 (316 ) 1,002 1,335 (460 ) 875 Amortization of net actuarial (gain)/loss 31,057 (7,454 ) 23,603 27,488 (9,269 ) 18,219 Regulatory adjustment (6,020 ) 1,446 (4,574 ) 10,515 (115 ) 10,400 Pension plans other comprehensive income (loss) 5,929 (1,422 ) 4,507 (3,689 ) 482 (3,207 ) FSIRS (designated hedging activities): Amounts reclassified into net income 3,344 (803 ) 2,541 3,345 (1,155 ) 2,190 FSIRS other comprehensive income 3,344 (803 ) 2,541 3,345 (1,155 ) 2,190 Total other comprehensive income (loss) - Southwest Gas Corporation 9,273 (2,225 ) 7,048 (344 ) (673 ) (1,017 ) Foreign currency translation adjustments: Translation adjustments (1,308 ) — (1,308 ) 640 — 640 Foreign currency other comprehensive income (loss) (1,308 ) — (1,308 ) 640 — 640 Total other comprehensive income (loss) - Southwest Gas Holdings, Inc. $ 7,965 $ (2,225 ) $ 5,740 $ 296 $ (673 ) $ (377 ) (1) Tax amounts are calculated using a 24% rate following the December 22, 2017 enactment date of U.S. tax reform. For periods prior to the enactment date (and included in specific line items of the tables for the twelve months ended March 31, 2018 ), tax amounts were calculated using a 38% rate. The tax effect of before-tax amounts remaining in the balance of Accumulated other comprehensive income (loss) as of March 31, 2019 is effectively computed using a 24%
Rollforward of Accumulated Other Comprehensive Income	The following table represents a rollforward of AOCI, presented on the Company’s Condensed Consolidated Balance Sheets: AOCI - Rollforward (Thousands of dollars) Defined Benefit Plans FSIRS Foreign Currency Items Before-Tax Tax (Expense) Benefit (4,5) After-Tax (5) Before-Tax Tax (Expense) Benefit (4,5) After-Tax (5) Before-Tax Tax (Expense) Benefit After-Tax AOCI Beginning Balance AOCI December 31, 2018 $ (55,227 ) $ 13,254 $ (41,973 ) $ (9,310 ) $ 2,234 $ (7,076 ) $ (3,619 ) $ — $ (3,619 ) $ (52,668 ) Translation adjustments — — — — — — 791 — 791 791 Other comprehensive income (loss) before reclassifications — — — — — — 791 — 791 791 FSIRS amounts reclassified from AOCI (1) — — — 836 (201 ) 635 — — — 635 Amortization of prior service cost (2) 317 (76 ) 241 — — — — — — 241 Amortization of net actuarial loss (2) 5,844 (1,403 ) 4,441 — — — — — — 4,441 Regulatory adjustment (3) (5,347 ) 1,284 (4,063 ) — — — — — — (4,063 ) Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc. 814 (195 ) 619 836 (201 ) 635 791 — 791 2,045 Ending Balance AOCI March 31, 2019 $ (54,413 ) $ 13,059 $ (41,354 ) $ (8,474 ) $ 2,033 $ (6,441 ) $ (2,828 ) $ — $ (2,828 ) $ (50,623 ) (1) The FSIRS reclassification amounts are included in Net interest deductions on the Company’s Condensed Consolidated Statements of Income. (2) These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details). (3) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on the Company’s Condensed Consolidated Balance Sheets). (4) Tax amounts are calculated using a 24% rate. (5) The beginning balances depict amounts attributable to the individual components of AOCI (Defined Benefit Plans and FSIRS) following the adoption of ASU No. 2018-02, with no impact to the total balance of AOCI resulting from the depiction. The following table represents a rollforward of AOCI, presented on Southwest’s Condensed Consolidated Balance Sheets: AOCI - Rollforward (Thousands of dollars) Defined Benefit Plans FSIRS Before-Tax Tax (Expense) Benefit (9,10) After-Tax (10) Before-Tax Tax (Expense) Benefit (9,10) After-Tax (10) AOCI Beginning Balance AOCI December 31, 2018 $ (55,227 ) $ 13,254 $ (41,973 ) $ (9,310 ) $ 2,234 $ (7,076 ) $ (49,049 ) FSIRS amounts reclassified from AOCI (6) — — — 836 (201 ) 635 635 Amortization of prior service cost (7) 317 (76 ) 241 — — — 241 Amortization of net actuarial loss (7) 5,844 (1,403 ) 4,441 — — — 4,441 Regulatory adjustment (8) (5,347 ) 1,284 (4,063 ) — — — (4,063 ) Net current period other comprehensive income attributable to Southwest Gas Corporation 814 (195 ) 619 836 (201 ) 635 1,254 Ending Balance AOCI March 31, 2019 $ (54,413 ) $ 13,059 $ (41,354 ) $ (8,474 ) $ 2,033 $ (6,441 ) $ (47,795 ) (6) The FSIRS reclassification amounts are included in Net interest deductions on Southwest’s Condensed Consolidated Statements of Income. (7) These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details). (8) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on Southwest’s Condensed Consolidated Balance Sheets). (9) Tax amounts are calculated using a 24% rate. (10)
Amount Recognized Before Income Tax in Accumulated Other Comprehensive Income	The following table represents amounts (before income tax impacts) included in AOCI (in the tables above), that have not yet been recognized in net periodic benefit cost: Amounts Recognized in AOCI (Before Tax) (Thousands of dollars) March 31, 2019 December 31, 2018 Net actuarial (loss) gain $ (429,520 ) $ (435,364 ) Prior service cost (2,716 ) (3,033 ) Less: amount recognized in regulatory assets 377,823 383,170 Recognized in AOCI $ (54,413 ) $ (55,227 )

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	The following tables present revenues from external customers, intersegment revenues, and segment net income for the two reportable segments (thousands of dollars): Natural Gas Operations Utility Infrastructure Services Other Total Three Months Ended March 31, 2019 Revenues from external customers $ 520,677 $ 274,189 $ — $ 794,866 Intersegment revenues — 38,673 — 38,673 Total $ 520,677 $ 312,862 $ — $ 833,539 Segment net income (loss) $ 103,389 $ (8,031 ) $ (549 ) $ 94,809 Three Months Ended March 31, 2018 Revenues from external customers $ 494,313 $ 232,859 $ — $ 727,172 Intersegment revenues — 27,158 — 27,158 Total $ 494,313 $ 260,017 $ — $ 754,330 Segment net income (loss) $ 90,349 $ (11,001 ) $ (257 ) $ 79,091 Natural Gas Operations Utility Infrastructure Services Other Total Twelve Months Ended March 31, 2019 Revenues from external customers $ 1,384,092 $ 1,427,701 $ — $ 2,811,793 Intersegment revenues — 147,429 — 147,429 Total $ 1,384,092 $ 1,575,130 $ — $ 2,959,222 Segment net income (loss) $ 151,882 $ 47,947 $ (1,834 ) $ 197,995 Twelve Months Ended March 31, 2018 Revenues from external customers $ 1,334,019 $ 1,211,345 $ — $ 2,545,364 Intersegment revenues — 103,021 — 103,021 Total $ 1,334,019 $ 1,314,366 $ — $ 2,648,385 Segment net income (loss) $ 170,229 $ 34,693 $ (1,298 ) $ 203,624

Redeemable Noncontrolling Int_2

Redeemable Noncontrolling Interests (Tables)	3 Months Ended
	Mar. 31, 2019
Noncontrolling Interest [Abstract]
Summary of Redeemable Noncontrolling Interest	The following depicts changes to the balance of the redeemable noncontrolling interest between the indicated periods. Redeemable (Thousands of dollars): Balance, December 31, 2018 $ 81,831 Net income attributable to redeemable noncontrolling interest 575 Balance, March 31, 2019 $ 82,406

Business Acquisitions (Tables)

Business Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2019
Business Combinations [Abstract]
Summary of Fair Values of Assets Acquired and Liabilities Assumed	The preliminary estimated fair values of assets acquired and liabilities assumed as of November 30, 2018, are as follows (millions of dollars): Acquisition Date Measurement Period Adjustments Revised Acquisition Date Cash and cash equivalents $ 3.9 $ — $ 3.9 Accounts receivable 32.8 (0.5 ) 32.3 Revenue earned on contracts in progress in excess of billings 21.6 1.7 23.3 Prepaid expenses and other current assets 1.1 0.2 1.3 Property and equipment 89.4 (0.5 ) 88.9 Intangible assets 89.3 — 89.3 Goodwill 188.5 3.3 191.8 Total assets acquired 426.6 4.2 430.8 Accounts payable 8.0 — 8.0 Accrued liabilities 6.9 1.6 8.5 Deferred compensation and related accrued taxes 3.4 — 3.4 Redeemable noncontrolling interest 81.7 — 81.7 Total liabilities assumed and noncontrolling interest 100.0 1.6 101.6 Net assets acquired $ 326.6 $ 2.6 $ 329.2

Background, Organization, and_4

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Other Property and Investments (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Other property	$ 15,032	$ 14,153
Total	716,722	623,551
Southwest Gas Corporation
Investment [Line Items]
Net cash surrender value of COLI policies	122,048	114,405
Other property	1,735	1,741
Total	123,783	116,146
Centuri
Investment [Line Items]
Centuri property, equipment, and intangibles	894,739	792,191
Centuri accumulated depreciation/amortization	$ (316,832)	$ (298,939)

Background, Organization, and_5

Background, Organization, and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Nov. 30, 2018
Significant Accounting Policies [Line Items]
Goodwill impairment	$ 0
Gas Pipe Materials and Supplies | Prepaid and other current assets
Significant Accounting Policies [Line Items]
Gas pipe materials and operating supplies	55,000,000	$ 55,000,000	$ 56,000,000
Prepaid and other current assets	55,000,000	55,000,000	74,000,000
Centuri | Linetec
Significant Accounting Policies [Line Items]
Percentage of voting interests acquired				80.00%
Purchase consideration	73,500,000	73,500,000
Southwest Gas Corporation
Significant Accounting Policies [Line Items]
Dividends declared but not yet paid	22,800,000	22,800,000
Pooled Funds and Mutual Funds | Level 2 - Significant Other Observable Inputs
Significant Accounting Policies [Line Items]
Money market fund investments	54,400,000	54,400,000	59,900,000
Pooled Funds and Mutual Funds | Southwest Gas Corporation | Level 2 - Significant Other Observable Inputs
Significant Accounting Policies [Line Items]
Money market fund investments	$ 41,000,000	$ 41,000,000	$ 18,000,000

Background, Organization, and_6

Background, Organization, and Summary of Significant Accounting Policies - Accounts Receivable for Services (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Centuri
Segment Reporting Information [Line Items]
Centuri accounts receivable for services provided to Southwest	$ 16,837	$ 18,830

Background, Organization, and_7

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 359,045
Foreign currency translation adjustment	2,134
Goodwill, ending balance	364,482
Natural Gas Operations
Goodwill [Roll Forward]
Goodwill, beginning balance	10,095
Foreign currency translation adjustment	0
Goodwill, ending balance	10,095
Utility Infrastructure Services
Goodwill [Roll Forward]
Goodwill, beginning balance	348,950
Foreign currency translation adjustment	2,134
Goodwill, ending balance	354,387
Linetec
Goodwill [Roll Forward]
Measurement Period Adjustment - Linetec acquisition	3,303
Goodwill, ending balance	191,800
Linetec | Natural Gas Operations
Goodwill [Roll Forward]
Measurement Period Adjustment - Linetec acquisition	0
Linetec | Utility Infrastructure Services
Goodwill [Roll Forward]
Measurement Period Adjustment - Linetec acquisition	$ 3,303

Background, Organization, and_8

Background, Organization, and Summary of Significant Accounting Policies- Other Income (Deductions) (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Other income (deductions)
Total other income (deductions)	$ 6,839	$ (4,334)	$ (6,253)	$ (9,374)
Southwest Gas Corporation
Other income (deductions)
Total other income (deductions)	5,946	(4,603)	(6,691)	(9,747)
Operating Segments | Natural Gas Operations | Southwest Gas Corporation
Other income (deductions)
Change in COLI policies	7,600	(700)	5,100	6,800
Interest income	1,597	1,418	6,199	3,638
Equity AFUDC	960	229	4,358	2,049
Other components of net periodic benefit cost	(3,765)	(5,265)	(19,560)	(19,834)
Miscellaneous income and (expense)	(446)	(285)	(2,788)	(2,400)
Total other income (deductions)	5,946	(4,603)	(6,691)	(9,747)
Operating Segments | Utility Infrastructure Services | Centuri
Other income (deductions)
Interest income	0	1	87	4
Foreign transaction gain (loss)	531	147	162	(606)
Miscellaneous income and (expense)	344	115	125	956
Total other income (deductions)	875	263	374	354
Corporate and administrative
Other income (deductions)
Total other income (deductions)	$ 18	$ 6	$ 64	$ 19

Components of Net Periodic Be_3

Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Qualified Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6,466	$ 7,139	$ 27,882	$ 24,683
Interest cost	12,252	11,043	45,383	45,606
Expected return on plan assets	(15,061)	(14,689)	(59,127)	(56,086)
Amortization of net actuarial loss	5,589	8,029	29,675	26,032
Net periodic benefit cost	9,246	11,522	43,813	40,235
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost	66	61	250	292
Interest cost	440	415	1,683	1,827
Amortization of net actuarial loss	255	375	1,382	1,456
Net periodic benefit cost	761	851	3,315	3,575
PBOP
Defined Benefit Plan Disclosure [Line Items]
Service cost	319	368	1,424	1,469
Interest cost	762	687	2,823	3,111
Expected return on plan assets	(789)	(930)	(3,577)	(3,448)
Amortization of prior service costs	317	334	1,318	1,335
Net periodic benefit cost	$ 609	$ 459	$ 1,988	$ 2,467

Revenue - Additional Informatio

Revenue - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)SegmentContract
Southwest Gas Corporation
Segment Reporting Information [Line Items]
Number of operating segment | Segment	1
Centuri
Segment Reporting Information [Line Items]
Change in contract liability, revenue recognized | $	$ 4.2
Number of contracts with original duration more than one year | Contract	17

Revenue - Revenue Performance O

Revenue - Revenue Performance Obligation (Details) - Centuri - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01 $ in Millions	Mar. 31, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to unsatisfied performance obligations of contracts	$ 60.7
Revenue, remaining performance obligation, expected timing of satisfaction, period	3 years

Revenue - Schedule of Gas Opera

Revenue - Schedule of Gas Operating Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 552,180	$ 478,558	$ 1,379,596	$ 1,275,799
Alternative revenue program revenues (deferrals)	(34,545)	27,209	(15,775)	66,788
Other revenues	3,042	(11,454)	20,271	(8,568)
Total Gas operating revenues	520,677	494,313	1,384,092	1,334,019
Tax Reform Savings Revenue Adjustments
Disaggregation of Revenue [Line Items]
Other revenues		14,000
Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	417,228	344,611	959,837	859,078
Small commercial
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	89,610	87,943	256,750	250,331
Large commercial
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13,962	15,440	51,714	54,224
Industrial/other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,478	6,510	23,457	23,085
Transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 24,902	$ 24,054	$ 87,838	$ 89,081

Revenue - Summary of Revenue Di

Revenue - Summary of Revenue Disaggregated by Service Type, and Contract Type (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 552,180	$ 478,558	$ 1,379,596	$ 1,275,799
Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	312,862	260,017	1,575,130	1,314,366
Master services agreement | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	235,655	194,464	1,143,603	932,804
Bid contract | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	77,207	65,553	431,527	381,562
Unit priced contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	235,686	197,322	1,296,783	1,013,642
Fixed priced contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	38,538	25,541	130,295	137,724
Time and materials contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	38,638	37,154	148,052	163,000
Gas infrastructure services | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	197,893	193,527	1,128,048	938,342
Electric power infrastructure services | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	52,301	5,402	79,528	19,893
Other | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 62,668	$ 61,088	$ 367,554	$ 356,131

Revenue - Summary of Informatio

Revenue - Summary of Information about Receivables (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contracts receivable, net	$ 160,973	$ 186,249
Revenue earned on contracts in progress in excess of billings	97,642	87,520
Amounts billed in excess of revenue earned on contracts	$ 4,588	$ 4,211

Revenue - Schedule of Construct

Revenue - Schedule of Construction Services Contracts Receivable (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Billed on completed contracts and contracts in progress	$ 159,829	$ 184,100
Other receivables	1,527	2,588
Contracts receivable, gross	161,356	186,688
Allowance for doubtful accounts	(383)	(439)
Contracts receivable, net	$ 160,973	$ 186,249

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease ROU assets		$ 58,400
Lease liabilities		60,800
Southwest Gas Corporation
Lessee, Lease, Description [Line Items]
Operating lease ROU assets	$ 1,977
Lease liabilities	$ 1,998
Lease renewal term (up to)	3 years
Southwest Gas Corporation | Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease ROU assets		1,900
Lease liabilities		$ 1,900
Centuri
Lessee, Lease, Description [Line Items]
Operating lease ROU assets	$ 57,267
Lease liabilities	$ 59,825
Lease renewal term (up to)	5 years
Lease termination period	1 year
Short-term lease cost	$ 2,575
Minimum | Southwest Gas Corporation
Lessee, Lease, Description [Line Items]
Lease remaining lease term	1 year
Minimum | Centuri
Lessee, Lease, Description [Line Items]
Lease remaining lease term	1 year
Maximum | Southwest Gas Corporation
Lessee, Lease, Description [Line Items]
Lease remaining lease term	10 years
Maximum | Centuri
Lessee, Lease, Description [Line Items]
Lease remaining lease term	14 years

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Finance lease cost:
Total lease cost	$ 5,828
Southwest Gas Corporation
Lessee, Lease, Description [Line Items]
Operating lease cost	406
Centuri
Lessee, Lease, Description [Line Items]
Operating lease cost	2,805
Finance lease cost:
Amortization of ROU assets	35
Interest on lease liabilities	7
Total finance lease cost	42
Short-term lease cost	$ 2,575

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information Related to Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases	$ 2,951
Operating cash flows from finance leases	7
Financing cash flows from finance leases	51
ROU assets obtained in exchange for operating leases obligations	2,844
ROU assets obtained in exchange for finance leases obligations	84
Southwest Gas Corporation
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases	396
Operating cash flows from finance leases	0
Financing cash flows from finance leases	0
ROU assets obtained in exchange for operating leases obligations	523
ROU assets obtained in exchange for finance leases obligations	0
Centuri
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases	2,555
Operating cash flows from finance leases	7
Financing cash flows from finance leases	51
ROU assets obtained in exchange for operating leases obligations	2,321
ROU assets obtained in exchange for finance leases obligations	$ 84

Leases - Supplemental Informati

Leases - Supplemental Information Related to Leases Included in Balance Sheet (Details) $ in Thousands	Mar. 31, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease, weighted average remaining lease term (in years)	9 years 3 months 29 days
Operating lease, weighted average discount rate	4.08%
Finance lease ROU assets	$ 639
Finance lease liabilities, current	256
Finance lease liabilities, noncurrent	239
Finance lease liabilities	$ 495
Finance lease, weighted average remaining lease term (in years)	1 year 7 months 17 days
Finance lease, weighted average discount rate	5.84%
Southwest Gas Corporation
Lessee, Lease, Description [Line Items]
Operating lease ROU assets	$ 1,977
Operating lease liabilities, current	745
Operating lease liabilities, noncurrent	1,253
Operating lease liabilities	$ 1,998
Operating lease, weighted average remaining lease term (in years)	4 years 2 months 19 days
Operating lease, weighted average discount rate	3.39%
Centuri
Lessee, Lease, Description [Line Items]
Operating lease ROU assets	$ 57,267
Operating lease liabilities, current	7,178
Operating lease liabilities, noncurrent	52,647
Operating lease liabilities	59,825
Finance lease liabilities	$ 495

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019USD ($)
Finance leases
Total	$ 495
Centuri
Operating leases
2020	10,394
2021	9,327
2022	8,328
2023	7,645
2024	5,710
Thereafter	31,303
Total lease payments	72,707
Less imputed interest	12,882
Total	59,825
Finance leases
2020	281
2021	128
2022	67
2023	38
2024	25
Thereafter	0
Total lease payments	539
Less imputed interest	44
Total	495
Southwest Gas Corporation
Operating leases
2020	800
2021	556
2022	295
2023	124
2024	78
Thereafter	307
Total lease payments	2,160
Less imputed interest	162
Total	$ 1,998

Leases - Schedule of Rental and

Leases - Schedule of Rental and Lease Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Lessee, Lease, Description [Line Items]
Rental payments/lease expense	$ 64,047	$ 67,236
Southwest Gas Corporation
Lessee, Lease, Description [Line Items]
Rental payments/lease expense	4,556	4,926
Centuri
Lessee, Lease, Description [Line Items]
Rental payments/lease expense	$ 59,491	$ 62,310

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Rental Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Lessee, Lease, Description [Line Items]
2019	$ 10,951
2020	8,019
2021	6,059
2022	5,326
2023	3,760
Thereafter	10,688
Total minimum lease payments	44,803
Southwest Gas Corporation
Lessee, Lease, Description [Line Items]
2019	898
2020	363
2021	299
2022	163
2023	79
Thereafter	177
Total minimum lease payments	1,979
Centuri
Lessee, Lease, Description [Line Items]
2019	10,053
2020	7,656
2021	5,760
2022	5,163
2023	3,681
Thereafter	10,511
Total minimum lease payments	$ 42,824

Derivatives - Additional Inform

Derivatives - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2019USD ($)Contract	Mar. 31, 2018USD ($)	Mar. 31, 2019USD ($)Contract	Mar. 31, 2018USD ($)
Derivative [Line Items]
Gains (losses) recognized in income or other comprehensive income for derivative designated cash flow hedges	$ 635,000	$ 635,000	$ 2,541,000	$ 2,190,000
Cash Flow Hedging
Derivative [Line Items]
Gains (losses) recognized in income or other comprehensive income for derivative designated cash flow hedges	$ 0
Arizona
Derivative [Line Items]
Natural gas portfolios, maximum % rate	25.00%
California
Derivative [Line Items]
Natural gas portfolios, maximum % rate	25.00%
Southwest Gas Corporation
Derivative [Line Items]
Gains (losses) recognized in income or other comprehensive income for derivative designated cash flow hedges	$ 635,000	$ 635,000	$ 2,541,000	$ 2,190,000
Derivative instrument loss at settlement amortization period	10 years
Southwest Gas Corporation | Forward-starting interest rate swaps | Cash Flow Hedging
Derivative [Line Items]
Number of derivative instruments held | Contract	2		2

Derivatives - Notional Amounts

Derivatives - Notional Amounts under Swaps Contracts (Detail) - MMBTU MMBTU in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Contract notional amounts	14,757	13,387

Derivatives - Amount of Gain or

Derivatives - Amount of Gain or Losses Recognized in Income on Derivatives (Detail) - Cash Flow Hedging - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) recognized in income on derivative	$ 0	$ 0	$ 0	$ 0
Net cost of gas sold
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) recognized in income on derivative	(3,533)	(5,196)	(450)	(11,631)
Regulatory Deferral Accounting Treatment | Net cost of gas sold
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain or (loss) recognized in income on derivative	$ 3,533	$ 5,196	$ 450	$ 11,631

Derivatives - Swaps in Balance

Derivatives - Swaps in Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Asset derivatives not designated as hedging instruments	$ 865	$ 1,979
Liability derivatives not designated as hedging instruments	(5,281)	(3,697)
Net total not designated as hedging instruments	(4,416)	(1,718)
Swaps | Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Asset derivatives not designated as hedging instruments		243
Liability derivatives not designated as hedging instruments		(99)
Net total not designated as hedging instruments		144
Swaps | Other current liabilities
Derivatives, Fair Value [Line Items]
Asset derivatives not designated as hedging instruments	805	1,595
Liability derivatives not designated as hedging instruments	(4,472)	(3,347)
Net total not designated as hedging instruments	(3,667)	(1,752)
Swaps | Other deferred credits
Derivatives, Fair Value [Line Items]
Asset derivatives not designated as hedging instruments	60	141
Liability derivatives not designated as hedging instruments	(809)	(251)
Net total not designated as hedging instruments	$ (749)	$ (110)

Derivatives - Paid to and Recei

Derivatives - Paid to and Received from Counterparties for Settlements of Matured Swaps (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Paid to counterparties	$ 1,882	$ 5,948
Received from counterparties	$ 1,047	$ 1,653

Derivatives - Regulatory Assets

Derivatives - Regulatory Assets/Liabilities Offsetting Derivatives (Detail) - Swaps - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Regulatory assets/(liabilities) offsetting the derivatives at fair value	$ 3,667	$ 1,752
Deferred charges and other assets
Derivatives, Fair Value [Line Items]
Regulatory assets/(liabilities) offsetting the derivatives at fair value	$ 749	110
Other current liabilities
Derivatives, Fair Value [Line Items]
Regulatory assets/(liabilities) offsetting the derivatives at fair value		$ (144)

Derivatives - Summary of Financ

Derivatives - Summary of Financial Assets and Liabilities (Detail) - Level 2 - Significant Other Observable Inputs - Swaps - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Net Assets (Liabilities)	$ (4,416)	$ (1,718)
Deferred charges and other assets
Derivatives, Fair Value [Line Items]
Derivative assets	0	144
Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	(3,667)	(1,752)
Other deferred credits
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ (749)	$ (110)

Common Stock (Detail)

Common Stock (Detail) - USD ($)	Mar. 29, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	May 02, 2019
Class of Stock [Line Items]
Maximum aggregate market value of potential common stock issuance	$ 150,000,000
Net proceeds to company		$ 25,879,000	$ 11,220,000	$ 369,061,000	$ 52,375,000
Common stock issued, amount		$ 27,389,000	10,395,000
Common stock available for issuance (in shares)		60,000,000		60,000,000
Equity Shelf Program
Class of Stock [Line Items]
Gross proceeds		$ 23,073,149	9,199,661	$ 99,023,464	50,976,456
Agent commissions		(230,731)	(91,997)	(990,234)	(509,765)
Net proceeds to company		$ 22,842,418	$ 9,107,664	$ 98,033,230	$ 50,466,691
Number of shares sold (in shares)		277,829	137,300	1,286,234	643,007
Weighted average price per share		$ 83.05	$ 67	$ 76.99	$ 79.28
Restricted Stock/Unit Plan, and Management Incentive Plan
Class of Stock [Line Items]
Common stock issued through Restricted Stock/Unit Plan, and Management Incentive Plan (in shares)		53,000
Dividend Reinvestment and Stock Purchase Plan
Class of Stock [Line Items]
Common stock issued through Restricted Stock/Unit Plan, and Management Incentive Plan (in shares)		34,000
Common stock issued, amount		$ 2,800,000
Subsequent Event
Class of Stock [Line Items]
Common stock available for issuance (in shares)						120,000,000

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Less: current maturities	$ (34,915)	$ (33,060)
Long-term debt, less current maturities	2,106,274	2,107,258
Long-term Debt, Current and Noncurrent Abstract
Less: current maturities	(34,915)	(33,060)
Long-term debt, less current maturities	2,106,274	2,107,258
Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, less current maturities	1,818,959	1,818,669
Long-term Debt, Current and Noncurrent Abstract
Long-term debt, less current maturities	$ 1,818,959	$ 1,818,669
Debentures | Notes, 4.45%, due 2020 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	4.45%	4.45%
Debentures | Notes, 6.1%, due 2041 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	6.10%	6.10%
Debentures | Notes, 3.875%, due 2022 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	3.875%	3.875%
Debentures | Notes, 4.875%, due 2043 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	4.875%	4.875%
Debentures | Notes, 3.8%, due 2046 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	3.80%	3.80%
Debentures | Notes, 3.7%, due 2028 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	3.70%	3.70%
Debentures | 8% Series, due 2026 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	8.00%	8.00%
Debentures | Medium-term notes, 7.78% series, due 2022 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	7.78%	7.78%
Debentures | Medium-term notes, 7.92% series, due 2027 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	7.92%	7.92%
Debentures | Medium-term notes, 6.76% series, due 2027 | Southwest Gas Corporation
Long-term Debt, Current and Noncurrent Abstract
Debt instrument interest rate	6.76%	6.76%
Carrying Amount
Debt Instrument [Line Items]
Long-term debt, less current maturities	$ 2,106,274	$ 2,107,258
Long-term Debt, Current and Noncurrent Abstract
Long-term debt, less current maturities	2,106,274	2,107,258
Carrying Amount | Southwest Gas Corporation
Debt Instrument [Line Items]
Less: current maturities	0	0
Long-term debt, less current maturities	1,818,959	1,818,669
Long-term Debt, Current and Noncurrent Abstract
Long-term debt	1,818,959	1,818,669
Less: current maturities	0	0
Long-term debt, less current maturities	1,818,959	1,818,669
Carrying Amount | Centuri
Debt Instrument [Line Items]
Less: current maturities	(34,915)	(33,060)
Long-term debt, less current maturities	287,315	288,589
Unamortized debt issuance costs	(1,343)	(1,414)
Long-term Debt, Current and Noncurrent Abstract
Long-term debt	322,230	321,649
Less: current maturities	(34,915)	(33,060)
Long-term debt, less current maturities	287,315	288,589
Centuri secured revolving credit facility	253,191	254,545
Carrying Amount | Centuri secured revolving credit facility | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri secured revolving credit facility	6,361	0
Carrying Amount | Centuri term loan facility | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri secured revolving credit facility	254,534	255,959
Carrying Amount | Centuri other debt obligations | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri other debt obligations	62,678	67,104
Carrying Amount | Debentures | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	1,470,859	1,470,693
Unamortized discount and debt issuance costs	(11,641)	(11,807)
Carrying Amount | Debentures | Notes, 4.45%, due 2020 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	125,000	125,000
Carrying Amount | Debentures | Notes, 6.1%, due 2041 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	125,000	125,000
Carrying Amount | Debentures | Notes, 3.875%, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	250,000	250,000
Carrying Amount | Debentures | Notes, 4.875%, due 2043 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	250,000	250,000
Carrying Amount | Debentures | Notes, 3.8%, due 2046 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	300,000	300,000
Carrying Amount | Debentures | Notes, 3.7%, due 2028 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	300,000	300,000
Carrying Amount | Debentures | 8% Series, due 2026 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	75,000	75,000
Carrying Amount | Debentures | Medium-term notes, 7.78% series, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	25,000	25,000
Carrying Amount | Debentures | Medium-term notes, 7.92% series, due 2027 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	25,000	25,000
Carrying Amount | Debentures | Medium-term notes, 6.76% series, due 2027 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	7,500	7,500
Carrying Amount | Debentures | Revolving credit facility and commercial paper | Southwest Gas Corporation
Debt Instrument [Line Items]
Line of credit facility	150,000	150,000
Carrying Amount | Industrial development revenue bonds | Southwest Gas Corporation
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(1,900)	(2,024)
Unsecured debt	198,100	197,976
Carrying Amount | Industrial development revenue bonds | Tax-exempt Series A, due 2028 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Carrying Amount | Industrial development revenue bonds | 2003 Series A, due 2038 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Carrying Amount | Industrial development revenue bonds | 2008 Series A, due 2038 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Carrying Amount | Industrial development revenue bonds | 2009 Series A, due 2039 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Market Value | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri secured revolving credit facility	257,579	260,135
Centuri other debt obligations	63,365	67,053
Market Value | Centuri secured revolving credit facility | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri secured revolving credit facility	6,363	0
Market Value | Debentures | Notes, 4.45%, due 2020 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	126,990	126,213
Market Value | Debentures | Notes, 6.1%, due 2041 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	154,294	150,728
Market Value | Debentures | Notes, 3.875%, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	255,015	254,195
Market Value | Debentures | Notes, 4.875%, due 2043 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	277,683	268,985
Market Value | Debentures | Notes, 3.8%, due 2046 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	283,635	267,030
Market Value | Debentures | Notes, 3.7%, due 2028 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	306,465	298,926
Market Value | Debentures | 8% Series, due 2026 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	95,128	93,827
Market Value | Debentures | Medium-term notes, 7.78% series, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	27,715	27,497
Market Value | Debentures | Medium-term notes, 7.92% series, due 2027 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	30,824	30,016
Market Value | Debentures | Medium-term notes, 6.76% series, due 2027 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	8,845	8,651
Market Value | Debentures | Revolving credit facility and commercial paper | Southwest Gas Corporation
Debt Instrument [Line Items]
Line of credit facility, fair value	150,000	150,000
Market Value | Industrial development revenue bonds | Tax-exempt Series A, due 2028 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Market Value | Industrial development revenue bonds | 2003 Series A, due 2038 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Market Value | Industrial development revenue bonds | 2008 Series A, due 2038 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt, fair value	50,000	50,000
Market Value | Industrial development revenue bonds | 2009 Series A, due 2039 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt, fair value	$ 50,000	$ 50,000

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Nov. 30, 2018	Oct. 31, 2018
Debt Instrument [Line Items]
Short term borrowings outstanding	$ 188,000,000	$ 152,000,000
Southwest Gas Corporation
Debt Instrument [Line Items]
Short term borrowings outstanding	188,000,000	$ 152,000,000
Southwest Gas Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	100,000,000
Southwest Gas Credit Facility | Southwest Gas Corporation
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	400,000,000
Line of credit designated as long term debt	150,000,000
Line of credit designated for working capital purposes	250,000,000
Long-term debt	150,000,000
Short term borrowings outstanding	$ 188,000,000
Southwest Gas Credit Facility | LIBOR | Southwest Gas Corporation
Debt Instrument [Line Items]
Applicable margin	1.00%
Southwest Gas Credit Facility | Alternative Base Rate | Southwest Gas Corporation
Debt Instrument [Line Items]
Applicable margin	0.00%
Commercial Paper Program | Southwest Gas Corporation
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 50,000,000
Borrowings outstanding under facility	50,000,000
Secured Revolving Credit Facility and Term Loan | Centuri
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity			$ 590,000,000	$ 450,000,000
Borrowings outstanding under facility	261,000,000
Debt secured by assets	$ 1,100,000,000
Line of Credit | Centuri
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity			325,000,000
Centuri term loan facility | Centuri
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity			$ 265,000,000

Short-Term Debt (Detail)

Short-Term Debt (Detail) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Short term borrowings outstanding	$ 188,000,000	$ 152,000,000
Southwest Gas Credit Facility
Short-term Debt [Line Items]
Credit facility maximum borrowing capacity	100,000,000
Southwest Gas Credit Facility | Credit Facility
Short-term Debt [Line Items]
Short term borrowings outstanding	0
Southwest Gas Corporation
Short-term Debt [Line Items]
Short term borrowings outstanding	188,000,000	$ 152,000,000
Southwest Gas Corporation | Southwest Gas Credit Facility
Short-term Debt [Line Items]
Credit facility maximum borrowing capacity	400,000,000
Short term borrowings outstanding	188,000,000
Line of credit designated for working capital purposes	$ 250,000,000

Equity, Other Comprehensive I_3

Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Detailed Activities of Equity (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	53,026,848
Beginning balance	$ 2,251,590	$ 1,812,403	$ 1,876,376
Common stock issuances	27,389	10,395
Net income (loss)	94,809	78,294
Foreign currency exchange translation adjustment	791	(911)
Other comprehensive income (loss):
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax	619	895
FSIRS amounts reclassified to net income, net of tax	$ 635	635	$ 2,541	$ 2,190
Reclassification of excess deferred taxes		0
Ending balance (in shares)	53,391,731		53,391,731
Ending balance	$ 2,346,548	$ 1,876,376	$ 2,346,548	1,876,376
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	81,831
Net income (loss)	575
Ending balance	$ 82,406		82,406
Dividends declared per share (in USD per share)	$ 0.545	$ 0.52
Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 1,782,460	$ 1,609,999	1,679,144
Net income (loss)	103,389	90,349
Other comprehensive income (loss):
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax	619	895
FSIRS amounts reclassified to net income, net of tax	635	635	2,541	2,190
Reclassification of excess deferred taxes		0
Stock-based compensation	758	(734)
Dividends declared	(22,800)	(22,000)
Contributions from Southwest Gas Holdings, Inc.	22,842
Ending balance	$ 1,887,903	$ 1,679,144	$ 1,887,903	$ 1,679,144
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	53,026,000	48,090,000	48,337,000
Beginning balance	$ 54,656	$ 49,720	$ 49,967
Common stock issuances (in shares)	365,000	247,000
Common stock issuances	$ 365	$ 247
Other comprehensive income (loss):
Ending balance (in shares)	53,391,000	48,337,000	53,391,000	48,337,000
Ending balance	$ 55,021	$ 49,967	$ 55,021	$ 49,967
Common Stock | Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	47,482,000	47,482,000	47,482,000
Beginning balance	$ 49,112	$ 49,112	$ 49,112
Other comprehensive income (loss):
Ending balance (in shares)	47,482,000	47,482,000	47,482,000	47,482,000
Ending balance	$ 49,112	$ 49,112	$ 49,112	$ 49,112
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,305,769	955,332	965,480
Common stock issuances	27,024	10,148
Other comprehensive income (loss):
Ending balance	1,332,793	965,480	1,332,793	965,480
Additional Paid-in Capital | Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,065,242	948,767	948,199
Other comprehensive income (loss):
Stock-based compensation	918	(568)
Contributions from Southwest Gas Holdings, Inc.	22,842
Ending balance	1,089,002	948,199	1,089,002	948,199
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(52,668)	(47,682)	(56,363)
Foreign currency exchange translation adjustment	791	(911)
Other comprehensive income (loss):
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax	619	895
FSIRS amounts reclassified to net income, net of tax	635	635
Reclassification of excess deferred taxes		(9,300)
Ending balance	(50,623)	(56,363)	(50,623)	(56,363)
Accumulated Other Comprehensive Income (Loss) | Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(49,049)	(47,073)	(54,843)
Other comprehensive income (loss):
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax	619	895
FSIRS amounts reclassified to net income, net of tax	635	635
Reclassification of excess deferred taxes		(9,300)
Ending balance	(47,795)	(54,843)	(47,795)	(54,843)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	944,285	857,398	920,454
Net income (loss)	94,809	79,091
Other comprehensive income (loss):
Reclassification of excess deferred taxes		9,300
Dividends declared	(29,285)	(25,335)
Ending balance	1,009,809	920,454	1,009,809	920,454
Retained Earnings | Southwest Gas Corporation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	717,155	659,193	736,676
Net income (loss)	103,389	90,349
Other comprehensive income (loss):
Reclassification of excess deferred taxes		9,300
Stock-based compensation	(160)	(166)
Dividends declared	(22,800)	(22,000)
Ending balance	797,584	736,676	797,584	736,676
Non-controlling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(452)	(2,365)	(3,162)
Net income (loss)		(797)
Other comprehensive income (loss):
Ending balance	$ (452)	$ (3,162)	$ (452)	$ (3,162)

Equity, Other Comprehensive I_4

Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Related Tax Effects Allocated to OCI (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, net of tax	$ 791
Other comprehensive income (loss), before tax	2,441	$ 1,104	$ 7,965		$ 296
Other comprehensive income (loss), tax	(396)	(485)	(2,225)		(673)
Total other comprehensive income (loss), net of tax	$ 2,045	619	5,740		(377)
Effective income tax rate	24.00%			38.00%
Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	$ 1,650	2,015	9,273		(344)
Other comprehensive income (loss), tax	(396)	(485)	(2,225)		(673)
Total other comprehensive income (loss), net of tax	1,254	1,530	7,048		(1,017)
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	814	1,178	5,929		(3,689)
Other comprehensive income (loss), tax	(195)	(283)	(1,422)		482
Total other comprehensive income (loss), net of tax	619	895	4,507		(3,207)
Defined Benefit Plans | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	814
Other comprehensive income (loss), tax	(195)
Total other comprehensive income (loss), net of tax	619
Amortization of prior service cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	317	334	1,318		1,335
Reclassification from AOCI, tax	(76)	(80)	(316)		(460)
Reclassification from AOCI, net of tax	241	254	1,002		875
Other comprehensive income (loss), before tax	317
Other comprehensive income (loss), tax	(76)
Total other comprehensive income (loss), net of tax	241
Amortization of prior service cost | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	317
Other comprehensive income (loss), tax	(76)
Total other comprehensive income (loss), net of tax	241
Net actuarial gain/(loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax			(20,426)		(43,027)
Other comprehensive income (loss) before reclassifications, tax			4,902		10,326
Other comprehensive income (loss) before reclassifications, net of tax			(15,524)		(32,701)
Reclassification from AOCI, before Tax	5,844	8,404	31,057		27,488
Reclassification from AOCI, tax	(1,403)	(2,017)	(7,454)		(9,269)
Reclassification from AOCI, net of tax	4,441	6,387	23,603		18,219
Other comprehensive income (loss), before tax	5,844
Other comprehensive income (loss), tax	(1,403)
Total other comprehensive income (loss), net of tax	4,441
Net actuarial gain/(loss) | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	5,844
Other comprehensive income (loss), tax	(1,403)
Total other comprehensive income (loss), net of tax	4,441
Regulatory adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	(5,347)	(7,560)	(6,020)		10,515
Reclassification from AOCI, tax	1,284	1,814	1,446		(115)
Reclassification from AOCI, net of tax	(4,063)	(5,746)	(4,574)		10,400
Other comprehensive income (loss), before tax	(5,347)
Other comprehensive income (loss), tax	1,284
Total other comprehensive income (loss), net of tax	(4,063)
Regulatory adjustment | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	(5,347)
Other comprehensive income (loss), tax	1,284
Total other comprehensive income (loss), net of tax	(4,063)
FSIRS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	836	837	3,344		3,345
Reclassification from AOCI, tax	(201)	(202)	(803)		(1,155)
Reclassification from AOCI, net of tax	635	635	2,541		2,190
Other comprehensive income (loss), before tax	836	837	3,344		3,345
Other comprehensive income (loss), tax	(201)	(202)	(803)		(1,155)
Total other comprehensive income (loss), net of tax	635	635	2,541		2,190
FSIRS | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	836
Reclassification from AOCI, tax	(201)
Reclassification from AOCI, net of tax	635
Other comprehensive income (loss), before tax	836
Other comprehensive income (loss), tax	(201)
Total other comprehensive income (loss), net of tax	635
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax	791	(911)	(1,308)		640
Other comprehensive income (loss) before reclassifications, tax	0	0	0		0
Other comprehensive income (loss) before reclassifications, net of tax	791	$ (911)	$ (1,308)		$ 640
Other comprehensive income (loss), before tax	791
Total other comprehensive income (loss), net of tax	$ 791

Equity, Other Comprehensive I_5

Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Additional Information (Detail) $ in Millions	Mar. 31, 2019USD ($)
Equity [Abstract]
Amount of FSIRS existing AOCI losses expected to reclassified income in next twelve months	$ 2.5

Equity, Other Comprehensive I_6

Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - AOCI Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 2,251,590	$ 1,812,403	$ 1,876,376	$ 1,812,403
Beginning balance, attributable to parent	2,252,042
Other comprehensive income (loss) before reclassifications, net of tax	791
Other comprehensive income (loss), before tax	2,441	1,104	7,965		$ 296
Other comprehensive income (loss), tax	(396)	(485)	(2,225)		(673)
Total other comprehensive income (loss), net of tax	2,045	619	5,740		(377)
Ending balance, attributable to parent	2,347,000		2,347,000	2,252,042
Ending balance	$ 2,346,548	1,876,376	2,346,548	$ 2,251,590	1,876,376
Effective income tax rate	24.00%			38.00%
Defined Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	$ (55,227)
Beginning balance, tax	13,254
Beginning balance	(41,973)
Other comprehensive income (loss), before tax	814	1,178	5,929		(3,689)
Other comprehensive income (loss), tax	(195)	(283)	(1,422)		482
Total other comprehensive income (loss), net of tax	619	895	4,507		(3,207)
Ending balance, before tax	(54,413)		(54,413)	$ (55,227)
Ending balance, tax	13,059		13,059	13,254
Ending balance	(41,354)		(41,354)	(41,973)
Amortization of prior service cost
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, before Tax	317	334	1,318		1,335
Reclassification from AOCI, tax	(76)	(80)	(316)		(460)
Reclassification from AOCI, net of tax	241	254	1,002		875
Other comprehensive income (loss), before tax	317
Other comprehensive income (loss), tax	(76)
Total other comprehensive income (loss), net of tax	241
Amortization of net actuarial loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications, before tax			(20,426)		(43,027)
Other comprehensive income (loss) before reclassifications, net of tax			(15,524)		(32,701)
Reclassification from AOCI, before Tax	5,844	8,404	31,057		27,488
Reclassification from AOCI, tax	(1,403)	(2,017)	(7,454)		(9,269)
Reclassification from AOCI, net of tax	4,441	6,387	23,603		18,219
Other comprehensive income (loss), before tax	5,844
Other comprehensive income (loss), tax	(1,403)
Total other comprehensive income (loss), net of tax	4,441
Regulatory adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, before Tax	(5,347)	(7,560)	(6,020)		10,515
Reclassification from AOCI, tax	1,284	1,814	1,446		(115)
Reclassification from AOCI, net of tax	(4,063)	(5,746)	(4,574)		10,400
Other comprehensive income (loss), before tax	(5,347)
Other comprehensive income (loss), tax	1,284
Total other comprehensive income (loss), net of tax	(4,063)
FSIRS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	(9,310)
Beginning balance, tax	2,234
Beginning balance	(7,076)
Reclassification from AOCI, before Tax	836	837	3,344		3,345
Reclassification from AOCI, tax	(201)	(202)	(803)		(1,155)
Reclassification from AOCI, net of tax	635	635	2,541		2,190
Other comprehensive income (loss), before tax	836	837	3,344		3,345
Other comprehensive income (loss), tax	(201)	(202)	(803)		(1,155)
Total other comprehensive income (loss), net of tax	635	635	2,541		2,190
Ending balance, before tax	(8,474)		(8,474)	(9,310)
Ending balance, tax	2,033		2,033	2,234
Ending balance	(6,441)		(6,441)	(7,076)
Foreign Currency Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	(3,619)
Beginning balance	(3,619)
Other comprehensive income (loss) before reclassifications, before tax	791	(911)	(1,308)		640
Other comprehensive income (loss) before reclassifications, net of tax	791	(911)	(1,308)		640
Other comprehensive income (loss), before tax	791
Total other comprehensive income (loss), net of tax	791
Ending balance, before tax	(2,828)		(2,828)	(3,619)
Ending balance	(2,828)		(2,828)	(3,619)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(52,668)	(47,682)	(56,363)	(47,682)
Ending balance	(50,623)	(56,363)	(50,623)	(52,668)	(56,363)
Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	1,782,460	1,609,999	1,679,144	1,609,999
Beginning balance, attributable to parent	1,782,460
Other comprehensive income (loss), before tax	1,650	2,015	9,273		(344)
Other comprehensive income (loss), tax	(396)	(485)	(2,225)		(673)
Total other comprehensive income (loss), net of tax	1,254	1,530	7,048		(1,017)
Ending balance, attributable to parent	1,887,903		1,887,903	1,782,460
Ending balance	1,887,903	1,679,144	1,887,903	1,782,460	1,679,144
Southwest Gas Corporation | Defined Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent, before tax	(55,227)
Beginning balance, attributable to parent, tax	13,254
Beginning balance, attributable to parent	(41,973)
Other comprehensive income (loss), before tax	814
Other comprehensive income (loss), tax	(195)
Total other comprehensive income (loss), net of tax	619
Ending balance, attributable to parent, before tax	(54,413)		(54,413)	(55,227)
Ending balance, attributable to parent, tax	13,059		13,059	13,254
Ending balance, attributable to parent	(41,354)		(41,354)	(41,973)
Southwest Gas Corporation | Amortization of prior service cost
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	317
Other comprehensive income (loss), tax	(76)
Total other comprehensive income (loss), net of tax	241
Southwest Gas Corporation | Amortization of net actuarial loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	5,844
Other comprehensive income (loss), tax	(1,403)
Total other comprehensive income (loss), net of tax	4,441
Southwest Gas Corporation | Regulatory adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	(5,347)
Other comprehensive income (loss), tax	1,284
Total other comprehensive income (loss), net of tax	(4,063)
Southwest Gas Corporation | FSIRS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent, before tax	(9,310)
Beginning balance, attributable to parent, tax	2,234
Beginning balance, attributable to parent	(7,076)
Reclassification from AOCI, before Tax	836
Reclassification from AOCI, tax	(201)
Reclassification from AOCI, net of tax	635
Other comprehensive income (loss), before tax	836
Other comprehensive income (loss), tax	(201)
Total other comprehensive income (loss), net of tax	635
Ending balance, attributable to parent, before tax	(8,474)		(8,474)	(9,310)
Ending balance, attributable to parent, tax	2,033		2,033	2,234
Ending balance, attributable to parent	(6,441)		(6,441)	(7,076)
Southwest Gas Corporation | AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(49,049)	(47,073)	(54,843)	(47,073)
Beginning balance, attributable to parent	(49,049)
Ending balance, attributable to parent	(47,795)		(47,795)	(49,049)
Ending balance	$ (47,795)	$ (54,843)	$ (47,795)	$ (49,049)	$ (54,843)

Equity, Other Comprehensive I_7

Equity, Other Comprehensive Income, and Accumulated Other Comprehensive Income - Amounts Recognized Before Tax, Defined Benefit Plans (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Net actuarial (loss) gain	$ (429,520)	$ (435,364)
Prior service cost	(2,716)	(3,033)
Less: amount recognized in regulatory assets	377,823	383,170
Recognized in AOCI	$ (54,413)	$ (55,227)

Segment Information - Additiona

Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2019Segment
Segment Reporting [Abstract]
Number of segments	2

Segment Information - Schedule

Segment Information - Schedule of Reporting Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 833,539	$ 754,330	$ 2,959,222	$ 2,648,385
Segment net income (loss)	94,809	79,091	197,995	203,624
Operating Segments
Segment Reporting Information [Line Items]
Revenues	794,866	727,172	2,811,793	2,545,364
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	38,673	27,158	147,429	103,021
Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Segment net income (loss)	(549)	(257)	(1,834)	(1,298)
Natural Gas Operations
Segment Reporting Information [Line Items]
Revenues	520,677	494,313	1,384,092	1,334,019
Segment net income (loss)	103,389	90,349	151,882	170,229
Natural Gas Operations | Operating Segments
Segment Reporting Information [Line Items]
Revenues	520,677	494,313	1,384,092	1,334,019
Natural Gas Operations | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Utility Infrastructure Services
Segment Reporting Information [Line Items]
Revenues	312,862	260,017	1,575,130	1,314,366
Segment net income (loss)	(8,031)	(11,001)	47,947	34,693
Utility Infrastructure Services | Operating Segments
Segment Reporting Information [Line Items]
Revenues	274,189	232,859	1,427,701	1,211,345
Utility Infrastructure Services | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	$ 38,673	$ 27,158	$ 147,429	$ 103,021

Redeemable Noncontrolling Int_3

Redeemable Noncontrolling Interests - Additional Information (Detail)	Mar. 31, 2019	Nov. 30, 2018
Noncontrolling Interest [Line Items]
Percentage of interest retained by noncontrolling party subject to election	100.00%
Linetec
Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners		20.00%

Redeemable Noncontrolling Int_4

Redeemable Noncontrolling Interests - Summary of Redeemable Noncontrolling Interest (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Movement In Redeemable Noncontrolling Interest [Roll Forward]
Balance, December 31, 2018	$ 81,831
Net income attributable to redeemable noncontrolling interest	(575)
Balance, March 31, 2019	$ 82,406

Business Acquisitions - Narrati

Business Acquisitions - Narrative (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2019	Nov. 30, 2018
Linetec
Business Acquisition [Line Items]
Acquisition costs	$ 0	$ 6,900,000
Centuri | Linetec
Business Acquisition [Line Items]
Percentage of voting interests acquired			80.00%
Linetec
Business Acquisition [Line Items]
Ownership percentage by noncontrolling owners			20.00%

Business Acquisitions - Summary

Business Acquisitions - Summary of Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	4 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Nov. 30, 2018
Fair Values of Assets Acquired and Liabilities Assumed
Goodwill	$ 364,482	$ 359,045
Linetec
Fair Values of Assets Acquired and Liabilities Assumed
Cash and cash equivalents	3,900		$ 3,900
Accounts receivable	32,300		32,800
Revenue earned on contracts in progress in excess of billings	23,300		21,600
Prepaid expenses and other current assets	1,300		1,100
Property and equipment	88,900		89,400
Intangible assets	89,300		89,300
Goodwill	191,800		188,500
Total assets acquired	430,800		426,600
Accounts payable	8,000		8,000
Accrued liabilities	8,500		6,900
Deferred compensation and related accrued taxes	3,400		3,400
Redeemable noncontrolling interest	81,700		81,700
Total liabilities assumed and noncontrolling interest	101,600		100,000
Net assets acquired	329,200		$ 326,600
Measurement Period Adjustments
Accounts receivable, measurement period adjustments	(500)
Revenue earned on contracts in progress in excess of billings, measurement period adjustments	1,700
Prepaid expenses and other current assets, measurement period adjustments	200
Property and equipment, measurement period adjustments	(500)
Intangible assets, measurement period adjustments	0
Goodwill, measurement period adjustments	3,300
Total assets acquired, measurement period adjustments	4,200
Accrued liabilities, measurement period adjustments	1,600
Total liabilities assumed and noncontrolling interest, measurement period adjustments	1,600
Net assets acquired, measurement period adjustments	$ 2,600