Document and Entity Information
Document and Entity Information - USD ($) | 12 Months Ended | ||
Dec. 31, 2015 | Feb. 16, 2016 | Jun. 30, 2015 | |
Document And Entity Information [Abstract] | |||
Document Type | 10-K | ||
Amendment Flag | false | ||
Document Period End Date | Dec. 31, 2015 | ||
Document Fiscal Year Focus | 2,015 | ||
Document Fiscal Period Focus | FY | ||
Trading Symbol | SWX | ||
Entity Registrant Name | SOUTHWEST GAS CORP | ||
Entity Central Index Key | 92,416 | ||
Current Fiscal Year End Date | --12-31 | ||
Entity Well-known Seasoned Issuer | Yes | ||
Entity Current Reporting Status | Yes | ||
Entity Voluntary Filers | No | ||
Entity Filer Category | Large Accelerated Filer | ||
Entity Common Stock, Shares Outstanding | 47,456,479 | ||
Entity Public Float | $ 2,503,122,220 |
Consolidated Balance Sheets
Consolidated Balance Sheets - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Utility plant: | ||
Gas plant | $ 5,854,917 | $ 5,556,599 |
Less: accumulated depreciation | (2,084,007) | (1,973,098) |
Acquisition adjustments, net | 370 | 550 |
Construction work in progress | 119,805 | 74,332 |
Net utility plant (Note 2) | 3,891,085 | 3,658,383 |
Other property and investments (Note 1) | 313,531 | 326,743 |
Restricted cash | 821 | |
Current assets: | ||
Cash and cash equivalents | 35,997 | 39,566 |
Accounts receivable, net of allowances (Note 3) | 314,512 | 281,824 |
Accrued utility revenue | 74,700 | 73,900 |
Income taxes receivable, net | 34,175 | 21,853 |
Deferred income taxes, net (Note 12) | 2,109 | |
Deferred purchased gas costs (Note 4) | 3,591 | 87,556 |
Prepaids and other current assets (Notes 1, 4, and 13) | 95,199 | 99,803 |
Total current assets | 558,174 | 606,611 |
Noncurrent assets: | ||
Goodwill (Note 1) | 126,145 | 143,160 |
Deferred income taxes (Note 12) | 428 | |
Deferred charges and other assets (Notes 2, 4, and 13) | 469,322 | 472,579 |
Total noncurrent assets | 595,895 | 615,739 |
Total assets | 5,358,685 | 5,208,297 |
Capitalization: | ||
Common stock, $1 par (authorized - 60,000,000 shares; issued and outstanding - 47,377,575 and 46,523,184 shares) (Note 11) | 49,007 | 48,153 |
Additional paid-in capital | 896,448 | 851,381 |
Accumulated other comprehensive income (loss), net (Note 5) | (50,268) | (50,175) |
Retained earnings | 699,221 | 639,164 |
Total Southwest Gas Corporation equity | 1,594,408 | 1,488,523 |
Noncontrolling interest | (2,083) | (2,257) |
Total equity | 1,592,325 | 1,486,266 |
Redeemable noncontrolling interest (Note 16) | 16,108 | 20,042 |
Long-term debt, less current maturities (Note 7) | 1,551,204 | 1,631,374 |
Total capitalization | $ 3,159,637 | $ 3,137,682 |
Commitments and contingencies (Note 9) | ||
Current liabilities: | ||
Current maturities of long-term debt (Note 7) | $ 19,475 | $ 19,192 |
Short-term debt (Note 8) | 18,000 | 5,000 |
Accounts payable | 164,857 | 167,988 |
Customer deposits | 72,631 | 71,546 |
Income taxes payable, net | 940 | |
Accrued general taxes | 47,337 | 44,339 |
Accrued interest | 16,173 | 16,468 |
Deferred purchased gas costs (Note 4) | 45,601 | |
Other current liabilities (Notes 2, 4, and 13) | 150,031 | 145,584 |
Total current liabilities | 535,045 | 470,117 |
Deferred income taxes and other credits: | ||
Deferred income taxes and investment tax credits, net (Note 12) | 769,445 | 723,688 |
Accumulated removal costs (Note 4) | 303,000 | 304,000 |
Other deferred credits and other long-term liabilities (Notes 2, 4, 10, and 13) | 591,558 | 572,810 |
Total deferred income taxes and other credits | 1,664,003 | 1,600,498 |
Total capitalization and liabilities | $ 5,358,685 | $ 5,208,297 |
Consolidated Balance Sheets (Pa
Consolidated Balance Sheets (Parenthetical) - $ / shares | Dec. 31, 2015 | Dec. 31, 2014 |
Statement of Financial Position [Abstract] | ||
Common stock, par | $ 1 | $ 1 |
Common stock, authorized | 60,000,000 | 60,000,000 |
Common stock, issued | 47,377,575 | 46,523,184 |
Common stock, outstanding | 47,377,575 | 46,523,184 |
Consolidated Statements of Inco
Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Operating revenues: | |||
Gas operating revenues | $ 1,454,639 | $ 1,382,087 | $ 1,300,154 |
Construction revenues | 1,008,986 | 739,620 | 650,628 |
Total operating revenues | 2,463,625 | 2,121,707 | 1,950,782 |
Operating expenses: | |||
Net cost of gas sold | 563,809 | 505,356 | 436,001 |
Operations and maintenance | 393,199 | 383,732 | 384,914 |
Depreciation and amortization | 270,111 | 253,027 | 236,817 |
Taxes other than income taxes | 49,393 | 47,252 | 45,551 |
Construction expenses | 898,781 | 647,857 | 573,284 |
Total operating expenses | 2,175,293 | 1,837,224 | 1,676,567 |
Operating income | 288,332 | 284,483 | 274,215 |
Other income and (expenses): | |||
Net interest deductions (Notes 7 and 8) | (71,879) | (72,069) | (63,700) |
Other income (deductions) | 2,879 | 7,107 | 12,300 |
Total other income and (expenses) | (69,000) | (64,962) | (51,400) |
Income before income taxes | 219,332 | 219,521 | 222,815 |
Income tax expense (Note 12) | 79,902 | 78,373 | 77,942 |
Net income | 139,430 | 141,148 | 144,873 |
Net income (loss) attributable to noncontrolling interests | 1,113 | 22 | (447) |
Net income attributable to Southwest Gas Corporation | $ 138,317 | $ 141,126 | $ 145,320 |
Basic earnings per share (Notes 1 and 15) | $ 2.94 | $ 3.04 | $ 3.14 |
Diluted earnings per share (Notes 1 and 15) | $ 2.92 | $ 3.01 | $ 3.11 |
Average number of common shares outstanding | 46,992 | 46,494 | 46,318 |
Average shares outstanding (assuming dilution) | 47,383 | 46,944 | 46,758 |
Consolidated Statements of Comp
Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Statement of Comprehensive Income [Abstract] | |||
Net Income | $ 139,430 | $ 141,148 | $ 144,873 |
Defined benefit pension plans: | |||
Net actuarial gain (loss) | (18,922) | (107,661) | 62,214 |
Amortization of prior service cost | 828 | 220 | 220 |
Amortization of net actuarial loss | 21,316 | 14,667 | 21,190 |
Prior service cost | (4,130) | ||
Regulatory adjustment | (3,500) | 86,991 | (76,651) |
Net defined benefit pension plans | (278) | (9,913) | 6,973 |
Forward-starting interest rate swaps: | |||
Amounts reclassified into net income | 2,073 | 2,073 | 2,074 |
Net forward-starting interest rate swaps | 2,073 | 2,073 | 2,074 |
Foreign currency translation adjustments | (1,954) | (659) | |
Total other comprehensive income (loss), net of tax | (159) | (8,499) | 9,047 |
Comprehensive income | 139,271 | 132,649 | 153,920 |
Comprehensive income (loss) attributable to noncontrolling interests | 1,047 | (447) | |
Comprehensive income attributable to Southwest Gas Corporation | $ 138,224 | $ 132,649 | $ 154,367 |
Consolidated Statements of Cash
Consolidated Statements of Cash Flows - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
CASH FLOW FROM OPERATING ACTIVITIES: | |||
Net Income | $ 139,430 | $ 141,148 | $ 144,873 |
Adjustments to reconcile net income to net cash provided by operating activities: | |||
Depreciation and amortization | 270,111 | 253,027 | 236,817 |
Deferred income taxes | 48,785 | 64,309 | 68,639 |
Changes in current assets and liabilities: | |||
Accounts receivable, net of allowances | (39,850) | (3,683) | (22,556) |
Accrued utility revenue | (800) | (1,200) | (700) |
Deferred purchased gas costs | 129,566 | (69,339) | (111,143) |
Accounts payable | (3,491) | (41,499) | 27,668 |
Accrued taxes | (8,405) | (13,573) | 925 |
Other current assets and liabilities | 18,300 | 23,379 | 5,084 |
Gains on sale | (3,102) | (6,171) | (4,112) |
Changes in undistributed stock compensation | 2,914 | 7,973 | 6,958 |
AFUDC | (3,008) | (1,995) | (2,274) |
Changes in other assets and deferred charges | (14,166) | (21,732) | (21,719) |
Changes in other liabilities and deferred credits | 10,863 | 15,779 | 17,749 |
Net cash provided by operating activities | 547,147 | 346,423 | 346,209 |
CASH FLOW FROM INVESTING ACTIVITIES: | |||
Construction expenditures and property additions | (488,000) | (396,898) | (364,276) |
Acquisition of businesses, net of cash acquired | (9,261) | (190,497) | |
Restricted cash | 785 | 1,233 | |
Changes in customer advances | 18,300 | 20,363 | 7,773 |
Miscellaneous inflows | 8,354 | 11,611 | 8,465 |
Miscellaneous outflows | (1,400) | ||
Net cash used in investing activities | (469,822) | (555,588) | (348,038) |
CASH FLOW FROM FINANCING ACTIVITIES: | |||
Issuance of common stock, net | 35,396 | 405 | 1,635 |
Dividends paid | (74,248) | (66,275) | (59,535) |
Centuri distribution to redeemable noncontrolling interest | (99) | ||
Issuance of long-term debt, net | 135,816 | 269,228 | 311,290 |
Retirement of long-term debt | (187,973) | (139,155) | (137,013) |
Change in credit facility and commercial paper | 140,000 | (101,000) | |
Change in short-term debt | 13,000 | 5,000 | 1,999 |
Principal payments on capital lease obligations | (1,420) | (434) | |
Other | 41 | (1,257) | |
Net cash provided by (used in) financing activities | (79,487) | 207,512 | 17,376 |
Effects of currency translation on cash and cash equivalents | (1,407) | 142 | |
Change in cash and cash equivalents | (3,569) | (1,511) | 15,547 |
Cash and cash equivalents at beginning of period | 39,566 | 41,077 | 25,530 |
Cash and cash equivalents at end of period | 35,997 | 39,566 | 41,077 |
Supplemental information: | |||
Interest paid, net of amounts capitalized | 66,623 | 65,552 | 58,730 |
Income taxes paid | $ 43,225 | $ 24,247 | $ 6,850 |
Consolidated Statements of Equi
Consolidated Statements of Equity and Redeemable Noncontrolling Interest - USD ($) $ in Thousands | Total | Common Stock [Member] | Additional Paid-in Capital [Member] | Accumulated Other Comprehensive Income (Loss) [Member] | Retained Earnings [Member] | Non-controlling Interest [Member] | Redeemable Noncontrolling Interest (Temporary Equity) [Member] | |
Balance at Dec. 31, 2012 | $ 1,308,498 | $ 47,778 | $ 828,777 | $ (50,745) | $ 484,369 | $ (1,681) | ||
Balance, Shares at Dec. 31, 2012 | 46,148,000 | |||||||
Common stock issuances, Value | 11,952 | $ 208 | 11,744 | |||||
Common stock issuances, Shares | 208,000 | |||||||
Net income (loss) | 144,873 | 145,320 | (447) | |||||
Net actuarial gain (loss) arising during the period, less amortization of unamortized benefit plan cost, net of tax (Notes 5 and 10) | 6,973 | 6,973 | ||||||
Amounts reclassified into net income | 2,074 | 2,074 | ||||||
Dividends declared Common | (61,975) | (61,975) | ||||||
Balance at Dec. 31, 2013 | 1,412,395 | $ 47,986 | 840,521 | (41,698) | 567,714 | (2,128) | ||
Balance, Shares at Dec. 31, 2013 | 46,356,000 | |||||||
Common stock issuances, Value | 11,027 | $ 167 | 10,860 | |||||
Common stock issuances, Shares | 167,000 | |||||||
Net income (loss) | 141,148 | |||||||
Redeemable noncontrolling interest attributable to acquisition | $ 18,952 | |||||||
Net income (loss) | 140,997 | 141,126 | (129) | |||||
Net income (loss) attributable to temporary equity | 151 | |||||||
Redemption value adjustments (Note 16) | (961) | (961) | ||||||
Redemption value adjustments attributable to temporary equity | 961 | |||||||
Foreign currency exchange translation adj. | (637) | (637) | ||||||
Foreign currency exchange translation adj attributable to temporary equity | (22) | |||||||
Net actuarial gain (loss) arising during the period, less amortization of unamortized benefit plan cost, net of tax (Notes 5 and 10) | (9,913) | (9,913) | ||||||
Amounts reclassified into net income | 2,073 | 2,073 | ||||||
Dividends declared Common | (68,715) | (68,715) | ||||||
Balance at Dec. 31, 2014 | $ 1,486,266 | $ 48,153 | 851,381 | (50,175) | 639,164 | (2,257) | ||
Balance, Shares at Dec. 31, 2014 | 46,523,184 | 46,523,000 | ||||||
Balance, Attributable to temporary equity | $ 20,042 | 20,042 | ||||||
Common stock issuances, Value | 40,144 | $ 854 | 39,290 | |||||
Common stock issuances, Shares | 854,000 | |||||||
Net income (loss) | 139,430 | |||||||
Net income (loss) | 138,491 | 138,317 | 174 | |||||
Net income (loss) attributable to temporary equity | 939 | |||||||
Redemption value adjustments (Note 16) | 4,708 | 5,777 | (1,069) | |||||
Redemption value adjustments attributable to temporary equity | (4,708) | |||||||
Foreign currency exchange translation adj. | (1,888) | (1,888) | ||||||
Foreign currency exchange translation adj attributable to temporary equity | (66) | |||||||
Net actuarial gain (loss) arising during the period, less amortization of unamortized benefit plan cost, net of tax (Notes 5 and 10) | (278) | (278) | ||||||
Amounts reclassified into net income | 2,073 | 2,073 | ||||||
Centuri distribution to redeemable noncontrolling interest | (99) | |||||||
Dividends declared Common | (77,191) | (77,191) | ||||||
Balance at Dec. 31, 2015 | $ 1,592,325 | $ 49,007 | $ 896,448 | $ (50,268) | $ 699,221 | $ (2,083) | ||
Balance, Shares at Dec. 31, 2015 | 47,377,575 | 47,377,000 | [1] | |||||
Balance, Attributable to temporary equity | $ 16,108 | $ 16,108 | ||||||
[1] | At December 31, 2015, 3.6 million common shares were registered and available for issuance under provisions of the Company's various stock issuance plans. In addition, approximately 17,000 common shares are registered for issuance upon the exercise of options granted under the Stock Incentive Plan (see Note 10). |
Consolidated Statements of Equ8
Consolidated Statements of Equity and Redeemable Noncontrolling Interest (Parenthetical) - $ / shares | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Statement of Stockholders' Equity [Abstract] | |||
Dividends declared Common, per share | $ 1.62 | $ 1.46 | $ 1.32 |
Shares registered and available for issuance | 3,600,000 | ||
Common shares registered for issuance upon exercise of options | 17,000 | 36,000 | 52,000 |
Summary of Significant Accounti
Summary of Significant Accounting Policies | 12 Months Ended |
Dec. 31, 2015 | |
Accounting Policies [Abstract] | |
Summary of Significant Accounting Policies | Note 1 – Summary of Significant Accounting Policies Nature of Operations. Note 17 – Acquisition of Construction Services Businesses for more information. Basis of Presentation. Consolidation. Centuri, through its subsidiaries, holds a 65% interest in a venture to market natural gas engine-driven heating, ventilating, and air conditioning (“HVAC”) technology and products. Centuri consolidates the entity (IntelliChoice Energy, LLC). Centuri, through its subsidiaries, holds a 50% interest in W.S. Nicholls Western Construction LTD. (“Western”), a Canadian construction services company that is a variable interest entity. Centuri determined that it is not the primary beneficiary of the entity due to a shared-power structure; therefore, Centuri does not consolidate the entity and has recorded its investment, and results related thereto, using the equity method. The Company’s investment in Western totaled $14.7 million and $10.8 million at December 31, 2014 and 2015, respectively. Both periods include the impacts of foreign currency exchange translation adjustments. No dividends were paid during 2015. The equity method investment in Western is included in Other Property and Investments in the Consolidated Balance Sheets. Centuri’s maximum exposure to loss as a result of its involvement with Western is estimated at $14.7 million. The estimated maximum exposure to loss represents the maximum loss that would be absorbed by Centuri in the event that all of the assets of Western are deemed worthless. Centuri recorded earnings of $310,000 from this investment in 2015 which is included in Other Income (deductions) in the Consolidated Statements of Income. Centuri, through its subsidiaries, also has a 25% interest in CCI-TBN Toronto, Inc. and a 50% interest in Matheson-Nicholls Joint Venture. Any future changes to the values of these entities will be recorded by Centuri using the equity method. Net Utility Plant. Other Property and Investments. 2015 2014 Centuri property, equipment, and intangibles $ 423 $ 405 Centuri accumulated provision for depreciation and amortization (221 ) (187 ) Net cash surrender value of COLI policies 99 99 Other property 13 10 Total $ 314 $ 327 Deferred Purchased Gas Costs. Prepaids and other current assets Income Taxes. Cash and Cash Equivalents. Significant non-cash investing activities for the natural gas operations segment included the following: Upon contract expiration, customer advances of approximately $3.1 million, $8.1 million, and $9.3 million during 2015, 2014, and 2013, respectively, were applied as contributions toward utility construction activity and represent non-cash investing activity. In 2014, investing activities included an $18.9 million non-cash investing outflow due to the equity of the noncontrolling interest associated with businesses acquired. In addition, a non-cash investing outflow activity of $10.8 million in 2014 related to acquisition consideration payable. Goodwill. Natural Construction Consolidated (In thousands of dollars) December 31, 2014 $ 10,095 $ 133,065 $ 143,160 Acquisition date adjustment — 1,380 1,380 Foreign currency translation adjustment — (18,395 ) (18,395 ) December 31, 2015 $ 10,095 $ 116,050 $ 126,145 Intangible Assets Centuri has $36.8 million and $48.2 million of intangible assets (varies due to foreign currency translation) at December 31, 2015 and 2014, respectively, as detailed in the following table (thousands of dollars): December 31, 2015 Gross Carrying Accumulated Net Carrying Customer relationships $ 31,226 $ (2,070 ) $ 29,156 Trade names and trademarks 8,621 (1,331 ) 7,290 Customer contracts backlog 1,606 (1,606 ) — Noncompete agreement 437 (110 ) 327 Total $ 41,890 $ (5,117 ) $ 36,773 December 31, 2014 Gross Carrying Accumulated Net Carrying Customer relationships $ 37,059 $ (524 ) $ 36,535 Trade names and trademarks 10,208 (241 ) 9,967 Customer contracts backlog 1,912 (724 ) 1,188 Noncompete agreement 519 (34 ) 485 Total $ 49,698 $ (1,523 ) $ 48,175 The intangible assets (other than goodwill and software-related intangibles) are included in Other property and investments in the Consolidated Balance Sheets. The estimated future amortization of the intangible assets for the next five years is as follows (in thousands): 2016 $ 2,809 2017 2,809 2018 2,605 2019 1,971 2020 1,906 See Note 2 – Utility Plant and Leases for additional information regarding natural gas operations intangible assets. Accumulated Removal Costs. Approved regulatory practices allow Southwest to include in depreciation expense a component to recover removal costs associated with utility plant retirements. In accordance with the Securities and Exchange Commission (“SEC”) position on presentation of these amounts, management reclassifies estimated removal costs from accumulated depreciation to accumulated removal costs within the liabilities section of the Consolidated Balance Sheets. Amounts fluctuate between periods depending on the level of replacement work performed, the estimated cost of removal in rates and the actual cost of removal experienced. Gas Operating Revenues. The Company acts as an agent for state and local taxing authorities in the collection and remission of a variety of taxes, including sales and use taxes and surcharges. These taxes are not included in gas operating revenues. The Company uses the net classification method to report taxes collected from customers to be remitted to governmental authorities. Construction Revenues. Construction Expenses. Net Cost of Gas Sold. Operations and Maintenance Expense. Depreciation and Amortization. Accumulated Removal Costs Allowance for Funds Used During Construction (“AFUDC”). 2015 2014 2013 (In thousands) AFUDC: Debt portion $ 1,666 $ 1,228 $ 1,260 Equity portion 3,008 1,995 2,274 AFUDC capitalized as part of utility plant $ 4,674 $ 3,223 $ 3,534 Other Income (Deductions). 2015 2014 2013 Change in COLI policies $ (500 ) $ 5,300 $ 12,400 Interest income 2,173 2,602 461 Equity AFUDC 3,008 1,995 2,274 Foreign currency transaction gain (loss) (824 ) (178 ) — Equity in earnings of unconsolidated investment - Western 310 107 — Miscellaneous income and (expense) (1,288 ) (2,719 ) (2,835 ) Total other income (deductions) $ 2,879 $ 7,107 $ 12,300 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 value components of COLI policies, as they progress towards the ultimate death benefits, are also recorded without tax consequences. Foreign Currency Translation. Earnings Per Share. 2015 2014 2013 (In thousands) Average basic shares 46,992 46,494 46,318 Effect of dilutive securities: Stock options 8 17 26 Performance shares 171 215 231 Restricted stock units 212 218 183 Average diluted shares 47,383 46,944 46,758 Recently Issued Accounting Standards Updates. In August 2014, the FASB issued the update “Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern,” which requires management to assess a company’s ability to continue as a going concern and to provide related footnote disclosures in certain circumstances. Under the update, disclosures are required when conditions give rise to substantial doubt about a company’s ability to continue as a going concern within one year from the financial statement issuance date. The update is effective for the annual period ending after December 15, 2016, and all annual and interim periods thereafter. This update and changes thereto are not expected to have a material impact on the Company’s disclosures. In April 2015, the FASB issued the update “Interest—Imputation of Interest (Subtopic 835-30) Simplifying the Presentation of Debt Issuance Costs.” To simplify presentation of debt issuance costs, the amendments in this update require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. While balance sheet presentation is impacted by the update, the recognition and measurement of debt issuance costs are not. Retrospective application of the update is required. The amendments in this update are effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within fiscal years beginning after December 15, 2015. Early adoption of the amendments in this update is permitted for financial statements that have not been previously issued. The Company adopted this update as of December 31, 2015, as permitted. See Note 7 – Long-Term Debt for additional information. In May 2015, the FASB issued the update “Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share (or its Equivalent).” This guidance simplifies disclosure requirements relating to investments for which fair value is measured using the net asset value per share, or its equivalent. The update removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. Investments that calculate net asset value per share (or its equivalent), but for which the practical expedient is not applied, will continue to be included in the fair value hierarchy. The update removes the requirement to make certain disclosures for all investments that are eligible to be measured at fair value using the net asset value per share practical expedient. A reporting entity should continue to disclose information on investments for which fair value is measured at net asset value as a practical expedient to help users understand the nature and risks of the investments and whether the investments, if sold, are probable of being sold at amounts different from net asset value. The amendments in this update are effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods thereafter. Early application is permitted and the Company adopted this update as of December 31, 2015. See Note 10 – Pension and Other Postretirement Benefits for additional information. In November 2015, the FASB issued the update “Income Taxes (Topic 740)” in order to simplify the presentation of deferred income taxes. The update requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. The previous guidance required an entity to separate deferred income tax liabilities and assets into current and noncurrent amounts in a classified statement of financial position. This update is effective for financial statements issued for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early application is permitted and the Company adopted this update as of December 31, 2015. See Note 12 – Income Taxes for additional information. In January 2016, the FASB issued the update “Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” in order to improve the recognition and measurement of financial instruments. The update makes targeted improvements to existing U.S. GAAP by: 1) requiring equity investments to be measured at fair value with changes in fair value recognized in net income; 2) requiring the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes; 3) requiring separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements; 4) eliminating the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; and 5) requiring a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The update is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. All entities can early adopt the provision to record fair value changes for financial liabilities under the fair value option resulting from instrument-specific credit risk in other comprehensive income. The Company is evaluating what impact, if any, this update might have on its consolidated financial statements and disclosures. Subsequent Events. Management of the Company monitors events occurring after the balance sheet date and prior to the issuance of the financial statements to determine the impacts, if any, of events on the financial statements to be issued or disclosures to be made, and has reflected them where appropriate. |
Utility Plant and Leases
Utility Plant and Leases | 12 Months Ended |
Dec. 31, 2015 | |
Leases [Abstract] | |
Utility Plant and Leases | Note 2 – Utility Plant and Leases Net utility plant as of December 31, 2015 and 2014 was as follows (thousands of dollars): December 31, 2015 2014 Gas plant: Storage $ 22,944 $ 22,531 Transmission 312,996 312,300 Distribution 4,935,730 4,655,640 General 365,865 356,072 Software and software-related intangibles 203,323 196,035 Other 14,059 14,021 5,854,917 5,556,599 Less: accumulated depreciation (2,084,007 ) (1,973,098 ) Acquisition adjustments, net 370 550 Construction work in progress 119,805 74,332 Net utility plant $ 3,891,085 $ 3,658,383 Utility plant depreciation is computed on the straight-line remaining life method at composite rates considered sufficient to amortize costs over estimated service lives, including components which compensate for removal costs (net of salvage value), and retirements, based on the processes of regulatory proceedings and related regulatory commission approvals and/or mandates. In 2015, annual depreciation and amortization expense averaged 3.6% of the original cost of depreciable and amortizable property. Average rates in 2014 and 2013 also approximated 3.6% on average. Depreciation and amortization expense on gas plant, including intangibles, was as follows (thousands of dollars): 2015 2014 2013 Depreciation and amortization expense $ 201,233 $ 194,360 $ 185,283 Included in the figures above is amortization of intangibles of $12.7 million in 2015, $11.7 million in 2014, and $10.3 million in 2013. Operating Leases and Rentals. 2015 2014 2013 Southwest Gas $ 4,186 $ 5,330 $ 8,308 Centuri 45,849 30,012 27,118 Consolidated rental payments/lease expense $ 50,035 $ 35,342 $ 35,426 The following is a schedule of future minimum lease payments for significant non-cancelable operating leases (with initial or remaining terms in excess of one year) as of December 31, 2015 (thousands of dollars): Year Ending December 31, 2016 $ 6,836 2017 4,732 2018 2,993 2019 2,110 2020 1,473 Thereafter 3,583 Total minimum lease payments $ 21,727 Capital Leases. December 31, 2015 2014 Capital leases of equipment $ 4,584 $ 5,763 Less: accumulated amortization (1,043 ) (287 ) Net capital leases $ 3,541 $ 5,476 The following is a schedule of future minimum lease payments for non-cancelable capital leases (with initial or remaining terms in excess of one year) as of December 31, 2015 (thousands of dollars): Year Ending December 31, 2016 $ 1,469 2017 869 2018 494 2019 21 2020 — Thereafter — 2,853 Less: amount representing interest (223 ) Total minimum lease payments $ 2,630 |
Receivables and Related Allowan
Receivables and Related Allowances | 12 Months Ended |
Dec. 31, 2015 | |
Receivables [Abstract] | |
Receivables and Related Allowances | Note 3 – Receivables and Related Allowances Business activity with respect to gas utility operations is conducted with customers located within the three-state region of Arizona, Nevada, and California. The table below contains information about the gas utility customer accounts receivable balance (net of allowance) at December 31, 2015 and 2014, and the percentage of customers in each of the three states. December 31, 2015 December 31, 2014 Gas utility customer accounts receivable balance (in thousands) $ 151,775 $ 136,148 December 31, 2015 Percent of customers by state Arizona 53 % Nevada 37 % California 10 % Although the Company seeks to minimize its credit risk related to utility operations by requiring security deposits from new customers, imposing late fees, and actively pursuing collection on overdue accounts, some accounts are ultimately not collected. Customer accounts are subject to collection procedures that vary by jurisdiction (late fee assessment, noticing requirements for disconnection of service, and procedures for actual disconnection and/or reestablishment of service). After disconnection of service, accounts are generally written off approximately one month after inactivation. Dependent upon the jurisdiction, reestablishment of service requires both payment of previously unpaid balances and additional deposit requirements. Provisions for uncollectible accounts are recorded monthly based on experience, customer and rate composition, and write-off processes. They are included in the ratemaking process as a cost of service. The Nevada jurisdictions have a regulatory mechanism associated with the gas cost-related portion of uncollectible accounts. Such amounts are deferred and collected through a surcharge in the ratemaking process. Activity in the allowance account for uncollectibles is summarized as follows (thousands of dollars): Allowance for Balance, December 31, 2012 $ 2,504 Additions charged to expense 3,583 Accounts written off, less recoveries (4,362 ) Balance, December 31, 2013 1,725 Additions charged to expense 4,146 Accounts written off, less recoveries (3,616 ) Balance, December 31, 2014 2,255 Additions charged to expense 4,113 Accounts written off, less recoveries (4,098 ) Balance, December 31, 2015 $ 2,270 At December 31, 2015, the construction services segment (Centuri) had $162 million in customer accounts receivable. Both the allowance for uncollectibles and write-offs have been insignificant and are not reflected in the table above. |
Regulatory Assets and Liabiliti
Regulatory Assets and Liabilities | 12 Months Ended |
Dec. 31, 2015 | |
Regulated Operations [Abstract] | |
Regulatory Assets and Liabilities | Note 4 – Regulatory Assets and Liabilities Natural gas operations are subject to the regulation of the Arizona Corporation Commission (“ACC”), the Public Utilities Commission of Nevada (“PUCN”), the California Public Utilities Commission (“CPUC”), and the Federal Energy Regulatory Commission (“FERC”). Accounting policies of Southwest conform to U.S. GAAP applicable to rate-regulated entities and reflect the effects of the ratemaking process. Accounting treatment for rate-regulated entities allows for deferral as regulatory assets, costs that otherwise would be expensed, if it is probable that future recovery from customers will occur. If rate recovery is no longer probable, due to competition or the actions of regulators, Southwest is required to write-off the related regulatory asset. Regulatory liabilities are recorded if it is probable that revenues will be reduced for amounts that will be credited to customers through the ratemaking process. The following table represents existing regulatory assets and liabilities (thousands of dollars): December 31, 2015 2014 Regulatory assets: Accrued pension and other postretirement benefit costs (1) $ 384,647 $ 390,293 Unrealized net loss on non-trading derivatives (Swaps) (2) 5,486 5,425 Deferred purchased gas costs (3) 3,591 87,556 Accrued purchased gas costs (4) — 2,600 Unamortized premium on reacquired debt (5) 21,511 20,478 Other (6) 73,022 72,132 488,257 578,484 Regulatory liabilities: Deferred purchased gas costs (3) (45,601 ) — Accumulated removal costs (303,000 ) (304,000 ) Accrued purchased gas costs (4) (10,400 ) — Deferred gain on southern Nevada division operations facility (7) — (115 ) Unamortized gain on reacquired debt (8) (10,325 ) (10,862 ) Other (9) (36,631 ) (34,233 ) Net regulatory assets $ 82,300 $ 229,274 (1) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovery period is greater than five years. (See Note 10). (2) The following table details the regulatory assets/(liabilities) offsetting the derivatives (Swaps) at fair value in the Consolidated Balance Sheets (thousands of dollars). The actual amounts, when realized at settlement, become a component of purchased gas costs under the Company’s purchased gas adjustment (“PGA”) mechanisms. (See Note 13). Instrument Balance Sheet Location 2015 2014 Swaps Deferred charges and other assets $ 1,219 $ 363 Swaps Prepaids and other current assets 4 ,267 5,062 (3) Balance recovered or refunded on an ongoing basis with interest. (4) Asset included in Prepaids and other current assets and liability included in Other current liabilities on the Consolidated Balance Sheets. Balance recovered or refunded on an ongoing basis. (5) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovered over life of debt instruments. (6) Other regulatory assets including deferred costs associated with rate cases, regulatory studies, and state mandated public purpose programs (including low income and conservation programs), as well as margin and interest-tracking accounts, amounts associated with accrued absence time, and deferred post-retirement benefits other than pensions. Recovery periods vary. (7) The amortization period ended October 2015. (8) Included in Other deferred credits on the Consolidated Balance Sheets. Amortized over life of debt instruments. (9) Other regulatory liabilities include amounts associated with income tax and gross-up. |
Other Comprehensive Income and
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") | 12 Months Ended |
Dec. 31, 2015 | |
Equity [Abstract] | |
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") | Note 5 – Other Comprehensive Income and Accumulated Other Comprehensive Income (“AOCI”) The following information provides insight into amounts impacting Other Comprehensive Income (Loss), both before and after-tax, within the Consolidated Statements of Comprehensive Income, which also impact Accumulated Other Comprehensive Income in the Company’s Consolidated Balance Sheets and Consolidated Statements of Equity, as well as the Redeemable Noncontrolling Interest. Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) (Thousands of dollars) 2015 2014 2013 Before- Tax Tax Net-of- Before- Tax Tax Net-of- Tax Amount Before- Tax Tax Net-of- Defined benefit pension plans: Net actuarial gain/(loss) $ (30,519 ) $ 11,597 $ (18,922 ) $ (173,646 ) $ 65,985 $ (107,661 ) $ 100,345 $ (38,131 ) $ 62,214 Amortization of prior service cost 1,335 (507 ) 828 355 (135 ) 220 355 (135 ) 220 Amortization of net actuarial (gain)/loss 34,381 (13,065 ) 21,316 23,656 (8,989 ) 14,667 34,177 (12,987 ) 21,190 Prior service cost — — — (6,661 ) 2,531 (4,130 ) — — — Regulatory adjustment (5,646 ) 2,146 (3,500 ) 140,308 (53,317 ) 86,991 (123,630 ) 46,979 (76,651 ) Pension plans other comprehensive income (loss) (449 ) 171 (278 ) (15,988 ) 6,075 (9,913 ) 11,247 (4,274 ) 6,973 Forward-starting interest rate swaps (“FSIRS”) (designated hedging activities): Amounts reclassified into net income 3,344 (1,271 ) 2,073 3,345 (1,272 ) 2,073 3,345 (1,271 ) 2,074 FSIRS other comprehensive income (loss) 3,344 (1,271 ) 2,073 3,345 (1,272 ) 2,073 3,345 (1,271 ) 2,074 Foreign currency translation adjustments: Translation adjustments (1,954 ) — (1,954 ) (659 ) — (659 ) — — — Foreign currency other comprehensive income (loss) (1,954 ) — (1,954 ) (659 ) — (659 ) — — — Total other comprehensive income (loss) $ 941 $ (1,100 ) $ (159 ) $ (13,302 ) $ 4,803 $ (8,499 ) $ 14,592 $ (5,545 ) $ 9,047 (1) Tax amounts are calculated using a 38% rate. 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, as repatriation of earnings is not anticipated. The estimated amounts that will be amortized from accumulated other comprehensive income or regulatory assets into net periodic benefit cost over the next year are summarized below (in thousands): Retirement plan net actuarial loss $ 25,000 SERP net actuarial loss 1,400 PBOP net actuarial loss 400 PBOP prior service cost 1,300 Approximately $2.1 million of realized losses (net of tax) related to the FSIRS, included in AOCI at December 31, 2015, will be reclassified into interest expense within the next twelve months as the related interest payments on long-term debt occur. The following table represents a rollforward of AOCI, presented on the Company’s Consolidated Balance Sheets and its Consolidated Statements of Equity: AOCI—Rollforward (Thousands of dollars) Defined Benefit Plans (Note 10) FSIRS (Note 13) Foreign Currency Items Before- Tax Tax After- Tax Before- Tax Tax After- Tax Before- Tax Tax After- Tax AOCI Beginning Balance AOCI December 31, 2014 $ (57,211) $ 21,740 $ (35,471 ) $ (22,688 ) $ 8,621 $ (14,067 ) $ (637 ) $ — $ (637 ) $ (50,175 ) Net actuarial gain/(loss) (30,519 ) 11,597 (18,922 ) — — — — — — (18,922 ) Translation adjustments — — — — — — (1,954 ) — (1,954 ) (1,954 ) Other comprehensive income before reclassifications (30,519 ) 11,597 (18,922 ) — — — (1,954 ) — (1,954 ) (20,876 ) FSIRS amounts reclassified from AOCI (1) — — — 3,344 (1,271 ) 2,073 — — — 2,073 Amortization of prior service cost (2) 1,335 (507 ) 828 — — — — — — 828 Amortization of net actuarial loss (2) 34,381 (13,065 ) 21,316 — — — — — — 21,316 Regulatory adjustment (3) (5,646 ) 2,146 (3,500 ) — — — — — — (3,500 ) Net current period other comprehensive income (loss) (449 ) 171 (278 ) 3,344 (1,271 ) 2,073 (1,954 ) — (1,954 ) (159 ) Less: Translation adjustment attributable to redeemable noncontrolling interest — — — — — — (66 ) — (66 ) (66 ) Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation (449 ) 171 (278 ) 3,344 (1,271 ) 2,073 (1,888 ) — (1,888 ) (93 ) Ending Balance AOCI December 31, 2015 $ (57,660 ) $ 21,911 $ (35,749 ) $ (19,344 ) $ 7,350 $ (11,994 ) $ (2,525 ) $ — $ (2,525 ) $ (50,268 ) (1) The FSIRS reclassification amounts are included in the Net interest deductions line item on the Consolidated Statements of Income. (2) These AOCI components are included in the computation of net periodic benefit cost (see Note 10 – Pension and Other Postretirement Benefits 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 the Deferred charges and other assets line item on the Consolidated Balance Sheets). The following table represents amounts (before income tax impacts) included in Accumulated other comprehensive income (in the table above), that have not yet been recognized in net periodic benefit cost as of December 31, 2015 and 2014: Amounts Recognized in AOCI (Before Tax) (Thousands of dollars) 2015 2014 Net actuarial (loss) gain $ (435,269 ) $ (439,131 ) Prior service cost (7,038 ) (8,373 ) Less: amount recognized in regulatory assets 384,647 390,293 Recognized in AOCI $ (57,660 ) $ (57,211 ) See Note 10 – Pension and Other Postretirement Benefits for more information on the defined benefit pension plans and Note 13 – Derivatives and Fair Value Measurements for more information on the FSIRS. |
Common Stock
Common Stock | 12 Months Ended |
Dec. 31, 2015 | |
Text Block [Abstract] | |
Common Stock | Note 6 – Common Stock On March 10, 2015, the Company filed with the Securities Exchange Commission (“SEC”) an automatic shelf registration statement on Form S-3 (File No. 333-202633), which became effective upon filing, for the offer and sale of up to $100,000,000 of the Company’s 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 10, 2015, between the Company and BNY Mellon Capital Markets, LLC (the “Equity Shelf Program”). During 2015, the Company sold an aggregate of 645,225 shares of common stock under this program resulting in proceeds to the Company of $35,167,584, net of $355,228 in agent commissions. No sales occurred in the fourth quarter of 2015. As of December 31, 2015, the Company had up to $64,477,188 of common stock available for sale under the program. Net proceeds from the sale 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 Southwest serves. In addition, during 2015, the Company issued approximately 209,000 shares of common stock through the Stock Incentive Plan, Restricted Stock/Unit Plan, and Management Incentive Plan. |
Long-Term Debt
Long-Term Debt | 12 Months Ended |
Dec. 31, 2015 | |
Debt Disclosure [Abstract] | |
Long-Term Debt | Note 7 – Long-Term Debt Carrying amounts of the Company’s long-term debt and their related estimated fair values as of December 31, 2015 and December 31, 2014 are disclosed in the following table. The fair values of the 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. They are categorized as Level 1 (quoted prices for identical financial instruments) within the three-level December 31, 2015 2014 Carrying Market Carrying Market (Thousands of dollars) Debentures: Notes, 4.45%, due 2020 $ 125,000 $ 130,273 $ 125,000 $ 133,403 Notes, 6.1%, due 2041 125,000 141,581 125,000 157,290 Notes, 3.875%, due 2022 250,000 253,600 250,000 262,030 Notes, 4.875%, due 2043 250,000 251,483 250,000 280,903 8% Series, due 2026 75,000 97,035 75,000 102,296 Medium-term notes, 7.59% series, due 2017 25,000 26,253 25,000 27,573 Medium-term notes, 7.78% series, due 2022 25,000 29,855 25,000 31,144 Medium-term notes, 7.92% series, due 2027 25,000 31,890 25,000 33,695 Medium-term notes, 6.76% series, due 2027 7,500 8,684 7,500 9,156 Unamortized discount and debt issuance costs (6,137 ) (6,604 ) 901,363 900,896 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 Fixed-rate bonds: 5.25% 2003 Series D, due 2038 — — 20,000 20,277 5.00% 2004 Series B, due 2033 — — 31,200 31,223 4.85% 2005 Series A, due 2035 100,000 100,452 100,000 100,071 4.75% 2006 Series A, due 2036 24,855 25,130 24,855 25,399 Unamortized discount and debt issuance costs (3,946 ) (5,964 ) 320,909 370,091 Centuri term loan facility 112,571 112,665 142,071 143,021 Unamortized debt issuance costs (692 ) (816 ) 111,879 141,255 Centuri secured revolving credit facility 60,627 60,724 57,196 57,320 Centuri other debt obligations 25,901 26,059 31,128 31,127 1,570,679 1,650,566 Less: current maturities (19,475 ) (19,192 ) Long-term debt, less current maturities $ 1,551,204 $ 1,631,374 In March 2015, Southwest amended its $300 million credit and commercial paper facility. The facility was previously scheduled to expire in March 2019, but was extended to March 2020. The Company will continue to use $150 million of the facility as long-term debt and the remaining $150 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 the Company’s senior unsecured debt rating. At December 31, 2015, 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 December 31, 2015, $150 million was outstanding on the long-term portion of the credit facility, including $50 million in commercial paper (see commercial paper program discussion below). The effective interest rate on the long-term portion of the credit facility was 1.45% at December 31, 2015. Borrowings under the credit facility ranged from none during the second quarter of 2015 to a high of $180 million during the fourth quarter of 2015. With regard to the short-term portion of the credit facility, there was $18 million outstanding at December 31, 2015 and $5 million outstanding at December 31, 2014. (See Note 8 – Short-Term Debt ). The Company has a $50 million commercial paper program. Any issuance under the commercial paper program is supported by the Company’s current revolving credit facility and, therefore, does not represent additional borrowing capacity. Any borrowing under the commercial paper program will be designated as long-term debt. Interest rates for the program are calculated at the then current commercial paper rate. At December 31, 2015, and as noted above, $50 million was outstanding on the commercial paper program. The effective interest rate on the commercial paper program was 1.01% at December 31, 2015. In May 2015, the Company redeemed at par the $31.2 million 5.00% 2004 Series B IDRBs originally due in 2033. The Company facilitated the redemption primarily from cash on hand and borrowings under its $300 million credit facility. In September 2015, the Company redeemed at par the $20 million 5.25% 2003 Series D IDRBs originally due in 2038. The Company facilitated the redemption primarily from cash on hand and borrowings under its $300 million credit facility. Centuri has a $300 million secured revolving credit and term loan facility that is scheduled to expire in October 2019. This facility includes a revolving credit facility and a term loan facility. The term loan facility had an initial limit of approximately $150 million, which was reached in 2014 and is in the process of being repaid. No further borrowing is permitted under the term loan facility. In January 2016, administrative amendments were made to the revolving credit and term loan facility with no impact to borrowing capacity, due dates, or interest provisions. The revolving credit facility has a limit of $150 million; amounts borrowed and repaid under the revolving credit facility are available to be re-borrowed. The revolving credit and term loan facility is secured by substantially all of Centuri’s assets except ones explicitly excluded under the terms of the agreement (including owned real estate and certain certificated vehicles). Centuri assets securing the facility at December 31, 2015 totaled $437 million. Interest rates for Centuri’s $300 million secured revolving credit and term loan facility are calculated at the LIBOR, the Canadian Dealer Offered Rate (“CDOR”), or an alternate base rate or Canadian base rate, plus in each case an applicable margin that is determined based on Centuri’s consolidated leverage ratio. The applicable margin ranges from 1.00% to 2.25% for loans bearing interest with reference to LIBOR or CDOR and from 0.00% to 1.25% for loans bearing interest with reference to the alternate base rate or Canadian base rate. Centuri is also required to pay a commitment fee on the unfunded portion of the commitments based on the consolidated leverage ratio. The commitment fee ranges from 0.15% to 0.40% per annum. Borrowings under the revolving credit facility ranged from a low of $60.6 million during December 2015 to a high of $105.2 million during May 2015. All amounts outstanding are considered long-term borrowings. The effective interest rate on the secured revolving credit and term loan facility was 2.46% at December 31, 2015. The effective interest rates on the variable-rate IDRBs are included in the table below: December 31, 2015 December 31, 2014 2003 Series A 0.87 % 0.85 % 2008 Series A 0.87 % 0.90 % 2009 Series A 0.75 % 0.89 % Tax-exempt Series A 0.81 % 0.84 % In Nevada, interest fluctuations due to changing interest rates on the 2003 Series A, 2008 Series A, and 2009 Series A variable-rate IDRBs are tracked and recovered from ratepayers through an interest balancing account. Estimated maturities of long-term debt for the next five years are (in thousands): 2016 $ 19,475 2017 42,245 2018 14,906 2019 142,452 2020 275,238 No debt instruments have credit triggers or other clauses that result in default if Company bond ratings are lowered by rating agencies. Certain Company debt instruments contain securities ratings covenants that, if set in motion, would increase financing costs. Certain debt instruments also have leverage ratio caps and minimum net worth requirements. At December 31, 2015, the Company is in compliance with all of its covenants. Under the most restrictive of the covenants, the Company could issue approximately $2.2 billion in additional debt and meet the leverage ratio requirement. The Company has at least $1 billion of cushion in equity relating to the minimum net worth requirement. Certain Centuri debt instruments have leverage ratio caps and fixed charge ratio coverage requirements. At December 31, 2015, Centuri is in compliance with all of its covenants. Under the most restrictive of the covenants, Centuri could issue approximately $75 million in additional debt and meet the leverage ratio requirement. Centuri has at least $15 million of cushion relating to the minimum fixed charge ratio coverage requirement. Early Adoption of Accounting Standards Update (“ASU”) No. 2015-03. In a related update, the SEC provided guidance that for line-of-credit (“LOC”) arrangements, companies could elect to present debt issuance costs within assets, regardless of whether there is an outstanding balance on such borrowings. Making such an election may make presentations less confusing as net negative balances would otherwise result in cases when there are no outstanding LOC borrowings but associated issuance costs are still being amortized. Therefore, for LOC arrangements, such as Southwest’s revolving credit facility and Centuri’s secured revolving credit portion of its facility, the Company has elected, as permitted, to continue to recognize unamortized debt issuance costs within its asset categories and no such amounts have been reclassified. The unamortized debt issuance costs associated with the term loan portion of Centuri’s $300 million facility, ($816,000), have been reclassified as a deduction from the related 2014 debt balance. The debt listing table has been updated to reflect these changes based on the elections made. |
Short-Term Debt
Short-Term Debt | 12 Months Ended |
Dec. 31, 2015 | |
Debt Disclosure [Abstract] | |
Short-Term Debt | Note 8 – Short-Term Debt As discussed in Note 7, Southwest has a $300 million credit facility that is scheduled to expire in March 2020, of which $150 million has been designated by management for working capital purposes. The Company had $18 million in short-term borrowings outstanding at December 31, 2015 and $5 million in short-term borrowings outstanding at December 31, 2014. The effective interest rate on the short-term portion of the credit facility was 1.37% at December 31, 2015. |
Commitments and Contingencies
Commitments and Contingencies | 12 Months Ended |
Dec. 31, 2015 | |
Commitments and Contingencies Disclosure [Abstract] | |
Commitments and Contingencies | Note 9 – Commitments and Contingencies The Company is a defendant in miscellaneous legal proceedings. The Company is also a party to various regulatory proceedings. The ultimate dispositions of these proceedings are not presently determinable; however, it is the opinion of management that no litigation or regulatory proceeding to which the Company is currently subject will have a material adverse impact on its financial position or results of operations. The Company maintains liability insurance for various risks associated with the operation of its natural gas pipelines and facilities. In connection with these liability insurance policies, the Company is responsible for an initial deductible or self-insured retention amount per incident, after which the insurance carriers would be responsible for amounts up to the policy limits. For the policy year August 2015 to July 2016, these liability insurance policies require Southwest to be responsible for the first $1 million (self-insured retention) of each incident plus the first $4 million in aggregate claims above its self-insured retention in the policy year. Through an assessment process, the Company may determine that certain costs are likely to be incurred in the future related to specific legal matters. In these circumstances and in accordance with accounting policies, the Company will make an accrual, as necessary. |
Pension and Other Postretiremen
Pension and Other Postretirement Benefits | 12 Months Ended |
Dec. 31, 2015 | |
Compensation and Retirement Disclosure [Abstract] | |
Pension and Other Postretirement Benefits | Note 10 – Pension and Other Postretirement Benefits Southwest has an Employees’ Investment Plan that provides for purchases of various mutual fund investments and Company common stock by eligible Southwest employees through deduction of a percentage of base compensation, subject to IRS limitations. Southwest matches one-half of amounts deferred by employees, up to a maximum matching contribution of 3.5% of an employee’s annual compensation. Centuri has a separate plan, the cost and liability of which are not significant. The cost of the Southwest plan is listed below (in thousands): 2015 2014 2013 Employee Investment Plan cost $ 5,072 $ 4,816 $ 4,850 Southwest has a deferred compensation plan for all officers and a separate deferred compensation plan for members of the Board of Directors. The plans provide the opportunity to defer up to 100% of annual cash compensation. Southwest matches one-half of amounts deferred by officers, up to a maximum matching contribution of 3.5% of an officer’s annual base salary. Upon retirement, payments of compensation deferred, plus interest, are made in equal monthly installments over 10, 15, or 20 years, as elected by the participant. Directors have an additional option to receive such payments over a five-year period. Deferred compensation earns interest at a rate determined each January. The interest rate equals 150% of Moody’s Seasoned Corporate Bond Rate Index. Southwest has a noncontributory qualified retirement plan with defined benefits covering substantially all employees and a separate unfunded supplemental executive 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 benefits. The Company recognizes the overfunded or underfunded positions of defined benefit postretirement plans, including pension plans, in its Consolidated Balance Sheets. Any actuarial gains and losses, prior service costs and transition assets or obligations are recognized in Accumulated other comprehensive income under Stockholders’ equity, net of tax, until they are amortized as a component of net periodic benefit cost. The Company has established a regulatory asset for the portion of the total amounts otherwise chargeable to accumulated other comprehensive income that are expected to be recovered through rates in future periods. Changes in actuarial gains and losses and prior service costs pertaining to the regulatory asset will be recognized as an adjustment to the regulatory asset account as these amounts are amortized and recognized as components of net periodic pension costs each year. Investment objectives and strategies for the qualified retirement plan are developed and approved by the Pension Plan Investment Committee of the Board of Directors of the Company. They are designed to enhance capital, maintain minimum liquidity required for retirement plan operations and effectively manage pension assets. A target portfolio of investments in the qualified retirement plan is developed by the Pension Plan Investment Committee and is reevaluated periodically. Asset return assumptions are determined by evaluating performance expectations of the target portfolio. Projected benefit obligations are estimated using actuarial assumptions and Company benefit policy. A target mix of assets is then determined based on acceptable risk versus estimated returns in order to fund the benefit obligation. At December 31, 2015, the percentage ranges of the target portfolio are: Type of Investment Percentage Range Equity securities 59 to 71 Debt securities 31 to 37 Other up to 5 The Company’s pension costs for these plans are affected by the amount and timing of cash contributions to the plans, the return on plan assets, discount rates, and by employee demographics, including age, compensation, and length of service. Changes made to the provisions of the plans may also impact current and future pension costs. Actuarial formulas are used in the determination of pension costs and are affected by actual plan experience and assumptions about future experience. Key actuarial assumptions include the expected return on plan assets, the discount rate used in determining the projected benefit obligation and pension costs, and the assumed rate of increase in employee compensation. Relatively small changes in these assumptions, particularly the discount rate, may significantly affect pension costs and plan obligations for the qualified retirement plan. In determining the discount rate, the Company matches the plan’s projected cash flows to a spot-rate yield curve based on highly rated corporate bonds. Changes to the discount rate from year-to-year, if any, are generally made in increments of 25 basis points. Due to a higher interest rate environment for high-quality fixed income investments, the Company increased the discount rate at December 31, 2015 from 2014. The methodology utilized to determine the discount rate was consistent with prior years. The weighted-average rate of compensation increase was also raised (consistent with management’s expectations overall). The asset return assumption (which impacts the following year’s expense) was lowered. The rates are presented in the table below: December 31, 2015 December 31, 2014 Discount rate 4.50 % 4.25 % Weighted-average rate of compensation increase 3.25 % 2.75 % Asset return assumption 7.25 % 7.75 % Pension expense for 2016 is estimated to decrease by $6.7 million compared to 2015 notably due to the higher discount rate and lower mortality projection. Future years expense level movements (up or down) will continue to be greatly influenced by long-term interest rates, asset returns, and funding levels. The following table sets forth the retirement plan, SERP, and PBOP funded statuses and amounts recognized on the Consolidated Balance Sheets and Consolidated Statements of Income. 2015 2014 Qualified Retirement Plan SERP PBOP Qualified SERP PBOP (Thousands of dollars) Change in benefit obligations Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO) $ 1,060,240 $ 41,176 $ 72,202 $ 886,714 $ 36,143 $ 58,020 Service cost 25,123 320 1,641 21,360 292 1,101 Interest cost 44,229 1,695 2,999 43,440 1,745 2,829 Plan amendments — — — — — 6,661 Actuarial loss (gain) (44,553 ) 2,322 (3,251 ) 144,606 5,459 4,567 Benefits paid (40,222 ) (2,793 ) (959 ) (35,880 ) (2,463 ) (976 ) Benefit obligation at end of year (PBO/PBO/APBO) 1,044,817 42,720 72,632 1,060,240 41,176 72,202 Change in plan assets Market value of plan assets at beginning of year 754,796 — 44,892 719,944 — 42,314 Actual return on plan assets (13,694 ) — (1,034 ) 34,732 — 2,859 Employer contributions 36,000 2,793 — 36,000 2,463 — Benefits paid (40,222 ) (2,793 ) (274 ) (35,880 ) (2,463 ) (281 ) Market value of plan assets at end of year 736,880 — 43,584 754,796 — 44,892 Funded status at year end $ (307,937 ) $ (42,720 ) $ (29,048 ) $ (305,444 ) $ (41,176 ) $ (27,310 ) Weighted-average assumptions (benefit obligation) Discount rate 4.50 % 4.50 % 4.50 % 4.25 % 4.25 % 4.25 % Weighted-average rate of compensation increase 3.25 % 3.25 % N/A 2.75 % 2.75 % N/A Estimated funding for the plans above during calendar year 2016 is approximately $39 million of which $36 million pertains to the retirement plan. Management monitors plan assets and liabilities and could, at its discretion, increase plan funding levels above the minimum in order to achieve a desired funded status and avoid or minimize potential benefit restrictions. The accumulated benefit obligation for the retirement plan and the SERP is presented below (in thousands): December 31, 2015 December 31, 2014 Retirement plan $ 922,992 $ 886,215 SERP 39,270 39,125 Benefits expected to be paid for the pension, PBOP, and the SERP over the next 10 years are as follows (in millions): 2016 2017 2018 2019 2020 2021-2025 Pension $44.0 $45.5 $47.2 $48.9 $50.5 $283.5 PBOP 3.9 4.1 4.3 4.5 4.5 21.3 SERP 2.8 2.8 2.8 2.9 2.9 14.1 No assurance can be made that actual funding and benefits paid will match these estimates. For PBOP measurement purposes, the per capita cost of the covered health care benefits medical rate trend assumption is 7.5% declining to 4.5%. The Company makes fixed contributions for health care benefits of employees who retire after 1988, but pays all covered health care costs for employees who retired prior to 1989. The medical trend rate assumption noted above applies to the benefit obligations of pre-1989 retirees only. Components of net periodic benefit cost Qualified Retirement Plan SERP PBOP 2015 2014 2013 2015 2014 2013 2015 2014 2013 (Thousands of dollars) Service cost $ 25,123 $ 21,360 $ 23,056 $ 320 $ 292 $ 373 $ 1,641 $ 1,101 $ 1,220 Interest cost 44,229 43,440 37,607 1,695 1,745 1,535 2,999 2,829 2,482 Expected return on plan assets (57,808 ) (53,342 ) (49,840 ) — — — (3,464 ) (3,264 ) (2,824 ) Amortization of prior service cost — — — — — — 1,335 355 355 Amortization of net actuarial loss 32,743 22,873 32,261 1,293 783 971 345 — 945 Net periodic benefit cost $ 44,287 $ 34,331 $ 43,084 $ 3,308 $ 2,820 $ 2,879 $ 2,856 $ 1,021 $ 2,178 Weighted-average assumptions (net benefit cost) Discount rate 4.25 % 5.00 % 4.25 % 4.25 % 5.00 % 4.25 % 4.25 % 5.00 % 4.25 % Expected return on plan assets 7.75 % 7.75 % 8.00 % 7.75 % 7.75 % 8.00 % 7.75 % 7.75 % 8.00 % Weighted-average rate of compensation increase 2.75 % 3.25 % 2.75 % 2.75 % 3.25 % 2.75 % N/A N/A N/A Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income 2015 2014 2013 Total Qualified SERP PBOP Total Qualified SERP PBOP Total Qualified SERP PBOP (Thousands of dollars) Net actuarial loss (gain) (a) $ 30,519 $ 26,949 $ 2,322 $ 1,248 $ 173,646 $ 163,215 $ 5,460 $ 4,971 $ (100,345 ) $ (91,115 ) $ (662 ) $ (8,568 ) Amortization of prior service cost (b) (1,335 ) — — (1,335 ) (355 ) — — (355 ) (355 ) — — (355 ) Amortization of net actuarial loss (b) (34,381 ) (32,743 ) (1,293 ) (345 ) (23,656 ) (22,872 ) (784 ) — (34,177 ) (32,261 ) (971 ) (945 ) Prior service cost — — — — 6,661 — — 6,661 — — — — Regulatory adjustment 5,646 5,214 — 432 (140,308 ) (129,031 ) — (11,277 ) 123,630 113,762 — 9,868 Recognized in other comprehensive (income) loss 449 (580 ) 1,029 — 15,988 11,312 4,676 — (11,247 ) (9,614 ) (1,633 ) — Net periodic benefit costs recognized in net income 50,451 44,287 3,308 2,856 38,172 34,331 2,820 1,021 48,141 43,084 2,879 2,178 Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss $ 50,900 $ 43,707 $ 4,337 $ 2,856 $ 54,160 $ 45,643 $ 7,496 $ 1,021 $ 36,894 $ 33,470 $ 1,246 $ 2,178 The table above discloses the net gain or loss and prior service cost recognized in other comprehensive income, separated into (a) amounts initially recognized in other comprehensive income, and (b) amounts subsequently recognized as adjustments to other comprehensive income as those amounts are amortized as components of net periodic benefit cost. See also Note 5 – Other Comprehensive Income and Accumulated Other Comprehensive Income (“AOCI”). 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 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 following table sets forth, by level within the three-level fair value hierarchy, the fair values of the assets of the qualified pension plan and the PBOP as of December 31, 2015 and December 31, 2014. The SERP has no assets. The FASB issued guidance in 2015, which the Company has adopted early as permitted, removing the requirement to categorize assets in the fair value hierarchy that are measured using the net asset value (“NAV”) practical expedient. See note (3) to the table below. Based on this guidance, no Level 3 assets existed (nor are reflected in the table below) at December 31, 2015 and December 31, 2014. December 31, 2015 December 31, 2014 Qualified PBOP Total Qualified PBOP Total Assets at fair value (thousands of dollars): Level 1 – Quoted prices in active markets for identical financial assets Common stock Agriculture $ 7,021 $ 209 $ 7,230 $ 6,661 $ 198 $ 6,859 Capital equipment 533 16 549 2,222 66 2,288 Chemicals/materials 3,304 98 3,402 5,233 155 5,388 Consumer goods 41,035 1,221 42,256 41,731 1,238 42,969 Energy and mining 11,066 329 11,395 18,502 549 19,051 Finance/insurance 29,957 892 30,849 20,685 613 21,298 Healthcare 37,930 1,129 39,059 37,846 1,122 38,968 Information technology 29,229 870 30,099 25,881 767 26,648 Services 12,341 367 12,708 28,846 855 29,701 Telecommunications/internet/media 25,883 770 26,653 18,498 549 19,047 Other 9,043 269 9,312 10,958 325 11,283 Real estate investment trusts 5,010 149 5,159 5,713 169 5,882 Mutual funds 87,483 23,985 111,468 86,159 24,567 110,726 Government fixed income securities 33,482 996 34,478 44,694 1,325 46,019 Preferred securities — — — 568 17 585 Futures contracts (7 ) — (7 ) — — — Total Level 1 Assets (1) $ 333,310 $ 31,300 $ 364,610 $ 354,197 $ 32,515 $ 386,712 Level 2 – Significant other observable inputs Government fixed income and mortgage backed securities $ 49,571 $ 1,475 $ 51,046 $ 48,312 $ 1,433 $ 49,745 Corporate fixed income securities Asset-backed and mortgage-backed 23,542 701 24,243 27,071 803 27,874 Banking 20,857 621 21,478 23,289 691 23,980 Insurance 4,896 146 5,042 6,182 183 6,365 Utilities 3,826 114 3,940 4,232 126 4,358 Other 30,995 922 31,917 23,120 686 23,806 Pooled funds and mutual funds 14,808 796 15,604 11,968 984 12,952 Real estate investment trusts 1,949 58 2,007 — — — State and local obligations 950 28 978 1,499 44 1,543 Preferred securities 554 17 571 — — — Convertible securities 196 6 202 — — — Total Level 2 assets (2) $ 152,144 $ 4,884 $ 157,028 $ 145,673 $ 4,950 $ 150,623 Total Plan assets at fair value $ 485,454 $ 36,184 $ 521,638 $ 499,870 $ 37,465 $ 537,335 Commingled equity funds (3) 250,511 7,455 257,966 259,235 7,687 266,922 Insurance company general account contracts (4) 3,719 — 3,719 4,003 — 4,003 Total Plan assets (5) $ 739,684 $ 43,639 $ 783,323 $ 763,108 $ 45,152 $ 808,260 (1) Common stock, Real Estate Investment Trusts, Mutual funds, and U.S. Government securities listed or regularly traded on a national securities exchange are valued at quoted market prices as of the last business day of the calendar year. The Mutual funds category above is an intermediate-term bond fund whose manager employs multiple concurrent strategies and takes only moderate risk in each, thereby reducing the risk of poor performance arising from any single source, and a balanced fund that invests in a diversified portfolio of common stocks, preferred stocks and fixed-income securities. Strategies utilized by the bond fund include duration management, yield curve or maturity structuring, sector rotation, and all bottom-up techniques including in-house credit and quantitative research. Strategies employed by the balanced fund include pursuit of regular income, conservation of principal, and an opportunity for long-term growth of principal and income. (2) The fair value of investments in debt securities with remaining maturities of one year or more is determined by dealers who make markets in such securities or by an independent pricing service, which considers yield or price of bonds of comparable quality, coupon, maturity, and type. The pooled funds and mutual funds are two collective short-term funds that invest in Treasury bills and money market funds. These funds are used as a temporary cash repository for the pension plan’s various investment managers. (3) The commingled equity funds include private equity funds that invest in domestic and international securities regularly traded on securities exchanges. These funds are shown in the above table at net asset value, which is the value of securities in the fund less the amount of any liabilities outstanding. Investment strategies employed by the funds include: • Domestic large capitalization value equities • International developed countries value and growth equities • Emerging markets equities • International small capitalization equities The terms and conditions under which shares in the commingled equity funds may be redeemed vary among the funds; the notice required ranges from one day to 30 days prior to the valuation date (month end). One of the commingled equity funds requires the payment of a minimal impact fee to be applied to redemptions and subscriptions of $5 million or greater; the relative fee diminishes the greater the transaction. Other such funds may impose fees to recover direct costs incurred by the fund at redemption, but are indeterminable prior to redemption. Early adoption of ASU No. 2015-07: (4) The insurance company general account contracts are annuity insurance contracts used to pay the pensions of employees who retired prior to 1989. The balance of the account disclosed in the above table is the contract value, which is the result of deposits, withdrawals, and interest credits. (5) The assets in the above table exceed the market value of plan assets shown in the funded status table by $2,859,000 (qualified retirement plan – $2,803,000, PBOP – $56,000) and $8,572,000 (qualified retirement plan – $8,312,000, PBOP – $260,000) for 2015 and 2014, respectively, which includes a payable for securities purchased, partially offset by receivables for interest, dividends, and securities sold. |
Stock-Based Compensation
Stock-Based Compensation | 12 Months Ended |
Dec. 31, 2015 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |
Stock-Based Compensation | Note 11 – Stock-Based Compensation At December 31, 2015, the Company had three stock-based compensation plans: a stock option plan, a performance share stock plan which includes a cash award, and a restricted stock/unit plan. The table below shows total stock-based plan compensation expense, including the cash award, which was recognized in the Consolidated Statements of Income (in thousands): 2015 2014 2013 Stock-based compensation plan expense, net of related tax benefits $ 7,278 $ 8,130 $ 8,012 Stock-based compensation plan related tax benefits 4,461 4,983 4,910 Under the option plan, the Company previously granted options to purchase shares of common stock, to key employees and outside directors. The last option grants were in 2006 and no future grants are anticipated. Each option had an exercise price equal to the market price of Company common stock on the date of grant and a maximum term of ten years. Therefore, remaining options, if not exercised prior to the anniversary date of the 2006 grant (in 2016), will then expire. The following tables summarize Company stock option plan activity and related information (thousands of options): 2015 2014 2013 Number of Weighted- Number of Weighted- Number of Weighted- Outstanding at the beginning of the year 36 $ 28.97 52 $ 27.57 125 $ 28.13 Exercised during the year (19 ) 26.69 (16 ) 24.31 (72 ) 28.44 Forfeited or expired during the year — — — — (1 ) 33.07 Outstanding and exercisable at year end 17 $ 31.64 36 $ 28.97 52 $ 27.57 The intrinsic value of a stock option is the amount by which the market value of the underlying stock exceeds the exercise price of the option. The aggregate intrinsic value of outstanding and exercisable options, and options that were exercised, are presented in the table below (in thousands): 2015 2014 2013 Outstanding and exercisable $ 394 $ 1,194 $ 1,473 Exercised 590 451 1,402 December 31, 2015 December 31, 2014 December 31, 2013 Market value of Southwest Gas stock $ 55.16 $ 61.81 $ 55.91 The weighted-average remaining contractual life for outstanding options was less than one year for 2015. All outstanding options are fully vested and exercisable. The following table summarizes information about stock options outstanding at December 31, 2015 (thousands of options): Options Outstanding and Exercisable Range of Number outstanding Weighted-average Weighted-average $29.08 to $33.07 17 0.5 Years $ 31.64 The Company received $523,000 in cash from the exercise of options during 2015 and a corresponding tax benefit of $218,000 which was recorded in additional paid-in capital. Under the performance share stock plan, the Company may issue performance shares to encourage key employees to remain in its employment and to achieve short-term and long-term performance goals. Plan participants are eligible to receive a cash bonus (i.e., short-term incentive) and performance shares (i.e., long-term incentive). The performance shares vest three years after grant and are then issued as common stock. The Company awards restricted stock/units under the restricted stock/unit plan to attract, motivate, retain, and reward key employees with an incentive to attain high levels of individual performance and improved financial performance of the Company. The restricted stock/units vest 40% at the end of year one and 30% at the end of years two and three and are issued annually as common stock in accordance with the percentage vested. The restricted stock/unit plan was also established to attract, motivate, and retain experienced and knowledgeable independent directors. Vesting for grants of restricted stock/units to directors occurs immediately upon grant. The issuance of common stock for directors occurs when their service on the Board ends. The following table summarizes the activity of the performance share stock and restricted stock/unit plans as of December 31, 2015 (thousands of shares): Performance Weighted- Restricted Weighted- Nonvested/unissued at beginning of year 271 $ 43.71 257 $ 41.22 Granted 80 63.09 73 63.09 Dividends 6 7 Forfeited or expired — — — — Vested and issued* (160 ) 43.12 (109 ) 46.65 Nonvested/unissued at December 31, 2015 197 $ 50.63 228 $ 44.36 * Includes shares for retiree payouts and those converted for taxes. The average grant date fair value of performance shares and restricted stock/units granted in 2014 and 2013 was $53.73 and $44.83, respectively. As of December 31, 2015, total compensation cost related to nonvested performance shares and restricted stock/units not yet recognized is $3.3 million. |
Income Taxes
Income Taxes | 12 Months Ended |
Dec. 31, 2015 | |
Income Tax Disclosure [Abstract] | |
Income Taxes | Note 12 – Income Taxes The following is a summary of income before taxes and noncontrolling interest for domestic and foreign operations (thousands of dollars): Year ended December 31, 2015 2014 2013 U.S. $ 221,660 $ 221,471 $ 222,815 Foreign (2,328 ) (1,950 ) — Total income before income taxes $ 219,332 $ 219,521 $ 222,815 Income tax expense (benefit) consists of the following (thousands of dollars): Year Ended December 31, 2015 2014 2013 Current: Federal $ 21,321 $ 1,739 $ 3,549 State 9,899 5,073 5,107 Foreign 650 2,193 — 31,870 9,005 8,656 Deferred: Federal 51,132 71,439 67,414 State (2,574 ) 614 1,872 Foreign (526 ) (2,685 ) — 48,032 69,368 69,286 Total income tax expense $ 79,902 $ 78,373 $ 77,942 Deferred income tax expense (benefit) consists of the following significant components (thousands of dollars): Year Ended December 31, 2015 2014 2013 Deferred federal and state: Property-related items $ 65,931 $ 52,814 $ 62,737 Purchased gas cost adjustments (32,993 ) 15,049 16,189 Employee benefits 623 109 (2,769 ) All other deferred 15,332 2,257 (6,010 ) Total deferred federal and state 48,893 70,229 70,147 Deferred ITC, net (861 ) (861 ) (861 ) Total deferred income tax expense $ 48,032 $ 69,368 $ 69,286 A reconciliation of the U.S. federal statutory rate to the consolidated effective tax rate for 2013, 2014, and 2015 (and the sources of these differences and the effect of each) are summarized as follows: Year Ended December 31, 2015 2014 2013 U.S. federal statutory income tax rate 35.0 % 35.0 % 35.0 % Net state taxes 1.8 1.9 2.4 Property-related items 0.1 0.1 0.1 Tax credits (0.4 ) (0.5 ) (0.4 ) Company owned life insurance 0.1 (1.0 ) (2.1 ) All other differences (0.2 ) 0.2 — Consolidated effective income tax rate 36.4 % 35.7 % 35.0 % Deferred tax assets and liabilities consist of the following (thousands of dollars): December 31, 2015 2014 Deferred tax assets: Deferred income taxes for future amortization of ITC $ 1,614 $ 2,146 Employee benefits 36,923 31,557 Alternative minimum tax credit 4,809 20,172 Net operating losses and credits 868 9,719 Interest rate swap 7,351 8,622 Other 24,636 25,872 Valuation allowance (499 ) (253 ) 75,702 97,835 Deferred tax liabilities: Property-related items, including accelerated depreciation 794,850 736,810 Regulatory balancing accounts 743 33,736 Unamortized ITC 2,549 3,410 Debt-related costs 5,497 5,066 Intangibles 9,547 12,792 Other 31,533 27,600 844,719 819,414 Net deferred tax liabilities 769,017 721,579 Current — (2,109 ) Noncurrent 769,017 723,688 Net deferred tax liabilities $ 769,017 $ 721,579 The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction, various states, and in Canada. With few exceptions, the Company is no longer subject to United States federal, state and local, or Canadian income tax examinations for years before 2011. At December 31, 2015, the Company has U.S. federal net capital loss carryforwards of $505,000, which begin to expire in 2016. At December 31, 2015, the Company has an income tax net operating loss carryforward related to Canadian operations of $3 million which begins to expire in 2032. As of December 31, 2015, the Company sustained losses in its foreign jurisdiction and therefore has no undistributed foreign earnings. However, the Company intends to permanently reinvest any future foreign earnings in Canada. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (thousands of dollars): 2015 2014 Unrecognized tax benefits at beginning of year $ 305 $ — Gross increases-tax positions in prior period — 305 Gross decreases-tax positions in prior period (9 ) — Gross increases-current period tax positions — — Gross decreases-current period tax positions — — Settlements — — Lapse in statute of limitations — — Unrecognized tax benefits at end of year $ 296 $ 305 In assessing whether uncertain tax positions should be recognized in its financial statements, Southwest first determines whether it is more-likely-than-not that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. In evaluating whether a tax position has met the more-likely-than-not recognition threshold, Southwest presumes that the position will be examined by the appropriate taxing authority that would have full knowledge of all relevant information. For tax positions that meet the more-likely-than-not recognition threshold, Southwest measures the amount of benefit recognized in the financial statements at the largest amount of benefit that is greater than 50 percent likely of being realized upon ultimate settlement. Southwest recognizes unrecognized tax benefits in the first financial reporting period in which information becomes available indicating that such benefits will more-likely-than-not be realized. For each reporting period, management applies a consistent methodology to measure unrecognized tax benefits, and all unrecognized tax benefits are reviewed periodically and adjusted as circumstances warrant. Southwest’s measurement of its unrecognized tax benefits is based on management’s assessment of all relevant information, including prior audit experience, the status of audits, conclusions of tax audits, lapsing of applicable statutes of limitation, identification of new issues, and any administrative guidance or developments The total amount of unrecognized tax benefits that, if recognized, would impact the effective tax rate was $0 at December 31, 2015. No significant increases or decreases in unrecognized tax benefit are expected within the next 12 months. The Company recognizes interest expense and income and penalties related to income tax matters in income tax expense. There was no tax-related interest income for 2015, 2014, and 2013. Income Tax Regulations Early Adoption of ASU No. 2015-17. |
Derivatives and Fair Value Meas
Derivatives and Fair Value Measurements | 12 Months Ended |
Dec. 31, 2015 | |
Derivative Instruments and Hedging Activities Disclosure [Abstract] | |
Derivatives and Fair Value Measurements | Note 13 – Derivatives and Fair Value Measurements Derivatives. The fixed-price contracts and Swaps are utilized by Southwest under its ongoing 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 January 2016 through March 2018. 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): December 31, 2015 December 31, 2014 Contract notional amounts 7,407 5,105 In late 2013, the Company suspended using swaps and fixed-price purchases pursuant to the Volatility Mitigation Program (“VMP”) for its Nevada service territories. The Company, along with its regulators, will continue to evaluate this strategy in light of prevailing or anticipated changing market conditions. Southwest does not utilize derivative financial instruments for speculative purposes, nor does it have trading operations. The following table sets forth the gains and (losses) recognized on the Company’s Swaps (derivatives) for the years ended December 31, 2015, 2014, and 2013 and their location in the Consolidated Statements of Income: Gains (losses) recognized in income for derivatives not designated as hedging instruments: (Thousands of dollars) Instrument Location of Gain or (Loss) 2015 2014 2013 Swaps Net cost of gas sold $ (7,598 ) $ (2,363 ) $ 976 Swaps Net cost of gas sold 7,598 * 2,363 * (976 )* 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 Company’s Swaps and their location in the Consolidated Balance Sheets (thousands of dollars): Fair values of derivatives not designated as hedging instruments: December 31, 2015 Instrument Balance Sheet Location Asset Derivatives Liability Derivatives Net Swaps Other current liabilities $ — $ (4,267 ) $ (4,267 ) Swaps Other deferred credits 4 (1,223 ) (1,219 ) Total $ 4 $ (5,490 ) $ (5,486 ) December 31, 2014 Instrument Balance Sheet Location Asset Derivatives Liability Derivatives Net Total Swaps Other current liabilities $ — $ (5,062 ) $ (5,062 ) Swaps Other deferred credits — (363 ) (363 ) Total $ — $ (5,425 ) $ (5,425 ) The estimated fair values of the natural gas derivatives were determined using future natural gas index prices (as more fully described below). The Company has master netting arrangements with each counterparty that provide for the net settlement (in the settlement month) of all contracts through a single payment. As applicable, the Company has elected to reflect the net amounts in its balance sheets. The Company had 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, Southwest records the unrealized gains and losses in fair value of the Swaps as a regulatory asset and/or liability. When the Swaps mature, Southwest reverses any prior positions held and records the settled position as an increase or decrease of purchased gas under the related purchased gas adjustment (“PGA”) mechanism in determining its 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. Year ended December 31, Year ended December 31, Year ended December 31, (Thousands of dollars) Paid to counterparties $ 7,537 $ 829 $ 3,148 Received from counterparties $ — $ 4,713 $ 915 The following table details the regulatory assets/(liabilities) offsetting the derivatives at fair value in the Consolidated Balance Sheets (thousands of dollars). December 31, 2015 Instrument Balance Sheet Location Net Total Swaps Prepaids and other current assets $ 4,267 Swaps Deferred charges and other assets 1,219 December 31, 2014 Instrument Balance Sheet Location Net Total Swaps Prepaids and other current assets $ 5,062 Swaps Deferred charges and other assets 363 Fair Value Measurements. 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 Company’s financial assets and liabilities that were accounted for at fair value (see Note 10 – Pension and Other Post Retirement Benefits for definitions of the levels of the fair value hierarchy): Level 2—Significant other observable inputs December 31, 2015 December 31, 2014 (Thousands of dollars) Liabilities at fair value: Other current liabilities—Swaps $ (4,267 ) $ (5,062 ) Other deferred credits—Swaps (1,219 ) (363 ) Net Assets (Liabilities) $ (5,486 ) $ (5,425 ) No financial assets or liabilities associated with the Swaps, which were accounted for at fair value, fell within Level 1 or Level 3 of the fair value hierarchy. |
Segment Information
Segment Information | 12 Months Ended |
Dec. 31, 2015 | |
Segment Reporting [Abstract] | |
Segment Information | Note 14 – Segment Information Company operating segments are determined based on the nature of their activities. The natural gas operations segment is engaged in the business of purchasing, distributing, and transporting natural gas. Revenues are generated from the distribution and transportation of natural gas. The construction services segment is primarily engaged in the business of providing utility companies with trenching and installation, replacement, and maintenance services for energy distribution systems, and providing industrial construction solutions. Over 99% of the total Company’s long-lived assets are in the United States. The accounting policies of the reported segments are the same as those described within Note 1—Summary of Significant Accounting Policies . Centuri accounts for the services provided to Southwest at contractual (market) prices at contract inception. Accounts receivable for these services, which are not eliminated during consolidation, are presented in the table below (in thousands). December 31, 2015 December 31, 2014 Accounts receivable for Centuri services $ 10,006 $ 9,169 The following table presents the amount of revenues and long-lived assets for both segments by geographic area (thousands of dollars): December 31, December 31, Revenues (a) United States $ 2,289,133 $ 2,069,513 Canada 174,492 52,194 Total $ 2,463,625 $ 2,121,707 (a) Revenues are attributed to countries based on the location of customers. The financial information pertaining to the natural gas operations and construction services segments for each of the three years in the period ended December 31, 2015 is as follows (thousands of dollars): 2015 Gas Operations Construction Services Adjustments Total Revenues from unaffiliated customers $ 1,454,639 $ 904,870 $ 2,359,509 Intersegment sales — 104,116 104,116 Total $ 1,454,639 $ 1,008,986 $ 2,463,625 Interest revenue $ 1,754 $ 419 $ 2,173 Interest expense $ 64,095 $ 7,784 $ 71,879 Depreciation and amortization $ 213,455 $ 56,656 $ 270,111 Income tax expense $ 61,355 $ 18,547 $ 79,902 Segment net income $ 111,625 $ 26,692 $ 138,317 Segment assets $ 4,822,845 $ 535,840 $ 5,358,685 Capital expenditures $ 438,289 $ 49,711 $ 488,000 2014 Gas Operations Construction Services Adjustments (a) Total Revenues from unaffiliated customers $ 1,382,087 $ 647,432 $ 2,029,519 Intersegment sales — 92,188 92,188 Total $ 1,382,087 $ 739,620 $ 2,121,707 Interest revenue $ 2,596 $ 6 $ 2,602 Interest expense $ 68,299 $ 3,770 $ 72,069 Depreciation and amortization $ 204,144 $ 48,883 $ 253,027 Income tax expense $ 63,597 $ 14,776 $ 78,373 Segment net income $ 116,872 $ 24,254 $ 141,126 Segment assets $ 4,652,307 $ 566,589 $ (10,599 ) $ 5,208,297 Capital expenditures $ 350,025 $ 46,873 $ 396,898 2013 Gas Operations Construction Services Adjustments (b) Total Revenues from unaffiliated customers $ 1,300,154 $ 562,475 $ 1,862,629 Intersegment sales — 88,153 88,153 Total $ 1,300,154 $ 650,628 $ 1,950,782 Interest revenue $ 456 $ 5 $ 461 Interest expense $ 62,555 $ 1,145 $ 63,700 Depreciation and amortization $ 193,848 $ 42,969 $ 236,817 Income tax expense $ 65,377 $ 12,565 $ 77,942 Segment net income $ 124,169 $ 21,151 $ 145,320 Segment assets $ 4,272,029 $ 293,811 $ (666 ) $ 4,565,174 Capital expenditures $ 314,578 $ 49,698 $ 364,276 (a) Construction services segment assets included two liabilities that were netted against gas operations segment assets during consolidation in 2014. They are: Income taxes payable of $3.3 million, netted against income taxes receivable, net and deferred income taxes of $1.4 million, netted against deferred income taxes, net. Construction services segment assets exclude a long-term deferred tax benefit of $1.4 million, which was netted against gas operations segment deferred income taxes and investment tax credits, net during consolidation. Gas operations segment assets include a deferred income tax liability of $4.5 million, which was netted against a construction services segment asset for deferred income taxes, net during consolidation. (b) Construction services segment assets included income taxes payable of $666,000 in 2013, which was netted against gas operations segment income taxes receivable, net during consolidation. |
Quarterly Financial Data
Quarterly Financial Data | 12 Months Ended |
Dec. 31, 2015 | |
Quarterly Financial Information Disclosure [Abstract] | |
Quarterly Financial Data | Note 15 – Quarterly Financial Data (Unaudited) Quarter Ended March 31 June 30 September 30 December 31 (Thousand of dollars, except per share amounts) 2015 Operating revenues $ 734,220 $ 538,604 $ 505,396 $ 685,405 Operating income 129,556 25,047 16,143 117,586 Net income (loss) 71,879 5,063 (4,210 ) 66,698 Net income (loss) attributable to Southwest Gas Corporation 71,983 4,949 (4,734 ) 66,119 Basic earnings (loss) per common share* 1.54 0.11 (0.10 ) 1.40 Diluted earnings (loss) per common share* 1.53 0.10 (0.10 ) 1.38 2014 Operating revenues $ 608,396 $ 453,153 $ 432,475 $ 627,683 Operating income 127,065 26,755 18,290 112,373 Net income 70,697 9,627 1,927 58,897 Net income attributable to Southwest Gas Corporation 70,783 9,627 1,970 58,746 Basic earnings per common share* 1.52 0.21 0.04 1.26 Diluted earnings per common share* 1.51 0.21 0.04 1.25 2013 Operating revenues $ 613,505 $ 411,574 $ 387,346 $ 538,357 Operating income 138,394 28,908 6,141 100,772 Net income (loss) 80,674 10,067 (3,057 ) 57,189 Net income (loss) attributable to Southwest Gas Corporation 80,773 10,108 (2,864 ) 57,303 Basic earnings (loss) per common share* 1.75 0.22 (0.06 ) 1.24 Diluted earnings (loss) per common share* 1.73 0.22 (0.06 ) 1.22 * The sum of quarterly earnings (loss) per average common share may not equal the annual earnings (loss) per share due to the ongoing change in the weighted-average number of common shares outstanding. The demand for natural gas is seasonal, and it is the opinion of management that comparisons of earnings for interim periods do not reliably reflect overall trends and changes in the operations of the Company. Also, the timing of general rate relief can have a significant impact on earnings for interim periods. See Management’s Discussion and Analysis for additional discussion of operating results. Additionally, see Note 16 – Construction Services Noncontrolling Interests regarding allocation of earnings and Note 17 – Acquisition of Construction Services Businesses regarding the acquisition in the last quarter of 2014. |
Construction Services Noncontro
Construction Services Noncontrolling Interests | 12 Months Ended |
Dec. 31, 2015 | |
Noncontrolling Interest [Abstract] | |
Construction Services Noncontrolling Interests | Note 16 – Construction Services Noncontrolling Interests Associated with the agreement reached in conjunction with the acquisition of the Canadian constriction businesses, the previous owners of the acquired companies initially retained an approximate 10% equity interest in the Canadian-specific businesses. The agreement, associated with that approximate 10% equity interest, provided special dividend rights which entitled the sellers, as holders, to dividends equal to 3.4% of dividends paid at the level of Centuri, and subject to certain conditions, such interests could become exchangeable for a 3.4% equity interest in Centuri. In consideration of the underlying exchange rights of the original agreement, earnings attribution by Centuri to the previous owners also occurred in an amount equivalent to 3.4% of Centuri earnings since October 2014. During the third quarter of 2015, the sellers formally exercised their exchange rights under the terms of the original agreement. No new rights were conveyed to the noncontrolling parties as a result of the exchange and no new consideration was involved. The previous owners continue to be able to exit their investment retained by requiring the purchase of a portion of their interest commencing July 2017 and in incremental amounts each anniversary date thereafter. The shares subject to the election cumulate (if earlier elections are not made) such that 100% of their interest retained is subject to the election beginning in July 2022. Due to the continued ability of the noncontrolling parties to redeem their interest for cash, their interest continues to be presented on the Company’s Consolidated Balance Sheet at December 31, 2015 as a Redeemable noncontrolling interest, a category of mezzanine equity (temporary equity), in accordance with SEC guidance. However, that interest, previously associated with the Canadian businesses, is now formally an interest in Centuri. Significant changes in the value of the redeemable noncontrolling interest are recognized as they occur, and the carrying value is adjusted as necessary at each reporting date. Guidance by the SEC indicates that downward adjustments in the value of redeemable noncontrolling interests are only permitted to the extent that upward adjustments in value were previously recognized. A floor for the noncontrolling interest was originally set at the acquisition date (in October 2014). However, U.S. GAAP generally views changes in ownership interest, where the parent retains its controlling interest, as an equity transaction, whereby the carrying amount of the noncontrolling interest is adjusted to reflect the change in ownership interest in the subsidiary. In connection with the exchange rights being exercised during the third quarter, an updated valuation was conducted. A significant decrease in the value of the redeemable noncontrolling interest was recognized, due in part to the exchange option no longer being subject to probability estimates. In light of the U.S. GAAP requirement to adjust the carrying amount, a new floor was set for the redeemable noncontrolling interest at the exchange date (July 31, 2015), with a corresponding adjustment made to additional paid in capital of the Company. Future adjustments to the redemption value are not permitted below the new floor. The following depicts impacts to the balance of the redeemable noncontrolling interest between the indicated periods. Redeemable (Thousands of dollars): Balance, December 31, 2014 $ 20,042 Net Income (loss) attributable to redeemable noncontrolling interest 939 Foreign currency exchange translation adjustment (66 ) Centuri distribution to redeemable noncontrolling interest (99 ) Adjustment to redemption value (4,708 ) Balance, December 31, 2015 $ 16,108 The redemption value of the redeemable noncontrolling interest utilizes a market approach to determine a construction services enterprise value. Publicly traded “guideline” companies are identified by using a selection criteria, including actively traded equities, their financial solvency, and other factors. Once the guideline companies are determined, enterprise value is calculated using a weighted approach of projected earnings before interest expense and taxes (“EBIT”) and earnings before interest expense, taxes, and depreciation and amortization expense (“EBITDA”). After an estimated fair value is determined, it is multiplied by 3.4%. A discount is then applied due to limitations of the nonpublic noncontrolling interest being valued. Prior to the exchange rights being exercised in the third quarter of 2015, a Monte Carlo simulation methodology was used to assign a value to the redeemable noncontrolling interest. Each quarter, market changes in the guideline companies are considered and the weighted approach to projected EBIT and EBITDA, in relation to the guideline companies, is re-evaluated to determine if value changes are necessary at each quarterly reporting date. The negative adjustment to the redemption value in the table above reflects the sum of adjustments made during the year. Centuri also holds a 65% interest in a venture to market natural gas engine-driven heating, ventilating, and air conditioning (“HVAC”) technology and products. Centuri consolidates the entity (IntelliChoice Energy, LLC) as a majority-owned subsidiary. The interest is immaterial to the consolidated financial statements, but is identified as the Noncontrolling interest within Total equity on the Consolidated Balance Sheets. |
Acquisition of Construction Ser
Acquisition of Construction Services Businesses | 12 Months Ended |
Dec. 31, 2015 | |
Business Combinations [Abstract] | |
Acquisition of Construction Services Businesses | Note 17 – Acquisition of Construction Services Businesses In October 2014, the Company, through its subsidiaries, completed the acquisition of three privately held, affiliated construction businesses. The acquisition extended the construction services operations into Canada and provides additional opportunities for market expansion. Funding for the acquisition was primarily provided by a new $300 million secured revolving credit and term loan facility described in Note 7 – Long-Term Debt . The acquired companies comprise: (i) Link-Line Contractors Ltd., an Ontario corporation (“Link-Line”), (ii) W.S. Nicholls Construction, Inc., an Ontario corporation, as well as two additional companies also operating under the name W.S. Nicholls (collectively “W.S. Nicholls”); and (iii) via asset purchase, the business of Brigadier Pipelines Inc., a Delaware corporation, operating primarily in Pennsylvania (“Brigadier”). 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 in 2014. The Company’s allocation of the purchase price in 2014 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 the impacts of differences between Accounting Standards for Private Enterprises in Canada and U. S. GAAP applicable to public companies, as well as consideration of types of intangibles that were acquired, including non-competition agreements, customer relationships, trade names, and work backlog. The final purchase accounting has been completed. The October 1, 2014 fair values of assets acquired and liabilities assumed, revised during the first quarter of 2015, are as follows (in millions of dollars): Acquisition Measurement Revised Cash, cash equivalents, and restricted cash $ 3 $ — $ 3 Contracts receivable and other receivables 62 — 62 Property, plant and equipment 17 — 17 Other assets 17 (2 ) 15 Intangible assets 52 — 52 Goodwill 130 1 131 Total assets acquired 281 (1 ) 280 Current liabilities 39 1 40 Deferred income tax—long-term 17 — 17 Other long-term liabilities 4 — 4 Net assets acquired $ 221 $ (2 ) $ 219 The Company incurred and expensed acquisition costs of $5 million in 2014; no acquisition costs were incurred during 2015. The allocation of the purchase price of Link-Line, W.S. Nicholls, and Brigadier was accounted for in accordance with the applicable accounting guidance. Goodwill consisted of the value associated with the assembled workforce and consolidation of operations. When acquisition-date values were updated in the first quarter of 2015, as reflected in the table above, there was no significant overall impact to the Company’s Consolidated Balance Sheets. The unaudited pro forma consolidated financial information for fiscal 2014 (assuming the acquisition of Link-Line, W.S. Nicholls, and Brigadier occurred as of the beginning of fiscal 2014) is as follows (in thousands of dollars, except per share amounts): Year Ended Total operating revenues $ 2,295,318 Net income attributable to Southwest Gas Corporation $ 149,588 Basic earnings per share $ 3.22 Diluted earnings per share $ 3.19 |
Summary of Significant Accoun26
Summary of Significant Accounting Policies (Policies) | 12 Months Ended |
Dec. 31, 2015 | |
Accounting Policies [Abstract] | |
Nature of Operations | Nature of Operations. Note 17 – Acquisition of Construction Services Businesses for more information. |
Basis of Presentation | Basis of Presentation. |
Consolidation | Consolidation. Centuri, through its subsidiaries, holds a 65% interest in a venture to market natural gas engine-driven heating, ventilating, and air conditioning (“HVAC”) technology and products. Centuri consolidates the entity (IntelliChoice Energy, LLC). Centuri, through its subsidiaries, holds a 50% interest in W.S. Nicholls Western Construction LTD. (“Western”), a Canadian construction services company that is a variable interest entity. Centuri determined that it is not the primary beneficiary of the entity due to a shared-power structure; therefore, Centuri does not consolidate the entity and has recorded its investment, and results related thereto, using the equity method. The Company’s investment in Western totaled $14.7 million and $10.8 million at December 31, 2014 and 2015, respectively. Both periods include the impacts of foreign currency exchange translation adjustments. No dividends were paid during 2015. The equity method investment in Western is included in Other Property and Investments in the Consolidated Balance Sheets. Centuri’s maximum exposure to loss as a result of its involvement with Western is estimated at $14.7 million. The estimated maximum exposure to loss represents the maximum loss that would be absorbed by Centuri in the event that all of the assets of Western are deemed worthless. Centuri recorded earnings of $310,000 from this investment in 2015 which is included in Other Income (deductions) in the Consolidated Statements of Income. Centuri, through its subsidiaries, also has a 25% interest in CCI-TBN Toronto, Inc. and a 50% interest in Matheson-Nicholls Joint Venture. Any future changes to the values of these entities will be recorded by Centuri using the equity method. |
Net Utility Plant | Net Utility Plant. |
Other Property and Investments | Other Property and Investments. 2015 2014 Centuri property, equipment, and intangibles $ 423 $ 405 Centuri accumulated provision for depreciation and amortization (221 ) (187 ) Net cash surrender value of COLI policies 99 99 Other property 13 10 Total $ 314 $ 327 |
Deferred Purchased Gas Costs | Deferred Purchased Gas Costs. |
Prepaids and Other Current Assets | Prepaids and other current assets |
Income Taxes | Income Taxes. |
Cash and Cash Equivalents | Cash and Cash Equivalents. Significant non-cash investing activities for the natural gas operations segment included the following: Upon contract expiration, customer advances of approximately $3.1 million, $8.1 million, and $9.3 million during 2015, 2014, and 2013, respectively, were applied as contributions toward utility construction activity and represent non-cash investing activity. In 2014, investing activities included an $18.9 million non-cash investing outflow due to the equity of the noncontrolling interest associated with businesses acquired. In addition, a non-cash investing outflow activity of $10.8 million in 2014 related to acquisition consideration payable. |
Goodwill | Goodwill. Natural Construction Consolidated (In thousands of dollars) December 31, 2014 $ 10,095 $ 133,065 $ 143,160 Acquisition date adjustment — 1,380 1,380 Foreign currency translation adjustment — (18,395 ) (18,395 ) December 31, 2015 $ 10,095 $ 116,050 $ 126,145 |
Intangible Assets | Intangible Assets Centuri has $36.8 million and $48.2 million of intangible assets (varies due to foreign currency translation) at December 31, 2015 and 2014, respectively, as detailed in the following table (thousands of dollars): December 31, 2015 Gross Carrying Accumulated Net Carrying Customer relationships $ 31,226 $ (2,070 ) $ 29,156 Trade names and trademarks 8,621 (1,331 ) 7,290 Customer contracts backlog 1,606 (1,606 ) — Noncompete agreement 437 (110 ) 327 Total $ 41,890 $ (5,117 ) $ 36,773 December 31, 2014 Gross Carrying Accumulated Net Carrying Customer relationships $ 37,059 $ (524 ) $ 36,535 Trade names and trademarks 10,208 (241 ) 9,967 Customer contracts backlog 1,912 (724 ) 1,188 Noncompete agreement 519 (34 ) 485 Total $ 49,698 $ (1,523 ) $ 48,175 The intangible assets (other than goodwill and software-related intangibles) are included in Other property and investments in the Consolidated Balance Sheets. The estimated future amortization of the intangible assets for the next five years is as follows (in thousands): 2016 $ 2,809 2017 2,809 2018 2,605 2019 1,971 2020 1,906 See Note 2 – Utility Plant and Leases for additional information regarding natural gas operations intangible assets. |
Accumulated Removal Costs | Accumulated Removal Costs. Approved regulatory practices allow Southwest to include in depreciation expense a component to recover removal costs associated with utility plant retirements. In accordance with the Securities and Exchange Commission (“SEC”) position on presentation of these amounts, management reclassifies estimated removal costs from accumulated depreciation to accumulated removal costs within the liabilities section of the Consolidated Balance Sheets. Amounts fluctuate between periods depending on the level of replacement work performed, the estimated cost of removal in rates and the actual cost of removal experienced. |
Gas Operating Revenues | Gas Operating Revenues. The Company acts as an agent for state and local taxing authorities in the collection and remission of a variety of taxes, including sales and use taxes and surcharges. These taxes are not included in gas operating revenues. The Company uses the net classification method to report taxes collected from customers to be remitted to governmental authorities. |
Construction Revenues | Construction Revenues. |
Construction Expenses | Construction Expenses. |
Net Cost of Gas Sold | Net Cost of Gas Sold. |
Operations and Maintenance Expense | Operations and Maintenance Expense. |
Depreciation and Amortization | Depreciation and Amortization. Accumulated Removal Costs |
Allowance for Funds Used During Construction ("AFUDC") | Allowance for Funds Used During Construction (“AFUDC”). 2015 2014 2013 (In thousands) AFUDC: Debt portion $ 1,666 $ 1,228 $ 1,260 Equity portion 3,008 1,995 2,274 AFUDC capitalized as part of utility plant $ 4,674 $ 3,223 $ 3,534 |
Other Income (Deductions) | Other Income (Deductions). 2015 2014 2013 Change in COLI policies $ (500 ) $ 5,300 $ 12,400 Interest income 2,173 2,602 461 Equity AFUDC 3,008 1,995 2,274 Foreign currency transaction gain (loss) (824 ) (178 ) — Equity in earnings of unconsolidated investment - Western 310 107 — Miscellaneous income and (expense) (1,288 ) (2,719 ) (2,835 ) Total other income (deductions) $ 2,879 $ 7,107 $ 12,300 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 value components of COLI policies, as they progress towards the ultimate death benefits, are also recorded without tax consequences. |
Foreign Currency Translation | Foreign Currency Translation. |
Earnings Per Share | Earnings Per Share. 2015 2014 2013 (In thousands) Average basic shares 46,992 46,494 46,318 Effect of dilutive securities: Stock options 8 17 26 Performance shares 171 215 231 Restricted stock units 212 218 183 Average diluted shares 47,383 46,944 46,758 |
Recently Issued Accounting Standards Updates | Recently Issued Accounting Standards Updates. In August 2014, the FASB issued the update “Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern,” which requires management to assess a company’s ability to continue as a going concern and to provide related footnote disclosures in certain circumstances. Under the update, disclosures are required when conditions give rise to substantial doubt about a company’s ability to continue as a going concern within one year from the financial statement issuance date. The update is effective for the annual period ending after December 15, 2016, and all annual and interim periods thereafter. This update and changes thereto are not expected to have a material impact on the Company’s disclosures. In April 2015, the FASB issued the update “Interest—Imputation of Interest (Subtopic 835-30) Simplifying the Presentation of Debt Issuance Costs.” To simplify presentation of debt issuance costs, the amendments in this update require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. While balance sheet presentation is impacted by the update, the recognition and measurement of debt issuance costs are not. Retrospective application of the update is required. The amendments in this update are effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within fiscal years beginning after December 15, 2015. Early adoption of the amendments in this update is permitted for financial statements that have not been previously issued. The Company adopted this update as of December 31, 2015, as permitted. See Note 7 – Long-Term Debt for additional information. In May 2015, the FASB issued the update “Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share (or its Equivalent).” This guidance simplifies disclosure requirements relating to investments for which fair value is measured using the net asset value per share, or its equivalent. The update removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. Investments that calculate net asset value per share (or its equivalent), but for which the practical expedient is not applied, will continue to be included in the fair value hierarchy. The update removes the requirement to make certain disclosures for all investments that are eligible to be measured at fair value using the net asset value per share practical expedient. A reporting entity should continue to disclose information on investments for which fair value is measured at net asset value as a practical expedient to help users understand the nature and risks of the investments and whether the investments, if sold, are probable of being sold at amounts different from net asset value. The amendments in this update are effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods thereafter. Early application is permitted and the Company adopted this update as of December 31, 2015. See Note 10 – Pension and Other Postretirement Benefits for additional information. In November 2015, the FASB issued the update “Income Taxes (Topic 740)” in order to simplify the presentation of deferred income taxes. The update requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. The previous guidance required an entity to separate deferred income tax liabilities and assets into current and noncurrent amounts in a classified statement of financial position. This update is effective for financial statements issued for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early application is permitted and the Company adopted this update as of December 31, 2015. See Note 12 – Income Taxes for additional information. In January 2016, the FASB issued the update “Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” in order to improve the recognition and measurement of financial instruments. The update makes targeted improvements to existing U.S. GAAP by: 1) requiring equity investments to be measured at fair value with changes in fair value recognized in net income; 2) requiring the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes; 3) requiring separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements; 4) eliminating the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; and 5) requiring a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The update is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. All entities can early adopt the provision to record fair value changes for financial liabilities under the fair value option resulting from instrument-specific credit risk in other comprehensive income. The Company is evaluating what impact, if any, this update might have on its consolidated financial statements and disclosures. |
Subsequent Events | Subsequent Events. Management of the Company monitors events occurring after the balance sheet date and prior to the issuance of the financial statements to determine the impacts, if any, of events on the financial statements to be issued or disclosures to be made, and has reflected them where appropriate. |
Summary of Significant Accoun27
Summary of Significant Accounting Policies (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Accounting Policies [Abstract] | |
Schedule of Other Property and Investments | Other Property and Investments. 2015 2014 Centuri property, equipment, and intangibles $ 423 $ 405 Centuri accumulated provision for depreciation and amortization (221 ) (187 ) Net cash surrender value of COLI policies 99 99 Other property 13 10 Total $ 314 $ 327 |
Schedule of Goodwill | Natural Construction Consolidated (In thousands of dollars) December 31, 2014 $ 10,095 $ 133,065 $ 143,160 Acquisition date adjustment — 1,380 1,380 Foreign currency translation adjustment — (18,395 ) (18,395 ) December 31, 2015 $ 10,095 $ 116,050 $ 126,145 |
Summary of Intangible Assets | Centuri has $36.8 million and $48.2 million of intangible assets (varies due to foreign currency translation) at December 31, 2015 and 2014, respectively, as detailed in the following table (thousands of dollars): December 31, 2015 Gross Carrying Accumulated Net Carrying Customer relationships $ 31,226 $ (2,070 ) $ 29,156 Trade names and trademarks 8,621 (1,331 ) 7,290 Customer contracts backlog 1,606 (1,606 ) — Noncompete agreement 437 (110 ) 327 Total $ 41,890 $ (5,117 ) $ 36,773 December 31, 2014 Gross Carrying Accumulated Net Carrying Customer relationships $ 37,059 $ (524 ) $ 36,535 Trade names and trademarks 10,208 (241 ) 9,967 Customer contracts backlog 1,912 (724 ) 1,188 Noncompete agreement 519 (34 ) 485 Total $ 49,698 $ (1,523 ) $ 48,175 |
Schedule of Estimated Future Amortization of Intangible Assets | The estimated future amortization of the intangible assets for the next five years is as follows (in thousands): 2016 $ 2,809 2017 2,809 2018 2,605 2019 1,971 2020 1,906 |
Schedule of Capitalized and Debt Portion of AFUDC | Utility plant construction costs, including AFUDC, are recovered in authorized rates through depreciation when completed projects are placed into operation, and general rate relief is requested and granted. 2015 2014 2013 (In thousands) AFUDC: Debt portion $ 1,666 $ 1,228 $ 1,260 Equity portion 3,008 1,995 2,274 AFUDC capitalized as part of utility plant $ 4,674 $ 3,223 $ 3,534 |
Other Income (Deductions) | The following table provides the composition of significant items included in Other income (deductions) on the consolidated statements of income (thousands of dollars): 2015 2014 2013 Change in COLI policies $ (500 ) $ 5,300 $ 12,400 Interest income 2,173 2,602 461 Equity AFUDC 3,008 1,995 2,274 Foreign currency transaction gain (loss) (824 ) (178 ) — Equity in earnings of unconsolidated investment - Western 310 107 — Miscellaneous income and (expense) (1,288 ) (2,719 ) (2,835 ) Total other income (deductions) $ 2,879 $ 7,107 $ 12,300 |
Schedule of Earnings Per Share, Basic and Diluted | A reconciliation of the denominator used in the Basic and Diluted EPS calculations is shown in the following table. 2015 2014 2013 (In thousands) Average basic shares 46,992 46,494 46,318 Effect of dilutive securities: Stock options 8 17 26 Performance shares 171 215 231 Restricted stock units 212 218 183 Average diluted shares 47,383 46,944 46,758 |
Utility Plant and Leases (Table
Utility Plant and Leases (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Leases [Abstract] | |
Schedule of Net Utility Plant | Net utility plant as of December 31, 2015 and 2014 was as follows (thousands of dollars): December 31, 2015 2014 Gas plant: Storage $ 22,944 $ 22,531 Transmission 312,996 312,300 Distribution 4,935,730 4,655,640 General 365,865 356,072 Software and software-related intangibles 203,323 196,035 Other 14,059 14,021 5,854,917 5,556,599 Less: accumulated depreciation (2,084,007 ) (1,973,098 ) Acquisition adjustments, net 370 550 Construction work in progress 119,805 74,332 Net utility plant $ 3,891,085 $ 3,658,383 |
Schedule of Depreciation and Amortization Expense | Depreciation and amortization expense on gas plant, including intangibles, was as follows (thousands of dollars): 2015 2014 2013 Depreciation and amortization expense $ 201,233 $ 194,360 $ 185,283 |
Schedule of Rental Payments for Operating Leases | The table below presents Southwest’s rental payments and Centuri’s lease payments that are included in operating expenses (in thousands): 2015 2014 2013 Southwest Gas $ 4,186 $ 5,330 $ 8,308 Centuri 45,849 30,012 27,118 Consolidated rental payments/lease expense $ 50,035 $ 35,342 $ 35,426 |
Schedule of Future Minimum Lease Payments for Operating Leases | The following is a schedule of future minimum lease payments for significant non-cancelable operating leases (with initial or remaining terms in excess of one year) as of December 31, 2015 (thousands of dollars): Year Ending December 31, 2016 $ 6,836 2017 4,732 2018 2,993 2019 2,110 2020 1,473 Thereafter 3,583 Total minimum lease payments $ 21,727 |
Schedule of Capital Leases of Equipment | The amounts associated with capital leases of equipment as of December 31, 2015 and 2014 are as follows (thousands of dollars): December 31, 2015 2014 Capital leases of equipment $ 4,584 $ 5,763 Less: accumulated amortization (1,043 ) (287 ) Net capital leases $ 3,541 $ 5,476 |
Schedule of Future Minimum Lease Payments for Capital Leases | The following is a schedule of future minimum lease payments for non-cancelable capital leases (with initial or remaining terms in excess of one year) as of December 31, 2015 (thousands of dollars): Year Ending December 31, 2016 $ 1,469 2017 869 2018 494 2019 21 2020 — Thereafter — 2,853 Less: amount representing interest (223 ) Total minimum lease payments $ 2,630 |
Receivables and Related Allow29
Receivables and Related Allowances (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Receivables [Abstract] | |
Schedule of Accounts Receivable | The table below contains information about the gas utility customer accounts receivable balance (net of allowance) at December 31, 2015 and 2014, and the percentage of customers in each of the three states. December 31, 2015 December 31, 2014 Gas utility customer accounts receivable balance (in thousands) $ 151,775 $ 136,148 |
Schedule of Percent of Customers by State | December 31, 2015 Percent of customers by state Arizona 53 % Nevada 37 % California 10 % |
Schedule of Allowance for Uncollectibles | Activity in the allowance account for uncollectibles is summarized as follows (thousands of dollars): Allowance for Balance, December 31, 2012 $ 2,504 Additions charged to expense 3,583 Accounts written off, less recoveries (4,362 ) Balance, December 31, 2013 1,725 Additions charged to expense 4,146 Accounts written off, less recoveries (3,616 ) Balance, December 31, 2014 2,255 Additions charged to expense 4,113 Accounts written off, less recoveries (4,098 ) Balance, December 31, 2015 $ 2,270 |
Regulatory Assets and Liabili30
Regulatory Assets and Liabilities (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Regulated Operations [Abstract] | |
Schedule of Regulatory Assets and Liabilities | The following table represents existing regulatory assets and liabilities (thousands of dollars): December 31, 2015 2014 Regulatory assets: Accrued pension and other postretirement benefit costs (1) $ 384,647 $ 390,293 Unrealized net loss on non-trading derivatives (Swaps) (2) 5,486 5,425 Deferred purchased gas costs (3) 3,591 87,556 Accrued purchased gas costs (4) — 2,600 Unamortized premium on reacquired debt (5) 21,511 20,478 Other (6) 73,022 72,132 488,257 578,484 Regulatory liabilities: Deferred purchased gas costs (3) (45,601 ) — Accumulated removal costs (303,000 ) (304,000 ) Accrued purchased gas costs (4) (10,400 ) — Deferred gain on southern Nevada division operations facility (7) — (115 ) Unamortized gain on reacquired debt (8) (10,325 ) (10,862 ) Other (9) (36,631 ) (34,233 ) Net regulatory assets $ 82,300 $ 229,274 (1) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovery period is greater than five years. (See Note 10). (2) The following table details the regulatory assets/(liabilities) offsetting the derivatives (Swaps) at fair value in the Consolidated Balance Sheets (thousands of dollars). The actual amounts, when realized at settlement, become a component of purchased gas costs under the Company’s purchased gas adjustment (“PGA”) mechanisms. (See Note 13). Instrument Balance Sheet Location 2015 2014 Swaps Deferred charges and other assets $ 1,219 $ 363 Swaps Prepaids and other current assets 4 ,267 5,062 (3) Balance recovered or refunded on an ongoing basis with interest. (4) Asset included in Prepaids and other current assets and liability included in Other current liabilities on the Consolidated Balance Sheets. Balance recovered or refunded on an ongoing basis. (5) Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovered over life of debt instruments. (6) Other regulatory assets including deferred costs associated with rate cases, regulatory studies, and state mandated public purpose programs (including low income and conservation programs), as well as margin and interest-tracking accounts, amounts associated with accrued absence time, and deferred post-retirement benefits other than pensions. Recovery periods vary. (7) The amortization period ended October 2015. (8) Included in Other deferred credits on the Consolidated Balance Sheets. Amortized over life of debt instruments. (9) Other regulatory liabilities include amounts associated with income tax and gross-up. |
Other Comprehensive Income an31
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Equity [Abstract] | |
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) 2015 2014 2013 Before- Tax Tax Net-of- Before- Tax Tax Net-of- Tax Amount Before- Tax Tax Net-of- Defined benefit pension plans: Net actuarial gain/(loss) $ (30,519 ) $ 11,597 $ (18,922 ) $ (173,646 ) $ 65,985 $ (107,661 ) $ 100,345 $ (38,131 ) $ 62,214 Amortization of prior service cost 1,335 (507 ) 828 355 (135 ) 220 355 (135 ) 220 Amortization of net actuarial (gain)/loss 34,381 (13,065 ) 21,316 23,656 (8,989 ) 14,667 34,177 (12,987 ) 21,190 Prior service cost — — — (6,661 ) 2,531 (4,130 ) — — — Regulatory adjustment (5,646 ) 2,146 (3,500 ) 140,308 (53,317 ) 86,991 (123,630 ) 46,979 (76,651 ) Pension plans other comprehensive income (loss) (449 ) 171 (278 ) (15,988 ) 6,075 (9,913 ) 11,247 (4,274 ) 6,973 Forward-starting interest rate swaps (“FSIRS”) (designated hedging activities): Amounts reclassified into net income 3,344 (1,271 ) 2,073 3,345 (1,272 ) 2,073 3,345 (1,271 ) 2,074 FSIRS other comprehensive income (loss) 3,344 (1,271 ) 2,073 3,345 (1,272 ) 2,073 3,345 (1,271 ) 2,074 Foreign currency translation adjustments: Translation adjustments (1,954 ) — (1,954 ) (659 ) — (659 ) — — — Foreign currency other comprehensive income (loss) (1,954 ) — (1,954 ) (659 ) — (659 ) — — — Total other comprehensive income (loss) $ 941 $ (1,100 ) $ (159 ) $ (13,302 ) $ 4,803 $ (8,499 ) $ 14,592 $ (5,545 ) $ 9,047 (1) Tax amounts are calculated using a 38% rate. 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, as repatriation of earnings is not anticipated. |
Schedule of Estimated Amounts Amortized from Accumulated Other Comprehensive Income or Regulatory Assets into Net Periodic Benefit Cost | The estimated amounts that will be amortized from accumulated other comprehensive income or regulatory assets into net periodic benefit cost over the next year are summarized below (in thousands): Retirement plan net actuarial loss $ 25,000 SERP net actuarial loss 1,400 PBOP net actuarial loss 400 PBOP prior service cost 1,300 |
Rollforward of Accumulated Other Comprehensive Income | The following table represents a rollforward of AOCI, presented on the Company’s Consolidated Balance Sheets and its Consolidated Statements of Equity: AOCI—Rollforward (Thousands of dollars) Defined Benefit Plans (Note 10) FSIRS (Note 13) Foreign Currency Items Before- Tax Tax After- Tax Before- Tax Tax After- Tax Before- Tax Tax After- Tax AOCI Beginning Balance AOCI December 31, 2014 $ (57,211) $ 21,740 $ (35,471 ) $ (22,688 ) $ 8,621 $ (14,067 ) $ (637 ) $ — $ (637 ) $ (50,175 ) Net actuarial gain/(loss) (30,519 ) 11,597 (18,922 ) — — — — — — (18,922 ) Translation adjustments — — — — — — (1,954 ) — (1,954 ) (1,954 ) Other comprehensive income before reclassifications (30,519 ) 11,597 (18,922 ) — — — (1,954 ) — (1,954 ) (20,876 ) FSIRS amounts reclassified from AOCI (1) — — — 3,344 (1,271 ) 2,073 — — — 2,073 Amortization of prior service cost (2) 1,335 (507 ) 828 — — — — — — 828 Amortization of net actuarial loss (2) 34,381 (13,065 ) 21,316 — — — — — — 21,316 Regulatory adjustment (3) (5,646 ) 2,146 (3,500 ) — — — — — — (3,500 ) Net current period other comprehensive income (loss) (449 ) 171 (278 ) 3,344 (1,271 ) 2,073 (1,954 ) — (1,954 ) (159 ) Less: Translation adjustment attributable to redeemable noncontrolling interest — — — — — — (66 ) — (66 ) (66 ) Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation (449 ) 171 (278 ) 3,344 (1,271 ) 2,073 (1,888 ) — (1,888 ) (93 ) Ending Balance AOCI December 31, 2015 $ (57,660 ) $ 21,911 $ (35,749 ) $ (19,344 ) $ 7,350 $ (11,994 ) $ (2,525 ) $ — $ (2,525 ) $ (50,268 ) (1) The FSIRS reclassification amounts are included in the Net interest deductions line item on the Consolidated Statements of Income. (2) These AOCI components are included in the computation of net periodic benefit cost (see Note 10 – Pension and Other Postretirement Benefits 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 the Deferred charges and other assets line item on the Consolidated Balance Sheets). |
Amount Recognized Before Income Tax in Accumulated Other Comprehensive Income | The following table represents amounts (before income tax impacts) included in Accumulated other comprehensive income (in the table above), that have not yet been recognized in net periodic benefit cost as of December 31, 2015 and 2014: Amounts Recognized in AOCI (Before Tax) (Thousands of dollars) 2015 2014 Net actuarial (loss) gain $ (435,269 ) $ (439,131 ) Prior service cost (7,038 ) (8,373 ) Less: amount recognized in regulatory assets 384,647 390,293 Recognized in AOCI $ (57,660 ) $ (57,211 ) |
Long-Term Debt (Tables)
Long-Term Debt (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Debt Disclosure [Abstract] | |
Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt | Since 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. December 31, 2015 2014 Carrying Market Carrying Market (Thousands of dollars) Debentures: Notes, 4.45%, due 2020 $ 125,000 $ 130,273 $ 125,000 $ 133,403 Notes, 6.1%, due 2041 125,000 141,581 125,000 157,290 Notes, 3.875%, due 2022 250,000 253,600 250,000 262,030 Notes, 4.875%, due 2043 250,000 251,483 250,000 280,903 8% Series, due 2026 75,000 97,035 75,000 102,296 Medium-term notes, 7.59% series, due 2017 25,000 26,253 25,000 27,573 Medium-term notes, 7.78% series, due 2022 25,000 29,855 25,000 31,144 Medium-term notes, 7.92% series, due 2027 25,000 31,890 25,000 33,695 Medium-term notes, 6.76% series, due 2027 7,500 8,684 7,500 9,156 Unamortized discount and debt issuance costs (6,137 ) (6,604 ) 901,363 900,896 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 Fixed-rate bonds: 5.25% 2003 Series D, due 2038 — — 20,000 20,277 5.00% 2004 Series B, due 2033 — — 31,200 31,223 4.85% 2005 Series A, due 2035 100,000 100,452 100,000 100,071 4.75% 2006 Series A, due 2036 24,855 25,130 24,855 25,399 Unamortized discount and debt issuance costs (3,946 ) (5,964 ) 320,909 370,091 Centuri term loan facility 112,571 112,665 142,071 143,021 Unamortized debt issuance costs (692 ) (816 ) 111,879 141,255 Centuri secured revolving credit facility 60,627 60,724 57,196 57,320 Centuri other debt obligations 25,901 26,059 31,128 31,127 1,570,679 1,650,566 Less: current maturities (19,475 ) (19,192 ) Long-term debt, less current maturities $ 1,551,204 $ 1,631,374 |
Summary of Effective Interest Rates on Variable-Rate IDRBs | The effective interest rates on the variable-rate IDRBs are included in the table below: December 31, 2015 December 31, 2014 2003 Series A 0.87 % 0.85 % 2008 Series A 0.87 % 0.90 % 2009 Series A 0.75 % 0.89 % Tax-exempt Series A 0.81 % 0.84 % |
Estimated Maturities of Long-Term Debt | Estimated maturities of long-term debt for the next five years are (in thousands): 2016 $ 19,475 2017 42,245 2018 14,906 2019 142,452 2020 275,238 |
Pension and Other Postretirem33
Pension and Other Postretirement Benefits (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Compensation and Retirement Disclosure [Abstract] | |
Cost of Retirement Plan | The cost of the Southwest plan is listed below (in thousands): 2015 2014 2013 Employee Investment Plan cost $ 5,072 $ 4,816 $ 4,850 |
Schedule of Allocation of Plan Assets | At December 31, 2015, the percentage ranges of the target portfolio are: Type of Investment Percentage Range Equity securities 59 to 71 Debt securities 31 to 37 Other up to 5 |
Schedule of Assumptions Used | The rates are presented in the table below: December 31, 2015 December 31, 2014 Discount rate 4.50 % 4.25 % Weighted-average rate of compensation increase 3.25 % 2.75 % Asset return assumption 7.25 % 7.75 % |
Schedule of Amounts Recognized in Balance Sheet and Income Statement | The following table sets forth the retirement plan, SERP, and PBOP funded statuses and amounts recognized on the Consolidated Balance Sheets and Consolidated Statements of Income. 2015 2014 Qualified Retirement Plan SERP PBOP Qualified SERP PBOP (Thousands of dollars) Change in benefit obligations Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO) $ 1,060,240 $ 41,176 $ 72,202 $ 886,714 $ 36,143 $ 58,020 Service cost 25,123 320 1,641 21,360 292 1,101 Interest cost 44,229 1,695 2,999 43,440 1,745 2,829 Plan amendments — — — — — 6,661 Actuarial loss (gain) (44,553 ) 2,322 (3,251 ) 144,606 5,459 4,567 Benefits paid (40,222 ) (2,793 ) (959 ) (35,880 ) (2,463 ) (976 ) Benefit obligation at end of year (PBO/PBO/APBO) 1,044,817 42,720 72,632 1,060,240 41,176 72,202 Change in plan assets Market value of plan assets at beginning of year 754,796 — 44,892 719,944 — 42,314 Actual return on plan assets (13,694 ) — (1,034 ) 34,732 — 2,859 Employer contributions 36,000 2,793 — 36,000 2,463 — Benefits paid (40,222 ) (2,793 ) (274 ) (35,880 ) (2,463 ) (281 ) Market value of plan assets at end of year 736,880 — 43,584 754,796 — 44,892 Funded status at year end $ (307,937 ) $ (42,720 ) $ (29,048 ) $ (305,444 ) $ (41,176 ) $ (27,310 ) Weighted-average assumptions (benefit obligation) Discount rate 4.50 % 4.50 % 4.50 % 4.25 % 4.25 % 4.25 % Weighted-average rate of compensation increase 3.25 % 3.25 % N/A 2.75 % 2.75 % N/A |
Schedule of Accumulated Benefit Obligation | The accumulated benefit obligation for the retirement plan and the SERP is presented below (in thousands): December 31, 2015 December 31, 2014 Retirement plan $ 922,992 $ 886,215 SERP 39,270 39,125 |
Schedule of Expected Benefit Payments | Benefits expected to be paid for the pension, PBOP, and the SERP over the next 10 years are as follows (in millions): 2016 2017 2018 2019 2020 2021-2025 Pension $44.0 $45.5 $47.2 $48.9 $50.5 $283.5 PBOP 3.9 4.1 4.3 4.5 4.5 21.3 SERP 2.8 2.8 2.8 2.9 2.9 14.1 |
Schedule of Net Periodic Benefit Cost and Weighted-Average Assumptions | Components of net periodic benefit cost Qualified Retirement Plan SERP PBOP 2015 2014 2013 2015 2014 2013 2015 2014 2013 (Thousands of dollars) Service cost $ 25,123 $ 21,360 $ 23,056 $ 320 $ 292 $ 373 $ 1,641 $ 1,101 $ 1,220 Interest cost 44,229 43,440 37,607 1,695 1,745 1,535 2,999 2,829 2,482 Expected return on plan assets (57,808 ) (53,342 ) (49,840 ) — — — (3,464 ) (3,264 ) (2,824 ) Amortization of prior service cost — — — — — — 1,335 355 355 Amortization of net actuarial loss 32,743 22,873 32,261 1,293 783 971 345 — 945 Net periodic benefit cost $ 44,287 $ 34,331 $ 43,084 $ 3,308 $ 2,820 $ 2,879 $ 2,856 $ 1,021 $ 2,178 Weighted-average assumptions (net benefit cost) Discount rate 4.25 % 5.00 % 4.25 % 4.25 % 5.00 % 4.25 % 4.25 % 5.00 % 4.25 % Expected return on plan assets 7.75 % 7.75 % 8.00 % 7.75 % 7.75 % 8.00 % 7.75 % 7.75 % 8.00 % Weighted-average rate of compensation increase 2.75 % 3.25 % 2.75 % 2.75 % 3.25 % 2.75 % N/A N/A N/A |
Schedule of Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income | Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income 2015 2014 2013 Total Qualified SERP PBOP Total Qualified SERP PBOP Total Qualified SERP PBOP (Thousands of dollars) Net actuarial loss (gain) (a) $ 30,519 $ 26,949 $ 2,322 $ 1,248 $ 173,646 $ 163,215 $ 5,460 $ 4,971 $ (100,345 ) $ (91,115 ) $ (662 ) $ (8,568 ) Amortization of prior service cost (b) (1,335 ) — — (1,335 ) (355 ) — — (355 ) (355 ) — — (355 ) Amortization of net actuarial loss (b) (34,381 ) (32,743 ) (1,293 ) (345 ) (23,656 ) (22,872 ) (784 ) — (34,177 ) (32,261 ) (971 ) (945 ) Prior service cost — — — — 6,661 — — 6,661 — — — — Regulatory adjustment 5,646 5,214 — 432 (140,308 ) (129,031 ) — (11,277 ) 123,630 113,762 — 9,868 Recognized in other comprehensive (income) loss 449 (580 ) 1,029 — 15,988 11,312 4,676 — (11,247 ) (9,614 ) (1,633 ) — Net periodic benefit costs recognized in net income 50,451 44,287 3,308 2,856 38,172 34,331 2,820 1,021 48,141 43,084 2,879 2,178 Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss $ 50,900 $ 43,707 $ 4,337 $ 2,856 $ 54,160 $ 45,643 $ 7,496 $ 1,021 $ 36,894 $ 33,470 $ 1,246 $ 2,178 The table above discloses the net gain or loss and prior service cost recognized in other comprehensive income, separated into (a) amounts initially recognized in other comprehensive income, and (b) amounts subsequently recognized as adjustments to other comprehensive income as those amounts are amortized as components of net periodic benefit cost. |
Schedule of Fair Value of Plan Assets | The following table sets forth, by level within the three-level fair value hierarchy, the fair values of the assets of the qualified pension plan and the PBOP as of December 31, 2015 and December 31, 2014. The SERP has no assets. The FASB issued guidance in 2015, which the Company has adopted early as permitted, removing the requirement to categorize assets in the fair value hierarchy that are measured using the net asset value (“NAV”) practical expedient. See note (3) to the table below. Based on this guidance, no Level 3 assets existed (nor are reflected in the table below) at December 31, 2015 and December 31, 2014. December 31, 2015 December 31, 2014 Qualified PBOP Total Qualified PBOP Total Assets at fair value (thousands of dollars): Level 1 – Quoted prices in active markets for identical financial assets Common stock Agriculture $ 7,021 $ 209 $ 7,230 $ 6,661 $ 198 $ 6,859 Capital equipment 533 16 549 2,222 66 2,288 Chemicals/materials 3,304 98 3,402 5,233 155 5,388 Consumer goods 41,035 1,221 42,256 41,731 1,238 42,969 Energy and mining 11,066 329 11,395 18,502 549 19,051 Finance/insurance 29,957 892 30,849 20,685 613 21,298 Healthcare 37,930 1,129 39,059 37,846 1,122 38,968 Information technology 29,229 870 30,099 25,881 767 26,648 Services 12,341 367 12,708 28,846 855 29,701 Telecommunications/internet/media 25,883 770 26,653 18,498 549 19,047 Other 9,043 269 9,312 10,958 325 11,283 Real estate investment trusts 5,010 149 5,159 5,713 169 5,882 Mutual funds 87,483 23,985 111,468 86,159 24,567 110,726 Government fixed income securities 33,482 996 34,478 44,694 1,325 46,019 Preferred securities — — — 568 17 585 Futures contracts (7 ) — (7 ) — — — Total Level 1 Assets (1) $ 333,310 $ 31,300 $ 364,610 $ 354,197 $ 32,515 $ 386,712 Level 2 – Significant other observable inputs Government fixed income and mortgage backed securities $ 49,571 $ 1,475 $ 51,046 $ 48,312 $ 1,433 $ 49,745 Corporate fixed income securities Asset-backed and mortgage-backed 23,542 701 24,243 27,071 803 27,874 Banking 20,857 621 21,478 23,289 691 23,980 Insurance 4,896 146 5,042 6,182 183 6,365 Utilities 3,826 114 3,940 4,232 126 4,358 Other 30,995 922 31,917 23,120 686 23,806 Pooled funds and mutual funds 14,808 796 15,604 11,968 984 12,952 Real estate investment trusts 1,949 58 2,007 — — — State and local obligations 950 28 978 1,499 44 1,543 Preferred securities 554 17 571 — — — Convertible securities 196 6 202 — — — Total Level 2 assets (2) $ 152,144 $ 4,884 $ 157,028 $ 145,673 $ 4,950 $ 150,623 Total Plan assets at fair value $ 485,454 $ 36,184 $ 521,638 $ 499,870 $ 37,465 $ 537,335 Commingled equity funds (3) 250,511 7,455 257,966 259,235 7,687 266,922 Insurance company general account contracts (4) 3,719 — 3,719 4,003 — 4,003 Total Plan assets (5) $ 739,684 $ 43,639 $ 783,323 $ 763,108 $ 45,152 $ 808,260 (1) Common stock, Real Estate Investment Trusts, Mutual funds, and U.S. Government securities listed or regularly traded on a national securities exchange are valued at quoted market prices as of the last business day of the calendar year. The Mutual funds category above is an intermediate-term bond fund whose manager employs multiple concurrent strategies and takes only moderate risk in each, thereby reducing the risk of poor performance arising from any single source, and a balanced fund that invests in a diversified portfolio of common stocks, preferred stocks and fixed-income securities. Strategies utilized by the bond fund include duration management, yield curve or maturity structuring, sector rotation, and all bottom-up techniques including in-house credit and quantitative research. Strategies employed by the balanced fund include pursuit of regular income, conservation of principal, and an opportunity for long-term growth of principal and income. (2) The fair value of investments in debt securities with remaining maturities of one year or more is determined by dealers who make markets in such securities or by an independent pricing service, which considers yield or price of bonds of comparable quality, coupon, maturity, and type. The pooled funds and mutual funds are two collective short-term funds that invest in Treasury bills and money market funds. These funds are used as a temporary cash repository for the pension plan’s various investment managers. (3) The commingled equity funds include private equity funds that invest in domestic and international securities regularly traded on securities exchanges. These funds are shown in the above table at net asset value, which is the value of securities in the fund less the amount of any liabilities outstanding. Investment strategies employed by the funds include: • Domestic large capitalization value equities • International developed countries value and growth equities • Emerging markets equities • International small capitalization equities The terms and conditions under which shares in the commingled equity funds may be redeemed vary among the funds; the notice required ranges from one day to 30 days prior to the valuation date (month end). One of the commingled equity funds requires the payment of a minimal impact fee to be applied to redemptions and subscriptions of $5 million or greater; the relative fee diminishes the greater the transaction. Other such funds may impose fees to recover direct costs incurred by the fund at redemption, but are indeterminable prior to redemption. Early adoption of ASU No. 2015-07: (4) The insurance company general account contracts are annuity insurance contracts used to pay the pensions of employees who retired prior to 1989. The balance of the account disclosed in the above table is the contract value, which is the result of deposits, withdrawals, and interest credits. (5) The assets in the above table exceed the market value of plan assets shown in the funded status table by $2,859,000 (qualified retirement plan – $2,803,000, PBOP – $56,000) and $8,572,000 (qualified retirement plan – $8,312,000, PBOP – $260,000) for 2015 and 2014, respectively, which includes a payable for securities purchased, partially offset by receivables for interest, dividends, and securities sold. |
Stock-Based Compensation (Table
Stock-Based Compensation (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |
Schedule of Stock-Based Plan Compensation Expense, Including Cash Award | The table below shows total stock-based plan compensation expense, including the cash award, which was recognized in the Consolidated Statements of Income (in thousands): 2015 2014 2013 Stock-based compensation plan expense, net of related tax benefits $ 7,278 $ 8,130 $ 8,012 Stock-based compensation plan related tax benefits 4,461 4,983 4,910 |
Schedule of Stock Options Activity | The following tables summarize Company stock option plan activity and related information (thousands of options): 2015 2014 2013 Number of Weighted- Number of Weighted- Number of Weighted- Outstanding at the beginning of the year 36 $ 28.97 52 $ 27.57 125 $ 28.13 Exercised during the year (19 ) 26.69 (16 ) 24.31 (72 ) 28.44 Forfeited or expired during the year — — — — (1 ) 33.07 Outstanding and exercisable at year end 17 $ 31.64 36 $ 28.97 52 $ 27.57 |
Schedule of Aggregate Intrinsic Value of Outstanding and Exercisable Options | The aggregate intrinsic value of outstanding and exercisable options, and options that were exercised, are presented in the table below (in thousands): 2015 2014 2013 Outstanding and exercisable $ 394 $ 1,194 $ 1,473 Exercised 590 451 1,402 |
Summary of Market Prices of Common Stock | December 31, 2015 December 31, 2014 December 31, 2013 Market value of Southwest Gas stock $ 55.16 $ 61.81 $ 55.91 |
Schedule of Stock Options Outstanding and Exercisable | The following table summarizes information about stock options outstanding at December 31, 2015 (thousands of options): Options Outstanding and Exercisable Range of Number outstanding Weighted-average Weighted-average $29.08 to $33.07 17 0.5 Years $ 31.64 |
Schedule of Nonvested Performance and Restricted Stock Unit Plans | The following table summarizes the activity of the performance share stock and restricted stock/unit plans as of December 31, 2015 (thousands of shares): Performance Weighted- Restricted Weighted- Nonvested/unissued at beginning of year 271 $ 43.71 257 $ 41.22 Granted 80 63.09 73 63.09 Dividends 6 7 Forfeited or expired — — — — Vested and issued* (160 ) 43.12 (109 ) 46.65 Nonvested/unissued at December 31, 2015 197 $ 50.63 228 $ 44.36 * Includes shares for retiree payouts and those converted for taxes. |
Income Taxes (Tables)
Income Taxes (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Income Tax Disclosure [Abstract] | |
Summary of Income Before Taxes and Noncontrolling Interest for Domestic and Foreign Operations | The following is a summary of income before taxes and noncontrolling interest for domestic and foreign operations (thousands of dollars): Year ended December 31, 2015 2014 2013 U.S. $ 221,660 $ 221,471 $ 222,815 Foreign (2,328 ) (1,950 ) — Total income before income taxes $ 219,332 $ 219,521 $ 222,815 |
Summary of Income Tax Expense (Benefit) | Income tax expense (benefit) consists of the following (thousands of dollars): Year Ended December 31, 2015 2014 2013 Current: Federal $ 21,321 $ 1,739 $ 3,549 State 9,899 5,073 5,107 Foreign 650 2,193 — 31,870 9,005 8,656 Deferred: Federal 51,132 71,439 67,414 State (2,574 ) 614 1,872 Foreign (526 ) (2,685 ) — 48,032 69,368 69,286 Total income tax expense $ 79,902 $ 78,373 $ 77,942 |
Significant Components of Deferred Income Tax Expense (Benefit) | Deferred income tax expense (benefit) consists of the following significant components (thousands of dollars): Year Ended December 31, 2015 2014 2013 Deferred federal and state: Property-related items $ 65,931 $ 52,814 $ 62,737 Purchased gas cost adjustments (32,993 ) 15,049 16,189 Employee benefits 623 109 (2,769 ) All other deferred 15,332 2,257 (6,010 ) Total deferred federal and state 48,893 70,229 70,147 Deferred ITC, net (861 ) (861 ) (861 ) Total deferred income tax expense $ 48,032 $ 69,368 $ 69,286 |
Reconciliation of U.S Federal Statutory Rate to Consolidated Effective Tax Rate | A reconciliation of the U.S. federal statutory rate to the consolidated effective tax rate for 2013, 2014, and 2015 (and the sources of these differences and the effect of each) are summarized as follows: Year Ended December 31, 2015 2014 2013 U.S. federal statutory income tax rate 35.0 % 35.0 % 35.0 % Net state taxes 1.8 1.9 2.4 Property-related items 0.1 0.1 0.1 Tax credits (0.4 ) (0.5 ) (0.4 ) Company owned life insurance 0.1 (1.0 ) (2.1 ) All other differences (0.2 ) 0.2 — Consolidated effective income tax rate 36.4 % 35.7 % 35.0 % |
Deferred Tax Assets and Liabilities | Deferred tax assets and liabilities consist of the following (thousands of dollars): December 31, 2015 2014 Deferred tax assets: Deferred income taxes for future amortization of ITC $ 1,614 $ 2,146 Employee benefits 36,923 31,557 Alternative minimum tax credit 4,809 20,172 Net operating losses and credits 868 9,719 Interest rate swap 7,351 8,622 Other 24,636 25,872 Valuation allowance (499 ) (253 ) 75,702 97,835 Deferred tax liabilities: Property-related items, including accelerated depreciation 794,850 736,810 Regulatory balancing accounts 743 33,736 Unamortized ITC 2,549 3,410 Debt-related costs 5,497 5,066 Intangibles 9,547 12,792 Other 31,533 27,600 844,719 819,414 Net deferred tax liabilities 769,017 721,579 Current — (2,109 ) Noncurrent 769,017 723,688 Net deferred tax liabilities $ 769,017 $ 721,579 |
Reconciliation of Unrecognized Tax Benefits | A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (thousands of dollars): 2015 2014 Unrecognized tax benefits at beginning of year $ 305 $ — Gross increases-tax positions in prior period — 305 Gross decreases-tax positions in prior period (9 ) — Gross increases-current period tax positions — — Gross decreases-current period tax positions — — Settlements — — Lapse in statute of limitations — — Unrecognized tax benefits at end of year $ 296 $ 305 |
Derivatives and Fair Value Me36
Derivatives and Fair Value Measurements (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Fair Value Disclosures [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): December 31, 2015 December 31, 2014 Contract notional amounts 7,407 5,105 |
Amount of Gain or Losses Recognized in Income on Derivatives | The following table sets forth the gains and (losses) recognized on the Company’s Swaps (derivatives) for the years ended December 31, 2015, 2014, and 2013 and their location in the Consolidated Statements of Income: Gains (losses) recognized in income for derivatives not designated as hedging instruments: (Thousands of dollars) Instrument Location of Gain or (Loss) 2015 2014 2013 Swaps Net cost of gas sold $ (7,598 ) $ (2,363 ) $ 976 Swaps Net cost of gas sold 7,598 * 2,363 * (976 )* 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 Company’s Swaps and their location in the Consolidated Balance Sheets (thousands of dollars): Fair values of derivatives not designated as hedging instruments: December 31, 2015 Instrument Balance Sheet Location Asset Derivatives Liability Derivatives Net Swaps Other current liabilities $ — $ (4,267 ) $ (4,267 ) Swaps Other deferred credits 4 (1,223 ) (1,219 ) Total $ 4 $ (5,490 ) $ (5,486 ) December 31, 2014 Instrument Balance Sheet Location Asset Derivatives Liability Derivatives Net Total Swaps Other current liabilities $ — $ (5,062 ) $ (5,062 ) Swaps Other deferred credits — (363 ) (363 ) Total $ — $ (5,425 ) $ (5,425 ) |
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. Year ended December 31, Year ended December 31, Year ended December 31, (Thousands of dollars) Paid to counterparties $ 7,537 $ 829 $ 3,148 Received from counterparties $ — $ 4,713 $ 915 |
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 Consolidated Balance Sheets (thousands of dollars). December 31, 2015 Instrument Balance Sheet Location Net Total Swaps Prepaids and other current assets $ 4,267 Swaps Deferred charges and other assets 1,219 December 31, 2014 Instrument Balance Sheet Location Net Total Swaps Prepaids and other current assets $ 5,062 Swaps Deferred charges and other assets 363 |
Significant Other Observable Inputs | 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 Company’s financial assets and liabilities that were accounted for at fair value (see Note 10 – Pension and Other Post Retirement Benefits for definitions of the levels of the fair value hierarchy): Level 2—Significant other observable inputs December 31, 2015 December 31, 2014 (Thousands of dollars) Liabilities at fair value: Other current liabilities—Swaps $ (4,267 ) $ (5,062 ) Other deferred credits—Swaps (1,219 ) (363 ) Net Assets (Liabilities) $ (5,486 ) $ (5,425 ) |
Segment Information (Tables)
Segment Information (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Segment Reporting [Abstract] | |
Accounts Receivable for Services | Accounts receivable for these services, which are not eliminated during consolidation, are presented in the table below (in thousands). December 31, 2015 December 31, 2014 Accounts receivable for Centuri services $ 10,006 $ 9,169 |
Schedule of Revenues and Long-Lived Assets by Geographic Area | The following table presents the amount of revenues and long-lived assets for both segments by geographic area (thousands of dollars): December 31, December 31, Revenues (a) United States $ 2,289,133 $ 2,069,513 Canada 174,492 52,194 Total $ 2,463,625 $ 2,121,707 (a) Revenues are attributed to countries based on the location of customers. |
Schedule of Segment Reporting Information | The financial information pertaining to the natural gas operations and construction services segments for each of the three years in the period ended December 31, 2015 is as follows (thousands of dollars): 2015 Gas Operations Construction Services Adjustments Total Revenues from unaffiliated customers $ 1,454,639 $ 904,870 $ 2,359,509 Intersegment sales — 104,116 104,116 Total $ 1,454,639 $ 1,008,986 $ 2,463,625 Interest revenue $ 1,754 $ 419 $ 2,173 Interest expense $ 64,095 $ 7,784 $ 71,879 Depreciation and amortization $ 213,455 $ 56,656 $ 270,111 Income tax expense $ 61,355 $ 18,547 $ 79,902 Segment net income $ 111,625 $ 26,692 $ 138,317 Segment assets $ 4,822,845 $ 535,840 $ 5,358,685 Capital expenditures $ 438,289 $ 49,711 $ 488,000 2014 Gas Operations Construction Services Adjustments (a) Total Revenues from unaffiliated customers $ 1,382,087 $ 647,432 $ 2,029,519 Intersegment sales — 92,188 92,188 Total $ 1,382,087 $ 739,620 $ 2,121,707 Interest revenue $ 2,596 $ 6 $ 2,602 Interest expense $ 68,299 $ 3,770 $ 72,069 Depreciation and amortization $ 204,144 $ 48,883 $ 253,027 Income tax expense $ 63,597 $ 14,776 $ 78,373 Segment net income $ 116,872 $ 24,254 $ 141,126 Segment assets $ 4,652,307 $ 566,589 $ (10,599 ) $ 5,208,297 Capital expenditures $ 350,025 $ 46,873 $ 396,898 2013 Gas Operations Construction Services Adjustments (b) Total Revenues from unaffiliated customers $ 1,300,154 $ 562,475 $ 1,862,629 Intersegment sales — 88,153 88,153 Total $ 1,300,154 $ 650,628 $ 1,950,782 Interest revenue $ 456 $ 5 $ 461 Interest expense $ 62,555 $ 1,145 $ 63,700 Depreciation and amortization $ 193,848 $ 42,969 $ 236,817 Income tax expense $ 65,377 $ 12,565 $ 77,942 Segment net income $ 124,169 $ 21,151 $ 145,320 Segment assets $ 4,272,029 $ 293,811 $ (666 ) $ 4,565,174 Capital expenditures $ 314,578 $ 49,698 $ 364,276 (a) Construction services segment assets included two liabilities that were netted against gas operations segment assets during consolidation in 2014. They are: Income taxes payable of $3.3 million, netted against income taxes receivable, net and deferred income taxes of $1.4 million, netted against deferred income taxes, net. Construction services segment assets exclude a long-term deferred tax benefit of $1.4 million, which was netted against gas operations segment deferred income taxes and investment tax credits, net during consolidation. Gas operations segment assets include a deferred income tax liability of $4.5 million, which was netted against a construction services segment asset for deferred income taxes, net during consolidation. (b) Construction services segment assets included income taxes payable of $666,000 in 2013, which was netted against gas operations segment income taxes receivable, net during consolidation. |
Quarterly Financial Data (Table
Quarterly Financial Data (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Quarterly Financial Information Disclosure [Abstract] | |
Schedule of Quarterly Financial Information | Quarter Ended March 31 June 30 September 30 December 31 (Thousand of dollars, except per share amounts) 2015 Operating revenues $ 734,220 $ 538,604 $ 505,396 $ 685,405 Operating income 129,556 25,047 16,143 117,586 Net income (loss) 71,879 5,063 (4,210 ) 66,698 Net income (loss) attributable to Southwest Gas Corporation 71,983 4,949 (4,734 ) 66,119 Basic earnings (loss) per common share* 1.54 0.11 (0.10 ) 1.40 Diluted earnings (loss) per common share* 1.53 0.10 (0.10 ) 1.38 2014 Operating revenues $ 608,396 $ 453,153 $ 432,475 $ 627,683 Operating income 127,065 26,755 18,290 112,373 Net income 70,697 9,627 1,927 58,897 Net income attributable to Southwest Gas Corporation 70,783 9,627 1,970 58,746 Basic earnings per common share* 1.52 0.21 0.04 1.26 Diluted earnings per common share* 1.51 0.21 0.04 1.25 2013 Operating revenues $ 613,505 $ 411,574 $ 387,346 $ 538,357 Operating income 138,394 28,908 6,141 100,772 Net income (loss) 80,674 10,067 (3,057 ) 57,189 Net income (loss) attributable to Southwest Gas Corporation 80,773 10,108 (2,864 ) 57,303 Basic earnings (loss) per common share* 1.75 0.22 (0.06 ) 1.24 Diluted earnings (loss) per common share* 1.73 0.22 (0.06 ) 1.22 * The sum of quarterly earnings (loss) per average common share may not equal the annual earnings (loss) per share due to the ongoing change in the weighted-average number of common shares outstanding. |
Construction Services Noncont39
Construction Services Noncontrolling Interests (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Noncontrolling Interest [Abstract] | |
Summary of Redeemable Noncontrolling Interest | The following depicts impacts to the balance of the redeemable noncontrolling interest between the indicated periods. Redeemable (Thousands of dollars): Balance, December 31, 2014 $ 20,042 Net Income (loss) attributable to redeemable noncontrolling interest 939 Foreign currency exchange translation adjustment (66 ) Centuri distribution to redeemable noncontrolling interest (99 ) Adjustment to redemption value (4,708 ) Balance, December 31, 2015 $ 16,108 |
Acquisition of Construction S40
Acquisition of Construction Services Businesses (Tables) | 12 Months Ended |
Dec. 31, 2015 | |
Business Combinations [Abstract] | |
Revised Fair Values of Assets Acquired and Liabilities Assumed | The October 1, 2014 fair values of assets acquired and liabilities assumed, revised during the first quarter of 2015, are as follows (in millions of dollars): Acquisition Measurement Revised Cash, cash equivalents, and restricted cash $ 3 $ — $ 3 Contracts receivable and other receivables 62 — 62 Property, plant and equipment 17 — 17 Other assets 17 (2 ) 15 Intangible assets 52 — 52 Goodwill 130 1 131 Total assets acquired 281 (1 ) 280 Current liabilities 39 1 40 Deferred income tax—long-term 17 — 17 Other long-term liabilities 4 — 4 Net assets acquired $ 221 $ (2 ) $ 219 |
Schedule of Unaudited Pro Forma Consolidated Financial Information | The unaudited pro forma consolidated financial information for fiscal 2014 (assuming the acquisition of Link-Line, W.S. Nicholls, and Brigadier occurred as of the beginning of fiscal 2014) is as follows (in thousands of dollars, except per share amounts): Year Ended Total operating revenues $ 2,295,318 Net income attributable to Southwest Gas Corporation $ 149,588 Basic earnings per share $ 3.22 Diluted earnings per share $ 3.19 |
Summary of Significant Accoun41
Summary of Significant Accounting Policies - Additional Information (Detail) | 12 Months Ended | ||
Dec. 31, 2015USD ($)SegmentMarkets | Dec. 31, 2014USD ($) | Dec. 31, 2013USD ($) | |
Significant Accounting Policies [Line Items] | |||
Number of segments | Segment | 2 | ||
Earnings from equity method investment | $ 310,000 | $ 107,000 | |
Non-cash construction advances - non-cash investing item | 3,100,000 | 8,100,000 | $ 9,300,000 |
Non-cash investing outflow activity | 10,800,000 | ||
Goodwill impairment charges | 0 | 0 | |
Acquisition date adjustments to goodwill | 1,380,000 | ||
Brigadier [Member] | |||
Significant Accounting Policies [Line Items] | |||
Goodwill assigned for deductible tax purpose | $ 4,900,000 | ||
Non-controlling Interest [Member] | |||
Significant Accounting Policies [Line Items] | |||
Non-cash investing outflow activity | 18,900,000 | ||
Intellichoice Energy, LLC [Member] | |||
Significant Accounting Policies [Line Items] | |||
Subsidiaries holding interest percentage | 65.00% | ||
W.S. Nicholls Western Construction LTD. [Member] | |||
Significant Accounting Policies [Line Items] | |||
Investment amount | $ 10,800,000 | 14,700,000 | |
Dividends | 0 | ||
Exposure to loss as a result of its investment | 14,700,000 | ||
Earnings from equity method investment | $ 310,000 | ||
Matheson-Nicholls Joint Venture [Member] | |||
Significant Accounting Policies [Line Items] | |||
Subsidiaries holding interest percentage | 50.00% | ||
CCI-TBN Toronto, Inc [Member] | |||
Significant Accounting Policies [Line Items] | |||
Subsidiaries holding interest percentage | 25.00% | ||
Centuri Construction Group Inc [Member] | |||
Significant Accounting Policies [Line Items] | |||
Ownership percentage in subsidiary | 96.60% | ||
Number of major markets | Markets | 20 | ||
Intangible assets | $ 36,773,000 | 48,175,000 | |
Construction expenses | 7,700,000 | ||
Final settlement amount | 4,000,000 | ||
Loss on construction contract | $ 3,400,000 | ||
Centuri Construction Group Inc [Member] | W.S. Nicholls Western Construction LTD. [Member] | |||
Significant Accounting Policies [Line Items] | |||
Subsidiaries holding interest percentage | 50.00% | ||
Pooled Funds and Mutual Funds [Member] | Level 2 - Significant Other Observable Inputs [Member] | |||
Significant Accounting Policies [Line Items] | |||
Money market fund investments | $ 250,000 | 250,000 | |
Gas Pipe Materials and Supplies [Member] | |||
Significant Accounting Policies [Line Items] | |||
Gas pipe inventory and operating supplies | $ 24,000,000 | $ 23,000,000 |
Summary of Significant Accoun42
Summary of Significant Accounting Policies - Schedule of Other Property and Investments (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Investment [Line Items] | ||
Net cash surrender value of COLI policies | $ 99,000 | $ 99,000 |
Other property | 13,000 | 10,000 |
Total | 313,531 | 326,743 |
Centuri Construction Group Inc [Member] | ||
Investment [Line Items] | ||
Centuri property, equipment, and intangibles | 423,000 | 405,000 |
Centuri accumulated provision for depreciation and amortization | $ (221,000) | $ (187,000) |
Summary of Significant Accoun43
Summary of Significant Accounting Policies - Schedule of Goodwill (Detail) $ in Thousands | 12 Months Ended |
Dec. 31, 2015USD ($) | |
Goodwill [Line Items] | |
Goodwill, Beginning balance | $ 143,160 |
Acquisition date adjustment | 1,380 |
Foreign currency translation adjustment | (18,395) |
Goodwill, Ending balance | 126,145 |
Natural Gas Operations [Member] | |
Goodwill [Line Items] | |
Goodwill, Beginning balance | 10,095 |
Acquisition date adjustment | 0 |
Foreign currency translation adjustment | 0 |
Goodwill, Ending balance | 10,095 |
Construction Services [Member] | |
Goodwill [Line Items] | |
Goodwill, Beginning balance | 133,065 |
Acquisition date adjustment | 1,380 |
Foreign currency translation adjustment | (18,395) |
Goodwill, Ending balance | $ 116,050 |
Summary of Significant Accoun44
Summary of Significant Accounting Policies - Summary of Intangible Assets (Detail) - Centuri Construction Group Inc [Member] - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Finite-Lived Intangible Assets [Line Items] | ||
Gross Carrying Amount | $ 41,890 | $ 49,698 |
Accumulated Amortization | (5,117) | (1,523) |
Net Carrying Amount | 36,773 | 48,175 |
Customer Relationships [Member] | ||
Finite-Lived Intangible Assets [Line Items] | ||
Gross Carrying Amount | 31,226 | 37,059 |
Accumulated Amortization | (2,070) | (524) |
Net Carrying Amount | 29,156 | 36,535 |
Trade Names and Trademarks [Member] | ||
Finite-Lived Intangible Assets [Line Items] | ||
Gross Carrying Amount | 8,621 | 10,208 |
Accumulated Amortization | (1,331) | (241) |
Net Carrying Amount | 7,290 | 9,967 |
Customer Contracts Backlog [Member] | ||
Finite-Lived Intangible Assets [Line Items] | ||
Gross Carrying Amount | 1,606 | 1,912 |
Accumulated Amortization | (1,606) | (724) |
Net Carrying Amount | 1,188 | |
Non-compete Agreements [Member] | ||
Finite-Lived Intangible Assets [Line Items] | ||
Gross Carrying Amount | 437 | 519 |
Accumulated Amortization | (110) | (34) |
Net Carrying Amount | $ 327 | $ 485 |
Summary of Significant Accoun45
Summary of Significant Accounting Policies - Schedule of Estimated Future Amortization of Intangible Assets (Detail) $ in Thousands | Dec. 31, 2015USD ($) |
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] | |
2,016 | $ 2,809 |
2,017 | 2,809 |
2,018 | 2,605 |
2,019 | 1,971 |
2,020 | $ 1,906 |
Summary of Significant Accoun46
Summary of Significant Accounting Policies - Schedule of Capitalized and Debt Portion of AFUDC (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Public Utilities, Allowance for Funds Used During Construction, Net Increase [Abstract] | |||
Debt portion | $ 1,666 | $ 1,228 | $ 1,260 |
Equity portion | 3,008 | 1,995 | 2,274 |
AFUDC capitalized as part of utility plant | $ 4,674 | $ 3,223 | $ 3,534 |
Summary of Significant Accoun47
Summary of Significant Accounting Policies - Other Income (Deductions) (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Other Income and Expenses [Abstract] | |||
Change in COLI policies | $ (500) | $ 5,300 | $ 12,400 |
Interest income | 2,173 | 2,602 | 461 |
Equity AFUDC | 3,008 | 1,995 | 2,274 |
Foreign currency transaction gain (loss) | (824) | (178) | |
Equity in earnings of unconsolidated investment - Western | 310 | 107 | |
Miscellaneous income and (expense) | (1,288) | (2,719) | (2,835) |
Total other income (deductions) | $ 2,879 | $ 7,107 | $ 12,300 |
Summary of Significant Accoun48
Summary of Significant Accounting Policies - Schedule of Earnings Per Share, Basic and Diluted (Detail) - shares shares in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Weighted Average Number of Shares Outstanding, Diluted [Abstract] | |||
Average basic shares | 46,992 | 46,494 | 46,318 |
Stock options | 8 | 17 | 26 |
Performance shares | 171 | 215 | 231 |
Restricted stock units | 212 | 218 | 183 |
Average diluted shares | 47,383 | 46,944 | 46,758 |
Utility Plant and Leases - Sche
Utility Plant and Leases - Schedule of Net Utility Plant (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Public Utility, Property, Plant and Equipment [Line Items] | ||
Gas plant | $ 5,854,917 | $ 5,556,599 |
Less: accumulated depreciation | (2,084,007) | (1,973,098) |
Acquisition adjustments, net | 370 | 550 |
Construction work in progress | 119,805 | 74,332 |
Net utility plant | 3,891,085 | 3,658,383 |
Software and Software-related Intangibles [Member] | ||
Public Utility, Property, Plant and Equipment [Line Items] | ||
Gas plant | 203,323 | 196,035 |
Storage [Member] | ||
Public Utility, Property, Plant and Equipment [Line Items] | ||
Gas plant | 22,944 | 22,531 |
Transmission [Member] | ||
Public Utility, Property, Plant and Equipment [Line Items] | ||
Gas plant | 312,996 | 312,300 |
Distribution [Member] | ||
Public Utility, Property, Plant and Equipment [Line Items] | ||
Gas plant | 4,935,730 | 4,655,640 |
General [Member] | ||
Public Utility, Property, Plant and Equipment [Line Items] | ||
Gas plant | 365,865 | 356,072 |
Other [Member] | ||
Public Utility, Property, Plant and Equipment [Line Items] | ||
Gas plant | $ 14,059 | $ 14,021 |
Utility Plant and Leases - Addi
Utility Plant and Leases - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Public Utility, Property, Plant and Equipment [Line Items] | |||
Annual depreciation and amortization expense percentage | 3.60% | 3.60% | 3.60% |
Gas plant [Member] | |||
Public Utility, Property, Plant and Equipment [Line Items] | |||
Amortization of intangibles | $ 12.7 | $ 11.7 | $ 10.3 |
Utility Plant and Leases - Sc51
Utility Plant and Leases - Schedule of Depreciation and Amortization Expense (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Public Utility, Property, Plant and Equipment [Line Items] | |||
Depreciation and amortization expense | $ 270,111 | $ 253,027 | $ 236,817 |
Gas plant [Member] | |||
Public Utility, Property, Plant and Equipment [Line Items] | |||
Depreciation and amortization expense | $ 201,233 | $ 194,360 | $ 185,283 |
Utility Plant and Leases - Sc52
Utility Plant and Leases - Schedule of Rental Payments for Operating Leases (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Rental Payments And Lease Payments Included In Operating Expenses [Line Items] | |||
Consolidated rental payments/lease expense | $ 50,035 | $ 35,342 | $ 35,426 |
Southwest Gas [Member] | |||
Rental Payments And Lease Payments Included In Operating Expenses [Line Items] | |||
Consolidated rental payments/lease expense | 4,186 | 5,330 | 8,308 |
Centuri Construction Group Inc [Member] | |||
Rental Payments And Lease Payments Included In Operating Expenses [Line Items] | |||
Consolidated rental payments/lease expense | $ 45,849 | $ 30,012 | $ 27,118 |
Utility Plant and Leases - Sc53
Utility Plant and Leases - Schedule of Future Minimum Lease Payments for Operating Leases (Detail) $ in Thousands | Dec. 31, 2015USD ($) |
Leases [Abstract] | |
2,016 | $ 6,836 |
2,017 | 4,732 |
2,018 | 2,993 |
2,019 | 2,110 |
2,020 | 1,473 |
Thereafter | 3,583 |
Total minimum lease payments | $ 21,727 |
Utility Plant and Leases - Sc54
Utility Plant and Leases - Schedule of Capital Leases of Equipment (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Leases [Abstract] | ||
Capital leases of equipment | $ 4,584 | $ 5,763 |
Less: accumulated amortization | (1,043) | (287) |
Net capital leases | $ 3,541 | $ 5,476 |
Utility Plant and Leases - Sc55
Utility Plant and Leases - Schedule of Future Minimum Lease Payments for Capital Leases (Detail) $ in Thousands | Dec. 31, 2015USD ($) |
Leases [Abstract] | |
2,016 | $ 1,469 |
2,017 | 869 |
2,018 | 494 |
2,019 | 21 |
2,020 | 0 |
Thereafter | 0 |
Future minimum lease payments due | 2,853 |
Less: amount representing interest | (223) |
Total minimum lease payments | $ 2,630 |
Receivables and Related Allow56
Receivables and Related Allowances - Schedule of Accounts Receivable (Detail) - USD ($) $ in Thousands | 12 Months Ended | |
Dec. 31, 2015 | Dec. 31, 2014 | |
Receivables [Abstract] | ||
Gas utility customer accounts receivable balance | $ 151,775 | $ 136,148 |
Receivables and Related Allow57
Receivables and Related Allowances - Schedule of Percent of Customers by State (Detail) | 12 Months Ended |
Dec. 31, 2015 | |
Arizona [Member] | |
Receivables And Related Allowances [Line Items] | |
Percent of customers by state | 53.00% |
Nevada [Member] | |
Receivables And Related Allowances [Line Items] | |
Percent of customers by state | 37.00% |
California [Member] | |
Receivables And Related Allowances [Line Items] | |
Percent of customers by state | 10.00% |
Receivables and Related Allow58
Receivables and Related Allowances - Schedule of Allowance for Uncollectibles (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Receivables [Abstract] | |||
Beginning Balance | $ 2,255 | $ 1,725 | $ 2,504 |
Additions charged to expense | 4,113 | 4,146 | 3,583 |
Accounts written off, less recoveries | (4,098) | (3,616) | (4,362) |
Ending Balance | $ 2,270 | $ 2,255 | $ 1,725 |
Receivables and Related Allow59
Receivables and Related Allowances - Additional Information (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Receivables And Related Allowances [Line Items] | ||
Customer accounts receivable | $ 314,512 | $ 281,824 |
Centuri Construction Group Inc [Member] | ||
Receivables And Related Allowances [Line Items] | ||
Customer accounts receivable | $ 162,000 |
Regulatory Assets and Liabili60
Regulatory Assets and Liabilities - Schedule of Regulatory Assets and Liabilities (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets, total | $ 488,257 | $ 578,484 |
Net regulatory assets | 82,300 | 229,274 |
Accrued Pension and Other Postretirement Benefit Costs [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets, total | 384,647 | 390,293 |
Unrealized Net Loss on Non-trading Derivatives (Swaps) [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets, total | 5,486 | 5,425 |
Deferred Purchased Gas Costs [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets, total | 3,591 | 87,556 |
Regulatory liabilities, total | (45,601) | |
Accrued Purchased Gas Costs [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets, total | 2,600 | |
Regulatory liabilities, total | (10,400) | |
Unamortized Premium on Reacquired Debt [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets, total | 21,511 | 20,478 |
Other [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets, total | 73,022 | 72,132 |
Accumulated Removal Costs [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory liabilities, total | (303,000) | (304,000) |
Deferred Gain on Southern Nevada Division Operations Facility [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory liabilities, total | (115) | |
Unamortized Gain on Reacquired Debt [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory liabilities, total | (10,325) | (10,862) |
Other [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory liabilities, total | $ (36,631) | $ (34,233) |
Regulatory Assets and Liabili61
Regulatory Assets and Liabilities - Schedule of Regulatory Assets and Liabilities (Parenthetical) (Detail) - Swaps [Member] - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Deferred Charges and Other Assets [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets and liabilities offsetting derivatives at fair value | $ 1,219 | $ 363 |
Prepaids and Other Current Assets [Member] | ||
Regulatory Assets And Liabilities [Line Items] | ||
Regulatory assets and liabilities offsetting derivatives at fair value | $ 4,267 | $ 5,062 |
Other Comprehensive Income an62
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Equity [Abstract] | |||
Net actuarial gain/(loss), Before-Tax Amount | $ (30,519) | $ (173,646) | $ 100,345 |
Amortization of prior service cost, Before-Tax Amount | 1,335 | 355 | 355 |
Amortization of net actuarial (gain)/loss, Before-Tax Amount | 34,381 | 23,656 | 34,177 |
Prior service cost, Before-Tax Amount | 0 | (6,661) | 0 |
Regulatory adjustment, Before-Tax Amount | (5,646) | 140,308 | (123,630) |
Net current period other comprehensive income (loss), Defined Benefit Plans Before-Tax | (449) | (15,988) | 11,247 |
Amounts reclassified into net income, Before-Tax Amount | 3,344 | 3,345 | 3,345 |
FSIRS other comprehensive income (loss), Before-Tax Amount | 3,344 | 3,345 | 3,345 |
Translation adjustments, Before-Tax Amount | (1,954) | (659) | 0 |
Foreign currency other comprehensive income (loss), Before-Tax Amount | (1,954) | (659) | 0 |
Total other comprehensive income (loss), Before-Tax Amount | 941 | (13,302) | 14,592 |
Net actuarial gain/(loss), Tax (Expense) or Benefit | 11,597 | 65,985 | (38,131) |
Amortization of prior service cost, Tax (Expense) or Benefit | (507) | (135) | (135) |
Amortization of net actuarial (gain)/loss, Tax (Expense) or Benefit | (13,065) | (8,989) | (12,987) |
Prior service cost, Tax (Expense) or Benefit | 0 | 2,531 | 0 |
Regulatory adjustment, Tax (Expense) or Benefit | 2,146 | (53,317) | 46,979 |
Pension plans other comprehensive income (loss), Tax (Expense) or Benefit | 171 | 6,075 | (4,274) |
Amounts reclassified into net income, Tax (Expense) or Benefit | (1,271) | (1,272) | (1,271) |
FSIRS other comprehensive income (loss), Tax (Expense) or Benefit | (1,271) | (1,272) | (1,271) |
Translation adjustments, Tax (Expense) or Benefit | 0 | 0 | 0 |
Foreign currency other comprehensive income (loss), Tax (Expense) or Benefit | 0 | 0 | 0 |
Total other comprehensive income (loss), Tax (Expense) or Benefit | (1,100) | 4,803 | (5,545) |
Net actuarial gain/(loss), Net-of-Tax Amount | (18,922) | (107,661) | 62,214 |
Amortization of prior service cost, Net-of-Tax Amount | 828 | 220 | 220 |
Amortization of net actuarial (gain)/loss, Defined Benefit Plans After-Tax | 21,316 | 14,667 | 21,190 |
Prior service cost, Net-of-Tax Amount | (4,130) | ||
Regulatory adjustment, Net-of-Tax Amount | (3,500) | 86,991 | (76,651) |
Pension plans other comprehensive income (loss), Net-of-Tax Amount | (278) | (9,913) | 6,973 |
Amounts reclassified into net income | 2,073 | 2,073 | 2,074 |
FSIRS other comprehensive income (loss), Net-of-Tax Amount | 2,073 | 2,073 | 2,074 |
Translation adjustments, Net-of-Tax Amount | (1,954) | (659) | |
Foreign currency other comprehensive income (loss), Net-of-Tax Amount | (1,954) | (659) | |
Total other comprehensive income (loss), net of tax | $ (159) | $ (8,499) | $ 9,047 |
Other Comprehensive Income an63
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) (Parenthetical) (Detail) | 12 Months Ended |
Dec. 31, 2015USD ($) | |
Equity [Abstract] | |
Other comprehensive income loss, effective income tax rate | 38.00% |
Tax expense or benefit for currency translation adjustment | $ 0 |
Other Comprehensive Income an64
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - Schedule of Estimated Amounts Amortized from Accumulated Other Comprehensive Income or Regulatory Assets into Net Periodic Benefit Cost (Detail) $ in Thousands | 12 Months Ended |
Dec. 31, 2015USD ($) | |
Qualified Retirement Plan [Member] | |
Defined Benefit Plan Disclosure [Line Items] | |
Retirement plan net actuarial loss | $ 25,000 |
SERP [Member] | |
Defined Benefit Plan Disclosure [Line Items] | |
Retirement plan net actuarial loss | 1,400 |
PBOP [Member] | |
Defined Benefit Plan Disclosure [Line Items] | |
Retirement plan net actuarial loss | 400 |
PBOP prior service cost | $ 1,300 |
Other Comprehensive Income an65
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - Rollforward of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Equity [Abstract] | |||
Beginning Balance AOCI December 31, 2014, Defined Benefit Plans Before-Tax | $ (57,211) | ||
Net actuarial gain/(loss), Defined Benefit Plans Before-Tax | (30,519) | $ (173,646) | $ 100,345 |
Translation adjustments, Defined Benefit Plans Before-Tax | 0 | ||
Other comprehensive income before reclassifications, Defined Benefit Plans Before-Tax | (30,519) | ||
Amortization of prior service cost, Defined Benefit Plans Before-Tax | 1,335 | 355 | 355 |
Amortization of net actuarial loss, Defined Benefit Plans Before-Tax | 34,381 | 23,656 | 34,177 |
Regulatory adjustment, Defined Benefit Plans Before-Tax | (5,646) | 140,308 | (123,630) |
Net current period other comprehensive income (loss), Defined Benefit Plans Before-Tax | (449) | (15,988) | 11,247 |
Less: Translation adjustment attributable to redeemable noncontrolling interest, Defined Benefit Plans Before-Tax | 0 | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, Defined Benefit Plans Before-Tax | (449) | ||
Ending Balance AOCI December 31, 2015, Defined Benefit Plans Before-Tax | (57,660) | (57,211) | |
Beginning Balance AOCI December 31, 2014, Defined Benefit Plans Tax (Expense) Benefit | 21,740 | ||
Net actuarial gain/(loss), Tax (Expense) or Benefit | 11,597 | 65,985 | (38,131) |
Translation adjustments, Defined Benefit Plans Tax (Expense) Benefit | 0 | ||
Other comprehensive income before reclassifications, Defined Benefit Plans Tax (Expense) Benefit | 11,597 | ||
Amortization of prior service cost, Defined Benefit Plans Tax (Expense) Benefit | (507) | (135) | (135) |
Amortization of net actuarial loss, Defined Benefit Plans Tax (Expense) Benefit | (13,065) | (8,989) | (12,987) |
Regulatory adjustment, Defined Benefit Plans Tax (Expense) Benefit | 2,146 | (53,317) | 46,979 |
Pension plans other comprehensive income (loss), Tax (Expense) or Benefit | 171 | 6,075 | (4,274) |
Less: Translation adjustment attributable to redeemable noncontrolling interest, Defined Benefit Plans Tax (Expense) Benefit | 0 | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, Defined Benefit Plans Tax (Expense) Benefit | 171 | ||
Ending Balance AOCI December 31, 2015, Defined Benefit Plans Tax (Expense) Benefit | 21,911 | 21,740 | |
Beginning Balance AOCI December 31, 2014, Defined Benefit Plans After-Tax | (35,471) | ||
Net actuarial gain/(loss), Defined Benefit Plans After-Tax | (18,922) | (107,661) | 62,214 |
Translation adjustments, Defined Benefit Plans After-Tax | 0 | ||
Other comprehensive income before reclassifications, Defined Benefit Plans After-Tax | (18,922) | ||
Amortization of prior service cost, Defined Benefit Plans After-Tax | 828 | 220 | 220 |
Amortization of net actuarial (gain)/loss, Defined Benefit Plans After-Tax | 21,316 | 14,667 | 21,190 |
Regulatory adjustment, Defined Benefit Plans After-Tax | (3,500) | ||
Net defined benefit pension plans | (278) | (9,913) | 6,973 |
Less: Translation adjustment attributable to redeemable noncontrolling interest, Defined Benefit Plans After-Tax | 0 | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, Defined Benefit Plans After-Tax | (278) | ||
Ending Balance AOCI December 31, 2015, Defined Benefit Plans After-Tax | (35,749) | 35,471 | |
Beginning Balance AOCI December 31, 2014, FSIRS - Before-Tax | (22,688) | ||
Translation adjustments, FSIRS - Before-Tax | 0 | ||
Other comprehensive income before reclassifications, FSIRS - Before-Tax | 0 | ||
FSIRS amounts reclassified from AOCI, FSIRS - Before-Tax | 3,344 | 3,345 | 3,345 |
Net current period other comprehensive income (loss), FSIRS - Before-Tax | 3,344 | 3,345 | 3,345 |
Less: Translation adjustment attributable to redeemable noncontrolling interest, FSIRS - Before-Tax | 0 | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, FSIRS - Before-Tax | 3,344 | ||
Ending Balance AOCI December 31, 2015, FSIRS - Before-Tax | (19,344) | (22,688) | |
Beginning Balance AOCI December 31, 2014, FSIRS - Tax (Expense) Benefit | 8,621 | ||
Translation adjustments, FSIRS - Tax (Expense) Benefit | 0 | ||
Other comprehensive income before reclassifications, FSIRS - Tax (Expense) Benefit | 0 | ||
FSIRS amounts reclassified from AOCI, FSIRS - Tax (Expense) Benefit | (1,271) | (1,272) | (1,271) |
Net current period other comprehensive income (loss), FSIRS - Tax (Expense) Benefit | (1,271) | (1,272) | (1,271) |
Less: Translation adjustment attributable to redeemable noncontrolling interest, FSIRS - Tax (Expense) Benefit | 0 | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, FSIRS - Tax (Expense) Benefit | (1,271) | ||
Ending Balance AOCI December 31, 2015, FSIRS - Tax (Expense) Benefit | 7,350 | 8,621 | |
Beginning Balance AOCI December 31, 2014, FSIRS - After-Tax | (14,067) | ||
Translation adjustments, FSIRS - After-Tax | 0 | ||
Other comprehensive income before reclassifications | 0 | ||
FSIRS amounts reclassified from AOCI, FSIRS - After-Tax | 2,073 | 2,073 | 2,074 |
Net current period other comprehensive income (loss) | 2,073 | 2,073 | 2,074 |
Less: Translation adjustment attributable to redeemable noncontrolling interest | 0 | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, FSIRS - After-Tax | 2,073 | ||
Ending Balance AOCI December 31, 2015, FSIRS - After-Tax | (11,994) | (14,067) | |
Beginning Balance AOCI December 31, 2014, Foreign Currency Items Before-Tax | (637) | ||
Net actuarial gain (loss) | 0 | ||
Translation adjustments, Foreign Currency Items Before-Tax | (1,954) | (659) | 0 |
Other comprehensive income before reclassifications | (1,954) | (659) | 0 |
FSIRS amounts reclassified from AOCI, Foreign Currency Items Before-Tax | 0 | ||
Amortization of prior service cost, Foreign Currency Items Before-Tax | 0 | ||
Amortization of net actuarial loss, Foreign Currency Items Before-Tax | 0 | ||
Regulatory adjustment, Foreign Currency Items Before-Tax | 0 | ||
Net current period other comprehensive income (loss) | (1,954) | ||
Less: Translation adjustment attributable to redeemable noncontrolling interest, Foreign Currency Items Before-Tax | (66) | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, Foreign Currency Items Before-Tax | (1,888) | (637) | |
Ending Balance AOCI December 31, 2015 | (2,525) | (637) | |
Beginning Balance AOCI December 31, 2014, Foreign Currency items - Tax (Expense) Benefit | 0 | ||
Net actuarial gain (loss) | 0 | ||
Translation adjustments, Foreign Currency items - Tax (Expense) Benefit | 0 | 0 | 0 |
Other comprehensive income before reclassifications, Foreign Currency items - Tax (Expense) Benefit | 0 | ||
FSIRS amounts reclassified from AOCI, Foreign Currency items - Tax (Expense) Benefit | 0 | ||
Amortization of prior service cost ,Foreign Currency items - Tax (Expense) Benefit | 0 | ||
Amortization of net actuarial loss, Foreign Currency items - Tax (Expense) Benefit | 0 | ||
Regulatory adjustment, Foreign Currency items - Tax (Expense) Benefit | 0 | ||
Net current period other comprehensive income (loss), Foreign Currency items - Tax (Expense) Benefit | 0 | ||
Less: Translation adjustment attributable to redeemable noncontrolling interest, Foreign Currency items - Tax (Expense) Benefit | 0 | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, Foreign Currency items - Tax (Expense) Benefit | 0 | 0 | 0 |
Ending Balance AOCI December 31, 2015, Foreign Currency items - Tax (Expense) Benefit | 0 | 0 | |
Beginning Balance AOCI December 31, 2014, Foreign Currency items - After-Tax | (637) | ||
Net actuarial gain (loss) | 0 | ||
Translation adjustments, Foreign Currency items - After-Tax | (1,954) | (659) | |
Other comprehensive income before reclassifications, Foreign Currency items - After-Tax | (1,954) | (659) | |
FSIRS amounts reclassified from AOCI, Foreign Currency items - After-Tax | 0 | ||
Amortization of prior service cost, Foreign Currency items - After-Tax | 0 | ||
Amortization of net actuarial loss, Foreign Currency items - After-Tax | 0 | ||
Regulatory adjustment, Foreign Currency items - After-Tax | 0 | ||
Net current period other comprehensive income (loss), Foreign Currency items - After-Tax | (1,954) | ||
Less: Translation adjustment attributable to redeemable noncontrolling interest, Foreign Currency items - After-Tax | (66) | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, Foreign Currency Items - After-Tax | (1,888) | ||
Ending Balance AOCI December 31, 2015, Foreign Currency items - After-Tax | (2,525) | (637) | |
Beginning Balance AOCI December 31, 2014, AOCI | (50,175) | ||
Net actuarial gain (loss) | (18,922) | (107,661) | 62,214 |
Translation adjustments, AOCI | (1,954) | ||
Other comprehensive income before reclassifications, AOCI | (20,876) | ||
Amounts reclassified into net income | 2,073 | 2,073 | 2,074 |
Amortization of prior service cost, AOCI | 828 | 220 | 220 |
Amortization of net actuarial loss | 21,316 | 14,667 | 21,190 |
Regulatory adjustment, AOCI | (3,500) | ||
Total other comprehensive income (loss), net of tax | (159) | (8,499) | $ 9,047 |
Less: Translation adjustment attributable to redeemable noncontrolling interest, AOCI | (66) | ||
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation, AOCI | (93) | ||
Ending Balance AOCI December 31, 2015, AOCI | $ (50,268) | $ (50,175) |
Other Comprehensive Income an66
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - Additional Information (Detail) $ in Millions | Dec. 31, 2015USD ($) |
Equity [Abstract] | |
Amount of FSIRS existing AOCI losses expected to reclassified income in next twelve months | $ 2.1 |
Other Comprehensive Income an67
Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - Amount Recognized Before Income Tax Associated with Defined Benefit Plans in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Accumulated Other Comprehensive Income (Loss) [Line Items] | ||
Less: amount recognized in regulatory assets | $ 488,257 | $ 578,484 |
Recognized in AOCI | 57,660 | 57,211 |
Defined Benefit Plans [Member] | ||
Accumulated Other Comprehensive Income (Loss) [Line Items] | ||
Net actuarial (loss) gain | (435,269) | (439,131) |
Prior service cost | (7,038) | (8,373) |
Less: amount recognized in regulatory assets | 384,647 | 390,293 |
Recognized in AOCI | $ (57,660) | $ (57,211) |
Common Stock - Additional Infor
Common Stock - Additional Information (Detail) - USD ($) | Mar. 10, 2015 | Dec. 31, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 |
Value of common stock | $ 100,000,000 | ||||
Net proceeds to Company | $ 35,396,000 | $ 405,000 | $ 1,635,000 | ||
Common stock issued through Stock Incentive Plan, Restricted Stock/Unit Plan, and Management Incentive Plan | 209,000 | ||||
BNY Mellon Capital Markets, LLC [Member] | |||||
Common stock sold through agent | 0 | 645,225 | |||
Net proceeds to Company | $ 35,167,584 | ||||
Agent commissions | 355,228 | ||||
Common stock available for sale under the program | $ 64,477,188 | $ 64,477,188 |
Long-Term Debt - Schedule of Ca
Long-Term Debt - Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Detail) - USD ($) | Dec. 31, 2015 | Dec. 31, 2014 |
Debt Instrument [Line Items] | ||
Unamortized debt issuance costs | $ (816,000) | |
Long-term Debt, Current and Noncurrent Abstract | ||
Less: current maturities | $ (19,475,000) | (19,192,000) |
Long-term debt, less current maturities | 1,551,204,000 | 1,631,374,000 |
Variable-rate bonds [Member] | 2009 Series A, due 2039 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt, fair value | 50,000,000 | 50,000,000 |
Carrying Amount [Member] | ||
Debt Instrument [Line Items] | ||
Unamortized debt issuance costs | (692,000) | (816,000) |
Total long-term debt | 1,570,679,000 | 1,650,566,000 |
Long-term Debt, Current and Noncurrent Abstract | ||
Less: current maturities | (19,475,000) | (19,192,000) |
Long-term debt, less current maturities | 1,551,204,000 | 1,631,374,000 |
Total long-term debt | 1,570,679,000 | 1,650,566,000 |
Carrying Amount [Member] | Centuri Secured Revolving Credit Facility [Member] | ||
Debt Instrument [Line Items] | ||
Centuri term loan/secured revolving credit facility | 60,627,000 | 57,196,000 |
Carrying Amount [Member] | IDRBs [Member] | ||
Debt Instrument [Line Items] | ||
Centuri term loan/secured revolving credit facility | 111,879,000 | 141,255,000 |
Unsecured debt | 320,909,000 | 370,091,000 |
Carrying Amount [Member] | Centuri Term Loan Facility [Member] | ||
Debt Instrument [Line Items] | ||
Centuri term loan/secured revolving credit facility | 112,571,000 | 142,071,000 |
Carrying Amount [Member] | Centuri Other Debt Obligations [Member] | ||
Debt Instrument [Line Items] | ||
Centuri other debt obligations | 25,901,000 | 31,128,000 |
Carrying Amount [Member] | Debentures [Member] | ||
Debt Instrument [Line Items] | ||
Unamortized discount and debt issuance costs | (6,137,000) | (6,604,000) |
Notes payable | 901,363,000 | 900,896,000 |
Carrying Amount [Member] | Debentures [Member] | Notes, 4.45%, due 2020 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 125,000,000 | 125,000,000 |
Carrying Amount [Member] | Debentures [Member] | Notes, 6.1%, due 2041 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 125,000,000 | 125,000,000 |
Carrying Amount [Member] | Debentures [Member] | Notes, 3.875%, due 2022 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 250,000,000 | 250,000,000 |
Carrying Amount [Member] | Debentures [Member] | Notes, 4.875%, due 2043 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 250,000,000 | 250,000,000 |
Carrying Amount [Member] | Debentures [Member] | 8% Series, due 2026 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 75,000,000 | 75,000,000 |
Carrying Amount [Member] | Debentures [Member] | Medium-term notes, 7.59% series, due 2017 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 25,000,000 | 25,000,000 |
Carrying Amount [Member] | Debentures [Member] | Medium-term notes, 7.78% series, due 2022 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 25,000,000 | 25,000,000 |
Carrying Amount [Member] | Debentures [Member] | Medium-term notes, 7.92% series, due 2027 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 25,000,000 | 25,000,000 |
Carrying Amount [Member] | Debentures [Member] | Medium-term notes, 6.76% series, due 2027 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable | 7,500,000 | 7,500,000 |
Carrying Amount [Member] | Debentures [Member] | Revolving Credit Facility and Commercial Paper [Member] | ||
Debt Instrument [Line Items] | ||
Line of credit facility | 150,000,000 | 150,000,000 |
Carrying Amount [Member] | Variable-rate bonds [Member] | Tax-exempt Series A, due 2028 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt | 50,000,000 | 50,000,000 |
Carrying Amount [Member] | Variable-rate bonds [Member] | 2003 Series A, due 2038 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt | 50,000,000 | 50,000,000 |
Carrying Amount [Member] | Variable-rate bonds [Member] | 2008 Series A, due 2038 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt | 50,000,000 | 50,000,000 |
Carrying Amount [Member] | Variable-rate bonds [Member] | 2009 Series A, due 2039 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt | 50,000,000 | 50,000,000 |
Carrying Amount [Member] | Fixed-Rate Bonds [Member] | ||
Debt Instrument [Line Items] | ||
Unamortized discount and debt issuance costs | (3,946,000) | (5,964,000) |
Carrying Amount [Member] | Fixed-Rate Bonds [Member] | 5.25% 2003 Series D, due 2038 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt | 20,000,000 | |
Carrying Amount [Member] | Fixed-Rate Bonds [Member] | 5.00% 2004 Series B, due 2033 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt | 31,200,000 | |
Carrying Amount [Member] | Fixed-Rate Bonds [Member] | 4.85% 2005 Series A, due 2035 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt | 100,000,000 | 100,000,000 |
Carrying Amount [Member] | Fixed-Rate Bonds [Member] | 4.75% 2006 Series A, due 2036 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt | 24,855,000 | 24,855,000 |
Market Value [Member] | ||
Debt Instrument [Line Items] | ||
Centuri term loan/secured revolving credit facility | 112,665,000 | 143,021,000 |
Centuri other debt obligations | 26,059,000 | 31,127,000 |
Market Value [Member] | Centuri Secured Revolving Credit Facility [Member] | ||
Debt Instrument [Line Items] | ||
Centuri term loan/secured revolving credit facility | 60,724,000 | 57,320,000 |
Market Value [Member] | Debentures [Member] | Notes, 4.45%, due 2020 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 130,273,000 | 133,403,000 |
Market Value [Member] | Debentures [Member] | Notes, 6.1%, due 2041 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 141,581,000 | 157,290,000 |
Market Value [Member] | Debentures [Member] | Notes, 3.875%, due 2022 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 253,600,000 | 262,030,000 |
Market Value [Member] | Debentures [Member] | Notes, 4.875%, due 2043 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 251,483,000 | 280,903,000 |
Market Value [Member] | Debentures [Member] | 8% Series, due 2026 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 97,035,000 | 102,296,000 |
Market Value [Member] | Debentures [Member] | Medium-term notes, 7.59% series, due 2017 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 26,253,000 | 27,573,000 |
Market Value [Member] | Debentures [Member] | Medium-term notes, 7.78% series, due 2022 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 29,855,000 | 31,144,000 |
Market Value [Member] | Debentures [Member] | Medium-term notes, 7.92% series, due 2027 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 31,890,000 | 33,695,000 |
Market Value [Member] | Debentures [Member] | Medium-term notes, 6.76% series, due 2027 [Member] | ||
Debt Instrument [Line Items] | ||
Notes payable, fair value disclosure | 8,684,000 | 9,156,000 |
Market Value [Member] | Debentures [Member] | Revolving Credit Facility and Commercial Paper [Member] | ||
Debt Instrument [Line Items] | ||
Line of credit facility, fair value | 150,000,000 | 150,000,000 |
Market Value [Member] | Variable-rate bonds [Member] | Tax-exempt Series A, due 2028 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt, fair value | 50,000,000 | 50,000,000 |
Market Value [Member] | Variable-rate bonds [Member] | 2003 Series A, due 2038 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt, fair value | 50,000,000 | 50,000,000 |
Market Value [Member] | Variable-rate bonds [Member] | 2008 Series A, due 2038 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt, fair value | 50,000,000 | 50,000,000 |
Market Value [Member] | Fixed-Rate Bonds [Member] | 5.25% 2003 Series D, due 2038 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt, fair value | 20,277,000 | |
Market Value [Member] | Fixed-Rate Bonds [Member] | 5.00% 2004 Series B, due 2033 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt, fair value | 31,223,000 | |
Market Value [Member] | Fixed-Rate Bonds [Member] | 4.85% 2005 Series A, due 2035 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt, fair value | 100,452,000 | 100,071,000 |
Market Value [Member] | Fixed-Rate Bonds [Member] | 4.75% 2006 Series A, due 2036 [Member] | ||
Debt Instrument [Line Items] | ||
Unsecured debt, fair value | $ 25,130,000 | $ 25,399,000 |
Long-Term Debt - Schedule of 70
Long-Term Debt - Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Parenthetical) (Detail) | 9 Months Ended | 12 Months Ended | ||
Sep. 30, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | May. 31, 2015 | |
5.25% 2003 Series D, due 2038 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 5.25% | |||
Debt instrument due date | Dec. 1, 2038 | |||
5.00% 2004 Series B, due 2033 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 5.00% | |||
Debt instrument due date | Dec. 1, 2033 | |||
Debentures [Member] | Notes, 4.45%, due 2020 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 4.45% | 4.45% | ||
Debt instrument due date | Dec. 1, 2020 | Dec. 1, 2020 | ||
Debentures [Member] | Notes, 6.1%, due 2041 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 6.10% | 6.10% | ||
Debt instrument due date | Feb. 15, 2041 | Feb. 15, 2041 | ||
Debentures [Member] | Notes, 3.875%, due 2022 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 3.875% | 3.875% | ||
Debt instrument due date | Apr. 1, 2022 | Apr. 1, 2022 | ||
Debentures [Member] | Notes, 4.875%, due 2043 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 4.875% | 4.875% | ||
Debt instrument due date | Oct. 1, 2043 | Oct. 1, 2043 | ||
Debentures [Member] | 8% Series, due 2026 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 8.00% | 8.00% | ||
Debt instrument due date | Aug. 1, 2026 | Aug. 1, 2026 | ||
Debentures [Member] | Medium-term notes, 7.59% series, due 2017 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 7.59% | 7.59% | ||
Debt instrument due date | Jan. 17, 2017 | Jan. 17, 2017 | ||
Debentures [Member] | Medium-term notes, 7.78% series, due 2022 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 7.78% | 7.78% | ||
Debt instrument due date | Feb. 3, 2022 | Feb. 3, 2022 | ||
Debentures [Member] | Medium-term notes, 7.92% series, due 2027 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 7.92% | 7.92% | ||
Debt instrument due date | Jun. 4, 2027 | Jun. 4, 2027 | ||
Debentures [Member] | Medium-term notes, 6.76% series, due 2027 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 6.76% | 6.76% | ||
Debt instrument due date | Sep. 24, 2027 | Sep. 24, 2027 | ||
Variable-rate bonds [Member] | Tax-exempt Series A, due 2028 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument due date | Dec. 1, 2028 | Dec. 1, 2028 | ||
Variable-rate bonds [Member] | 2003 Series A, due 2038 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument due date | Mar. 1, 2038 | Mar. 1, 2038 | ||
Variable-rate bonds [Member] | 2008 Series A, due 2038 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument due date | Mar. 1, 2038 | Mar. 1, 2038 | ||
Variable-rate bonds [Member] | Market Value [Member] | 2009 Series A, due 2039 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument due date | Dec. 1, 2039 | Dec. 1, 2039 | ||
Fixed-Rate Bonds [Member] | 5.25% 2003 Series D, due 2038 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 5.25% | 5.25% | ||
Debt instrument due date | Mar. 1, 2038 | Mar. 1, 2038 | ||
Fixed-Rate Bonds [Member] | 5.00% 2004 Series B, due 2033 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 5.00% | 5.00% | ||
Debt instrument due date | Dec. 1, 2033 | Dec. 1, 2033 | ||
Fixed-Rate Bonds [Member] | 4.85% 2005 Series A, due 2035 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 4.85% | 4.85% | ||
Debt instrument due date | Oct. 1, 2035 | Oct. 1, 2035 | ||
Fixed-Rate Bonds [Member] | 4.75% 2006 Series A, due 2036 [Member] | ||||
Debt Instrument [Line Items] | ||||
Debt instrument interest rate | 4.75% | 4.75% | ||
Debt instrument due date | Sep. 1, 2036 | Sep. 1, 2036 |
Long-Term Debt - Additional Inf
Long-Term Debt - Additional Information (Detail) - USD ($) | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended | |||||
Sep. 30, 2015 | May. 31, 2015 | Dec. 31, 2015 | Jun. 30, 2015 | Sep. 30, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Oct. 31, 2014 | |
Debt Instrument [Line Items] | |||||||||
Line of credit designated for working capital purposes | $ 150,000,000 | $ 150,000,000 | |||||||
Minimum current borrowing usage | $ 0 | ||||||||
Maximum current borrowing usage | 180,000,000 | ||||||||
Redemption of long term debt | $ 187,973,000 | $ 139,155,000 | $ 137,013,000 | ||||||
Debt instrument covenant description | Certain Company debt instruments contain securities ratings covenants that, if set in motion, would increase financing costs. Certain debt instruments also have leverage ratio caps and minimum net worth requirements. At December 31, 2015, the Company is in compliance with all of its covenants. | ||||||||
Issuance of additional debt | $ 2,200,000,000 | ||||||||
Minimum net worth | 1,000,000,000 | ||||||||
Long-term debt, less current maturities | 1,551,204,000 | 1,551,204,000 | 1,631,374,000 | ||||||
Deferred charges and other assets | 469,322,000 | 469,322,000 | 472,579,000 | ||||||
Prepaids and other current assets | 95,199,000 | 95,199,000 | 99,803,000 | ||||||
Unamortized debt issuance costs | 816,000 | ||||||||
Carrying Amount [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Long-term debt, less current maturities | 1,551,204,000 | 1,551,204,000 | 1,631,374,000 | ||||||
Unamortized debt issuance costs | 692,000 | 692,000 | 816,000 | ||||||
Carrying Amount [Member] | Debentures [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Unamortized discount | (5,223,000) | ||||||||
Carrying Amount [Member] | Fixed-Rate Bonds [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Unamortized discount | (1,943,000) | ||||||||
Short-Term Credit Facility [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Borrowings outstanding under facility | 18,000,000 | $ 18,000,000 | 5,000,000 | ||||||
Adjustments for New Accounting Principle, Early Adoption [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Long-term debt, less current maturities | 1,631,374,000 | ||||||||
Deferred charges and other assets | 472,579,000 | ||||||||
Prepaids and other current assets | $ 99,803,000 | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Credit facility maximum borrowing capacity | $ 300,000,000 | ||||||||
Effective interest rate | 2.46% | ||||||||
Minimum current borrowing usage | $ 60,600,000 | ||||||||
Maximum current borrowing usage | $ 105,200,000 | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | Minimum [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Commitment fee | 0.15% | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | Maximum [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Commitment fee | 0.40% | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | LIBOR [Member] | Minimum [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Applicable margin | 1.00% | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | LIBOR [Member] | Maximum [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Applicable margin | 2.25% | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | CDOR [Member] | Minimum [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Applicable margin | 1.00% | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | CDOR [Member] | Maximum [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Applicable margin | 2.25% | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | Alternate Base Rate or Canadian Base Rate [Member] | Minimum [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Applicable margin | 0.00% | ||||||||
Secured Revolving Credit and Term Loan Facility [Member] | Alternate Base Rate or Canadian Base Rate [Member] | Maximum [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Applicable margin | 1.25% | ||||||||
Centuri Construction Group Inc [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Debt instrument covenant description | Certain Centuri debt instruments have leverage ratio caps and fixed charge ratio coverage requirements. At December 31, 2015, Centuri is in compliance with all of its covenants. | ||||||||
Issuance of additional debt | $ 75,000,000 | ||||||||
Equity cushion relating to minimum fixed charge ratio coverage requirement | 15,000,000 | ||||||||
Centuri Construction Group Inc [Member] | Secured Revolving Credit and Term Loan Facility [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Credit facility maximum borrowing capacity | 300,000,000 | $ 300,000,000 | |||||||
Credit facility expiration date | Oct. 31, 2019 | ||||||||
Debt secured by assets | 437,000,000 | $ 437,000,000 | |||||||
Centuri Construction Group Inc [Member] | Centuri Secured Revolving Credit Facility [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Credit facility maximum borrowing capacity | 150,000,000 | 150,000,000 | |||||||
Southwest Gas Credit Facility [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Credit facility maximum borrowing capacity | 300,000,000 | 300,000,000 | |||||||
Line of credit designated as long term debt | 150,000,000 | 150,000,000 | |||||||
Line of credit designated for working capital purposes | 150,000,000 | $ 150,000,000 | |||||||
Credit facility expiration date | Mar. 1, 2020 | ||||||||
Borrowings outstanding under facility | $ 150,000,000 | $ 150,000,000 | |||||||
Effective interest rate | 1.45% | ||||||||
Southwest Gas Credit Facility [Member] | LIBOR [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Applicable margin | 1.00% | ||||||||
Southwest Gas Credit Facility [Member] | Alternative Base Rate [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Applicable margin | 0.00% | ||||||||
Southwest Gas Credit Facility [Member] | Before Amendment [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Credit facility expiration date | Mar. 1, 2019 | ||||||||
5.00% 2004 Series B, due 2033 [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Redemption of long term debt | $ 31,200,000 | ||||||||
Debt instrument interest rate | 5.00% | ||||||||
Debt instrument original due date | Dec. 1, 2033 | ||||||||
5.00% 2004 Series B, due 2033 [Member] | Fixed-Rate Bonds [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Debt instrument interest rate | 5.00% | 5.00% | 5.00% | ||||||
Debt instrument original due date | Dec. 1, 2033 | Dec. 1, 2033 | |||||||
5.25% 2003 Series D, due 2038 [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Redemption of long term debt | $ 20,000,000 | ||||||||
Debt instrument interest rate | 5.25% | 5.25% | |||||||
Debt instrument original due date | Dec. 1, 2038 | ||||||||
5.25% 2003 Series D, due 2038 [Member] | Fixed-Rate Bonds [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Debt instrument interest rate | 5.25% | 5.25% | 5.25% | ||||||
Debt instrument original due date | Mar. 1, 2038 | Mar. 1, 2038 | |||||||
Commercial Paper Program [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Credit facility maximum borrowing capacity | $ 50,000,000 | $ 50,000,000 | |||||||
Borrowings outstanding under facility | 50,000,000 | $ 50,000,000 | |||||||
Commercial Paper Program [Member] | Short-Term Credit Facility [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Effective interest rate | 1.01% | ||||||||
Centuri Term Loan Facility [Member] | Centuri Construction Group Inc [Member] | |||||||||
Debt Instrument [Line Items] | |||||||||
Credit facility, face amount | $ 150,000,000 | $ 150,000,000 |
Long-Term Debt - Summary of Eff
Long-Term Debt - Summary of Effective Interest Rates on Variable-Rate IDRBs (Detail) | Dec. 31, 2015 | Dec. 31, 2014 |
2003 Series A, due 2038 [Member] | ||
Debt Instrument [Line Items] | ||
Effective interest rates | 0.87% | 0.85% |
2008 Series A, due 2038 [Member] | ||
Debt Instrument [Line Items] | ||
Effective interest rates | 0.87% | 0.90% |
2009 Series A, due 2039 [Member] | ||
Debt Instrument [Line Items] | ||
Effective interest rates | 0.75% | 0.89% |
Tax-exempt Series A, due 2028 [Member] | ||
Debt Instrument [Line Items] | ||
Effective interest rates | 0.81% | 0.84% |
Long-Term Debt - Estimated Matu
Long-Term Debt - Estimated Maturities of Long-Term Debt (Detail) $ in Thousands | Dec. 31, 2015USD ($) |
Debt Disclosure [Abstract] | |
2,016 | $ 19,475 |
2,017 | 42,245 |
2,018 | 14,906 |
2,019 | 142,452 |
2,020 | $ 275,238 |
Short-Term Debt - Additional In
Short-Term Debt - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended | |
Dec. 31, 2015 | Dec. 31, 2014 | |
Short-term Debt [Line Items] | ||
Line of credit designated for working capital purposes | $ 150,000 | |
Short-term borrowings outstanding on the credit facility | $ 18,000 | $ 5,000 |
Effective interest rate on short-term borrowings | 1.37% | |
March 2019 [Member] | ||
Short-term Debt [Line Items] | ||
Current borrowing capacity | $ 300,000 | |
Credit facility expiration date | Mar. 1, 2020 |
Commitments and Contingencies -
Commitments and Contingencies - Additional Information (Detail) $ in Millions | Dec. 31, 2015USD ($) |
Commitments and Contingencies Disclosure [Abstract] | |
Self-insured retention amount associated with general liability claims | $ 1 |
Additional self-insured retention amount of general liability | $ 4 |
Pension and Other Postretirem76
Pension and Other Postretirement Benefits - Additional Information (Detail) $ in Millions | 12 Months Ended |
Dec. 31, 2015USD ($)BasisPoint | |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |
Maximum contribution of employer | 3.50% |
Deferment of annual cash compensation | 100.00% |
Matching contribution of employer | 3.50% |
Deferred compensation payments on retirement | Upon retirement, payments of compensation deferred, plus interest, are made in equal monthly installments over 10, 15, or 20 years, as elected by the participant. |
Additional Deferred Compensation Payment Options, period of payment, years | 5 years |
Deferred compensation, percentage of multiple interest rate | 150.00% |
Increments of changes to the discount rate, basis points | BasisPoint | 25 |
Estimated decrease in pension expense | $ 6.7 |
Future estimated funding amount | 39 |
Future estimated funding amount of retirement plan | $ 36 |
Maximum [Member] | |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |
Per capita cost of covered health care benefits medical rate trend assumption | 7.50% |
Minimum [Member] | |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |
Per capita cost of covered health care benefits medical rate trend assumption | 4.50% |
Pension and Other Postretirem77
Pension and Other Postretirement Benefits - Cost of Retirement Plan (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract] | |||
Employee Investment Plan cost | $ 5,072 | $ 4,816 | $ 4,850 |
Pension and Other Postretirem78
Pension and Other Postretirement Benefits - Schedule of Allocation of Plan Assets (Detail) | 12 Months Ended |
Dec. 31, 2015 | |
Equity Securities [Member] | |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |
Investment percentage range, minimum | 59.00% |
Investment percentage range, maximum | 71.00% |
Debt Securities [Member] | |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |
Investment percentage range, minimum | 31.00% |
Investment percentage range, maximum | 37.00% |
Other [Member] | |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |
Investment percentage range, maximum | 5.00% |
Pension and Other Postretirem79
Pension and Other Postretirement Benefits - Schedule of Assumptions Used (Detail) | 12 Months Ended | |
Dec. 31, 2015 | Dec. 31, 2014 | |
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract] | ||
Discount rate | 4.50% | 4.25% |
Weighted-average rate of compensation increase | 3.25% | 2.75% |
Asset return assumption | 7.25% | 7.75% |
Pension and Other Postretirem80
Pension and Other Postretirement Benefits - Schedule of Amounts Recognized in Balance Sheet and Income Statement (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Qualified Retirement Plan [Member] | |||
Change in benefit obligations | |||
Change in benefit obligations Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO) | $ 1,060,240 | $ 886,714 | |
Service cost | 25,123 | 21,360 | $ 23,056 |
Interest cost | 44,229 | 43,440 | 37,607 |
Net actuarial loss (gain) | (44,553) | 144,606 | |
Benefits paid | (40,222) | (35,880) | |
Benefit obligation at end of year (PBO/PBO/APBO) | 1,044,817 | 1,060,240 | 886,714 |
Change in plan assets | |||
Market value of plan assets, beginning balance | 754,796 | 719,944 | |
Actual return on plan assets | (13,694) | 34,732 | |
Employer contributions | 36,000 | 36,000 | |
Benefits paid | (40,222) | (35,880) | |
Market value of plan assets, ending balance | 736,880 | 754,796 | 719,944 |
Funded status at year end | $ (307,937) | $ (305,444) | |
Weighted-average assumptions (benefit obligation) | |||
Discount rate | 4.50% | 4.25% | |
Weighted-average rate of compensation increase | 3.25% | 2.75% | |
SERP [Member] | |||
Change in benefit obligations | |||
Change in benefit obligations Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO) | $ 41,176 | $ 36,143 | |
Service cost | 320 | 292 | 373 |
Interest cost | 1,695 | 1,745 | 1,535 |
Net actuarial loss (gain) | 2,322 | 5,459 | |
Benefits paid | (2,793) | (2,463) | |
Benefit obligation at end of year (PBO/PBO/APBO) | 42,720 | 41,176 | 36,143 |
Change in plan assets | |||
Employer contributions | 2,793 | 2,463 | |
Benefits paid | (2,793) | (2,463) | |
Funded status at year end | $ (42,720) | $ (41,176) | |
Weighted-average assumptions (benefit obligation) | |||
Discount rate | 4.50% | 4.25% | |
Weighted-average rate of compensation increase | 3.25% | 2.75% | |
PBOP [Member] | |||
Change in benefit obligations | |||
Change in benefit obligations Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO) | $ 72,202 | $ 58,020 | |
Service cost | 1,641 | 1,101 | 1,220 |
Interest cost | 2,999 | 2,829 | 2,482 |
Plan amendments | 6,661 | ||
Net actuarial loss (gain) | (3,251) | 4,567 | |
Benefits paid | (959) | (976) | |
Benefit obligation at end of year (PBO/PBO/APBO) | 72,632 | 72,202 | 58,020 |
Change in plan assets | |||
Market value of plan assets, beginning balance | 44,892 | 42,314 | |
Actual return on plan assets | (1,034) | 2,859 | |
Benefits paid | (274) | (281) | |
Market value of plan assets, ending balance | 43,584 | 44,892 | $ 42,314 |
Funded status at year end | $ (29,048) | $ (27,310) | |
Weighted-average assumptions (benefit obligation) | |||
Discount rate | 4.50% | 4.25% |
Pension and Other Postretirem81
Pension and Other Postretirement Benefits - Schedule of Accumulated Benefit Obligation (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Qualified Retirement Plan [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Accumulated benefit obligation | $ 922,992 | $ 886,215 |
SERP [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Accumulated benefit obligation | $ 39,270 | $ 39,125 |
Pension and Other Postretirem82
Pension and Other Postretirement Benefits - Schedule of Expected Benefit Payments (Detail) $ in Millions | Dec. 31, 2015USD ($) |
Pension [Member] | |
Defined Benefit Plan Disclosure [Line Items] | |
2,016 | $ 44 |
2,017 | 45.5 |
2,018 | 47.2 |
2,019 | 48.9 |
2,020 | 50.5 |
2021-2025 | 283.5 |
PBOP [Member] | |
Defined Benefit Plan Disclosure [Line Items] | |
2,016 | 3.9 |
2,017 | 4.1 |
2,018 | 4.3 |
2,019 | 4.5 |
2,020 | 4.5 |
2021-2025 | 21.3 |
SERP [Member] | |
Defined Benefit Plan Disclosure [Line Items] | |
2,016 | 2.8 |
2,017 | 2.8 |
2,018 | 2.8 |
2,019 | 2.9 |
2,020 | 2.9 |
2021-2025 | $ 14.1 |
Pension and Other Postretirem83
Pension and Other Postretirement Benefits - Schedule of Net Periodic Benefit Cost and Weighted-Average Assumptions (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Defined Benefit Plan Disclosure [Line Items] | |||
Net periodic benefit cost | $ 50,451 | $ 38,172 | $ 48,141 |
Weighted-average assumptions (net benefit cost) | |||
Discount rate | 4.50% | 4.25% | |
Expected return on plan assets | 7.25% | 7.75% | |
Weighted-average rate of compensation increase | 3.25% | 2.75% | |
Qualified Retirement Plan [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Service cost | $ 25,123 | $ 21,360 | 23,056 |
Interest cost | 44,229 | 43,440 | 37,607 |
Expected return on plan assets | (57,808) | (53,342) | (49,840) |
Amortization of net actuarial loss | 32,743 | 22,873 | 32,261 |
Net periodic benefit cost | $ 44,287 | $ 34,331 | $ 43,084 |
Weighted-average assumptions (net benefit cost) | |||
Discount rate | 4.25% | 5.00% | 4.25% |
Expected return on plan assets | 7.75% | 7.75% | 8.00% |
Weighted-average rate of compensation increase | 2.75% | 3.25% | 2.75% |
SERP [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Service cost | $ 320 | $ 292 | $ 373 |
Interest cost | 1,695 | 1,745 | 1,535 |
Amortization of net actuarial loss | 1,293 | 783 | 971 |
Net periodic benefit cost | $ 3,308 | $ 2,820 | $ 2,879 |
Weighted-average assumptions (net benefit cost) | |||
Discount rate | 4.25% | 5.00% | 4.25% |
Expected return on plan assets | 7.75% | 7.75% | 8.00% |
Weighted-average rate of compensation increase | 2.75% | 3.25% | 2.75% |
PBOP [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Service cost | $ 1,641 | $ 1,101 | $ 1,220 |
Interest cost | 2,999 | 2,829 | 2,482 |
Expected return on plan assets | (3,464) | (3,264) | (2,824) |
Amortization of prior service cost | 1,335 | 355 | 355 |
Amortization of net actuarial loss | 345 | 945 | |
Net periodic benefit cost | $ 2,856 | $ 1,021 | $ 2,178 |
Weighted-average assumptions (net benefit cost) | |||
Discount rate | 4.25% | 5.00% | 4.25% |
Expected return on plan assets | 7.75% | 7.75% | 8.00% |
Pension and Other Postretirem84
Pension and Other Postretirement Benefits - Schedule of Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |||
Net actuarial loss (gain) | $ 30,519 | $ 173,646 | $ (100,345) |
Amortization of prior service cost | (1,335) | (355) | (355) |
Amortization of net actuarial loss | (34,381) | (23,656) | (34,177) |
Prior service cost | 0 | 6,661 | 0 |
Regulatory adjustment | 5,646 | (140,308) | 123,630 |
Recognized in other comprehensive (income) loss | 449 | 15,988 | (11,247) |
Net periodic benefit costs recognized in net income | 50,451 | 38,172 | 48,141 |
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss | 50,900 | 54,160 | 36,894 |
Qualified Retirement Plan [Member] | |||
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |||
Net actuarial loss (gain) | 26,949 | 163,215 | (91,115) |
Amortization of net actuarial loss | (32,743) | (22,872) | (32,261) |
Regulatory adjustment | 5,214 | (129,031) | 113,762 |
Recognized in other comprehensive (income) loss | (580) | 11,312 | (9,614) |
Net periodic benefit costs recognized in net income | 44,287 | 34,331 | 43,084 |
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss | 43,707 | 45,643 | 33,470 |
SERP [Member] | |||
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |||
Net actuarial loss (gain) | 2,322 | 5,460 | (662) |
Amortization of net actuarial loss | (1,293) | (784) | (971) |
Recognized in other comprehensive (income) loss | 1,029 | 4,676 | (1,633) |
Net periodic benefit costs recognized in net income | 3,308 | 2,820 | 2,879 |
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss | 4,337 | 7,496 | 1,246 |
PBOP [Member] | |||
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] | |||
Net actuarial loss (gain) | 1,248 | 4,971 | (8,568) |
Amortization of prior service cost | (1,335) | (355) | (355) |
Amortization of net actuarial loss | (345) | (945) | |
Prior service cost | 6,661 | ||
Regulatory adjustment | 432 | (11,277) | 9,868 |
Net periodic benefit costs recognized in net income | 2,856 | 1,021 | 2,178 |
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss | $ 2,856 | $ 1,021 | $ 2,178 |
Pension and Other Postretirem85
Pension and Other Postretirement Benefits - Schedule of Fair Value of Plan Assets (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets, including insurance contracts | $ 783,323 | $ 808,260 | |
Assets at Fair Value [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 521,638 | 537,335 | |
Commingled Equity Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 257,966 | 266,922 | |
Insurance Company General Account Contracts (Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Contract value of insurance contracts | 3,719 | 4,003 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 364,610 | 386,712 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Agriculture [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 7,230 | 6,859 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Capital Equipment [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 549 | 2,288 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Chemicals/Materials [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 3,402 | 5,388 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Consumer Goods [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 42,256 | 42,969 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Energy and Mining [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 11,395 | 19,051 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Finance/Insurance [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 30,849 | 21,298 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Healthcare [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 39,059 | 38,968 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Information Technology [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 30,099 | 26,648 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Services [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 12,708 | 29,701 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Telecommunications/Internet/Media [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 26,653 | 19,047 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Other [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 9,312 | 11,283 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Real Estate Investment Trusts [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 5,159 | 5,882 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Mutual Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 111,468 | 110,726 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Government Fixed Income Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 34,478 | 46,019 | |
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Preferred Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 585 | ||
Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Futures Contracts [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | (7) | ||
Level 2 - Significant Other Observable Inputs [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 157,028 | 150,623 | |
Level 2 - Significant Other Observable Inputs [Member] | Other [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 31,917 | 23,806 | |
Level 2 - Significant Other Observable Inputs [Member] | Real Estate Investment Trusts [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 2,007 | ||
Level 2 - Significant Other Observable Inputs [Member] | Preferred Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 571 | ||
Level 2 - Significant Other Observable Inputs [Member] | Government Fixed Income and Mortgage Backed Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 51,046 | 49,745 | |
Level 2 - Significant Other Observable Inputs [Member] | Asset-Backed and Mortgage-Backed [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 24,243 | 27,874 | |
Level 2 - Significant Other Observable Inputs [Member] | Banking [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 21,478 | 23,980 | |
Level 2 - Significant Other Observable Inputs [Member] | Insurance [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 5,042 | 6,365 | |
Level 2 - Significant Other Observable Inputs [Member] | Utilities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 3,940 | 4,358 | |
Level 2 - Significant Other Observable Inputs [Member] | Pooled Funds and Mutual Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 15,604 | 12,952 | |
Level 2 - Significant Other Observable Inputs [Member] | State and Local Obligations [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 978 | 1,543 | |
Level 2 - Significant Other Observable Inputs [Member] | Convertible Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 202 | ||
Qualified Retirement Plan [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 736,880 | 754,796 | $ 719,944 |
Fair value of plan assets, including insurance contracts | 739,684 | 763,108 | |
Qualified Retirement Plan [Member] | Assets at Fair Value [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 485,454 | 499,870 | |
Qualified Retirement Plan [Member] | Commingled Equity Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 250,511 | 259,235 | |
Qualified Retirement Plan [Member] | Insurance Company General Account Contracts (Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Contract value of insurance contracts | 3,719 | 4,003 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 333,310 | 354,197 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Agriculture [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 7,021 | 6,661 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Capital Equipment [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 533 | 2,222 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Chemicals/Materials [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 3,304 | 5,233 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Consumer Goods [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 41,035 | 41,731 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Energy and Mining [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 11,066 | 18,502 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Finance/Insurance [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 29,957 | 20,685 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Healthcare [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 37,930 | 37,846 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Information Technology [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 29,229 | 25,881 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Services [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 12,341 | 28,846 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Telecommunications/Internet/Media [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 25,883 | 18,498 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Other [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 9,043 | 10,958 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Real Estate Investment Trusts [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 5,010 | 5,713 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Mutual Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 87,483 | 86,159 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Government Fixed Income Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 33,482 | 44,694 | |
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Preferred Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 568 | ||
Qualified Retirement Plan [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Futures Contracts [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | (7) | ||
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 152,144 | 145,673 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Other [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 30,995 | 23,120 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Real Estate Investment Trusts [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 1,949 | ||
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Preferred Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 554 | ||
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Government Fixed Income and Mortgage Backed Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 49,571 | 48,312 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Asset-Backed and Mortgage-Backed [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 23,542 | 27,071 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Banking [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 20,857 | 23,289 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Insurance [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 4,896 | 6,182 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Utilities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 3,826 | 4,232 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Pooled Funds and Mutual Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 14,808 | 11,968 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | State and Local Obligations [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 950 | 1,499 | |
Qualified Retirement Plan [Member] | Level 2 - Significant Other Observable Inputs [Member] | Convertible Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 196 | ||
PBOP [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 43,584 | 44,892 | $ 42,314 |
Fair value of plan assets, including insurance contracts | 43,639 | 45,152 | |
PBOP [Member] | Assets at Fair Value [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 36,184 | 37,465 | |
PBOP [Member] | Commingled Equity Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 7,455 | 7,687 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 31,300 | 32,515 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Agriculture [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 209 | 198 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Capital Equipment [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 16 | 66 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Chemicals/Materials [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 98 | 155 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Consumer Goods [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 1,221 | 1,238 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Energy and Mining [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 329 | 549 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Finance/Insurance [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 892 | 613 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Healthcare [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 1,129 | 1,122 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Information Technology [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 870 | 767 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Services [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 367 | 855 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Telecommunications/Internet/Media [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 770 | 549 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Other [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 269 | 325 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Real Estate Investment Trusts [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 149 | 169 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Mutual Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 23,985 | 24,567 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Government Fixed Income Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 996 | 1,325 | |
PBOP [Member] | Level 1 - Quoted Prices in Active Markets for Identical Financial Assets [Member] | Preferred Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 17 | ||
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 4,884 | 4,950 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Other [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 922 | 686 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Real Estate Investment Trusts [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 58 | ||
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Preferred Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 17 | ||
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Government Fixed Income and Mortgage Backed Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 1,475 | 1,433 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Asset-Backed and Mortgage-Backed [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 701 | 803 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Banking [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 621 | 691 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Insurance [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 146 | 183 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Utilities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 114 | 126 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Pooled Funds and Mutual Funds [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 796 | 984 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | State and Local Obligations [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | 28 | $ 44 | |
PBOP [Member] | Level 2 - Significant Other Observable Inputs [Member] | Convertible Securities [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Fair value of plan assets | $ 6 |
Pension and Other Postretirem86
Pension and Other Postretirement Benefits - Schedule of Fair Value of Plan Assets (Parenthetical) (Detail) - USD ($) | 12 Months Ended | |
Dec. 31, 2015 | Dec. 31, 2014 | |
Defined Benefit Plan Disclosure [Line Items] | ||
Amounts not included in funded status table | $ 2,859,000 | $ 8,572,000 |
Qualified Retirement Plan [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Amounts not included in funded status table | 2,803,000 | 8,312,000 |
PBOP [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Amounts not included in funded status table | $ 56,000 | $ 260,000 |
Minimum [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Redemption notice period | 1 day | |
Impact fee on redemptions and subscriptions of $5 million or more | $ 5,000,000 | |
Maximum [Member] | ||
Defined Benefit Plan Disclosure [Line Items] | ||
Redemption notice period | 30 days |
Stock-Based Compensation - Sche
Stock-Based Compensation - Schedule of Stock-Based Plan Compensation Expense, Including Cash Award (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |||
Stock-based compensation plan expense, net of related tax benefits | $ 7,278 | $ 8,130 | $ 8,012 |
Stock-based compensation plan related tax benefits | $ 4,461 | $ 4,983 | $ 4,910 |
Stock-Based Compensation - Addi
Stock-Based Compensation - Additional Information (Detail) | 12 Months Ended | ||
Dec. 31, 2015USD ($) | Dec. 31, 2014$ / shares | Dec. 31, 2013$ / shares | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
Options, maximum term, years | 10 years | ||
Cash received from exercise of stock options | $ 523,000 | ||
Tax benefit realized from exercise of stock options | $ 218,000 | ||
Percentage of restricted stock/units vested during first year | 0.40 | ||
Percentage of restricted stock/units vested during second and third years | 0.30 | ||
Average grant date fair value of performance shares and restricted stock/units granted | $ / shares | $ 53.73 | $ 44.83 | |
Total compensation cost related to nonvested performance shares and restricted stock/units not yet recognized | $ 3,300,000 | ||
Maximum [Member] | |||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
Weighted-average remaining contractual life of outstanding options, years | 1 year |
Stock-Based Compensation - Sc89
Stock-Based Compensation - Schedule of Stock Options Activity (Detail) - $ / shares shares in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |||
Number of options, Outstanding at the beginning of the year | 36 | 52 | 125 |
Number of options, Exercised during the year | (19) | (16) | (72) |
Number of options, Forfeited or expired during the year | (1) | ||
Number of options, Outstanding and exercisable at year end | 17 | 36 | 52 |
Weighted-average exercise price, Outstanding at the beginning of the year | $ 28.97 | $ 27.57 | $ 28.13 |
Weighted-average exercise price, Exercised during the year | 26.69 | 24.31 | 28.44 |
Weighted-average exercise price, Forfeited or expired during the year | 33.07 | ||
Weighted-average exercise price, Outstanding and exercisable at year end | $ 31.64 | $ 28.97 | $ 27.57 |
Stock-Based Compensation - Sc90
Stock-Based Compensation - Schedule of Aggregate Intrinsic Value of Outstanding and Exercisable Options (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |||
Outstanding and exercisable | $ 394 | $ 1,194 | $ 1,473 |
Exercised | $ 590 | $ 451 | $ 1,402 |
Stock-Based Compensation - Summ
Stock-Based Compensation - Summary of Market Prices of Common Stock (Detail) - USD ($) | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 |
Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |||
Market value of Southwest Gas stock | $ 55.16 | $ 61.81 | $ 55.91 |
Stock-Based Compensation - Sc92
Stock-Based Compensation - Schedule of Stock Options Outstanding and Exercisable (Detail) - $29.08 to $33.07 [Member] shares in Thousands | 12 Months Ended |
Dec. 31, 2015$ / sharesshares | |
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items] | |
Range of Exercise Price, Lower limit | $ 29.08 |
Range of Exercise Price, Upper limit | $ 33.07 |
Number outstanding | shares | 17 |
Weighted-remaining average contractual life, years | 6 months |
Weighted-average exercise price | $ 31.64 |
Stock-Based Compensation - Sc93
Stock-Based Compensation - Schedule of Nonvested Performance and Restricted Stock Unit Plans (Detail) - $ / shares shares in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
Weighted-average grant date fair value, Granted | $ 53.73 | $ 44.83 | |
Performance Shares [Member] | |||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
Nonvested/unissued, Number of Units, at beginning of year | 271 | ||
Nonvested, Number of Units, Granted | 80 | ||
Nonvested, Number of Units, Dividends | 6 | ||
Nonvested, Number of Units, Forfeited or expired | 0 | ||
Nonvested, Number of Units, Vested and issued | (160) | ||
Nonvested/unissued, Number of Units, Ending balance | 197 | 271 | |
Weighted-average grant date fair value, Beginning balance | $ 43.71 | ||
Weighted-average grant date fair value, Granted | 63.09 | ||
Weighted-average grant date fair value, Dividends | 0 | ||
Weighted-average grant date fair value, Forfeited or expired | 0 | ||
Weighted-average grant date fair value, Vested and issued | 43.12 | ||
Weighted-average grant date fair value, Ending balance | $ 50.63 | $ 43.71 | |
Restricted Stock/Units [Member] | |||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
Nonvested/unissued, Number of Units, at beginning of year | 257 | ||
Nonvested, Number of Units, Granted | 73 | ||
Nonvested, Number of Units, Dividends | 7 | ||
Nonvested, Number of Units, Forfeited or expired | 0 | ||
Nonvested, Number of Units, Vested and issued | (109) | ||
Nonvested/unissued, Number of Units, Ending balance | 228 | 257 | |
Weighted-average grant date fair value, Beginning balance | $ 41.22 | ||
Weighted-average grant date fair value, Granted | 63.09 | ||
Weighted-average grant date fair value, Dividends | 0 | ||
Weighted-average grant date fair value, Forfeited or expired | 0 | ||
Weighted-average grant date fair value, Vested and issued | 46.65 | ||
Weighted-average grant date fair value, Ending balance | $ 44.36 | $ 41.22 |
Income Taxes - Summary of Incom
Income Taxes - Summary of Income Before Taxes and Noncontrolling Interest for Domestic and Foreign Operations (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Income Tax [Line Items] | |||
Total income before income taxes | $ 219,332 | $ 219,521 | $ 222,815 |
Foreign [Member] | |||
Income Tax [Line Items] | |||
Total income before income taxes | (2,328) | (1,950) | |
United States [Member] | |||
Income Tax [Line Items] | |||
Total income before income taxes | $ 221,660 | $ 221,471 | $ 222,815 |
Income Taxes - Summary of Inc95
Income Taxes - Summary of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Current: | |||
Federal | $ 21,321 | $ 1,739 | $ 3,549 |
State | 9,899 | 5,073 | 5,107 |
Foreign | 650 | 2,193 | |
Income tax expense (benefit), Current | 31,870 | 9,005 | 8,656 |
Deferred: | |||
Federal | 51,132 | 71,439 | 67,414 |
State | (2,574) | 614 | 1,872 |
Foreign | (526) | (2,685) | |
Total deferred income tax expense | 48,032 | 69,368 | 69,286 |
Total income tax expense | $ 79,902 | $ 78,373 | $ 77,942 |
Income Taxes - Significant Comp
Income Taxes - Significant Components of Deferred Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Deferred federal and state: | |||
Total deferred federal and state | $ 48,893 | $ 70,229 | $ 70,147 |
Deferred ITC, net | (861) | (861) | (861) |
Total deferred income tax expense | 48,032 | 69,368 | 69,286 |
Property-related Items [Member] | |||
Deferred federal and state: | |||
Total deferred federal and state | 65,931 | 52,814 | 62,737 |
Purchased Gas Cost Adjustments [Member] | |||
Deferred federal and state: | |||
Total deferred federal and state | (32,993) | 15,049 | 16,189 |
Employee Benefits [Member] | |||
Deferred federal and state: | |||
Total deferred federal and state | 623 | 109 | (2,769) |
All Other Deferred [Member] | |||
Deferred federal and state: | |||
Total deferred federal and state | $ 15,332 | $ 2,257 | $ (6,010) |
Income Taxes - Reconciliation o
Income Taxes - Reconciliation of U.S Federal Statutory Rate to Consolidated Effective Tax Rate (Detail) | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Income Tax Disclosure [Abstract] | |||
U.S. federal statutory income tax rate | 35.00% | 35.00% | 35.00% |
Net state taxes | 1.80% | 1.90% | 2.40% |
Property-related items | 0.10% | 0.10% | 0.10% |
Tax credits | (0.40%) | (0.50%) | (0.40%) |
Company owned life insurance | 0.10% | (1.00%) | (2.10%) |
All other differences | (0.20%) | 0.20% | |
Consolidated effective income tax rate | 36.40% | 35.70% | 35.00% |
Income Taxes - Deferred Tax Ass
Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Deferred tax assets: | ||
Deferred income taxes for future amortization of ITC | $ 1,614 | $ 2,146 |
Employee benefits | 36,923 | 31,557 |
Alternative minimum tax credit | 4,809 | 20,172 |
Net operating losses and credits | 868 | 9,719 |
Interest rate swap | 7,351 | 8,622 |
Other | 24,636 | 25,872 |
Valuation allowance | (499) | (253) |
Deferred tax assets, total | 75,702 | 97,835 |
Deferred tax liabilities: | ||
Property-related items, including accelerated depreciation | 794,850 | 736,810 |
Regulatory balancing accounts | 743 | 33,736 |
Unamortized ITC | 2,549 | 3,410 |
Debt-related costs | 5,497 | 5,066 |
Intangibles | 9,547 | 12,792 |
Other | 31,533 | 27,600 |
Deferred tax liabilities, total | 844,719 | 819,414 |
Net deferred tax liabilities | 769,017 | 721,579 |
Current | (2,109) | |
Noncurrent | 769,017 | 723,688 |
Net deferred tax liabilities | $ 769,017 | $ 721,579 |
Income Taxes - Additional Infor
Income Taxes - Additional Information (Detail) - USD ($) | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Income Tax Disclosure [Line Items] | |||
Undistributed foreign earnings | $ 0 | ||
Unrecognized tax benefits that, if recognized, would affect the effective tax rate | 0 | ||
Significant increases or decreases in unrecognized tax benefit within the next 12 months | 0 | ||
Tax-related interest income | $ 0 | $ 0 | $ 0 |
Minimum [Member] | |||
Income Tax Disclosure [Line Items] | |||
Amount of benefit being recognized in financial statements upon ultimate settlement, Percentage | 50.00% | ||
United States [Member] | |||
Income Tax Disclosure [Line Items] | |||
Federal net capital loss carryforward | $ 505,000 | ||
Net capital loss carryforward expiration year | 2,016 | ||
Canada [Member] | |||
Income Tax Disclosure [Line Items] | |||
Federal net operating loss carryforward | $ 3,000,000 | ||
Net operating loss carryforward expiration year | 2,032 |
Income Taxes - Reconciliatio100
Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands | 12 Months Ended | |
Dec. 31, 2015 | Dec. 31, 2014 | |
Income Tax Disclosure [Abstract] | ||
Unrecognized tax benefits at beginning of year | $ 305 | |
Gross increases - tax positions in prior period | $ 305 | |
Gross decreases - tax positions in prior period | (9) | |
Gross increases - current period tax positions | 0 | 0 |
Gross decreases - current period tax positions | 0 | 0 |
Settlements | 0 | 0 |
Lapse in statute of limitations | 0 | 0 |
Unrecognized tax benefits at end of year | $ 296 | $ 305 |
Derivatives and Fair Value M101
Derivatives and Fair Value Measurements - Additional Information (Detail) - USD ($) | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Derivative [Line Items] | |||
Gains (losses) recognized in income or other comprehensive income for derivative designated cash flow hedges | $ 2,073,000 | $ 2,073,000 | $ 2,074,000 |
Derivative instrument loss at settlement amortization period | 10 years | ||
Cash Flow Hedging [Member] | |||
Derivative [Line Items] | |||
Gains (losses) recognized in income or other comprehensive income for derivative designated cash flow hedges | $ 0 | ||
Minimum [Member] | |||
Derivative [Line Items] | |||
Maturities of natural gas swaps | Jan. 31, 2016 | ||
Maximum [Member] | |||
Derivative [Line Items] | |||
Maturities of natural gas swaps | Mar. 31, 2018 | ||
Arizona [Member] | |||
Derivative [Line Items] | |||
Natural gas portfolios, maximum % rate | 25.00% | ||
California [Member] | |||
Derivative [Line Items] | |||
Natural gas portfolios, maximum % rate | 25.00% |
Derivatives and Fair Value M102
Derivatives and Fair Value Measurements - Notional Amounts under Swaps Contracts (Detail) - MMBTU | Dec. 31, 2015 | Dec. 31, 2014 |
Offsetting [Abstract] | ||
Contract notional amounts | 7,407,000 | 5,105,000 |
Derivatives and Fair Value M103
Derivatives and Fair Value Measurements - Amount of Gain or Losses Recognized in Income on Derivatives (Detail) - Cash Flow Hedging [Member] - Net Cost of Gas Sold [Member] - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Derivative Instruments, Gain (Loss) [Line Items] | |||
Amount of gain or (loss) recognized in income on derivative | $ (7,598) | $ (2,363) | $ 976 |
Regulatory Deferral Accounting Treatment [Member] | |||
Derivative Instruments, Gain (Loss) [Line Items] | |||
Amount of gain or (loss) recognized in income on derivative | $ 7,598 | $ 2,363 | $ (976) |
Derivatives and Fair Value M104
Derivatives and Fair Value Measurements - Fair Values of Swaps in Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Derivatives, Fair Value [Line Items] | ||
Asset derivatives not designated as hedging instruments | $ 4 | |
Liability derivatives not designated as hedging instruments | (5,490) | $ (5,425) |
Net total not designated as hedging instruments | (5,486) | (5,425) |
Swaps [Member] | Other Current Liabilities [Member] | ||
Derivatives, Fair Value [Line Items] | ||
Liability derivatives not designated as hedging instruments | (4,267) | (5,062) |
Net total not designated as hedging instruments | (4,267) | (5,062) |
Swaps [Member] | Other Deferred Credits [Member] | ||
Derivatives, Fair Value [Line Items] | ||
Asset derivatives not designated as hedging instruments | 4 | |
Liability derivatives not designated as hedging instruments | (1,223) | (363) |
Net total not designated as hedging instruments | $ (1,219) | $ (363) |
Derivatives and Fair Value M105
Derivatives and Fair Value Measurements - Paid to and Received from Counterparties for Settlements of Matured Swaps (Detail) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Derivative Instruments And Hedging Activities Disclosure [Abstract] | |||
Paid to counterparties | $ 7,537 | $ 829 | $ 3,148 |
Received from counterparties | $ 4,713 | $ 915 |
Derivatives and Fair Value M106
Derivatives and Fair Value Measurements - Regulatory Assets/Liabilities Offsetting Derivatives at Fair Value in Condensed Consolidated Balance Sheets (Detail) - Swaps [Member] - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Prepaids and Other Current Assets [Member] | ||
Derivatives, Fair Value [Line Items] | ||
Net Total | $ 4,267 | $ 5,062 |
Deferred Charges and Other Assets [Member] | ||
Derivatives, Fair Value [Line Items] | ||
Net Total | $ 1,219 | $ 363 |
Derivatives and Fair Value M107
Derivatives and Fair Value Measurements - Significant Other Observable Inputs (Detail) - Level 2 - Significant Other Observable Inputs [Member] - Swaps [Member] - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Derivatives, Fair Value [Line Items] | ||
Net Assets (Liabilities) | $ (5,486) | $ (5,425) |
Other Current Liabilities [Member] | ||
Derivatives, Fair Value [Line Items] | ||
Derivative Liabilities | (4,267) | (5,062) |
Other Deferred Credits [Member] | ||
Derivatives, Fair Value [Line Items] | ||
Derivative Liabilities | $ (1,219) | $ (363) |
Segment Information - Additiona
Segment Information - Additional Information (Detail) | 12 Months Ended |
Dec. 31, 2015 | |
Segment Reporting [Abstract] | |
Long-lived assets | Over 99% of the total Company’s long-lived assets are in the United States. |
Segment Information - Accounts
Segment Information - Accounts Receivable for Services (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 |
Centuri Construction Group Inc [Member] | ||
Segment Reporting Information [Line Items] | ||
Accounts receivable for Centuri services | $ 10,006 | $ 9,169 |
Segment Information - Schedule
Segment Information - Schedule of Revenues and Long-Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended | |||||||||||||
Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Segment Reporting Information [Line Items] | |||||||||||||||
Total Revenues | $ 685,405 | $ 505,396 | $ 538,604 | $ 734,220 | $ 627,683 | $ 432,475 | $ 453,153 | $ 608,396 | $ 538,357 | $ 387,346 | $ 411,574 | $ 613,505 | $ 2,463,625 | $ 2,121,707 | $ 1,950,782 |
United States [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Total Revenues | 2,289,133 | 2,069,513 | |||||||||||||
Canada [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Total Revenues | $ 174,492 | $ 52,194 |
Segment Information - Schedu111
Segment Information - Schedule of Segment Reporting Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended | |||||||||||||
Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Segment Reporting Information [Line Items] | |||||||||||||||
Total operating revenues | $ 685,405 | $ 505,396 | $ 538,604 | $ 734,220 | $ 627,683 | $ 432,475 | $ 453,153 | $ 608,396 | $ 538,357 | $ 387,346 | $ 411,574 | $ 613,505 | $ 2,463,625 | $ 2,121,707 | $ 1,950,782 |
Interest revenue | 2,173 | 2,602 | 461 | ||||||||||||
Interest expense | 71,879 | 72,069 | 63,700 | ||||||||||||
Depreciation and amortization | 270,111 | 253,027 | 236,817 | ||||||||||||
Income tax expense | 79,902 | 78,373 | 77,942 | ||||||||||||
Segment net income | 66,119 | $ (4,734) | $ 4,949 | $ 71,983 | 58,746 | $ 1,970 | $ 9,627 | $ 70,783 | 57,303 | $ (2,864) | $ 10,108 | $ 80,773 | 138,317 | 141,126 | 145,320 |
Segment assets | 5,358,685 | 5,208,297 | 4,565,174 | 5,358,685 | 5,208,297 | 4,565,174 | |||||||||
Capital expenditures | 488,000 | 396,898 | 364,276 | ||||||||||||
Revenues from unaffiliated customers [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Revenues | 2,359,509 | 2,029,519 | 1,862,629 | ||||||||||||
Intersegment sales [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Revenues | 104,116 | 92,188 | 88,153 | ||||||||||||
Natural Gas Operations [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Total operating revenues | 1,454,639 | 1,382,087 | 1,300,154 | ||||||||||||
Interest revenue | 1,754 | 2,596 | 456 | ||||||||||||
Interest expense | 64,095 | 68,299 | 62,555 | ||||||||||||
Depreciation and amortization | 213,455 | 204,144 | 193,848 | ||||||||||||
Income tax expense | 61,355 | 63,597 | 65,377 | ||||||||||||
Segment net income | 111,625 | 116,872 | 124,169 | ||||||||||||
Segment assets | 4,822,845 | 4,652,307 | 4,272,029 | 4,822,845 | 4,652,307 | 4,272,029 | |||||||||
Capital expenditures | 438,289 | 350,025 | 314,578 | ||||||||||||
Natural Gas Operations [Member] | Revenues from unaffiliated customers [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Revenues | 1,454,639 | 1,382,087 | 1,300,154 | ||||||||||||
Construction Services [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Total operating revenues | 1,008,986 | 739,620 | 650,628 | ||||||||||||
Interest revenue | 419 | 6 | 5 | ||||||||||||
Interest expense | 7,784 | 3,770 | 1,145 | ||||||||||||
Depreciation and amortization | 56,656 | 48,883 | 42,969 | ||||||||||||
Income tax expense | 18,547 | 14,776 | 12,565 | ||||||||||||
Segment net income | 26,692 | 24,254 | 21,151 | ||||||||||||
Segment assets | $ 535,840 | 566,589 | 293,811 | 535,840 | 566,589 | 293,811 | |||||||||
Capital expenditures | 49,711 | 46,873 | 49,698 | ||||||||||||
Construction Services [Member] | Revenues from unaffiliated customers [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Revenues | 904,870 | 647,432 | 562,475 | ||||||||||||
Construction Services [Member] | Intersegment sales [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Revenues | $ 104,116 | 92,188 | 88,153 | ||||||||||||
Adjustments [Member] | |||||||||||||||
Segment Reporting Information [Line Items] | |||||||||||||||
Segment assets | $ (10,599) | $ (666) | $ (10,599) | $ (666) |
Segment Information - Schedu112
Segment Information - Schedule of Segment Reporting Information (Parenthetical) (Detail) - USD ($) | 12 Months Ended | ||
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Segment Reporting Information [Line Items] | |||
Income tax payable netted | $ 666,000 | ||
Long-term deferred tax benefit | $ 48,032,000 | $ 69,368,000 | $ 69,286,000 |
Natural Gas Operations [Member] | |||
Segment Reporting Information [Line Items] | |||
Deferred income tax liability | 4,500,000 | ||
Construction Services [Member] | |||
Segment Reporting Information [Line Items] | |||
Income tax payable netted | 3,300,000 | ||
Deferred income tax liability | 1,400,000 | ||
Long-term deferred tax benefit | $ 1,400,000 |
Quarterly Financial Data - Sche
Quarterly Financial Data - Schedule of Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 12 Months Ended | |||||||||||||
Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | |
Quarterly Financial Information Disclosure [Abstract] | |||||||||||||||
Operating revenues | $ 685,405 | $ 505,396 | $ 538,604 | $ 734,220 | $ 627,683 | $ 432,475 | $ 453,153 | $ 608,396 | $ 538,357 | $ 387,346 | $ 411,574 | $ 613,505 | $ 2,463,625 | $ 2,121,707 | $ 1,950,782 |
Operating income | 117,586 | 16,143 | 25,047 | 129,556 | 112,373 | 18,290 | 26,755 | 127,065 | 100,772 | 6,141 | 28,908 | 138,394 | 288,332 | 284,483 | 274,215 |
Net income (loss) | 66,698 | (4,210) | 5,063 | 71,879 | 58,897 | 1,927 | 9,627 | 70,697 | 57,189 | (3,057) | 10,067 | 80,674 | 139,430 | 141,148 | 144,873 |
Net income (loss) attributable to Southwest Gas Corporation | $ 66,119 | $ (4,734) | $ 4,949 | $ 71,983 | $ 58,746 | $ 1,970 | $ 9,627 | $ 70,783 | $ 57,303 | $ (2,864) | $ 10,108 | $ 80,773 | $ 138,317 | $ 141,126 | $ 145,320 |
Basic earnings (loss) per common share | $ 1.40 | $ (0.10) | $ 0.11 | $ 1.54 | $ 1.26 | $ 0.04 | $ 0.21 | $ 1.52 | $ 1.24 | $ (0.06) | $ 0.22 | $ 1.75 | $ 2.94 | $ 3.04 | $ 3.14 |
Diluted earnings (loss) per common share | $ 1.38 | $ (0.10) | $ 0.10 | $ 1.53 | $ 1.25 | $ 0.04 | $ 0.21 | $ 1.51 | $ 1.22 | $ (0.06) | $ 0.22 | $ 1.73 | $ 2.92 | $ 3.01 | $ 3.11 |
Construction Services Noncon114
Construction Services Noncontrolling Interests - Additional Information (Detail) | 1 Months Ended | 12 Months Ended |
Oct. 31, 2014 | Dec. 31, 2015 | |
Principal Previous Owners [Member] | Link-Line and WS Nicholls [Member] | ||
Noncontrolling Interest [Line Items] | ||
Equity interest percentage | 10.00% | |
Description of equity interest | The agreement, associated with that approximate 10% equity interest, provided special dividend rights which entitled the sellers, as holders, to dividends equal to 3.4% of dividends paid at the level of Centuri, and subject to certain conditions, such interests could become exchangeable for a 3.4% equity interest in Centuri. In consideration of the underlying exchange rights of the original agreement, earnings attribution by Centuri to the previous owners has also occurred in an amount equivalent to 3.4% of Centuri earnings since October 2014. During the third quarter of 2015, the sellers formally exercised their exchange rights under the terms of that original agreement. No new rights were conveyed to the noncontrolling parties as a result of the exchange and no new consideration was involved. The ability of the sellers to redeem their holdings for cash at specified dates remains intact. The previous owners may exit their investment retained by requiring the purchase of a portion of their interest commencing July 2017 and in incremental amounts each anniversary date thereafter. The shares subject to the election cumulate (if earlier elections are not made) such that 100% of their interest retained is subject to the election beginning in July 2022. | |
Equity interest dividend rights, percentage of dividends paid by Centuri | 3.40% | |
First redemption date to exchange holdings for cash | 2017-07 | |
Principal Previous Owners [Member] | Link-Line and WS Nicholls [Member] | Construction Services [Member] | ||
Noncontrolling Interest [Line Items] | ||
Equity interest exchangeable percentage in Centuri | 3.40% | |
Percentage of earnings attribution by Centuri to previous owners | 3.40% | |
Principal Previous Owners [Member] | Link-Line and WS Nicholls [Member] | Construction Services [Member] | Maximum [Member] | ||
Noncontrolling Interest [Line Items] | ||
Percentage of retained interest may elect to sell to centuri | 100.00% | |
Intellichoice Energy, LLC [Member] | ||
Noncontrolling Interest [Line Items] | ||
Subsidiaries holding interest percentage | 65.00% |
Construction Services Noncon115
Construction Services Noncontrolling Interests - Summary of Redeemable Noncontrolling Interest (Detail) - USD ($) $ in Thousands | 12 Months Ended | |
Dec. 31, 2015 | Dec. 31, 2014 | |
Redeemable Noncontrolling Interest [Line Items] | ||
Balance, December 31, 2014 | $ 20,042 | |
Balance, December 31, 2015 | 16,108 | $ 20,042 |
Redeemable Noncontrolling Interest (Temporary Equity) [Member] | ||
Redeemable Noncontrolling Interest [Line Items] | ||
Balance, December 31, 2014 | 20,042 | |
Net Income (loss) attributable to redeemable noncontrolling interest | 939 | 151 |
Foreign currency exchange translation adjustment | (66) | (22) |
Centuri distribution to redeemable noncontrolling interest | (99) | |
Adjustment to redemption value | (4,708) | |
Balance, December 31, 2015 | $ 16,108 | $ 20,042 |
Acquisition of Construction 116
Acquisition of Construction Services Businesses - Additional Information (Detail) | 1 Months Ended | 12 Months Ended | |
Oct. 31, 2014USD ($)Business | Dec. 31, 2015USD ($) | Dec. 31, 2014USD ($) | |
Business Acquisition [Line Items] | |||
Number of business acquisitions | Business | 3 | ||
Business acquisition cost | $ 0 | $ 5,000,000 | |
Secured Revolving Credit and Term Loan Facility [Member] | |||
Business Acquisition [Line Items] | |||
Credit facility maximum borrowing capacity | $ 300,000,000 |
Acquisition of Construction 117
Acquisition of Construction Services Businesses - Revised Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Mar. 31, 2015 | Dec. 31, 2014 |
Business Acquisition [Line Items] | |||
Goodwill | $ 126,145 | $ 143,160 | |
Link-Line, W.S. Nicholls, and Brigadier [Member] | |||
Business Acquisition [Line Items] | |||
Cash, cash equivalents, and restricted cash | $ 3,000 | ||
Contracts receivable and other receivables | 62,000 | ||
Property, plant and equipment | 17,000 | ||
Other assets | 15,000 | ||
Intangible assets | 52,000 | ||
Goodwill | 131,000 | ||
Total assets acquired | 280,000 | ||
Current liabilities | 40,000 | ||
Deferred income tax - long-term | 17,000 | ||
Other long-term liabilities | 4,000 | ||
Net assets acquired | 219,000 | ||
Link-Line, W.S. Nicholls, and Brigadier [Member] | Acquisition Date [Member] | |||
Business Acquisition [Line Items] | |||
Cash, cash equivalents, and restricted cash | 3,000 | ||
Contracts receivable and other receivables | 62,000 | ||
Property, plant and equipment | 17,000 | ||
Other assets | 17,000 | ||
Intangible assets | 52,000 | ||
Goodwill | 130,000 | ||
Total assets acquired | 281,000 | ||
Current liabilities | 39,000 | ||
Deferred income tax - long-term | 17,000 | ||
Other long-term liabilities | 4,000 | ||
Net assets acquired | 221,000 | ||
Link-Line, W.S. Nicholls, and Brigadier [Member] | Measurement Period Adjustments [Member] | |||
Business Acquisition [Line Items] | |||
Cash, cash equivalents, and restricted cash | 0 | ||
Contracts receivable and other receivables | 0 | ||
Property, plant and equipment | 0 | ||
Other assets | (2,000) | ||
Intangible assets | 0 | ||
Goodwill | 1,000 | ||
Total assets acquired | (1,000) | ||
Current liabilities | 1,000 | ||
Deferred income tax - long-term | 0 | ||
Other long-term liabilities | 0 | ||
Net assets acquired | $ (2,000) |
Acquisition of Construction 118
Acquisition of Construction Services Businesses - Schedule of Unaudited Pro Forma Consolidated Financial Information (Detail) - Link-Line, W.S. Nicholls, and Brigadier [Member] $ / shares in Units, $ in Thousands | 12 Months Ended |
Dec. 31, 2014USD ($)$ / shares | |
Business Acquisition [Line Items] | |
Total operating revenues | $ | $ 2,295,318 |
Net income attributable to Southwest Gas Corporation | $ | $ 149,588 |
Basic earnings per share | $ / shares | $ 3.22 |
Diluted earnings per share | $ / shares | $ 3.19 |