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Pay vs Performance Disclosure - USD ($) | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Pay vs Performance Disclosure |  |  |  |  |
Pay vs Performance Disclosure, Table |
Year 1 | Summary Compensation Table Total Compensation for Principal Executive Officer (PEO)2 ($) | Compensation Actually Paid to PEO 3 ($) | Average Summary Compensation Table Total Compensation for Non-PEO Named Executive Officers 4 ($) | Average Compensation Actually Paid to Non-PEO Named Executive Officers 5 ($) | Value of initial fixed $100 investment based on: | Net Income 8 (in thousands) ($) | Company Selected Measure - Business Segment Earnings 9 (in thousands) ($)
Total Stockholder Return 6 ($) | Peer Group Total Stockholder Return 7 ($)
2023 | 7,100,593 |  | 4,987,034 |  | 2,113,640 |  | 1,648,546 |  | 110.18 |  | 136.68 |  | 414,707 |  | 288,170 |
2022 | 5,257,288 |  | 5,644,274 |  | 1,901,639 |  | 1,998,863 |  | 111.98 |  | 123.90 |  | 367,489 |  | 379,149 |
2021 | 5,210,467 |  | 7,143,972 |  | 1,810,584 |  | 2,273,834 |  | 110.37 |  | 128.00 |  | 378,131 |  | 385,210 |
2020 | 6,423,410 |  | 5,664,783 |  | 2,042,921 |  | 1,901,274 |  | 91.69 |  | 101.04 |  | 390,205 |  | 394,570 |
Named Executive Officers, Footnote | Our PEO for years 2020 through 2023 was David L. Goodin. Our non-PEO named executive officers were as follows: •2020 to 2022 - Jason L. Vollmer, David C. Barney, Jeffrey S. Thiede and Nicole A. Kivisto •2023 - Jason L. Vollmer, Jeffrey S. Thiede, Nicole A. Kivisto and Anne M. Jones |  |  |  |
Peer Group Issuers, Footnote | Represents the value of $100 invested in the compensation peer group company stock on December 31, 2019, as of December 31, 2020, December 31, 2021, December 31, 2022, and December 31, 2023, assuming dividends are reinvested in the compensation peer group stock at the frequency paid. Returns of each peer group company are weighted according to the peer group company’s market capitalization at the beginning of the period. Our compensation benchmarking peer group companies for 2020, 2021, 2022 and 2023 included:
| 2020 and 2021 | 2022 and 2023* |
| Alliant Energy | Alliant Energy |
| Ameren Corporation | Ameren Corporation |
| Atmos Energy Corporation | Atmos Energy Corporation |
| Black Hills Corporation | Black Hills Corporation |
| CMS Energy Corporation | CMS Energy Corporation |
| Dycom Industries, Inc. | Dycom Industries, Inc. |
| EMCOR Group, Inc. | EMCOR Group, Inc. |
| Evergy, Inc. | Evergy, Inc. |
| Granite Construction Incorporated | Granite Construction Incorporated |
| Jacobs Engineering Group Inc. | KRB, Inc. |
| KRB, Inc. | Martin Marietta Materials, Inc. |
| Martin Marietta Materials, Inc. | MasTec, Inc. |
| MasTec, Inc. | MYR Group, Inc.* |
| NiSource Inc. | NiSource Inc. |
| Pinnacle West Capital Corporation | Pinnacle West Capital Corporation |
| Portland General Electric Company | Portland General Electric Company |
| Quanta Services, Inc. | Quanta Services, Inc. |
| Southwest Gas Holdings, Inc. | Southwest Gas Holdings, Inc. |
| Summit Materials, Inc. | Summit Materials, Inc. |
| Vulcan Materials Company | Vulcan Materials Company |
| WEC Energy Group, Inc. | WEC Energy Group, Inc. |
| *Jacobs Engineering Group, Inc. was replaced with MYR Group Inc. in 2022 due to size. |
| Total stockholder return for the peer group companies were as follows: |
|  | 12/31/2019 | 12/31/2020 | 12/31/2021 | 12/31/2022 | 12/31/2023 |
| 2020 & 2021 Peer Group | $ | 100.00 |  | $ | 101.04 |  | $ | 128.00 |  | $ | 124.22 |  | $ | 136.60 |  |
| 2022 & 2023 Peer Group | $ | 100.00 |  | $ | 100.01 |  | $ | 126.85 |  | $ | 123.90 |  | $ | 136.68 |  |
PEO Total Compensation Amount | $ 7,100,593 | $ 5,257,288 | $ 5,210,467 | $ 6,423,410 |
PEO Actually Paid Compensation Amount | $ 4,987,034 | 5,644,274 | 7,143,972 | 5,664,783 |
Adjustment To PEO Compensation, Footnote | To arrive at 2023 CAP for Mr. Goodin, total compensation as reported in the 2023 SCT was adjusted for the following:
| 2023 |  |  |
SCT Total Compensation for the PEO | 7,100,593 |  |  |  |
| less: Reported Value of Stock Awards in the SCT a | 3,359,339 |  |  |  |
| plus: Stock Award Adjustments a,b | 1,418,874 |  |  |  |
| less: Change in Actuarial Present Value of Defined Benefit and Pension Plans as Reported in the SCT | 173,094 |  |  |  |
| plus: Aggregate Service Cost and Prior Service Costs on Defined Benefit and Pension Plans | — |  |  |  |
CAP for the PEO | 4,987,034 |  |  |  |
a | Equity compensation grant date and year-end fair value for time-vesting awards was determined by the closing stock price on the date of grant or year-end, as applicable. |  |  |
b | Stock Award Adjustments in determining CAP: |  |  |
Year | Year-end Fair Value of Equity Awards Granted in the Year that are Unvested | Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years that are Unvested | Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year | Year-over-Year Change in Fair Value of Equity Award Granted in Prior Years that Vested in the Year | Prior Year-end Fair Value of Equity Awards that Failed to Meet Vesting Conditions in the Year | Value of Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Fair Value or Total Compensation | Total Equity Award Adjustments |
2023 | 3,088,246 |  | (783,245) |  | — |  | (886,127) |  | — |  | — |  | 1,418,874 |  |
Non-PEO NEO Average Total Compensation Amount | $ 2,113,640 | 1,901,639 | 1,810,584 | 2,042,921 |
Non-PEO NEO Average Compensation Actually Paid Amount | $ 1,648,546 | 1,998,863 | 2,273,834 | 1,901,274 |
Adjustment to Non-PEO NEO Compensation Footnote |
4 | Represents the average total compensation of our non-PEO named executive officers as shown in the SCT for the respective year.
5 | To arrive at the Average 2023 CAP for our non-PEO named executive officers, total compensation as reported in the 2023 SCT was adjusted for the following:
Average of SCT Total Compensation for Non-PEO Named Executive Officers | 2,113,640 |  |  |  |
| less: Reported Value of Stock Awards in the SCT a | 827,266 |  |  |  |
| plus: Stock Award Adjustments a,b | 386,066 |  |  |  |
| less: Change in Actuarial Present Value of Defined Benefit and Pension Plans as Reported in the SCT | 23,894 |  |  |  |
| plus: Aggregate Service Cost and Prior Service Costs on Defined Benefit and Pension Plans | — |  |  |  |
Average CAP for the Non-PEO Named Executive Officers | 1,648,546 |  |  |  |
a | Equity compensation grant date and year-end fair value for time-vesting awards was determined by the closing stock price on the date of grant or year-end, as applicable.
b | Stock Award Adjustments in determining CAP:
Year | Year-end Fair Value of Equity Awards Granted in the Year that are Unvested | Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years that are Unvested | Fair Value as of Vesting Date of Equity Awards Granted and Vested in the Year | Year-over-Year Change in Fair Value of Equity Award Granted in Prior Years that Vested in the Year | Prior Year-end Fair Value of Equity Awards that Failed to Meet Vesting Conditions in the Year | Value of Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Fair Value or Total Compensation | Total Equity Award Adjustments |
2023 | 761,063 |  | (174,537) |  | — |  | (200,460) |  | — |  | — |  | 386,066 |  |
Compensation Actually Paid vs. Total Shareholder Return | CAP vs. TSR Our TSR is a reflection of our stock price and dividends paid over a period of time and is important to stockholders as it measures the performance of an investment in our company stock in the marketplace. The following chart depicts the PEO and average non-PEO named executive officer CAP compared to the value of $100 invested in company and peer company stock on December 31, 2019 as of December 31, 2020, December 31, 2021, December 31, 2022, and December 31, 2023, assuming dividends are reinvested in company stock at the frequency paid. |  |  |  |
Compensation Actually Paid vs. Net Income | CAP vs. Net Income The following charts depicts the PEO and average non-PEO named executive officer CAP compared to the company’s net income for 2020, 2021, 2022 and 2023. |  |  |  |
Compensation Actually Paid vs. Company Selected Measure | CAP vs. Business Segment Earnings The following charts depicts the PEO and average non-PEO named executive officer CAP compared to the company’s Business Segment Earnings for 2020, 2021, 2022 and 2023. |  |  |  |
Total Shareholder Return Vs Peer Group | CAP vs. TSR Our TSR is a reflection of our stock price and dividends paid over a period of time and is important to stockholders as it measures the performance of an investment in our company stock in the marketplace. The following chart depicts the PEO and average non-PEO named executive officer CAP compared to the value of $100 invested in company and peer company stock on December 31, 2019 as of December 31, 2020, December 31, 2021, December 31, 2022, and December 31, 2023, assuming dividends are reinvested in company stock at the frequency paid. |  |  |  |
Tabular List, Table |
Performance Metrics Most Closely Linked to CAP for 2023
Business Segment Earnings
Electric & Natural Gas Distribution Earnings
Construction Services Earnings before income tax, interest, depreciation and amortization (EBITDA)
Strategic Initiatives including work associated with the spinoff of Knife River and the strategic review of the construction services business to maximize its value.
Total Shareholder Return Amount | $ 110.18 | 111.98 | 110.37 | 91.69 |
Peer Group Total Shareholder Return Amount | 136.68 | 123.90 | 128.00 | 101.04 |
Net Income (Loss) | $ 414,707,000 | $ 367,489,000 | $ 378,131,000 | $ 390,205,000 |
Company Selected Measure Amount | 288,170,000 | 379,149,000 | 385,210,000 | 394,570,000 |
PEO Name | David L. Goodin |  |  |  |
Additional 402(v) Disclosure | As required by Section 953(a) of the Dodd-Frank Wall Street Reform and Consumer Protection Act and Item 402(v) of Regulation S-K, we are providing information regarding the Compensation Actually Paid (CAP), as defined by SEC rules, to our named executive officers versus company financial performance. The CAP amounts shown in the table below do not reflect the actual amount of compensation earned by or paid to our named executive officers during the applicable year. Represents Mr. Goodin’s total compensation as shown in the Summary Compensation Table (SCT) for the respective years.Represents value of $100 invested in company stock on December 31, 2019, as of December 31, 2020, December 31, 2021, December 31, 2022 and December 31, 2023, assuming dividends are reinvested in company stock at the frequency paid. Represents GAAP Net Income reported for the company in 2020, 2021, 2022 and 2023. 9 Business segment earnings represent the earnings generated by our strategic business units lead by our non-corporate executives. The combined earnings of each of these strategic business units plus results of activities classified as Other and Discontinued Operations reflect net income as reported in our financial statements as follows:
| 2023 | 2022 | 2021 | 2020
Electric & Natural Gas Distribution | 120,079 |  | 102,248 |  | 103,502 |  | 99,650 |
Pipeline | 46,918 |  | 35,288 |  | 40,896 |  | 37,012 |
Construction Services | 137,230 |  | 124,781 |  | 109,402 |  | 109,721 |
Construction Materials & Contracting | (18,456) |  | 116,220 |  | 129,755 |  | 147,325 |
Business Segment Earnings 1 | 285,771 |  | 378,537 |  | 383,555 |  | 393,708 |
Other | 128,936 |  | (11,048) |  | (5,424) |  | (3,503) |
Net Income | 414,707 |  | 367,489 |  | 378,131 |  | 390,205 |
1 Business Segment Earnings includes earnings from continuing and discontinued operations associated with each business segment.
Business Segment Earnings | 285,771 |  | 378,537 |  | 383,555 |  | 393,708 |
Adjustments approved by the Compensation Committee for Incentive Purposes | 2,399 |  | 612 |  | 1,655 |  | 862 |
Business Segment Earnings for Incentive Purposes 2 | 288,170 |  | 379,149 |  | 385,210 |  | 394,570 |
2 Business Segment Earnings are adjusted for certain events approved by the compensation committee. Business Segment Earnings for incentive compensation purposes.
2023 Most Important Financial Measures The financial performance measures identified as the most important measures used by the company to link PEO and non-PEO named executive officer 2023 CAP to company performance are listed below in unranked order each of which is described in more detail in the “Compensation Discussion and Analysis”. Descriptions of the Information Presented in the Pay Versus Performance Table We are providing the following graphics to illustrate the relationship between our PEO CAP and our non-PEO named executive officers’ CAP as a group and company performance, as set forth and described in and under the “Pay Versus Performance” table, including the company’s cumulative TSR, net income and Business Segment Earnings. In addition, we are providing a graphic to illustrate the relationship between the company’s cumulative TSR and our compensation benchmarking peer group’s cumulative TSR. |  |  |  |
Measure:: 1 |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Name | Business Segment Earnings |  |  |  |
Measure:: 2 |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Name | Electric & Natural Gas Distribution Earnings |  |  |  |
Measure:: 3 |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Name | Construction Services Earnings before income tax, interest, depreciation and amortization (EBITDA) |  |  |  |
Measure:: 4 |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Name | Strategic Initiatives including work associated with the spinoff of Knife River and the strategic review of the construction services business to maximize its value. |  |  |  |
Jacobs Engineering Group Inc. [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Peer Group Total Shareholder Return Amount | $ 136.60 | $ 124.22 | $ 128.00 | $ 101.04 | $ 100.00
MYR Group, Inc. [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Peer Group Total Shareholder Return Amount | 136.68 | $ 123.90 | $ 126.85 | $ 100.01 | $ 100.00
PEO | Stock Awards Values Reported [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 3,359,339 |  |  |  |
PEO | Stock Awards Adjustments [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 1,418,874 |  |  |  |
PEO | Change in Pension Value [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 173,094 |  |  |  |
PEO | Aggregated Service Cost and Prior Service Cost [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 0 |  |  |  |
PEO | Equity Awards Granted During the Year, Unvested [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | 3,088,246 |  |  |  |
PEO | Equity Awards Granted in Prior Years, Unvested [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | (783,245) |  |  |  |
PEO | Equity Awards Granted During the Year, Vested [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | 0 |  |  |  |
PEO | Equity Awards Granted in Prior Years, Vested [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | (886,127) |  |  |  |
PEO | Equity Awards that Failed to Meet Vesting Conditions [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | 0 |  |  |  |
PEO | Dividends Or Other Earnings Paid On Equity Awards Not Otherwise Reflected In Value Or Total Compensation [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | 0 |  |  |  |
Non-PEO NEO | Stock Awards Values Reported [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 827,266 |  |  |  |
Non-PEO NEO | Stock Awards Adjustments [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 386,066 |  |  |  |
Non-PEO NEO | Change in Pension Value [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 23,894 |  |  |  |
Non-PEO NEO | Aggregated Service Cost and Prior Service Cost [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation, Amount | 0 |  |  |  |
Non-PEO NEO | Equity Awards Granted During the Year, Unvested [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | 761,063 |  |  |  |
Non-PEO NEO | Equity Awards Granted in Prior Years, Unvested [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | (174,537) |  |  |  |
Non-PEO NEO | Equity Awards Granted During the Year, Vested [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | 0 |  |  |  |
Non-PEO NEO | Equity Awards Granted in Prior Years, Vested [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | (200,460) |  |  |  |
Non-PEO NEO | Equity Awards that Failed to Meet Vesting Conditions [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | 0 |  |  |  |
Non-PEO NEO | Dividends Or Other Earnings Paid On Equity Awards Not Otherwise Reflected In Value Or Total Compensation [Member] |  |  |  |  |
Pay vs Performance Disclosure |  |  |  |  |
Adjustment to Compensation Amount, Equity Awards | $ 0 |  |  |  |

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