MDU Resources (MDU) 10-Q4 May 232023 Q1 Quarterly reportFinancial data

Company Profile

Cover page

Cover page - shares	3 Months Ended
Cover page - shares	Mar. 31, 2023	Apr. 27, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	1-03480
Entity Registrant Name	MDU RESOURCES GROUP INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	30-1133956
Entity Address, Address Line One	1200 West Century Avenue
Entity Address, Address Line Two	P.O. Box 5650
Entity Address, City or Town	Bismarck
Entity Address, State or Province	ND
Entity Address, Postal Zip Code	58506-5650
City Area Code	701
Local Phone Number	530-1000
Title of 12(b) Security	Common Stock, par value $1.00 per share
Trading Symbol	MDU
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity common stock, shares outstanding		203,638,373
Entity Central Index Key	0000067716
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Amendment Flag	false

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating revenues:
Operating revenues:	$ 1,737,337	$ 1,416,559
Operating expenses:
Operation and maintenance:	1,104,742	907,897
Purchased natural gas sold	371,015	267,353
Depreciation, depletion and amortization	81,862	80,121
Taxes, other than income	80,890	67,484
Electric fuel and purchased power	24,356	26,361
Total operating expenses	1,662,865	1,349,216
Operating income	74,472	67,343
Other income (expense)	10,868	(2,400)
Interest expense	38,020	25,260
Income before income taxes	47,320	39,683
Income taxes	8,977	7,950
Income from continuing operations	38,343	31,733
Discontinued operations, net of tax	10	30
Net income	$ 38,353	$ 31,763
Earnings per share - basic:
Income from continuing operations	$ 0.19	$ 0.16
Discontinued operations, net of tax	0	0
Earnings per share - basic	0.19	0.16
Earnings per share - diluted:
Income from continuing operations	0.19	0.16
Discontinued operations, net of tax	0	0
Earnings per share - diluted	$ 0.19	$ 0.16
Weighted average common shares outstanding - basic	203,624	203,351
Weighted average common shares outstanding - diluted	203,910	203,391
Regulated operation
Operating revenues:
Operating revenues:	$ 673,757	$ 553,456
Operating expenses:
Operation and maintenance:	101,866	97,665
Income from continuing operations	64,294	55,549
Nonregulated operation
Operating revenues:
Operating revenues:	1,063,580	863,103
Operating expenses:
Operation and maintenance:	1,002,876	810,232
Income from continuing operations	$ (25,951)	$ (23,816)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Net income	$ 38,353	$ 31,763
Other comprehensive income:
Reclassification adjustment for loss on derivative instruments included in net income, tax	11	36
Reclassification adjustment for loss on derivative instruments included in net income, net of tax	34	112
Postretirement liability adjustment:
Amortization of postretirement liability losses included in net periodic benefit credit, tax	34	164
Amortization of postretirement liability losses included in net periodic benefit credit, net of tax	100	445
Net unrealized gain (loss) on available-for-sale investments:
Net unrealized gain (loss) on available-for-sale investments arising during the period, tax	19	(85)
Net unrealized gain (loss) on available-for-sale investments arising during the period, net of tax	70	(320)
Reclassification adjustment for loss on available-for-sale investments included in net income, tax	3	8
Reclassification adjustment for loss on available-for-sale investments included in net income, net of tax	13	32
Net unrealized gain (loss) on available-for-sale investments	83	(288)
Other comprehensive income	217	269
Comprehensive income attributable to common stockholders	$ 38,570	$ 32,032

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Current assets:
Cash and cash equivalents	$ 93,189	$ 80,517	$ 64,904
Receivables, net	1,291,949	1,305,642	948,024
Inventories	425,834	387,525	380,316
Current regulatory assets	216,318	165,092	89,078
Prepayments and other current assets	81,424	72,972	89,586
Total current assets	2,108,714	2,011,748	1,571,908
Noncurrent assets:
Property, plant and equipment	9,475,608	9,364,038	8,958,600
Less accumulated depreciation, depletion and amortization	3,322,894	3,272,493	3,158,091
Net property, plant and equipment	6,152,714	6,091,545	5,800,509
Goodwill	763,500	763,500	763,262
Other intangible assets, net	16,334	17,532	21,389
Regulatory assets	349,500	329,659	359,228
Investments	172,467	161,913	174,555
Operating lease right-of-use assets	118,052	119,375	119,845
Other	161,306	165,509	160,019
Total noncurrent assets	7,733,873	7,649,033	7,398,807
Total assets	9,842,587	9,660,781	8,970,715
Current liabilities:
Short-term borrowings	501,500	246,500	99,958
Long-term debt due within one year	78,031	78,031	147,953
Accounts payable	547,188	657,168	449,746
Taxes payable	73,914	70,810	90,572
Dividends payable	45,306	45,245	44,229
Accrued compensation	65,509	88,662	64,796
Operating lease liabilities due within one year	34,975	34,516	34,618
Regulatory liabilities due within one year	44,395	26,440	31,186
Other accrued liabilities	245,511	232,231	203,670
Total current liabilities	1,636,329	1,479,603	1,166,728
Noncurrent liabilities:
Long-term debt	2,769,037	2,763,394	2,599,810
Deferred income taxes	642,069	631,303	587,940
Asset retirement obligations	409,547	405,885	463,080
Regulatory liabilities	454,669	448,454	433,628
Operating lease liabilities	83,632	85,534	85,874
Other	271,922	259,479	272,937
Total noncurrent liabilities	4,630,876	4,594,049	4,443,269
Commitments and contingencies
Stockholders' equity:
Common stock	204,163	204,163	203,889
Other paid-in capital	1,461,294	1,466,037	1,451,464
Retained earnings	1,943,917	1,951,138	1,749,726
Accumulated other comprehensive loss	(30,366)	(30,583)	(40,735)
Treasury Stock, Common, Value	3,626	3,626	3,626
Total stockholders' equity	3,575,382	3,587,129	3,360,718
Total liabilities and stockholders' equity	$ 9,842,587	$ 9,660,781	$ 8,970,715
Common Stock, Shares Authorized	500,000,000	500,000,000	500,000,000
Common Stock, Par or Stated Value Per Share	$ 1	$ 1	$ 1
Common Stock, Shares, Issued	204,162,814	204,162,814	203,889,661
Treasury Stock, Common, Shares	538,921	538,921	538,921

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common stock	Other paid-in capital	Retained earnings	Accumulated other comprehensive loss	Treasury Stock, Common
Common stock balance (in shares) at Dec. 31, 2021		203,889,661
Balance at Dec. 31, 2021	$ 3,382,874	$ 203,889	$ 1,461,205	$ 1,762,410	$ (41,004)	$ (3,626)
Treasury Stock, Common, Shares at Dec. 31, 2021						(538,921)
Net income	31,763			31,763
Other comprehensive income	269				269
Dividends declared on common stock	(44,447)			(44,447)
Stock-based compensation	2,689		2,689
Repurchase of common stock						(266,821)
Repurchase of common stock	(7,399)					$ (7,399)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(12,303)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						266,821
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						$ 7,399
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(4,904)
Issuance of common stock	$ (127)		(127)
Common stock balance (in shares) at Mar. 31, 2022	203,889,661	203,889,661
Balance at Mar. 31, 2022	$ 3,360,718	$ 203,889	1,451,464	1,749,726	(40,735)	$ (3,626)
Treasury Stock, Common, Shares at Mar. 31, 2022	538,921					(538,921)
Common stock balance (in shares) at Dec. 31, 2022	204,162,814	204,162,814
Balance at Dec. 31, 2022	$ 3,587,129	$ 204,163	1,466,037	1,951,138	(30,583)	$ (3,626)
Treasury Stock, Common, Shares at Dec. 31, 2022	538,921					538,921
Net income	$ 38,353			38,353
Other comprehensive income	217				217
Dividends declared on common stock	(45,574)			(45,574)
Stock-based compensation	3,108		3,108
Repurchase of common stock						(153,622)
Repurchase of common stock	(4,811)					$ (4,811)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(7,851)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						153,622
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						$ 4,811
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	$ (3,040)
Common stock balance (in shares) at Mar. 31, 2023	204,162,814	204,162,814
Balance at Mar. 31, 2023	$ 3,575,382	$ 204,163	$ 1,461,294	$ 1,943,917	$ (30,366)	$ (3,626)
Treasury Stock, Common, Shares at Mar. 31, 2023	538,921					(538,921)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating activities:
Net income	$ 38,353	$ 31,763
Discontinued operations, net of tax	10	30
Income from continuing operations	38,343	31,733
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	81,862	80,121
Deferred income taxes	8,856	(6,466)
Provision for credit losses	4,193	1,735
Amortization of debt issuance costs	380	341
Employee stock-based compensation costs	3,108	2,689
Pension and postretirement benefit plan net periodic benefit credit	(1,090)	(1,491)
Unrealized (gains) losses on investments	(3,957)	5,147
Gains on sales of assets	(4,361)	(3,136)
Changes in current assets and liabilities, net of acquisitions:
Receivables	14,969	(5,723)
Inventories	(40,885)	(44,080)
Other current assets	(58,308)	34,491
Accounts payable	(93,549)	2,980
Other current liabilities	16,715	13,086
Pension and postretirement benefit plan contributions	(159)	(149)
Other noncurrent changes	(9,794)	1,139
Net cash provided by (used in) continuing operations	(43,677)	112,417
Net cash provided by (used in) discontinued operations	29	(7)
Net cash provided by (used in) operating activities	(43,648)	112,410
Investing activities:
Capital expenditures	(154,049)	(150,288)
Acquisitions, net of cash acquired	0	(524)
Net proceeds from sale or disposition of property and other	7,282	4,586
Investments	(4,257)	(4,442)
Net cash used in investing activities	(151,024)	(150,668)
Financing activities:
Issuance of short-term borrowings	275,000	100,000
Repayment of short-term borrowings	(20,000)	0
Issuance of long-term debt	175,446	150,000
Repayment of long-term debt	(169,891)	(143,622)
Debt issuance costs	(114)	(718)
Net proceeds from issuance of common stock	0	(127)
Dividends paid	(45,246)	(44,229)
Repurchase of common stock	(4,811)	(7,399)
Tax withholding on stock-based compensation	(3,040)	(4,904)
Net cash provided by financing activities	207,344	49,001
Increase in cash and cash equivalents	12,672	10,743
Cash and cash equivalents -- beginning of year	80,517	54,161
Cash and cash equivalents -- end of period	$ 93,189	$ 64,904

Basis of presentation

Basis of presentation	3 Months Ended
Basis of presentation	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	Basis of presentation The accompanying consolidated interim financial statements were prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Interim financial statements do not include all disclosures provided in annual financial statements and, accordingly, these financial statements should be read in conjunction with those appearing in the 2022 Annual Report. The information is unaudited but includes all adjustments that are, in the opinion of management, necessary for a fair presentation of the accompanying consolidated interim financial statements and are of a normal recurring nature. Depreciation, depletion and amortization expense is reported separately on the Consolidated Statements of Income and therefore is excluded from the other line items within operating expenses. As part of the Company's continuous review of its business, the Company announced strategic initiatives in 2022 that are expected to enhance its value. On August 4, 2022, the Company announced that its board of directors approved a plan to pursue the separation of Knife River, the construction materials and contracting segment, from the Company. The separation will result in two independent, publicly traded companies, MDU Resources Group, Inc. and Knife River Holding Company, and is expected to be completed on May 31, 2023, subject to certain conditions, including the SEC declaring the Registration Statement on Form 10 for Knife River Holding Company to be effective. On May 3, 2023, the Company's board of directors approved the separation and the distribution of approximately 90 percent of the issued and outstanding shares of Knife River Holding Company to the Company's stockholders. Stockholders of the Company will receive one share of Knife River Holding Company common stock for every four shares of the Company's common stock held on May 22, 2023, the record date for the distribution. The Company will retain approximately 10 percent of Knife River Holding Company's common stock immediately following the separation with the intent to dispose of such shares within twelve months after the separation. Prior to completing the separation, the Company may adjust the percentage of Knife River Holding Company common stock to be distributed to the Company's stockholders and retained by the Company in response to market and other factors. The separation of Knife River is planned as a tax-free spinoff transaction to the Company’s stockholders for U.S. federal income tax purposes. The Company's financial results for the quarter ended March 31, 2023, include Knife River. Upon completion of the separation, the historical results of Knife River will be presented as discontinued operations in the Company's Consolidated Financial Statements. On November 3, 2022, the Company announced its intention to create two pure-play publicly traded companies, one focused on regulated energy delivery and the other on construction materials, and that, to achieve this future structure, the Company's board of directors authorized management to commence a strategic review process of MDU Construction Services. The strategic review is underway and the Company anticipates completing the strategic review during the second quarter of 2023. Discontinued operations include the supporting activities of Fidelity and are shown in income from discontinued operations on the Consolidated Statements of Income. Unless otherwise indicated, the amounts presented in the accompanying notes to the consolidated financial statements relate to the Company's continuing operations.

New accounting standards

New accounting standards	3 Months Ended
New accounting standards	Mar. 31, 2023
Accounting Standards Update and Change in Accounting Principle [Abstract]
New accounting standards	New accounting standards The following table provides a brief description of the accounting pronouncements applicable to the Company and the potential impact on its Consolidated Financial Statements and/or disclosures: Standard Description Effective date Impact on financial statements/disclosures Recently adopted accounting standards ASU 2020-04 - Reference Rate Reform In March 2020, the FASB issued optional guidance to ease the facilitation of the effects of reference rate reform on financial reporting. The guidance applies to certain contract modifications, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. Beginning January 1, 2022, LIBOR or other discontinued reference rates cannot be applied to new contracts. New contracts will incorporate a new reference rate, which includes SOFR. LIBOR or other discontinued reference rates cannot be applied to contract modifications or hedging relationships entered into or evaluated after December 31, 2022. Existing contracts referencing LIBOR or other reference rates expected to be discontinued must identify a replacement rate by June 30, 2023. Effective as of March 12, 2020 and will continue through December 31, 2022 For more information, see ASU 2022-06 - Reference Rate Reform: Deferral of Sunset Date in recently issued accounting standards not yet adopted. Recently issued accounting standards not yet adopted ASU 2022-06 - Reference Rate Reform: Deferral of Sunset Date In December 2022, the FASB included a sunset provision within ASC 848 based on expectations of when LIBOR would cease being published. At the time ASU 2020-04 was issued, the UK Financial Conduct Authority had established its intent to cease overnight tenors of LIBOR after December 31, 2021. In March 2021, the UK Financial Conduct Authority announced that the intended cessation date of the overnight tenors of LIBOR would be June 30, 2023 which is beyond the current sunset date of ASC 848. The amendments in this Update defer the sunset date of ASC 848 from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the relief in ASC 848. December 31, 2024 The Company has updated its credit agreements to include language regarding the successor or alternate rate to LIBOR, and a review of other contracts and agreements is on-going. The Company does not expect the guidance to have a material impact on its results of operations, financial position, cash flows or disclosures.

Seasonality of operations

Seasonality of operations	3 Months Ended
Seasonality of operations	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Seasonality of operations	Seasonality of operations Some of the Company's operations are highly seasonal and revenues from, and certain expenses for, such operations may fluctuate significantly among quarterly periods. Accordingly, the interim results for particular businesses, and for the Company as a whole, may not be indicative of results for the full fiscal year.

Receivables and allowance for e

Receivables and allowance for expected credit losses	3 Months Ended
Receivables and allowance for expected credit losses	Mar. 31, 2023
Credit Loss [Abstract]
Receivables and allowance for expected credit loss	Receivables and allowance for expected credit losses Receivables consist primarily of trade and contracting services contract receivables from the sale of goods and services, which are recorded at the invoiced amount, and contract assets, net of expected credit losses. For more information on contract assets, see Note 8. The Company's trade receivables are all due in 12 months or less. The total balance of receivables past due 90 days or more was $53.5 million, $50.7 million and $45.6 million at March 31, 2023 and 2022, and December 31, 2022, respectively. The Company's expected credit losses are determined through a review using historical credit loss experience; changes in asset specific characteristics; current conditions; and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly. The Company develops and documents its methodology to determine its allowance for expected credit losses at each of its reportable business segments. Risk characteristics used by the business segments may include customer mix, knowledge of customers and general economic conditions of the various local economies, among others. Specific account balances are written off when management determines the amounts to be uncollectible. Management has reviewed the balance reserved through the allowance for expected credit losses and believes it is reasonable. Details of the Company's expected credit losses were as follows: Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 2022 $ 375 $ 1,615 $ 2 $ 5,477 $ 2,162 $ 9,631 Current expected credit loss provision 615 2,324 — 428 826 4,193 Less write-offs charged against the allowance 667 1,225 — 83 51 2,026 Credit loss recoveries collected 145 229 — — 1 375 At March 31, 2023 $ 468 $ 2,943 $ 2 $ 5,822 $ 2,938 $ 12,173 Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 2021 $ 269 $ 1,506 $ 2 $ 5,406 $ 2,533 $ 9,716 Current expected credit loss provision 565 1,369 — (253) 54 1,735 Less write-offs charged against the allowance 597 932 — 27 71 1,627 Credit loss recoveries collected 124 180 — — 28 332 At March 31, 2022 $ 361 $ 2,123 $ 2 $ 5,126 $ 2,544 $ 10,156

Inventories and natural gas in

Inventories and natural gas in storage	3 Months Ended
Inventories and natural gas in storage	Mar. 31, 2023
Inventory Disclosure [Abstract]
Inventories and natural gas in storage	Inventories and natural gas in storage Natural gas in storage for the Company's regulated operations is generally valued at lower of cost or market using the last-in, first-out method or lower of cost or net realizable value using the average cost or first-in, first-out method. The majority of all other inventories are valued at the lower of cost or net realizable value using the average cost method. Inventories include production costs incurred as part of the Company's aggregate mining activities. These inventoriable production costs include all mining and processing costs associated with the production of aggregates. Stripping costs incurred during the production phase, which represent costs of removing overburden and waste materials to access mineral deposits, are a component of inventoriable production costs. The portion of the cost of natural gas in storage expected to be used within 12 months was included in inventories. Inventories on the Consolidated Balance Sheets were as follows: March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Aggregates held for resale $ 207,564 $ 195,489 $ 199,110 Asphalt oil 101,271 93,816 68,609 Materials and supplies 45,310 35,967 40,056 Merchandise for resale 42,603 33,393 40,296 Natural gas in storage (current) 8,662 10,801 22,533 Other 20,424 10,850 16,921 Total $ 425,834 $ 380,316 $ 387,525

Earnings per share

Earnings per share	3 Months Ended
Earnings per share	Mar. 31, 2023
Earnings Per Share [Abstract]
Earnings per share	Earnings per share Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted earnings per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the applicable period, plus the effect of non-vested performance share awards and restricted stock units. Common stock outstanding includes issued shares less shares held in treasury. Net income was the same for both the basic and diluted earnings per share calculations. A reconciliation of the weighted average common shares outstanding used in the basic and diluted earnings per share calculations follows: Three Months Ended March 31, 2023 2022 (In thousands, except per share amounts) Weighted average common shares outstanding - basic 203,624 203,351 Effect of dilutive performance share awards and restricted stock units 286 40 Weighted average common shares outstanding - diluted 203,910 203,391 Shares excluded from the calculation of diluted earnings per share — — Dividends declared per common share $ .2225 $ .2175

Accumulated other comprehensive

Accumulated other comprehensive loss	3 Months Ended
Accumulated other comprehensive loss	Mar. 31, 2023
Equity [Abstract]
Accumulated other comprehensive loss	Accumulated other comprehensive loss The after-tax changes in the components of accumulated other comprehensive loss were as follows: Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2022 $ (125) $ (29,900) $ (558) $ (30,583) Other comprehensive income before reclassifications — — 70 70 Amounts reclassified from accumulated other comprehensive loss 34 100 13 147 Net current-period other comprehensive income 34 100 83 217 At March 31, 2023 $ (91) $ (29,800) $ (475) $ (30,366) Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2021 $ (538) $ (40,461) $ (5) $ (41,004) Other comprehensive loss before reclassifications — — (320) (320) Amounts reclassified from accumulated other comprehensive loss 112 445 32 589 Net current-period other comprehensive income (loss) 112 445 (288) 269 At March 31, 2022 $ (426) $ (40,016) $ (293) $ (40,735) The following amounts were reclassified out of accumulated other comprehensive loss into net income. The amounts presented in parenthesis indicate a decrease to net income on the Consolidated Statements of Income. The reclassifications were as follows: Three Months Ended Location on Consolidated March 31, 2023 2022 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (45) $ (148) Interest expense 11 36 Income taxes (34) (112) Amortization of postretirement liability losses included in net periodic benefit credit (134) (609) Other income 34 164 Income taxes (100) (445) Reclassification adjustment on available-for-sale investments included in net income (16) (40) Other income 3 8 Income taxes (13) (32) Total reclassifications $ (147) $ (589)

Revenue from contracts with cus

Revenue from contracts with customers	3 Months Ended
Revenue from contracts with customers	Mar. 31, 2023
Revenue from Contract with Customer [Abstract]
Revenue from contracts with customers	Revenue from contracts with customers Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes. Disaggregation In the following tables, revenue is disaggregated by the type of customer or service provided. The Company believes this level of disaggregation best depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. The table also includes a reconciliation of the disaggregated revenue by reportable segments. For more information on the Company's business segments, see Note 17. Three Months Ended March 31, 2023 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 37,825 $ 327,651 $ — $ — $ — $ — $ 365,476 Commercial utility sales 36,347 204,927 — — — — 241,274 Industrial utility sales 10,763 16,838 — — — — 27,601 Other utility sales 1,774 — — — — — 1,774 Natural gas transportation — 13,504 34,983 — — — 48,487 Natural gas storage — — 3,861 — — — 3,861 Contracting services — — — 114,983 — — 114,983 Construction materials — — — 232,502 — — 232,502 Intrasegment eliminations — — — (39,585) — — (39,585) Electrical & mechanical specialty contracting — — — — 590,263 — 590,263 Transmission & distribution specialty contracting — — — — 152,022 — 152,022 Other 11,878 4,721 1,859 — 33 4,739 23,230 Intersegment eliminations (122) (150) (26,410) (132) (214) (4,739) (31,767) Revenues from contracts with customers 98,465 567,491 14,293 307,768 742,104 — 1,730,121 Revenues out of scope (2,863) (1,974) 38 — 12,015 — 7,216 Total external operating revenues $ 95,602 $ 565,517 $ 14,331 $ 307,768 $ 754,119 $ — $ 1,737,337 Three Months Ended March 31, 2022 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 37,304 $ 258,816 $ — $ — $ — $ — $ 296,120 Commercial utility sales 35,600 163,609 — — — — 199,209 Industrial utility sales 10,306 13,024 — — — — 23,330 Other utility sales 1,750 — — — — — 1,750 Natural gas transportation — 12,381 31,574 — — — 43,955 Natural gas storage — — 3,719 — — — 3,719 Contracting services — — — 114,267 — — 114,267 Construction materials — — — 241,732 — — 241,732 Intrasegment eliminations — — — (46,033) — — (46,033) Electrical & mechanical specialty contracting — — — — 392,808 — 392,808 Transmission & distribution specialty contracting — — — — 148,466 — 148,466 Other 12,753 2,609 1,709 — 48 4,341 21,460 Intersegment eliminations (124) (136) (25,940) (130) (1,059) (4,341) (31,730) Revenues from contracts with customers 97,589 450,303 11,062 309,836 540,263 — 1,409,053 Revenues out of scope (3,995) 115 58 — 11,328 — 7,506 Total external operating revenues $ 93,594 $ 450,418 $ 11,120 $ 309,836 $ 551,591 $ — $ 1,416,559 Presented in the previous tables are sales of materials to both third parties and internal customers within the construction materials and contracting segment to highlight the focus on vertical integration as this segment sells materials to both third parties and internal customers. Due to consolidation requirements, the internal sales revenues must be eliminated against the construction materials product used in the contracting services to arrive at the external operating revenue total for the segment. Contract balances The timing of revenue recognition may differ from the timing of invoicing to customers. The timing of invoicing to customers does not necessarily correlate with the timing of revenues being recognized under the cost-to-cost method of accounting. Contracts from construction work are billed as work progresses in accordance with agreed upon contractual terms. Generally, billing to the customer occurs contemporaneous to revenue recognition. A variance in timing of the billings may result in a contract asset or a contract liability. A contract asset occurs when revenues are recognized under the cost-to-cost measure of progress, which exceeds amounts billed on uncompleted contracts. Such amounts will be billed as standard contract terms allow, usually based on various measures of performance or achievement. A contract liability occurs when there are billings in excess of revenues recognized under the cost-to-cost measure of progress on uncompleted contracts. Contract liabilities decrease as revenue is recognized from the satisfaction of the related performance obligation. The changes in contract assets and liabilities were as follows: March 31, 2023 December 31, 2022 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 212,687 $ 185,289 $ 27,398 Receivables, net Contract liabilities - current (202,788) (208,204) 5,416 Accounts payable Contract liabilities - noncurrent (442) (6) (436) Noncurrent liabilities - other Net contract assets (liabilities) $ 9,457 $ (22,921) $ 32,378 The Company recognized $154.9 million in revenue for the three months ended March 31, 2023, which was previously included in contract liabilities at December 31, 2022. The Company recognized $121.8 million in revenue for the three months ended March 31, 2022, which was previously included in contract liabilities at December 31, 2021. The Company recognized a net increase in revenues of $21.3 million and $23.5 million for the three months ended March 31, 2023 and 2022, respectively, from performance obligations satisfied in prior periods. Remaining performance obligations The remaining performance obligations, also referred to as backlog, at the construction materials and contracting and construction services segments include unrecognized revenues that the Company reasonably expects to be realized. These unrecognized revenues can include: projects that have a written award, a letter of intent, a notice to proceed, an agreed upon work order to perform work on mutually accepted terms and conditions and change orders or claims to the extent management believes additional contract revenues will be earned and are deemed probable of collection. Excluded from remaining performance obligations are potential orders under master service agreements. The majority of the Company's contracting services contracts have an original duration of less than two years. The remaining performance obligations at the pipeline segment include firm transportation contracts with fixed pricing and fixed volumes. The Company has applied the practical expedient, which does not require additional disclosures for contracts with an original duration of less than 12 months, to certain firm transportation and non-regulated contracts. The Company's firm transportation contracts included in the remaining performance obligations have weighted average remaining durations of less than five years. At March 31, 2023, the Company's remaining performance obligations were $3.7 billion. The Company expects to recognize the following revenue amounts in future periods related to these remaining performance obligations: $2.6 billion within the next 12 months or less; $454.5 million within the next 13 to 24 months; and $592.8 million in 25 months or more.

Business Combinations

Business Combinations	3 Months Ended
Business Combinations	Mar. 31, 2023
Business Combinations [Abstract]
Business Combinations	Business combinations The following acquisition was accounted for as a business combination in accordance with ASC 805 - Business Combinations. The results of the business combination have been included in the Consolidated Financial Statements beginning on the acquisition date. Pro forma financial amounts reflecting the effects of the business combination are not presented because it was not material to the Company's financial position or results of operations. Acquisitions are also subject to customary adjustments based on, among other things, the amount of cash, debt and working capital in the business as of the closing date. The amounts included in the Consolidated Balance Sheets for these adjustments are considered provisional until final settlement has occurred. The Company had no acquisitions in the three months ended March 31, 2023. In December 2022, the construction materials and contracting segment acquired Allied Concrete and Supply Co., a producer of ready-mixed concrete in California. At March 31, 2023, the purchase price allocation was considered preliminary and will be finalized within 12 months of the acquisition date. The total purchase price for acquisitions that occurred in 2022 was $8.9 million, subject to certain adjustments, with cash acquired totaling $2.8 million. The purchase price includes consideration paid of $1.5 million, a $70,000 holdback liability, and 273,153 shares of common stock with a market value of $8.4 million as of the respective acquisition date. Due to the holding period restriction on the common stock, the share consideration was discounted to a fair value of approximately $7.3 million. The amounts allocated to the aggregated assets acquired and liabilities assumed during 2022 were as follows: $1.7 million to current assets; $5.9 million to property, plant and equipment; $200,000 to goodwill; $100,000 to current liabilities; $500,000 to noncurrent liabilities - other and $1.2 million to deferred tax liabilities. Costs incurred for acquisitions are included in operation and maintenance expense on the Consolidated Statements of Income and were immaterial for both the three months ended March 31, 2023 and 2022.

Leases

Leases	3 Months Ended
Leases	Mar. 31, 2023
Leases [Abstract]
Lessee, Operating Leases	Leases The Company's leases primarily include operating leases for equipment, buildings, easements and vehicles. The Company leases certain equipment to third parties through its utility and construction services segments, which are considered short-term operating leases with terms of less than 12 months. The Company recognized revenue from operating leases of $12.2 million and $11.4 million for the three months ended March 31, 2023 and 2022, respectively. At March 31, 2023, the Company had $9.1 million of lease receivables with a majority due within 12 months.

Goodwill and other intangible a

Goodwill and other intangible assets	3 Months Ended
Goodwill and other intangible assets	Mar. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and other intangible assets	Goodwill and other intangible assets The changes in the carrying amount of goodwill were as follows: Balance at January 1, 2023 Goodwill Measurement Balance at March 31, 2023 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 274,540 — — 274,540 Construction services 143,224 — — 143,224 Total $ 763,500 $ — $ — $ 763,500 Balance at January 1, 2022 Goodwill Measurement Balance at March 31, 2022 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 276,426 — (2,124) 274,302 Construction services 143,224 — — 143,224 Total $ 765,386 $ — $ (2,124) $ 763,262 Balance at January 1, 2022 Goodwill Measurement Balance at December 31, 2022 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 276,426 238 (2,124) 274,540 Construction services 143,224 — — 143,224 Total $ 765,386 $ 238 $ (2,124) $ 763,500 Other amortizable intangible assets were as follows: March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Customer relationships $ 28,990 $ 28,990 $ 28,990 Less accumulated amortization 14,680 10,846 13,724 14,310 18,144 15,266 Noncompete agreements 4,331 4,591 4,591 Less accumulated amortization 3,405 3,016 3,529 926 1,575 1,062 Other 2,479 6,969 5,280 Less accumulated amortization 1,381 5,299 4,076 1,098 1,670 1,204 Total $ 16,334 $ 21,389 $ 17,532 The previous tables include goodwill and intangible assets associated with the business combinations completed during 2022. For more information related to these business combinations, see Note 9. Amortization expense for amortizable intangible assets for both the three months ended March 31, 2023 and 2022, was $1.2 million. Estimated amortization expense for identifiable intangible assets as of March 31, 2023, was: Remainder of 2023 2024 2025 2026 2027 Thereafter (In thousands) Amortization expense $ 3,393 $ 4,249 $ 2,200 $ 1,782 $ 1,759 $ 2,951

Regulatory assets and liabiliti

Regulatory assets and liabilities	3 Months Ended
Regulatory assets and liabilities	Mar. 31, 2023
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Regulatory assets and liabilities The following table summarizes the individual components of unamortized regulatory assets and liabilities: Estimated Recovery or Refund Period as of March 31, 2023 * March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 198,166 $ 66,132 $ 141,306 Conservation programs Up to 1 year 8,599 7,567 8,544 Cost recovery mechanisms Up to 1 year 3,954 3,432 4,019 Other Up to 1 year 5,599 11,947 11,223 216,318 89,078 165,092 Noncurrent: Pension and postretirement benefits 143,349 142,681 143,349 Cost recovery mechanisms Up to 10 years 65,732 67,989 67,171 Plant costs/asset retirement obligations Over plant lives 44,131 63,325 44,462 Manufactured gas plant site remediation - 26,605 26,089 26,624 Environmental compliance programs - 21,942 — — Plant to be retired - 21,072 29,452 21,525 Taxes recoverable from customers Over plant lives 12,198 12,492 12,330 Long-term debt refinancing costs Up to 37 years 3,041 3,636 3,188 Other Up to 16 years 11,430 13,564 11,010 349,500 359,228 329,659 Total regulatory assets $ 565,818 $ 448,306 $ 494,751 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year 9,630 — 4,929 Natural gas costs refundable through rate adjustments Up to 1 year 6,331 13,107 955 Conservation programs Up to 1 year 3,834 144 4,126 Cost recovery mechanisms Up to 1 year 2,926 2,550 1,977 Taxes refundable to customers Up to 1 year 1,513 3,470 3,937 Refundable fuel and electric costs Up to 1 year 1,179 316 3,253 Other Up to 1 year 18,982 11,599 7,263 44,395 31,186 26,440 Noncurrent: Plant removal and decommissioning costs Over plant lives 214,467 171,485 208,650 Taxes refundable to customers Over plant lives 200,879 212,472 203,222 Cost recovery mechanisms Up to 19 years 16,313 9,508 14,025 Accumulated deferred investment tax credit Up to 19 years 13,996 13,352 13,594 Pension and postretirement benefits 7,376 20,434 7,376 Other Up to 15 years 1,638 6,377 1,587 454,669 433,628 448,454 Total regulatory liabilities $ 499,064 $ 464,814 $ 474,894 Net regulatory position $ 66,754 $ (16,508) $ 19,857 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made. At March 31, 2023 and 2022, and December 31, 2022, approximately $255.6 million, $268.1 million and $242.5 million, respectively, of regulatory assets were not earning a rate of return; however, these regulatory assets are expected to be recovered from customers in future rates. These assets are largely comprised of the unfunded portion of pension and postretirement benefits, accelerated depreciation on plant retirement, the estimated future cost of manufactured gas plant site remediation and the costs associated with environmental compliance. The Company is subject to environmental compliance regulations in certain states which require natural gas distribution companies to reduce overall GHG emissions to certain thresholds as established by each applicable state. Compliance with these standards may be achieved through increased energy efficiency and conservation measures, purchased emission allowances and offsets, purchases of community climate investment credits and purchases of low carbon fuels. Emission allowances are allocated by the respective states to the Company at no cost, of which a portion is required to be sold at auction. The Company expects the compliance costs for these regulations and the revenues from the sale of the allocated emissions allowances will be passed through to customers in rates and has, accordingly, deferred the environmental compliance obligation as a regulatory asset. In the last half of 2021 through 2022, the Company experienced high natural gas costs due to increase in demand outpacing the supply along with the impact of global events. Additionally, in December 2022 and January 2023, natural gas prices significantly increased across the Pacific Northwest from multiple price-pressuring events including wide-spread below-normal temperatures and higher natural gas consumption; reduced natural gas flows due to pipeline constraints, including maintenance in West Texas; and historically low regional natural gas storage levels. This increase in natural gas costs experienced in certain jurisdictions was partially offset by the recovery of prior period natural gas costs being recovered over a period longer than the normal one-year period. For a discussion of the Company's most recent cases by jurisdiction, see Note 19. In February 2019, the Company announced the retirement of three aging coal-fired electric generating units. The Company accelerated the depreciation related to these facilities in property, plant and equipment and recorded the difference between the accelerated depreciation, in accordance with GAAP, and the depreciation approved for rate-making purposes as regulatory assets. Requests were filed with the NDPSC and SDPUC, and subsequently approved, to offset the savings associated with the cessation of operations of these units with the amortization of the deferred regulatory assets. The Company ceased operations of Lewis & Clark Station in March 2021 and Units 1 and 2 at Heskett Station in February 2022. The Company subsequently reclassified the costs being recovered for these facilities from plant retirement to cost recovery mechanisms in the previous table and began amortizing the associated plant retirement and closure costs in the jurisdictions where requests were filed. The Company expects to recover the regulatory assets related to the plant retirements in future rates. If, for any reason, the Company's regulated businesses cease to meet the criteria for application of regulatory accounting for all or part of their operations, the regulatory assets and liabilities relating to those portions ceasing to meet such criteria would be written off and included in the statement of income or accumulated other comprehensive loss in the period in which the discontinuance of regulatory accounting occurs.

Fair value measurements

Fair value measurements	3 Months Ended
Fair value measurements	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. The fair value ASC establishes a hierarchy for grouping assets and liabilities, based on the significance of inputs. The estimated fair values of the Company's assets and liabilities measured on a recurring basis are determined using the market approach. The Company measures its investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income. The Company anticipates using these investments, which consist of insurance contracts, to satisfy its obligations under its unfunded, nonqualified defined benefit and defined contribution plans for executive officers and certain key management employees, and invests in these fixed-income and equity securities for the purpose of earning investment returns and capital appreciation. These investments, which totaled $105.9 million, $105.4 million and $98.0 million, at March 31, 2023 and 2022, and December 31, 2022, respectively, are classified as investments on the Consolidated Balance Sheets. The net unrealized gain on these investments was $3.8 million for the three months ended March 31, 2023. The net unrealized loss on these investments was $5.8 million for the three months ended March 31, 2022. The change in fair value, which is considered part of the cost of the plan, is classified in other income on the Consolidated Statements of Income. The Company did not elect the fair value option, which records gains and losses in income, for its available-for-sale securities, which include mortgage-backed securities and U.S. Treasury securities. These available-for-sale securities are recorded at fair value and are classified as investments on the Consolidated Balance Sheets. Unrealized gains or losses are recorded in accumulated other comprehensive loss. Details of available-for-sale securities were as follows: March 31, 2023 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,557 $ 3 $ 561 $ 7,999 U.S. Treasury securities 3,023 8 51 2,980 Total $ 11,580 $ 11 $ 612 $ 10,979 March 31, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,778 $ 3 $ 310 $ 8,471 U.S. Treasury securities 2,688 — 63 2,625 Total $ 11,466 $ 3 $ 373 $ 11,096 December 31, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,928 $ 2 $ 636 $ 8,294 U.S. Treasury securities 2,608 — 72 2,536 Total $ 11,536 $ 2 $ 708 $ 10,830 The Company's assets measured at fair value on a recurring basis were as follows: Fair Value Measurements at March 31, 2023, Using Quoted Prices in Significant Significant Balance at March 31, 2023 (In thousands) Assets: Money market funds $ — $ 7,919 $ — $ 7,919 Insurance contracts* — 105,857 — 105,857 Available-for-sale securities: Mortgage-backed securities — 7,999 — 7,999 U.S. Treasury securities — 2,980 — 2,980 Total assets measured at fair value $ — $ 124,755 $ — $ 124,755 * The insurance contracts invest approximately 61 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 7 percent in target date investments, 6 percent in common stock of small-cap companies, 2 percent in cash equivalents and 1 percent in international investments. Fair Value Measurements at March 31, 2022, Using Quoted Prices in Significant Significant Balance at March 31, 2022 (In thousands) Assets: Money market funds $ — $ 13,131 $ — $ 13,131 Insurance contracts* — 105,371 — 105,371 Available-for-sale securities: Mortgage-backed securities — 8,471 — 8,471 U.S. Treasury securities — 2,625 — 2,625 Total assets measured at fair value $ — $ 129,598 $ — $ 129,598 * The insurance contracts invest approximately 61 percent in fixed-income investments, 17 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at December 31, 2022, Using Quoted Prices in Significant Significant Balance at December 31, 2022 (In thousands) Assets: Money market funds $ — $ 7,361 $ — $ 7,361 Insurance contracts* — 98,041 — 98,041 Available-for-sale securities: Mortgage-backed securities — 8,294 — 8,294 U.S. Treasury securities — 2,536 — 2,536 Total assets measured at fair value $ — $ 116,232 $ — $ 116,232 * The insurance contracts invest approximately 63 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. The Company's money market funds are valued at the net asset value of shares held at the end of the period, based on published market quotations on active markets, or using other known sources including pricing from outside sources. The estimated fair value of the Company's mortgage-backed securities and U.S. Treasury securities are based on comparable market transactions, other observable inputs or other sources, including pricing from outside sources. The estimated fair value of the Company's insurance contracts are based on contractual cash surrender values that are determined primarily by investments in managed separate accounts of the insurer. These amounts approximate fair value. The managed separate accounts are valued based on other observable inputs or corroborated market data. Though the Company believes the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value. The Company applies the provisions of the fair value measurement standard to its nonrecurring, non-financial measurements, including long-lived asset impairments. These assets are not measured at fair value on an ongoing basis but are subject to fair value adjustments only in certain circumstances. The Company reviews the carrying value of its long-lived assets, excluding goodwill, whenever events or changes in circumstances indicate that such carrying amounts may not be recoverable. The Company performed fair value assessments of the assets acquired and liabilities assumed in the business combination that occurred during 2022. The fair value of these assets and liabilities were determined based on Level 2 and Level 3 inputs. The Company's long-term debt is not measured at fair value on the Consolidated Balance Sheets and the fair value is being provided for disclosure purposes only. The fair value was categorized as Level 2 in the fair value hierarchy and was based on discounted future cash flows using current market interest rates. The estimated fair value of the Company's Level 2 long-term debt was as follows: March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Carrying amount $ 2,847,068 $ 2,747,763 $ 2,841,425 Fair value $ 2,535,125 $ 2,755,041 $ 2,469,625 The carrying amounts of the Company's remaining financial instruments included in current assets and current liabilities approximate their fair values .

Debt

Debt	3 Months Ended
Debt	Mar. 31, 2023
Debt Disclosure [Abstract]
Debt	Debt Certain debt instruments of the Company's subsidiaries contain restrictive and financial covenants and cross-default provisions. In order to borrow under the debt agreements, the subsidiary companies must be in compliance with the applicable covenants and certain other conditions, all of which the subsidiaries, as applicable, were in compliance with at March 31, 2023. In the event the subsidiaries do not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued. Montana-Dakota's and Centennial's respective commercial paper programs are supported by revolving credit agreements. While the amount of commercial paper outstanding does not reduce available capacity under the respective revolving credit agreements, Montana-Dakota and Centennial do not issue commercial paper in an aggregate amount exceeding the available capacity under the credit agreements. The commercial paper borrowings may vary during the period, largely the result of fluctuations in working capital requirements due to the seasonality of certain operations of the Company's subsidiaries. Short-term debt Cascade On January 20, 2023, Cascade entered into a $150.0 million term loan agreement with a SOFR-based interest rate and a maturity date of January 19, 2024. The agreement contains customary covenants and provisions, including a covenant of Cascade not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. Intermountain On January 20, 2023, Intermountain entered into a $125.0 million term loan agreement with a SOFR-based interest rate and a maturity date of January 19, 2024. In March 2023, Intermountain paid down $20.0 million of the outstanding balance. The agreement contains customary covenants and provisions, including a covenant of Intermountain not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. Centennial On March 18, 2022, Centennial entered into a $100.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of March 17, 2023. On March 17, 2023, Centennial amended this agreement to extend the maturity date to September 15, 2023. The agreement contains customary covenants and provisions, including a covenant of Centennial not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. Long-term debt Long-term Debt Outstanding Long-term debt outstanding was as follows: Weighted Average Interest Rate at March 31, 2023 March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Senior Notes due on dates ranging from May 15, 2023 to June 15, 2062 4.32 % $ 2,258,500 $ 2,275,000 $ 2,258,500 Commercial paper supported by revolving credit agreements 6.18 % 462,600 348,500 415,500 Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 7.32 % 35,000 35,000 35,000 Credit agreements due on dates ranging from December 19, 2024 to November 30, 2027 8.04 % 89,144 85,800 130,000 Term Loan Agreement due on September 3, 2032 3.64 % 7,000 7,700 7,000 Other notes due on dates ranging from January 1, 2024 to January 1, 2061 1.43 % 1,561 2,445 2,253 Less unamortized debt issuance costs 6,453 6,605 6,542 Less discount 284 77 286 Total long-term debt 2,847,068 2,747,763 2,841,425 Less current maturities 78,031 147,953 78,031 Net long-term debt $ 2,769,037 $ 2,599,810 $ 2,763,394 Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs and discount, at March 31, 2023, were as follows: Remainder of 2023 2024 2025 2026 2027 Thereafter (In thousands) Long-term debt maturities $ 78,031 $ 601,846 $ 177,802 $ 140,802 $ 111,452 $ 1,743,872

Cash flow information

Cash flow information	3 Months Ended
Cash flow information	Mar. 31, 2023
Supplemental Cash Flow Information [Abstract]
Cash flow information	Cash flow information Cash expenditures for interest and income taxes were as follows: Three Months Ended March 31, 2023 2022 (In thousands) Interest, net* $ 28,442 $ 15,657 Income taxes paid (refunded), net $ 8,122 $ (363) * AFUDC - borrowed was $2.4 million and $586,000 for the three months ended March 31, 2023 and 2022, respectively. Noncash investing and financing transactions were as follows: March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 15,095 $ 10,175 $ 50,921 Property, plant and equipment additions in accounts payable $ 32,171 $ 25,730 $ 49,602 Accrual for holdback payment related to a business combination $ — $ — $ 70 Stock issued in connection with a business combination $ — $ — $ 7,304

Business segment data

Business segment data	3 Months Ended
Business segment data	Mar. 31, 2023
Segment Reporting [Abstract]
Business segment data	Business segment data The Company's reportable segments are those that are based on the Company's method of internal reporting, which generally segregates the strategic business units due to differences in products, services and regulation. The internal reporting of these operating segments is defined based on the reporting and review process used by the Company's chief executive officer. The Company's operations are located within the United States. The electric segment generates, transmits and distributes electricity in Montana, North Dakota, South Dakota and Wyoming. The natural gas distribution segment distributes natural gas in those states, as well as in Idaho, Minnesota, Oregon and Washington. These operations also supply related value-added services. The pipeline segment provides natural gas transportation and underground storage services through a regulated pipeline system primarily in the Rocky Mountain and northern Great Plains regions of the United States. This segment also provides non-regulated cathodic protection services. The construction materials and contracting segment mines, processes and sells construction aggregates (crushed stone and sand and gravel); produces and sells asphalt; and supplies ready-mix concrete. This segment's aggregate reserves provide the foundation for the vertical integration of its contracting services with its construction materials to support its aggregate-based product lines including heavy-civil construction, asphalt paving, concrete construction and site development and grading. Although not common to all locations, the segment also includes the sale of cement, liquid asphalt modification and distribution, various finished concrete products, merchandise and other building materials and related contracting services. This segment operates in the central, southern and western United States, including Alaska and Hawaii. The construction services segment provides a full spectrum of construction services through its electrical and mechanical and transmission and distribution specialty contracting services across the United States. These specialty contracting services are provided to utilities, manufacturing, transportation, commercial, industrial, institutional, renewable and governmental customers. Its electrical and mechanical contracting services include construction and maintenance of electrical and communication wiring and infrastructure, fire suppression systems, and mechanical piping and services. Its transmission and distribution contracting services include construction and maintenance of overhead and underground electrical, gas and communication infrastructure, as well as manufacturing and distribution of transmission line construction equipment and tools. The Other category includes the activities of Centennial Capital, which, through its subsidiary InterSource Insurance Company, insures various types of risks as a captive insurer for certain of the Company's subsidiaries. The function of the captive insurer is to fund the self-insured layers of the insured Company's general liability, automobile liability, pollution liability and other coverages. Centennial Capital also owns certain real and personal property. In addition, the Other category includes certain assets, liabilities and tax adjustments of the holding company primarily associated with corporate functions, as well as costs associated with the announced strategic initiatives. Also included are certain general and administrative costs (reflected in operation and maintenance expense) and interest expense, which were previously allocated to the refining business and Fidelity and do not meet the criteria for income (loss) from discontinued operations. Discontinued operations include the supporting activities of Fidelity other than certain general and administrative costs and interest expense as described above. The information below follows the same accounting policies as described in Note 2 of the Notes to Consolidated Financial Statements in the 2022 Annual Report. Information on the Company's segments was as follows: Three Months Ended March 31, 2023 2022 (In thousands) External operating revenues: Regulated operations: Electric $ 95,602 $ 93,594 Natural gas distribution 565,517 450,418 Pipeline 12,638 9,444 673,757 553,456 Non-regulated operations: Pipeline 1,693 1,676 Construction materials and contracting 307,768 309,836 Construction services 754,119 551,591 Other — — 1,063,580 863,103 Total external operating revenues $ 1,737,337 $ 1,416,559 Three Months Ended March 31, 2023 2022 (In thousands) Intersegment operating revenues: Regulated operations: Electric $ 122 $ 124 Natural gas distribution 150 136 Pipeline 26,259 25,933 26,531 26,193 Non-regulated operations: Pipeline 151 7 Construction materials and contracting 132 130 Construction services 214 1,059 Other 4,739 4,341 5,236 5,537 Total intersegment operating revenues $ 31,767 $ 31,730 Operating income (loss): Electric $ 21,091 $ 15,044 Natural gas distribution 58,505 56,256 Pipeline 13,040 11,882 Construction materials and contracting (44,563) (44,605) Construction services 35,217 29,498 Other (8,818) (732) Total operating income $ 74,472 $ 67,343 Net income (loss): Regulated operations: Electric $ 16,607 $ 11,278 Natural gas distribution 38,928 36,315 Pipeline 8,759 7,956 64,294 55,549 Non-regulated operations: Pipeline (460) (619) Construction materials and contracting (41,320) (40,010) Construction services 26,074 21,324 Other (10,245) (4,511) (25,951) (23,816) Income from continuing operations 38,343 31,733 Discontinued operations, net of tax 10 30 Net income $ 38,353 $ 31,763 A reconciliation of reportable segment operating revenues to consolidated operating revenues is as follows: Three Months Ended March 31, 2023 2022 (In thousands) Operating revenues reconciliation: Total reportable segment operating revenues $ 1,764,365 $ 1,443,948 Other revenue 4,739 4,341 Elimination of intersegment operating revenues (31,767) (31,730) Total consolidated operating revenues $ 1,737,337 $ 1,416,559

Employee benefit plans

Employee benefit plans	3 Months Ended
Employee benefit plans	Mar. 31, 2023
Retirement Benefits [Abstract]
Employee benefit plans	Employee benefit plans Pension and other postretirement plans The Company has noncontributory qualified defined benefit pension plans and other postretirement benefit plans for certain eligible employees. Components of net periodic benefit credit for the Company's pension benefit plans were as follows: Three Months Ended March 31, 2023 2022 (In thousands) Components of net periodic benefit credit: Interest cost $ 3,789 $ 2,631 Expected return on assets (4,749) (4,864) Amortization of net actuarial loss 901 1,671 Net periodic benefit credit $ (59) $ (562) Components of net periodic benefit credit for the Company's other postretirement benefit plans were as follows: Three Months Ended March 31, 2023 2022 (In thousands) Components of net periodic benefit credit: Service cost $ 227 $ 354 Interest cost 670 474 Expected return on assets (1,341) (1,322) Amortization of prior service credit (350) (350) Amortization of net actuarial gain (213) (54) Net periodic benefit credit, including amount capitalized (1,007) (898) Less amount capitalized 24 31 Net periodic benefit credit $ (1,031) $ (929) The components of net periodic benefit credit, other than the service cost component, are included in other income on the Consolidated Statements of Income. The service cost component is included in operation and maintenance expense on the Consolidated Statements of Income. Nonqualified defined benefit plans In addition to the qualified defined benefit pension plans reflected in the table at the beginning of this note, the Company also has unfunded, nonqualified defined benefit plans for executive officers and certain key management employees. The Company's net periodic benefit cost for these plans was $936,000 and $773,000 for the three months ended March 31, 2023 and 2022, respectively. The components of net periodic benefit cost for these plans are included in other income on the Consolidated Statements of Income.

Regulatory matters

Regulatory matters	3 Months Ended
Regulatory matters	Mar. 31, 2023
Regulated Operations [Abstract]
Regulatory Matters	Regulatory matters The Company regularly reviews the need for electric and natural gas rate changes in each of the jurisdictions in which service is provided. The Company files for rate adjustments to seek recovery of operating costs and capital investments, as well as reasonable returns as allowed by regulators. Certain regulatory proceedings and cases may also contain recurring mechanisms that can have an annual true-up. Examples of these recurring mechanisms include: infrastructure riders, transmission trackers, renewable resource cost adjustment riders, as well as weather normalization and decoupling mechanisms. The following paragraphs summarize the Company's significant open regulatory proceedings and cases by jurisdiction including updates to those reported in the 2022 Annual Report and should be read in conjunction with previous filings. The Company is unable to predict the ultimate outcome of these matters, the timing of final decisions of the various regulators and courts, or the effect on the Company's results of operations, financial position or cash flows. IPUC Intermountain filed a request with the IPUC for a natural gas general rate increase on December 1, 2022. The request was for an increase of $11.3 million annually or 3.2 percent above current rates, which was revised on March 9, 2023, to $6.8 million annually or 1.9 percent above current rates. The requested increase is primarily to recover investments made since the last rate case in 2016 and the depreciation, operation and maintenance expenses and taxes associated with the increased investments. A settlement in principle has been reached and is expected to be filed with the IPUC no later than May 15, 2023. This matter is pending before the IPUC. MTPSC On November 4, 2022, Montana-Dakota filed an application with the MTPSC for an electric general rate increase of approximately $10.5 million annually or 15.2 percent above current rates, which was revised on March 15, 2023, to $11.5 million annually or 17.0 percent above current rates to reflect the loss of a large industrial customer. The requested increase is primarily to recover investments made since the last rate case, including Heskett Unit 4, increases in operation and maintenance expenses, and increases in property taxes. On January 24, 2023, the MTPSC approved Montana-Dakota's request for an interim increase of approximately $1.7 million or 2.7 percent above current rates, subject to refund, effective February 1, 2023. The MTPSC has 9 months to render a final decision on the rate case. The matter is pending before the MTPSC with a hearing scheduled for June 20, 2023. NDPSC On May 16, 2022, Montana-Dakota filed an application with the NDPSC for an electric general rate increase of approximately $25.4 million annually or 12.3 percent above current rates. The requested increase is primarily to recover investments in production, transmission and distribution facilities and the associated depreciation, operation and maintenance expenses and taxes associated with the increased investment. On July 14, 2022, the NDPSC approved an interim rate increase of approximately $10.9 million annually or 5.3 percent above current rates, subject to refund, for service rendered on and after July 15, 2022. The lower interim rate increase is largely due to excluding the recovery of Heskett Unit 4 from interim rates due to not being in service until summer of 2023. On April 26, 2023, the Company filed with the NDPSC an all-party settlement reflecting an annual revenue increase of $15.3 million or 7.4 percent overall. The reduction from the original filing includes a return on equity of 9.75 percent and maintaining depreciation expense at current levels. A hearing was held May 2, 2023. The matter is pending before the NDPSC. WUTC On March 24, 2022, Cascade filed a request for tariff revision with the WUTC to rectify an inadvertent IRS normalization violation resulting from its tariff established in 2018 that passes back to customers the reversal of plant-related excess deferred income taxes through an annual rate adjustment. This request was made in response to the issuances of an IRS private letter ruling to another Washington utility with the same annual rate adjustment tariff, which addressed its normalization violations. The private letter ruling concluded the tariff to refund excess deferred income taxes without corresponding adjustments for other components of rate base or changes in depreciation or income tax expense, is an impermissible methodology under the IRS normalization and consistency rules. Cascade's request proposed a similar remedy through the tariff to recover the excess amounts refunded to customers while this tariff has been in place, and revised the method going forward to reflect excess deferred income taxes in rates in the same manner as other components of rate base from its most recent general rate case. Cascade requested recovery of the excess refunded to customers of approximately $3.3 million and elimination of the currently deferred, but not yet refunded balance. A multi-party settlement was filed with the WUTC on October 21, 2022. On January 23, 2023, the WUTC denied recovery of the excess refunded to customers, but approved the tariff revision going forward to rectify the inadvertent normalization violation. On February 1, 2023, Cascade filed a motion for clarification with the WUTC on the currently deferred but not yet refunded balance. A clarifying conference was held on February 27, 2023, resulting in approval to reverse the currently deferred but not yet refunded balance of approximately $1.1 million. On February 28, 2023, this matter was finalized by the WUTC with rates effective March 1, 2023. FERC On January 27, 2023, WBI Energy Transmission filed a general rate case with the FERC for increases in its transportation and storage services rates that also includes a Greenhouse Gas Cost Recovery Mechanism for anticipated future costs. New rates, which are pending FERC approval, will be in effect August 1, 2023.

Contingencies

Contingencies	3 Months Ended
Contingencies	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is party to claims and lawsuits arising out of its business and that of its consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual, statutory and regulatory obligations. The Company accrues a liability for those contingencies when the incurrence of a loss is probable and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. The Company does not accrue liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, the Company discloses the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss including, but not limited to when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories. At March 31, 2023 and 2022, and December 31, 2022, the Company accrued contingent liabilities, which have not been discounted, of $25.4 million, $30.0 million and $32.9 million, respectively. At March 31, 2023 and 2022, and December 31, 2022, the Company also recorded corresponding insurance receivables of $3.3 million, $7.1 million and $10.4 million, respectively, and regulatory assets of $20.9 million, $20.8 million and $20.9 million, respectively, related to the accrued liabilities. The accruals are for contingencies resulting from litigation and environmental matters. This includes amounts that have been accrued for matters discussed in Environmental matters within this note. The Company will continue to monitor each matter and adjust accruals as might be warranted based on new information and further developments. Management believes that the outcomes with respect to probable and reasonably possible losses in excess of the amounts accrued, net of insurance recoveries, while uncertain, either cannot be estimated or will not have a material effect upon the Company's financial position, results of operations or cash flows. Unless otherwise required by GAAP, legal costs are expensed as they are incurred. Environmental matters The Company is a party to claims for the cleanup of environmental contamination at certain manufactured gas plant sites, as well as a superfund site. There were no material changes to the Company's environmental matters that were previously reported in the 2022 Annual Report. Guarantees Certain subsidiaries of the Company have outstanding guarantees to third parties that guarantee the performance of other subsidiaries of the Company. These guarantees are related to construction contracts, insurance deductibles and loss limits, and certain other guarantees. At March 31, 2023, the fixed maximum amounts guaranteed under these agreements aggregate $350.0 million. Certain of the guarantees also have no fixed maximum amounts specified. At March 31, 2023, the amounts of scheduled expiration of the maximum amounts guaranteed under these agreements aggregate to $28.3 million in 2023; $144.1 million in 2024; $163.3 million in 2025; $1.5 million in 2026; $1.0 million in 2027; $300,000 thereafter; and $11.5 million, which has no scheduled maturity date. There were no amounts outstanding under the previously mentioned guarantees at March 31, 2023. In the event of default under these guarantee obligations, the subsidiary issuing the guarantee for that particular obligation would be required to make payments under its guarantee. Certain subsidiaries have outstanding letters of credit to third parties related to insurance policies and other agreements, some of which are guaranteed by other subsidiaries of the Company. At March 31, 2023, the fixed maximum amounts guaranteed under these letters of credit aggregated $26.0 million. At March 31, 2023, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $25.6 million in 2023, $400,000 in 2024. There were no amounts outstanding under the previously mentioned letters of credit at March 31, 2023. In the event of default under these letter of credit obligations, the subsidiary guaranteeing the letter of credit would be obligated for reimbursement of payments made under the letter of credit. In addition, Centennial, Knife River and MDU Construction Services have issued guarantees to third parties related to the routine purchase of maintenance items, materials and lease obligations for which no fixed maximum amounts have been specified. These guarantees have no scheduled maturity date. In the event a subsidiary of the Company defaults under these obligations, Centennial, Knife River or MDU Construction Services would be required to make payments under these guarantees. Any amounts outstanding by subsidiaries of the Company were reflected on the Consolidated Balance Sheet at March 31, 2023. In the normal course of business, Centennial has surety bonds related to construction contracts and reclamation obligations of its subsidiaries. In the event a subsidiary of Centennial does not fulfill a bonded obligation, Centennial would be responsible to the surety bond company for completion of the bonded contract or obligation. A large portion of the surety bonds is expected to expire within the next 12 months; however, Centennial will likely continue to enter into surety bonds for its subsidiaries in the future. At March 31, 2023, approximately $1.6 billion of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet. Variable interest entities The Company evaluates its arrangements and contracts with other entities to determine if they are VIEs and if so, if the Company is the primary beneficiary. Fuel Contract Coyote Station entered into a coal supply agreement with Coyote Creek that provides for the purchase of coal necessary to supply the coal requirements of the Coyote Station for the period May 2016 through December 2040. Coal purchased under the coal supply agreement is reflected in inventories on the Consolidated Balance Sheets and is recovered from customers as a component of electric fuel and purchased power. The coal supply agreement creates a variable interest in Coyote Creek due to the transfer of all operating and economic risk to the Coyote Station owners, as the agreement is structured so that the price of the coal will cover all costs of operations, as well as future reclamation costs. The Coyote Station owners are also providing a guarantee of the value of the assets of Coyote Creek as they would be required to buy the assets at book value should they terminate the contract prior to the end of the contract term and are providing a guarantee of the value of the equity of Coyote Creek in that they are required to buy the entity at the end of the contract term at equity value. Although the Company has determined that Coyote Creek is a VIE, the Company has concluded that it is not the primary beneficiary of Coyote Creek because the authority to direct the activities of the entity is shared by the four unrelated owners of the Coyote Station, with no primary beneficiary existing. As a result, Coyote Creek is not required to be consolidated in the Company's financial statements. At March 31, 2023, the Company's exposure to loss as a result of the Company's involvement with the VIE, based on the Company's ownership percentage, was $29.1 million.

Subsequent Events

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent event On April 21, 2023, Intermountain repaid an additional $30.0 million of the $125.0 million term loan agreement issued on January 20, 2023. For more information on this debt agreement, see Note 15. On April 25, 2023, Knife River Holding Company issued $425.0 million of 7.75 percent senior notes due May 1, 2031, pursuant to an indenture agreement. The proceeds from the issuance of these notes will be held in escrow until the effective date of the Knife River separation or, if the separation does not occur within the time frame specified, released back to the lenders, along with accrued interest. On May 1, 2023, the Company entered into a $75.0 million term loan agreement with a SOFR-based interest rate and a maturity date of November 1, 2023. The agreement contains customary covenants and provisions, including a covenant of the Company not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. On May 3, 2023, the Company's board of directors approved the separation and the distribution of approximately 90 percent of the issued and outstanding shares of Knife River Holding Company to the Company's stockholders. Stockholders of the Company will receive one share of Knife River Holding Company common stock for every four shares of the Company's common stock held on May 22, 2023, the record date for the distribution. The Company will retain approximately 10 percent of Knife River Holding Company's common stock immediately following the separation with the intent to dispose of such shares within twelve months after the separation. Prior to completing the separation, the Company may adjust the percentage of Knife River Holding Company common stock to be distributed to the Company's stockholders and retained by the Company in response to market and other factors. The separation is expected to be complete May 31, 2023, subject to certain conditions, including the SEC declaring the registration statement on Form 10 for Knife River Holding Company to be effective.

Basis of presentation (Policies

Basis of presentation (Policies)	3 Months Ended
Basis of presentation (Policies)	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	The accompanying consolidated interim financial statements were prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Interim financial statements do not include all disclosures provided in annual financial statements and, accordingly, these financial statements should be read in conjunction with those appearing in the 2022 Annual Report. The information is unaudited but includes all adjustments that are, in the opinion of management, necessary for a fair presentation of the accompanying consolidated interim financial statements and are of a normal recurring nature. Depreciation, depletion and amortization expense is reported separately on the Consolidated Statements of Income and therefore is excluded from the other line items within operating expenses.

New accounting standards (Polic

New accounting standards (Policies)	3 Months Ended
New accounting standards (Policies)	Mar. 31, 2023
Accounting Standards Update and Change in Accounting Principle [Abstract]
New accounting standards	The following table provides a brief description of the accounting pronouncements applicable to the Company and the potential impact on its Consolidated Financial Statements and/or disclosures: Standard Description Effective date Impact on financial statements/disclosures Recently adopted accounting standards ASU 2020-04 - Reference Rate Reform In March 2020, the FASB issued optional guidance to ease the facilitation of the effects of reference rate reform on financial reporting. The guidance applies to certain contract modifications, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. Beginning January 1, 2022, LIBOR or other discontinued reference rates cannot be applied to new contracts. New contracts will incorporate a new reference rate, which includes SOFR. LIBOR or other discontinued reference rates cannot be applied to contract modifications or hedging relationships entered into or evaluated after December 31, 2022. Existing contracts referencing LIBOR or other reference rates expected to be discontinued must identify a replacement rate by June 30, 2023. Effective as of March 12, 2020 and will continue through December 31, 2022 For more information, see ASU 2022-06 - Reference Rate Reform: Deferral of Sunset Date in recently issued accounting standards not yet adopted. Recently issued accounting standards not yet adopted ASU 2022-06 - Reference Rate Reform: Deferral of Sunset Date In December 2022, the FASB included a sunset provision within ASC 848 based on expectations of when LIBOR would cease being published. At the time ASU 2020-04 was issued, the UK Financial Conduct Authority had established its intent to cease overnight tenors of LIBOR after December 31, 2021. In March 2021, the UK Financial Conduct Authority announced that the intended cessation date of the overnight tenors of LIBOR would be June 30, 2023 which is beyond the current sunset date of ASC 848. The amendments in this Update defer the sunset date of ASC 848 from December 31, 2022 to December 31, 2024, after which entities will no longer be permitted to apply the relief in ASC 848. December 31, 2024 The Company has updated its credit agreements to include language regarding the successor or alternate rate to LIBOR, and a review of other contracts and agreements is on-going. The Company does not expect the guidance to have a material impact on its results of operations, financial position, cash flows or disclosures.

Receivables and allowance for_2

Receivables and allowance for expected credit losses (Policies)	3 Months Ended
	Mar. 31, 2023
Credit Loss [Abstract]
Accounts receivable and allowance for doubtful accounts	Receivables consist primarily of trade and contracting services contract receivables from the sale of goods and services, which are recorded at the invoiced amount, and contract assets, net of expected credit losses. For more information on contract assets, see Note 8. The Company's trade receivables are all due in 12 months or less.
Expected credit loss	The Company's expected credit losses are determined through a review using historical credit loss experience; changes in asset specific characteristics; current conditions; and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly. The Company develops and documents its methodology to determine its allowance for expected credit losses at each of its reportable business segments. Risk characteristics used by the business segments may include customer mix, knowledge of customers and general economic conditions of the various local economies, among others. Specific account balances are written off when management determines the amounts to be uncollectible.

Inventories and natural gas i_2

Inventories and natural gas in storage (Policies)	3 Months Ended
Inventories and natural gas in storage (Policies)	Mar. 31, 2023
Inventory Disclosure [Abstract]
Inventories and natural gas in storage	Natural gas in storage for the Company's regulated operations is generally valued at lower of cost or market using the last-in, first-out method or lower of cost or net realizable value using the average cost or first-in, first-out method. The majority of all other inventories are valued at the lower of cost or net realizable value using the average cost method.

Earnings per share (Policies)

Earnings per share (Policies)	3 Months Ended
Earnings per share (Policies)	Mar. 31, 2023
Earnings Per Share [Abstract]
Earnings per share	Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted earnings per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the applicable period, plus the effect of non-vested performance share awards and restricted stock units. Common stock outstanding includes issued shares less shares held in treasury.

Revenue from contracts with c_2

Revenue from contracts with customers (Policies)	3 Months Ended
Revenue from contracts with customers (Policies)	Mar. 31, 2023
Revenue from Contract with Customer [Abstract]
Revenue from contracts with customers	Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes.

Business Combinations (Policies

Business Combinations (Policies)	3 Months Ended
Business Combinations (Policies)	Mar. 31, 2023
Business Combinations [Abstract]
Business Combinations Policy	The following acquisition was accounted for as a business combination in accordance with ASC 805 - Business Combinations. The results of the business combination have been included in the Consolidated Financial Statements beginning on the acquisition date. Pro forma financial amounts reflecting the effects of the business combination are not presented because it was not material to the Company's financial position or results of operations.

Environmental allowances and ob

Environmental allowances and obligations (Policies)	3 Months Ended
Environmental allowances and obligations (Policies)	Mar. 31, 2023
Accounting Policies [Abstract]
Emission Credits or Allowances, Policy	Environmental allowances and obligations The Company's natural gas distribution segment acquires environmental allowances as part of its requirement to comply with environmental regulations in certain states. Allowances are allocated by the respective states to the Company at no cost and additional allowances are required to be purchased as needed based on the requirements in the respective states. The segment records purchased and allocated environmental allowances at weighted average cost under the inventory method of accounting. Environmental allowances are included in noncurrent assets - other on the Consolidated Balance Sheets. Environmental compliance obligations, which are based on GHG emissions, are measured at the carrying value of environmental allowances held plus the estimated value of additional allowances necessary to satisfy the compliance obligation. Environmental compliance obligations are included in noncurrent liabilities - other on the Consolidated Balance Sheets. At March 31, 2023, the Company accrued $21.9 million in compliance obligations. As environmental allowances are surrendered, the segment reduces the associated environmental compliance assets and liabilities from the Consolidated Balance Sheets. The expenses associated with the Company’s environmental allowances and obligations are deferred as regulatory assets. For more information on the Company’s regulatory assets and liabilities, see Note 12.

Fair value disclosures (Policie

Fair value disclosures (Policies)	3 Months Ended
Fair value disclosures (Policies)	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Fair value measurements	The Company measures its investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income.
Investments	The Company did not elect the fair value option, which records gains and losses in income, for its available-for-sale securities, which include mortgage-backed securities and U.S. Treasury securities. These available-for-sale securities are recorded at fair value and are classified as investments on the Consolidated Balance Sheets.

Business segment data (Policies

Business segment data (Policies)	3 Months Ended
Business segment data (Policies)	Mar. 31, 2023
Segment Reporting [Abstract]
Business segment data	The Company's reportable segments are those that are based on the Company's method of internal reporting, which generally segregates the strategic business units due to differences in products, services and regulation. The internal reporting of these operating segments is defined based on the reporting and review process used by the Company's chief executive officer.

Contingencies (Policies)

Contingencies (Policies)	3 Months Ended
Contingencies (Policies)	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Contingencies	The Company is party to claims and lawsuits arising out of its business and that of its consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual, statutory and regulatory obligations. The Company accrues a liability for those contingencies when the incurrence of a loss is probable and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. The Company does not accrue liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, the Company discloses the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss including, but not limited to when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories.
Variable interest entity	The Company evaluates its arrangements and contracts with other entities to determine if they are VIEs and if so, if the Company is the primary beneficiary.

Receivables and allowance for_3

Receivables and allowance for expected credit losses (Tables)	3 Months Ended
	Mar. 31, 2023
Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss	Details of the Company's expected credit losses were as follows: Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 2022 $ 375 $ 1,615 $ 2 $ 5,477 $ 2,162 $ 9,631 Current expected credit loss provision 615 2,324 — 428 826 4,193 Less write-offs charged against the allowance 667 1,225 — 83 51 2,026 Credit loss recoveries collected 145 229 — — 1 375 At March 31, 2023 $ 468 $ 2,943 $ 2 $ 5,822 $ 2,938 $ 12,173 Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 2021 $ 269 $ 1,506 $ 2 $ 5,406 $ 2,533 $ 9,716 Current expected credit loss provision 565 1,369 — (253) 54 1,735 Less write-offs charged against the allowance 597 932 — 27 71 1,627 Credit loss recoveries collected 124 180 — — 28 332 At March 31, 2022 $ 361 $ 2,123 $ 2 $ 5,126 $ 2,544 $ 10,156

Inventories and natural gas i_3

Inventories and natural gas in storage (Tables)	3 Months Ended
Inventories and natural gas in storage (Tables)	Mar. 31, 2023
Inventory Disclosure [Abstract]
Inventories	Inventories on the Consolidated Balance Sheets were as follows: March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Aggregates held for resale $ 207,564 $ 195,489 $ 199,110 Asphalt oil 101,271 93,816 68,609 Materials and supplies 45,310 35,967 40,056 Merchandise for resale 42,603 33,393 40,296 Natural gas in storage (current) 8,662 10,801 22,533 Other 20,424 10,850 16,921 Total $ 425,834 $ 380,316 $ 387,525

Earnings per share (Tables)

Earnings per share (Tables)	3 Months Ended
Earnings per share (Tables)	Mar. 31, 2023
Earnings Per Share [Abstract]
Weighted average common shares outstanding	A reconciliation of the weighted average common shares outstanding used in the basic and diluted earnings per share calculations follows: Three Months Ended March 31, 2023 2022 (In thousands, except per share amounts) Weighted average common shares outstanding - basic 203,624 203,351 Effect of dilutive performance share awards and restricted stock units 286 40 Weighted average common shares outstanding - diluted 203,910 203,391 Shares excluded from the calculation of diluted earnings per share — — Dividends declared per common share $ .2225 $ .2175

Accumulated other comprehensi_2

Accumulated other comprehensive loss (Tables)	3 Months Ended
Accumulated other comprehensive loss (Tables)	Mar. 31, 2023
Equity [Abstract]
Accumulated comprehensive loss	The after-tax changes in the components of accumulated other comprehensive loss were as follows: Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2022 $ (125) $ (29,900) $ (558) $ (30,583) Other comprehensive income before reclassifications — — 70 70 Amounts reclassified from accumulated other comprehensive loss 34 100 13 147 Net current-period other comprehensive income 34 100 83 217 At March 31, 2023 $ (91) $ (29,800) $ (475) $ (30,366) Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2021 $ (538) $ (40,461) $ (5) $ (41,004) Other comprehensive loss before reclassifications — — (320) (320) Amounts reclassified from accumulated other comprehensive loss 112 445 32 589 Net current-period other comprehensive income (loss) 112 445 (288) 269 At March 31, 2022 $ (426) $ (40,016) $ (293) $ (40,735)
Reclassification out of accumulated other comprehensive loss	The following amounts were reclassified out of accumulated other comprehensive loss into net income. The amounts presented in parenthesis indicate a decrease to net income on the Consolidated Statements of Income. The reclassifications were as follows: Three Months Ended Location on Consolidated March 31, 2023 2022 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (45) $ (148) Interest expense 11 36 Income taxes (34) (112) Amortization of postretirement liability losses included in net periodic benefit credit (134) (609) Other income 34 164 Income taxes (100) (445) Reclassification adjustment on available-for-sale investments included in net income (16) (40) Other income 3 8 Income taxes (13) (32) Total reclassifications $ (147) $ (589)

Revenue from contracts with c_3

Revenue from contracts with customers (Tables)	3 Months Ended
Revenue from contracts with customers (Tables)	Mar. 31, 2023
Revenue from Contract with Customer [Abstract]
Disaggregation of revenue	In the following tables, revenue is disaggregated by the type of customer or service provided. The Company believes this level of disaggregation best depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. The table also includes a reconciliation of the disaggregated revenue by reportable segments. For more information on the Company's business segments, see Note 17. Three Months Ended March 31, 2023 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 37,825 $ 327,651 $ — $ — $ — $ — $ 365,476 Commercial utility sales 36,347 204,927 — — — — 241,274 Industrial utility sales 10,763 16,838 — — — — 27,601 Other utility sales 1,774 — — — — — 1,774 Natural gas transportation — 13,504 34,983 — — — 48,487 Natural gas storage — — 3,861 — — — 3,861 Contracting services — — — 114,983 — — 114,983 Construction materials — — — 232,502 — — 232,502 Intrasegment eliminations — — — (39,585) — — (39,585) Electrical & mechanical specialty contracting — — — — 590,263 — 590,263 Transmission & distribution specialty contracting — — — — 152,022 — 152,022 Other 11,878 4,721 1,859 — 33 4,739 23,230 Intersegment eliminations (122) (150) (26,410) (132) (214) (4,739) (31,767) Revenues from contracts with customers 98,465 567,491 14,293 307,768 742,104 — 1,730,121 Revenues out of scope (2,863) (1,974) 38 — 12,015 — 7,216 Total external operating revenues $ 95,602 $ 565,517 $ 14,331 $ 307,768 $ 754,119 $ — $ 1,737,337 Three Months Ended March 31, 2022 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 37,304 $ 258,816 $ — $ — $ — $ — $ 296,120 Commercial utility sales 35,600 163,609 — — — — 199,209 Industrial utility sales 10,306 13,024 — — — — 23,330 Other utility sales 1,750 — — — — — 1,750 Natural gas transportation — 12,381 31,574 — — — 43,955 Natural gas storage — — 3,719 — — — 3,719 Contracting services — — — 114,267 — — 114,267 Construction materials — — — 241,732 — — 241,732 Intrasegment eliminations — — — (46,033) — — (46,033) Electrical & mechanical specialty contracting — — — — 392,808 — 392,808 Transmission & distribution specialty contracting — — — — 148,466 — 148,466 Other 12,753 2,609 1,709 — 48 4,341 21,460 Intersegment eliminations (124) (136) (25,940) (130) (1,059) (4,341) (31,730) Revenues from contracts with customers 97,589 450,303 11,062 309,836 540,263 — 1,409,053 Revenues out of scope (3,995) 115 58 — 11,328 — 7,506 Total external operating revenues $ 93,594 $ 450,418 $ 11,120 $ 309,836 $ 551,591 $ — $ 1,416,559
Contract balances	The changes in contract assets and liabilities were as follows: March 31, 2023 December 31, 2022 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 212,687 $ 185,289 $ 27,398 Receivables, net Contract liabilities - current (202,788) (208,204) 5,416 Accounts payable Contract liabilities - noncurrent (442) (6) (436) Noncurrent liabilities - other Net contract assets (liabilities) $ 9,457 $ (22,921) $ 32,378

Goodwill and other intangible_2

Goodwill and other intangible assets (Tables)	3 Months Ended
Goodwill and other intangible assets (Tables)	Mar. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the carrying amount of goodwill	The changes in the carrying amount of goodwill were as follows: Balance at January 1, 2023 Goodwill Measurement Balance at March 31, 2023 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 274,540 — — 274,540 Construction services 143,224 — — 143,224 Total $ 763,500 $ — $ — $ 763,500 Balance at January 1, 2022 Goodwill Measurement Balance at March 31, 2022 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 276,426 — (2,124) 274,302 Construction services 143,224 — — 143,224 Total $ 765,386 $ — $ (2,124) $ 763,262 Balance at January 1, 2022 Goodwill Measurement Balance at December 31, 2022 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 276,426 238 (2,124) 274,540 Construction services 143,224 — — 143,224 Total $ 765,386 $ 238 $ (2,124) $ 763,500
Other amortizable intangible assets	Other amortizable intangible assets were as follows: March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Customer relationships $ 28,990 $ 28,990 $ 28,990 Less accumulated amortization 14,680 10,846 13,724 14,310 18,144 15,266 Noncompete agreements 4,331 4,591 4,591 Less accumulated amortization 3,405 3,016 3,529 926 1,575 1,062 Other 2,479 6,969 5,280 Less accumulated amortization 1,381 5,299 4,076 1,098 1,670 1,204 Total $ 16,334 $ 21,389 $ 17,532
Estimated amortization expense	Estimated amortization expense for identifiable intangible assets as of March 31, 2023, was: Remainder of 2023 2024 2025 2026 2027 Thereafter (In thousands) Amortization expense $ 3,393 $ 4,249 $ 2,200 $ 1,782 $ 1,759 $ 2,951

Regulatory assets and liabili_2

Regulatory assets and liabilities (Tables)	3 Months Ended
Regulatory assets and liabilities (Tables)	Mar. 31, 2023
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets	The following table summarizes the individual components of unamortized regulatory assets and liabilities: Estimated Recovery or Refund Period as of March 31, 2023 * March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 198,166 $ 66,132 $ 141,306 Conservation programs Up to 1 year 8,599 7,567 8,544 Cost recovery mechanisms Up to 1 year 3,954 3,432 4,019 Other Up to 1 year 5,599 11,947 11,223 216,318 89,078 165,092 Noncurrent: Pension and postretirement benefits 143,349 142,681 143,349 Cost recovery mechanisms Up to 10 years 65,732 67,989 67,171 Plant costs/asset retirement obligations Over plant lives 44,131 63,325 44,462 Manufactured gas plant site remediation - 26,605 26,089 26,624 Environmental compliance programs - 21,942 — — Plant to be retired - 21,072 29,452 21,525 Taxes recoverable from customers Over plant lives 12,198 12,492 12,330 Long-term debt refinancing costs Up to 37 years 3,041 3,636 3,188 Other Up to 16 years 11,430 13,564 11,010 349,500 359,228 329,659 Total regulatory assets $ 565,818 $ 448,306 $ 494,751 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year 9,630 — 4,929 Natural gas costs refundable through rate adjustments Up to 1 year 6,331 13,107 955 Conservation programs Up to 1 year 3,834 144 4,126 Cost recovery mechanisms Up to 1 year 2,926 2,550 1,977 Taxes refundable to customers Up to 1 year 1,513 3,470 3,937 Refundable fuel and electric costs Up to 1 year 1,179 316 3,253 Other Up to 1 year 18,982 11,599 7,263 44,395 31,186 26,440 Noncurrent: Plant removal and decommissioning costs Over plant lives 214,467 171,485 208,650 Taxes refundable to customers Over plant lives 200,879 212,472 203,222 Cost recovery mechanisms Up to 19 years 16,313 9,508 14,025 Accumulated deferred investment tax credit Up to 19 years 13,996 13,352 13,594 Pension and postretirement benefits 7,376 20,434 7,376 Other Up to 15 years 1,638 6,377 1,587 454,669 433,628 448,454 Total regulatory liabilities $ 499,064 $ 464,814 $ 474,894 Net regulatory position $ 66,754 $ (16,508) $ 19,857 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made.
Regulatory Liabilities	The following table summarizes the individual components of unamortized regulatory assets and liabilities: Estimated Recovery or Refund Period as of March 31, 2023 * March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 198,166 $ 66,132 $ 141,306 Conservation programs Up to 1 year 8,599 7,567 8,544 Cost recovery mechanisms Up to 1 year 3,954 3,432 4,019 Other Up to 1 year 5,599 11,947 11,223 216,318 89,078 165,092 Noncurrent: Pension and postretirement benefits 143,349 142,681 143,349 Cost recovery mechanisms Up to 10 years 65,732 67,989 67,171 Plant costs/asset retirement obligations Over plant lives 44,131 63,325 44,462 Manufactured gas plant site remediation - 26,605 26,089 26,624 Environmental compliance programs - 21,942 — — Plant to be retired - 21,072 29,452 21,525 Taxes recoverable from customers Over plant lives 12,198 12,492 12,330 Long-term debt refinancing costs Up to 37 years 3,041 3,636 3,188 Other Up to 16 years 11,430 13,564 11,010 349,500 359,228 329,659 Total regulatory assets $ 565,818 $ 448,306 $ 494,751 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year 9,630 — 4,929 Natural gas costs refundable through rate adjustments Up to 1 year 6,331 13,107 955 Conservation programs Up to 1 year 3,834 144 4,126 Cost recovery mechanisms Up to 1 year 2,926 2,550 1,977 Taxes refundable to customers Up to 1 year 1,513 3,470 3,937 Refundable fuel and electric costs Up to 1 year 1,179 316 3,253 Other Up to 1 year 18,982 11,599 7,263 44,395 31,186 26,440 Noncurrent: Plant removal and decommissioning costs Over plant lives 214,467 171,485 208,650 Taxes refundable to customers Over plant lives 200,879 212,472 203,222 Cost recovery mechanisms Up to 19 years 16,313 9,508 14,025 Accumulated deferred investment tax credit Up to 19 years 13,996 13,352 13,594 Pension and postretirement benefits 7,376 20,434 7,376 Other Up to 15 years 1,638 6,377 1,587 454,669 433,628 448,454 Total regulatory liabilities $ 499,064 $ 464,814 $ 474,894 Net regulatory position $ 66,754 $ (16,508) $ 19,857 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made.

Fair value measurements (Tables

Fair value measurements (Tables)	3 Months Ended
Fair value measurements (Tables)	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Available-for-sale securities	Details of available-for-sale securities were as follows: March 31, 2023 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,557 $ 3 $ 561 $ 7,999 U.S. Treasury securities 3,023 8 51 2,980 Total $ 11,580 $ 11 $ 612 $ 10,979 March 31, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,778 $ 3 $ 310 $ 8,471 U.S. Treasury securities 2,688 — 63 2,625 Total $ 11,466 $ 3 $ 373 $ 11,096 December 31, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,928 $ 2 $ 636 $ 8,294 U.S. Treasury securities 2,608 — 72 2,536 Total $ 11,536 $ 2 $ 708 $ 10,830
Assets and liabilities measured at fair value on a recurring basis	The Company's assets measured at fair value on a recurring basis were as follows: Fair Value Measurements at March 31, 2023, Using Quoted Prices in Significant Significant Balance at March 31, 2023 (In thousands) Assets: Money market funds $ — $ 7,919 $ — $ 7,919 Insurance contracts* — 105,857 — 105,857 Available-for-sale securities: Mortgage-backed securities — 7,999 — 7,999 U.S. Treasury securities — 2,980 — 2,980 Total assets measured at fair value $ — $ 124,755 $ — $ 124,755 * The insurance contracts invest approximately 61 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 7 percent in target date investments, 6 percent in common stock of small-cap companies, 2 percent in cash equivalents and 1 percent in international investments. Fair Value Measurements at March 31, 2022, Using Quoted Prices in Significant Significant Balance at March 31, 2022 (In thousands) Assets: Money market funds $ — $ 13,131 $ — $ 13,131 Insurance contracts* — 105,371 — 105,371 Available-for-sale securities: Mortgage-backed securities — 8,471 — 8,471 U.S. Treasury securities — 2,625 — 2,625 Total assets measured at fair value $ — $ 129,598 $ — $ 129,598 * The insurance contracts invest approximately 61 percent in fixed-income investments, 17 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at December 31, 2022, Using Quoted Prices in Significant Significant Balance at December 31, 2022 (In thousands) Assets: Money market funds $ — $ 7,361 $ — $ 7,361 Insurance contracts* — 98,041 — 98,041 Available-for-sale securities: Mortgage-backed securities — 8,294 — 8,294 U.S. Treasury securities — 2,536 — 2,536 Total assets measured at fair value $ — $ 116,232 $ — $ 116,232 * The insurance contracts invest approximately 63 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents.
Fair value of long term debt outstanding	The estimated fair value of the Company's Level 2 long-term debt was as follows: March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Carrying amount $ 2,847,068 $ 2,747,763 $ 2,841,425 Fair value $ 2,535,125 $ 2,755,041 $ 2,469,625

Debt (Tables)

Debt (Tables)	3 Months Ended
Debt (Tables)	Mar. 31, 2023
Debt Disclosure [Abstract]
Long-term debt outstanding	Long-term debt outstanding was as follows: Weighted Average Interest Rate at March 31, 2023 March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Senior Notes due on dates ranging from May 15, 2023 to June 15, 2062 4.32 % $ 2,258,500 $ 2,275,000 $ 2,258,500 Commercial paper supported by revolving credit agreements 6.18 % 462,600 348,500 415,500 Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 7.32 % 35,000 35,000 35,000 Credit agreements due on dates ranging from December 19, 2024 to November 30, 2027 8.04 % 89,144 85,800 130,000 Term Loan Agreement due on September 3, 2032 3.64 % 7,000 7,700 7,000 Other notes due on dates ranging from January 1, 2024 to January 1, 2061 1.43 % 1,561 2,445 2,253 Less unamortized debt issuance costs 6,453 6,605 6,542 Less discount 284 77 286 Total long-term debt 2,847,068 2,747,763 2,841,425 Less current maturities 78,031 147,953 78,031 Net long-term debt $ 2,769,037 $ 2,599,810 $ 2,763,394
Schedule of debt maturities	Long-term debt maturities, which excludes unamortized debt issuance costs and discount, at March 31, 2023, were as follows: Remainder of 2023 2024 2025 2026 2027 Thereafter (In thousands) Long-term debt maturities $ 78,031 $ 601,846 $ 177,802 $ 140,802 $ 111,452 $ 1,743,872

Cash flow information (Tables)

Cash flow information (Tables)	3 Months Ended
Cash flow information (Tables)	Mar. 31, 2023
Supplemental Cash Flow Information [Abstract]
Cash expenditures for interest and income taxes and noncash investing and financing transactions	Cash expenditures for interest and income taxes were as follows: Three Months Ended March 31, 2023 2022 (In thousands) Interest, net* $ 28,442 $ 15,657 Income taxes paid (refunded), net $ 8,122 $ (363) * AFUDC - borrowed was $2.4 million and $586,000 for the three months ended March 31, 2023 and 2022, respectively. Noncash investing and financing transactions were as follows: March 31, 2023 March 31, 2022 December 31, 2022 (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 15,095 $ 10,175 $ 50,921 Property, plant and equipment additions in accounts payable $ 32,171 $ 25,730 $ 49,602 Accrual for holdback payment related to a business combination $ — $ — $ 70 Stock issued in connection with a business combination $ — $ — $ 7,304

Business segment data (Tables)

Business segment data (Tables)	3 Months Ended
Business segment data (Tables)	Mar. 31, 2023
Segment Reporting [Abstract]
Information on the Company's businesses	Information on the Company's segments was as follows: Three Months Ended March 31, 2023 2022 (In thousands) External operating revenues: Regulated operations: Electric $ 95,602 $ 93,594 Natural gas distribution 565,517 450,418 Pipeline 12,638 9,444 673,757 553,456 Non-regulated operations: Pipeline 1,693 1,676 Construction materials and contracting 307,768 309,836 Construction services 754,119 551,591 Other — — 1,063,580 863,103 Total external operating revenues $ 1,737,337 $ 1,416,559 Three Months Ended March 31, 2023 2022 (In thousands) Intersegment operating revenues: Regulated operations: Electric $ 122 $ 124 Natural gas distribution 150 136 Pipeline 26,259 25,933 26,531 26,193 Non-regulated operations: Pipeline 151 7 Construction materials and contracting 132 130 Construction services 214 1,059 Other 4,739 4,341 5,236 5,537 Total intersegment operating revenues $ 31,767 $ 31,730 Operating income (loss): Electric $ 21,091 $ 15,044 Natural gas distribution 58,505 56,256 Pipeline 13,040 11,882 Construction materials and contracting (44,563) (44,605) Construction services 35,217 29,498 Other (8,818) (732) Total operating income $ 74,472 $ 67,343 Net income (loss): Regulated operations: Electric $ 16,607 $ 11,278 Natural gas distribution 38,928 36,315 Pipeline 8,759 7,956 64,294 55,549 Non-regulated operations: Pipeline (460) (619) Construction materials and contracting (41,320) (40,010) Construction services 26,074 21,324 Other (10,245) (4,511) (25,951) (23,816) Income from continuing operations 38,343 31,733 Discontinued operations, net of tax 10 30 Net income $ 38,353 $ 31,763
Reconciliation of Revenue from Segments to Consolidated	A reconciliation of reportable segment operating revenues to consolidated operating revenues is as follows: Three Months Ended March 31, 2023 2022 (In thousands) Operating revenues reconciliation: Total reportable segment operating revenues $ 1,764,365 $ 1,443,948 Other revenue 4,739 4,341 Elimination of intersegment operating revenues (31,767) (31,730) Total consolidated operating revenues $ 1,737,337 $ 1,416,559

Employee benefit plans (Tables)

Employee benefit plans (Tables)	3 Months Ended
Employee benefit plans (Tables)	Mar. 31, 2023
Retirement Benefits [Abstract]
Schedule of net benefit costs	Components of net periodic benefit credit for the Company's pension benefit plans were as follows: Three Months Ended March 31, 2023 2022 (In thousands) Components of net periodic benefit credit: Interest cost $ 3,789 $ 2,631 Expected return on assets (4,749) (4,864) Amortization of net actuarial loss 901 1,671 Net periodic benefit credit $ (59) $ (562) Components of net periodic benefit credit for the Company's other postretirement benefit plans were as follows: Three Months Ended March 31, 2023 2022 (In thousands) Components of net periodic benefit credit: Service cost $ 227 $ 354 Interest cost 670 474 Expected return on assets (1,341) (1,322) Amortization of prior service credit (350) (350) Amortization of net actuarial gain (213) (54) Net periodic benefit credit, including amount capitalized (1,007) (898) Less amount capitalized 24 31 Net periodic benefit credit $ (1,031) $ (929)

Receivables and allowance for_4

Receivables and allowance for expected credit losses (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Credit Loss [Abstract]
Accounts Receivable, Noncurrent, 90 Days or More Past Due, Still Accruing	$ 53.5	$ 45.6	$ 50.7

Receivables and allowance for_5

Receivables and allowance for expected credit losses (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses	$ 4,193	$ 1,735
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	9,631	9,716
Provision for credit losses	4,193	1,735
Less write-offs charged against the allowance	2,026	1,627
Credit loss recoveries collected	375	332
Balance	12,173	10,156
Electric \| Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	375	269
Provision for credit losses	615	565
Less write-offs charged against the allowance	667	597
Credit loss recoveries collected	145	124
Balance	468	361
Natural gas distribution \| Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	1,615	1,506
Provision for credit losses	2,324	1,369
Less write-offs charged against the allowance	1,225	932
Credit loss recoveries collected	229	180
Balance	2,943	2,123
Pipeline \| Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2	2
Provision for credit losses	0	0
Less write-offs charged against the allowance	0	0
Credit loss recoveries collected	0	0
Balance	2	2
Construction materials and contracting \| Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	5,477	5,406
Provision for credit losses	428	(253)
Less write-offs charged against the allowance	83	27
Credit loss recoveries collected	0	0
Balance	5,822	5,126
Construction services \| Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2,162	2,533
Provision for credit losses	826	54
Less write-offs charged against the allowance	51	71
Credit loss recoveries collected	1	28
Balance	$ 2,938	$ 2,544

Inventories and natural gas i_4

Inventories and natural gas in storage (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Inventory Disclosure [Abstract]
Aggregates held for resale	$ 207,564	$ 199,110	$ 195,489
Asphalt oil	101,271	68,609	93,816
Materials and supplies	45,310	40,056	35,967
Merchandise for resale	42,603	40,296	33,393
Natural gas in storage (current)	8,662	22,533	10,801
Other	20,424	16,921	10,850
Total	425,834	387,525	380,316
Natural gas in storage noncurrent	$ 47,400	$ 47,500	$ 47,500

Earnings per share (Details)

Earnings per share (Details) - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share [Abstract]
Weighted average common shares outstanding - basic	203,624	203,351
Effect of dilutive performance share awards and restricted stock units	286	40
Weighted average common shares outstanding - diluted	203,910	203,391
Shares excluded from the calculation of diluted earnings per share	0	0
Dividends declared per common share	$ 0.2225	$ 0.2175

Accumulated other comprehensi_3

Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accumulated other comprehensive loss [Roll Forward]
Balance	$ 3,587,129	$ 3,382,874
Other comprehensive income (loss)	217	269
Balance	3,575,382	3,360,718
Net unrealized gain (loss) on derivative instruments qualifying as hedges
Accumulated other comprehensive loss [Roll Forward]
Balance	(125)	(538)
Other comprehensive loss before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	34	112
Other comprehensive income (loss)	34	112
Balance	(91)	(426)
Postretirement liability adjustment
Accumulated other comprehensive loss [Roll Forward]
Balance	(29,900)	(40,461)
Other comprehensive loss before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	100	445
Other comprehensive income (loss)	100	445
Balance	(29,800)	(40,016)
Net unrealized gain (loss) on available-for-sale investments
Accumulated other comprehensive loss [Roll Forward]
Balance	(558)	(5)
Other comprehensive loss before reclassifications	70	(320)
Amounts reclassified from accumulated other comprehensive loss	13	32
Other comprehensive income (loss)	83	(288)
Balance	(475)	(293)
Total accumulated other comprehensive loss
Accumulated other comprehensive loss [Roll Forward]
Balance	(30,583)	(41,004)
Other comprehensive loss before reclassifications	70	(320)
Amounts reclassified from accumulated other comprehensive loss	147	589
Other comprehensive income (loss)	217	269
Balance	$ (30,366)	$ (40,735)

Reclassification out of accumul

Reclassification out of accumulated other comprehensive loss (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	$ (38,020)	$ (25,260)
Income taxes	(8,977)	(7,950)
Other income	10,868	(2,400)
Net income	38,353	31,763
Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Net income	(147)	(589)
Reclassification adjustment for loss on derivative instruments included in net income \| Reclassification out of accumulated other comprehensive loss \| Interest rate contract
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	(45)	(148)
Income taxes	11	36
Net income	(34)	(112)
Amortization of postretirement liability losses included in net periodic benefit credit \| Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Income taxes	34	164
Other income	(134)	(609)
Net income	(100)	(445)
Reclassification adjustment on available-for-sale investments included in net income \| Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Income taxes	3	8
Other income	(16)	(40)
Net income	$ (13)	$ (32)

Disaggregation of revenue (Deta

Disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Operating revenues:	$ 1,737,337	$ 1,416,559
Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(31,767)	(31,730)
Intrasegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(39,585)	(46,033)
Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	48,487	43,955
Natural gas storage
Disaggregation of Revenue [Line Items]
Operating revenues:	3,861	3,719
Contracting services
Disaggregation of Revenue [Line Items]
Operating revenues:	114,983	114,267
Construction materials
Disaggregation of Revenue [Line Items]
Operating revenues:	232,502	241,732
Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	590,263	392,808
Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	152,022	148,466
Other
Disaggregation of Revenue [Line Items]
Operating revenues:	23,230	21,460
Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	1,730,121	1,409,053
Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	7,216	7,506
Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	365,476	296,120
Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	241,274	199,209
Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	27,601	23,330
Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	1,774	1,750
Electric
Disaggregation of Revenue [Line Items]
Operating revenues:	95,602	93,594
Electric \| Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(122)	(124)
Electric \| Other
Disaggregation of Revenue [Line Items]
Operating revenues:	11,878	12,753
Electric \| Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	98,465	97,589
Electric \| Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	(2,863)	(3,995)
Electric \| Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	37,825	37,304
Electric \| Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	36,347	35,600
Electric \| Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	10,763	10,306
Electric \| Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	1,774	1,750
Natural gas distribution
Disaggregation of Revenue [Line Items]
Operating revenues:	565,517	450,418
Natural gas distribution \| Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(150)	(136)
Natural gas distribution \| Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	13,504	12,381
Natural gas distribution \| Other
Disaggregation of Revenue [Line Items]
Operating revenues:	4,721	2,609
Natural gas distribution \| Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	567,491	450,303
Natural gas distribution \| Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	(1,974)	115
Natural gas distribution \| Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	327,651	258,816
Natural gas distribution \| Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	204,927	163,609
Natural gas distribution \| Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	16,838	13,024
Natural gas distribution \| Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0
Pipeline
Disaggregation of Revenue [Line Items]
Operating revenues:	14,331	11,120
Pipeline \| Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(26,410)	(25,940)
Pipeline \| Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	34,983	31,574
Pipeline \| Natural gas storage
Disaggregation of Revenue [Line Items]
Operating revenues:	3,861	3,719
Pipeline \| Other
Disaggregation of Revenue [Line Items]
Operating revenues:	1,859	1,709
Pipeline \| Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	14,293	11,062
Pipeline \| Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	38	58
Construction materials and contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	307,768	309,836
Construction materials and contracting \| Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(132)	(130)
Construction materials and contracting \| Intrasegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(39,585)	(46,033)
Construction materials and contracting \| Contracting services
Disaggregation of Revenue [Line Items]
Operating revenues:	114,983	114,267
Construction materials and contracting \| Construction materials
Disaggregation of Revenue [Line Items]
Operating revenues:	232,502	241,732
Construction materials and contracting \| Other
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0
Construction materials and contracting \| Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	307,768	309,836
Construction materials and contracting \| Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0
Construction services
Disaggregation of Revenue [Line Items]
Operating revenues:	754,119	551,591
Construction services \| Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(214)	(1,059)
Construction services \| Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	590,263	392,808
Construction services \| Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	152,022	148,466
Construction services \| Other
Disaggregation of Revenue [Line Items]
Operating revenues:	33	48
Construction services \| Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	742,104	540,263
Construction services \| Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	12,015	11,328
Other
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0
Other \| Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(4,739)	(4,341)
Other \| Other
Disaggregation of Revenue [Line Items]
Operating revenues:	4,739	4,341
Other \| Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0
Other \| Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	$ 0	$ 0

Contract balances (Details 2)

Contract balances (Details 2) - USD ($) $ in Thousands	3 Months Ended
Contract balances (Details 2) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Contract assets	$ 212,687		$ 185,289
Change in contract assets	27,398
Contract liabilities - current	(202,788)		(208,204)
Change in contract liabilities - current	5,416
Contract liabilities - noncurrent	(442)		(6)
Change in contract liabilities - noncurrent	(436)
Net contract assets (liabilities)	9,457		$ (22,921)
Change in net contract assets (liabilities)	32,378
Amounts included in contract liability at the beginning of the period	154,900	$ 121,800
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 21,300	$ 23,500

Revenue from contracts with c_4

Revenue from contracts with customers Remaining performance obligations (Details 3) $ in Millions	Mar. 31, 2023 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 3,700
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2,600
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 454.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	13 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 592.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	25 months

Business Combinations (Details)

Business Combinations (Details) - USD ($)	12 Months Ended
Business Combinations (Details) - USD ($)	Dec. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Goodwill	$ 763,500,000	$ 763,500,000	$ 763,262,000	$ 765,386,000
2022 Acquisition
Business Acquisition [Line Items]
Gross Aggregate Consideration	8,900,000
Cash Assumed	2,800,000
Business Combination, Consideration Transferred	1,500,000
Business Combination, Consideration Transferred, Liabilities Incurred	70,000
Business Combination, Current Assets	1,700,000
Business Combination, Property, Plant, and Equipment	5,900,000
Goodwill	200,000
Business Combination, Current Liabilities	100,000
Business Combination, Noncurrent Liabilities	500,000
Business Combination, Deferred Tax Liabilities	$ 1,200,000
2022 Acquisition \| Common stock
Business Acquisition [Line Items]
Common Stock Shares Issued	273,153
Common Stock Market Value	$ 8,400,000
Common Stock Discounted Fair Value	$ 7,300,000

Business Combinations - Acquisi

Business Combinations - Acquisition Costs Incurred (Details 2) - USD ($)	Mar. 31, 2023	Mar. 31, 2022
Operating Expense
Business Acquisition [Line Items]
Business Acquisition, Transaction Costs	$ 0	$ 0

Lessor accounting (Details)

Lessor accounting (Details) - USD ($) $ in Millions	3 Months Ended
Lessor accounting (Details) - USD ($) $ in Millions	Mar. 31, 2023	Mar. 31, 2022
Leases [Abstract]
Operating Lease, Lease Income	$ 12.2	$ 11.4
Lessor, Operating Lease, Payments to be Received, Next Twelve Months	$ 9.1

Goodwill rollforward (Details)

Goodwill rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
Goodwill rollforward (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Goodwill [Roll Forward]
Balance at beginning of period	$ 763,500	$ 765,386	$ 765,386
Goodwill acquired during the year	0	0	238
Measurement period adjustments	0	(2,124)	(2,124)
Balance at end of period	763,500	763,262	763,500
Natural gas distribution
Goodwill [Roll Forward]
Balance at beginning of period	345,736	345,736	345,736
Goodwill acquired during the year	0	0	0
Measurement period adjustments	0	0	0
Balance at end of period	345,736	345,736	345,736
Construction materials and contracting
Goodwill [Roll Forward]
Balance at beginning of period	274,540	276,426	276,426
Goodwill acquired during the year	0	0	238
Measurement period adjustments	0	(2,124)	(2,124)
Balance at end of period	274,540	274,302	274,540
Construction services
Goodwill [Roll Forward]
Balance at beginning of period	143,224	143,224	143,224
Goodwill acquired during the year	0	0	0
Measurement period adjustments	0	0	0
Balance at end of period	$ 143,224	$ 143,224	$ 143,224

Other intangible assets (Detail

Other intangible assets (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 16,334	$ 21,389	$ 17,532
Amortization of intangible assets	1,200	1,200
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	28,990	28,990	28,990
Intangible assets, less accumulated amortization	14,680	10,846	13,724
Intangible assets, net (excluding goodwill)	14,310	18,144	15,266
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	4,331	4,591	4,591
Intangible assets, less accumulated amortization	3,405	3,016	3,529
Intangible assets, net (excluding goodwill)	926	1,575	1,062
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	2,479	6,969	5,280
Intangible assets, less accumulated amortization	1,381	5,299	4,076
Intangible assets, net (excluding goodwill)	$ 1,098	$ 1,670	$ 1,204

Future amortization expense (De

Future amortization expense (Details 3) $ in Thousands	Mar. 31, 2023 USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2023	$ 3,393
2024	4,249
2025	2,200
2026	1,782
2027	1,759
Thereafter	$ 2,951

Regulatory assets (Details)

Regulatory assets (Details) - USD ($) $ in Thousands	3 Months Ended
Regulatory assets (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Regulatory Assets
Regulatory Assets, Current	$ 216,318	$ 165,092	$ 89,078
Regulatory Assets, Noncurrent	349,500	329,659	359,228
Total regulatory assets	565,818	494,751	448,306
Regulatory assets not earning a rate of return	$ 255,600	242,500	268,100
Natural gas costs recoverable through rate adjustments
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Regulatory Assets, Current	$ 198,166	141,306	66,132
Conservation programs
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Regulatory Assets, Current	$ 8,599	8,544	7,567
Cost recovery mechanisms
Regulatory Assets
Regulatory Assets, Current	3,954	4,019	3,432
Regulatory Assets, Noncurrent	$ 65,732	67,171	67,989
Cost recovery mechanisms \| Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Cost recovery mechanisms \| Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Up to 10 years
Other regulatory assets
Regulatory Assets
Regulatory Assets, Current	$ 5,599	11,223	11,947
Regulatory Assets, Noncurrent	$ 11,430	11,010	13,564
Other regulatory assets \| Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Other regulatory assets \| Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Up to 16 years
Pension and postretirement benefits
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	**
Regulatory Assets, Noncurrent	$ 143,349	143,349	142,681
Plant costs/asset retirement obligations
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Over plant lives
Regulatory Assets, Noncurrent	$ 44,131	44,462	63,325
Manufactured gas plant site remediation
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	-
Regulatory Assets, Noncurrent	$ 26,605	26,624	26,089
Environmental compliance programs
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	-
Regulatory Assets, Noncurrent	$ 21,942	0	0
Plant to be retired
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	-
Regulatory Assets, Noncurrent	$ 21,072	21,525	29,452
Taxes recoverable from customers
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Over plant lives
Regulatory Assets, Noncurrent	$ 12,198	12,330	12,492
Long-term debt refinancing costs
Regulatory Assets
Estimated Recovery or Refund Period as of March 31, 2023	Up to 37 years
Regulatory Assets, Noncurrent	$ 3,041	$ 3,188	$ 3,636

Regulatory liabilities (Details

Regulatory liabilities (Details 2) - USD ($) $ in Thousands	3 Months Ended
Regulatory liabilities (Details 2) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	$ 44,395	$ 26,440	$ 31,186
Regulatory liabilities	454,669	448,454	433,628
Total regulatory liabilities	499,064	474,894	464,814
Net regulatory position	$ 66,754	19,857	(16,508)
Electric fuel and purchased power deferral
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Regulatory liabilities due within one year	$ 9,630	4,929	0
Natural gas costs refundable through rate adjustments
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Regulatory liabilities due within one year	$ 6,331	955	13,107
Conservation programs
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Regulatory liabilities due within one year	$ 3,834	4,126	144
Cost Recovery Mechanisms
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	2,926	1,977	2,550
Regulatory liabilities	$ 16,313	14,025	9,508
Cost Recovery Mechanisms \| Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Cost Recovery Mechanisms \| Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 19 years
Taxes refundable to customers
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	$ 1,513	3,937	3,470
Regulatory liabilities	$ 200,879	203,222	212,472
Taxes refundable to customers \| Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Taxes refundable to customers \| Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Over plant lives
Refundable Fuel and Electric Costs
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Regulatory liabilities due within one year	$ 1,179	3,253	316
Other regulatory liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	18,982	7,263	11,599
Regulatory liabilities	$ 1,638	1,587	6,377
Other regulatory liabilities \| Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 1 year
Other regulatory liabilities \| Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 15 years
Plant removal and decommissioning costs
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Over plant lives
Regulatory liabilities	$ 214,467	208,650	171,485
Accumulated Deferred ITC
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	Up to 19 years
Regulatory liabilities	$ 13,996	13,594	13,352
Pension and postretirement benefits
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of March 31, 2023	**
Regulatory liabilities	$ 7,376	$ 7,376	$ 20,434

Environmental allowances and _2

Environmental allowances and obligations (Details) $ in Millions	Mar. 31, 2023 USD ($)
Accounting Policies [Abstract]
Environmental Compliance Obligations	$ 21.9

Fair value measurements Insuran

Fair value measurements Insurance contracts (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Investments used to satisfy nonqualified benefit plans obligations	$ 105.9	$ 105.4	$ 98
Net unrealized gain (loss) on investments used to satisfy obligations under nonqualified benefit plans	$ 3.8	$ 5.8

Available-for-sale securities (

Available-for-sale securities (Details 2) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Available-for-sale securities [Abstract]
Cost	$ 11,580	$ 11,536	$ 11,466
Gross Unrealized Gains	11	2	3
Gross Unrealized Losses	612	708	373
Fair Value	10,979	10,830	11,096
Mortgage-backed securities
Available-for-sale securities [Abstract]
Cost	8,557	8,928	8,778
Gross Unrealized Gains	3	2	3
Gross Unrealized Losses	561	636	310
Fair Value	7,999	8,294	8,471
U.S. Treasury securities
Available-for-sale securities [Abstract]
Cost	3,023	2,608	2,688
Gross Unrealized Gains	8	0	0
Gross Unrealized Losses	51	72	63
Fair Value	$ 2,980	$ 2,536	$ 2,625

Fair value measurements (Detail

Fair value measurements (Details 3) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Concentration risks, percentage [Abstract]
Percentage in fixed-income and other investments	61%	63%	61%
Percentage investment in common stock of large-cap companies	15%	15%	17%
Percentage investment in common stock of mid-cap companies	8%	8%	8%
Percentage investment in target date investments	7%	6%	6%
Percentage investment in common stock of small-cap companies	6%	6%	6%
Percentage investment in cash and cash equivalents	2%	2%	2%
Percentage investment in international investments	1%
Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 124,755	$ 116,232	$ 129,598
Fair value, inputs, level 2 \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	124,755	116,232	129,598
Money market funds \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,919	7,361	13,131
Money market funds \| Fair value, inputs, level 2 \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,919	7,361	13,131
Insurance contracts* \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	105,857	98,041	105,371
Insurance contracts* \| Fair value, inputs, level 2 \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	105,857	98,041	105,371
Mortgage-backed securities \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,999	8,294	8,471
Mortgage-backed securities \| Fair value, inputs, level 2 \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,999	8,294	8,471
U.S. Treasury securities \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	2,980	2,536	2,625
U.S. Treasury securities \| Fair value, inputs, level 2 \| Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 2,980	$ 2,536	$ 2,625

Fair value measurements (Deta_2

Fair value measurements (Details 4) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Fair value, balance sheet grouping [Line Items]
Long-term debt	$ 2,847,068	$ 2,841,425	$ 2,747,763
Carrying amount
Fair value, balance sheet grouping [Line Items]
Long-term debt	2,847,068	2,841,425	2,747,763
Fair value
Fair value, balance sheet grouping [Line Items]
Long-term debt, fair value	$ 2,535,125	$ 2,469,625	$ 2,755,041

Short-term Debt (Details 1)

Short-term Debt (Details 1) - USD ($) $ in Thousands	3 Months Ended
Short-term Debt (Details 1) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 31, 2022	Mar. 17, 2023	Jan. 20, 2023	Dec. 31, 2022
Short-Term Debt [Line Items]
Short-term borrowings	$ 501,500	$ 99,958			$ 246,500
Repayment of short-term borrowings	20,000	$ 0
Term Loan Agreement \| Cascade Natural Gas [Member]
Short-Term Debt [Line Items]
Short-term borrowings				$ 150,000
Ratio of total debt to total capitalization as specified in debt covenants				65%
Term Loan Agreement \| Intermountain Gas Company
Short-Term Debt [Line Items]
Short-term borrowings				$ 125,000
Ratio of total debt to total capitalization as specified in debt covenants				65%
Repayment of short-term borrowings	$ 20,000
Term Loan Agreement \| Centennial Energy Holdings, Inc.
Short-Term Debt [Line Items]
Short-term borrowings			$ 100,000
Ratio of total debt to total capitalization as specified in debt covenants			65%

Long-term debt outstanding (Det

Long-term debt outstanding (Details 2) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,847,068	$ 2,841,425	$ 2,747,763
Long-term debt due within one year	78,031	78,031	147,953
Long-term debt	$ 2,769,037	2,763,394	2,599,810
Senior Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	4.32%
Long-term debt	$ 2,258,500	2,258,500	2,275,000
Commercial Paper
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	6.18%
Long-term debt	$ 462,600	415,500	348,500
Medium-term Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	7.32%
Long-term debt	$ 35,000	35,000	35,000
Credit Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	8.04%
Long-term debt	$ 89,144	130,000	85,800
Term Loan Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	3.64%
Long-term debt	$ 7,000	7,000	7,700
Other Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	1.43%
Long-term debt	$ 1,561	2,253	2,445
Long-term Debt
Long-term debt outstanding [Line Items]
Unamortized Debt Issuance Costs	6,453	6,542	6,605
Discount	$ 284	$ 286	$ 77

Schedule of debt maturities (De

Schedule of debt maturities (Details 3) $ in Thousands	Mar. 31, 2023 USD ($)
Long-term debt maturities [Line Items]
Remainder of 2023	$ 78,031
2024	601,846
2025	177,802
2026	140,802
2027	111,452
Thereafter	$ 1,743,872

Cash flow information (Details)

Cash flow information (Details) - USD ($)	3 Months Ended		12 Months Ended
Cash flow information (Details) - USD ($)	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Supplemental Cash Flow Information [Abstract]
Interest, net*	$ 28,442,000	$ 15,657,000
Income taxes paid (refunded), net	8,122,000	(363,000)
AFUDC borrowed	2,400,000	586,000
Right-of-use assets obtained in exchange for new operating lease liabilities	15,095,000	10,175,000	$ 50,921,000
Property, plant and equipment additions in accounts payable	32,171,000	25,730,000	49,602,000
Accrual for holdback payment related to a business combination	0	0	70,000
Stock issued in connection with a business combination	$ 0	$ 0	$ 7,304,000

Business segment data (Details)

Business segment data (Details) - USD ($) $ in Thousands	3 Months Ended
Business segment data (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Revenues	$ 1,737,337	$ 1,416,559
Operating income	74,472	67,343
Income from continuing operations	38,343	31,733
Discontinued operations, net of tax	10	30
Net income	38,353	31,763
Electric
Segment Reporting Information [Line Items]
Revenues	95,602	93,594
Operating income	21,091	15,044
Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	565,517	450,418
Operating income	58,505	56,256
Pipeline
Segment Reporting Information [Line Items]
Revenues	14,331	11,120
Operating income	13,040	11,882
Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	307,768	309,836
Operating income	(44,563)	(44,605)
Construction services
Segment Reporting Information [Line Items]
Revenues	754,119	551,591
Operating income	35,217	29,498
Other
Segment Reporting Information [Line Items]
Revenues	0	0
Operating income	(8,818)	(732)
Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	(31,767)	(31,730)
Intersegment eliminations \| Electric
Segment Reporting Information [Line Items]
Revenues	(122)	(124)
Intersegment eliminations \| Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	(150)	(136)
Intersegment eliminations \| Pipeline
Segment Reporting Information [Line Items]
Revenues	(26,410)	(25,940)
Intersegment eliminations \| Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	(132)	(130)
Intersegment eliminations \| Construction services
Segment Reporting Information [Line Items]
Revenues	(214)	(1,059)
Intersegment eliminations \| Other
Segment Reporting Information [Line Items]
Revenues	(4,739)	(4,341)
Total intersegment operating revenues
Segment Reporting Information [Line Items]
Revenues	31,767	31,730
Regulated operation
Segment Reporting Information [Line Items]
Revenues	673,757	553,456
Income from continuing operations	64,294	55,549
Regulated operation \| Electric
Segment Reporting Information [Line Items]
Revenues	95,602	93,594
Income from continuing operations	16,607	11,278
Regulated operation \| Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	565,517	450,418
Income from continuing operations	38,928	36,315
Regulated operation \| Pipeline
Segment Reporting Information [Line Items]
Revenues	12,638	9,444
Income from continuing operations	8,759	7,956
Regulated operation \| Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	26,531	26,193
Regulated operation \| Intersegment eliminations \| Electric
Segment Reporting Information [Line Items]
Revenues	122	124
Regulated operation \| Intersegment eliminations \| Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	150	136
Regulated operation \| Intersegment eliminations \| Pipeline
Segment Reporting Information [Line Items]
Revenues	26,259	25,933
Nonregulated operation
Segment Reporting Information [Line Items]
Revenues	1,063,580	863,103
Income from continuing operations	(25,951)	(23,816)
Nonregulated operation \| Pipeline
Segment Reporting Information [Line Items]
Revenues	1,693	1,676
Income from continuing operations	(460)	(619)
Nonregulated operation \| Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	307,768	309,836
Income from continuing operations	(41,320)	(40,010)
Nonregulated operation \| Construction services
Segment Reporting Information [Line Items]
Revenues	754,119	551,591
Income from continuing operations	26,074	21,324
Nonregulated operation \| Other
Segment Reporting Information [Line Items]
Revenues	0	0
Income from continuing operations	(10,245)	(4,511)
Nonregulated operation \| Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	5,236	5,537
Nonregulated operation \| Intersegment eliminations \| Pipeline
Segment Reporting Information [Line Items]
Revenues	151	7
Nonregulated operation \| Intersegment eliminations \| Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	132	130
Nonregulated operation \| Intersegment eliminations \| Construction services
Segment Reporting Information [Line Items]
Revenues	214	1,059
Nonregulated operation \| Intersegment eliminations \| Other
Segment Reporting Information [Line Items]
Revenues	$ 4,739	$ 4,341

Business segment data operating

Business segment data operating revenues reconciliation (Details 2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 1,737,337	$ 1,416,559
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,764,365	1,443,948
Corporate, Non-Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	4,739	4,341
Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ (31,767)	$ (31,730)

Employee benefit plans (Details

Employee benefit plans (Details) - USD ($)	3 Months Ended
Employee benefit plans (Details) - USD ($)	Mar. 31, 2023	Mar. 31, 2022
Qualified plan \| Underfunded plan \| Pension benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Interest cost	$ 3,789,000	$ 2,631,000
Expected return on assets	(4,749,000)	(4,864,000)
Amortization of net actuarial (gain) loss	901,000	1,671,000
Net periodic benefit cost (credit)	(59,000)	(562,000)
Qualified plan \| Overfunded Plan \| Other postretirement benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Service cost	227,000	354,000
Interest cost	670,000	474,000
Expected return on assets	(1,341,000)	(1,322,000)
Amortization of prior service credit	(350,000)	(350,000)
Amortization of net actuarial (gain) loss	(213,000)	(54,000)
Net periodic benefit credit, including amount capitalized	(1,007,000)	(898,000)
Less amount capitalized	24,000	31,000
Net periodic benefit cost (credit)	(1,031,000)	(929,000)
Nonqualified plan \| Unfunded plan \| Supplemental employee retirement plans
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Net periodic benefit cost (credit)	$ 936,000	$ 773,000

IPUC (Details)

IPUC (Details) - Pending Rate Case [Member] - Gas Distribution [Member] - IPUC - Intermountain Gas Company - USD ($) $ in Millions	Mar. 09, 2023	Dec. 01, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 11.3
Public Utilities, Requested Rate Increase (Decrease), Percentage		3.20%
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 6.8
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	1.90%

MTPSC (Details 2)

MTPSC (Details 2) - Pending Rate Case [Member] - MTPSC - Montana-Dakota Utilities Co. [Member] - Electric - USD ($) $ in Millions	Mar. 15, 2023	Feb. 01, 2023	Nov. 04, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 10.5
Public Utilities, Requested Rate Increase (Decrease), Percentage			15.20%
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 11.5
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	17%
Public Utilities, Interim Rate Increase (Decrease), Amount		$ 1.7
Public Utilities, Interim Rate Increase (Decrease), Percentage		2.70%

NDPSC (Details 3)

NDPSC (Details 3) - Electric - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - USD ($) $ in Millions	Apr. 26, 2023	Jul. 14, 2022	May 16, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Interim Rate Increase (Decrease), Amount		$ 10.9
Public Utilities, Interim Rate Increase (Decrease), Percentage		5.30%
Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 25.4
Public Utilities, Requested Rate Increase (Decrease), Percentage			12.30%
Pending Rate Case [Member] \| Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 15.3
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	7.40%
Public Utilities, Requested Return on Equity, Percentage	9.75%

WUTC (Details 4)

WUTC (Details 4) - Gas Distribution [Member] - WUTC [Member] - Cascade Natural Gas [Member] - USD ($) $ in Millions	Mar. 01, 2023	Mar. 24, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 3.3
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 1.1

Litigation (Details)

Litigation (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Loss Contingencies [Line Items]
Potential liabilities related to litigation and environmental matters	$ 25.4	$ 32.9	$ 30
Insurance Receivable	3.3	10.4	7.1
Regulatory Assets	$ 20.9	$ 20.9	$ 20.8

Guarantees (Details 2)

Guarantees (Details 2)	Mar. 31, 2023 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 350,000,000
Fixed maximum amounts guaranteed by year 2023	28,300,000
Fixed maximum amounts guaranteed by year 2024	144,100,000
Fixed maximum amounts guaranteed by year 2025	163,300,000
Fixed maximum amounts guaranteed by year 2026	1,500,000
Fixed maximum amounts guaranteed by year 2027	1,000,000
Fixed maximum amounts guaranteed, thereafter	300,000
No scheduled maturity date	11,500,000
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit	26,000,000
Letters of credit set to expire - 2023	25,600,000
Letters of credit set to expire - 2024	400,000
Outstanding letters of credit	0
Amount of surety bonds outstanding	$ 1,600,000,000

Variable interest entities (Det

Variable interest entities (Details 3) $ in Millions	Mar. 31, 2023 USD ($)
Fuel contract
Variable Interest Entities [Line Items]
Variable interest entity, reporting entity involvement, maximum loss exposure, amount	$ 29.1

Subsequent Events (Details 1)

Subsequent Events (Details 1) - USD ($) $ in Thousands		3 Months Ended
Subsequent Events (Details 1) - USD ($) $ in Thousands	Apr. 21, 2023	Mar. 31, 2023	Mar. 31, 2022	May 01, 2023	Jan. 20, 2023	Dec. 31, 2022
Short-Term Debt [Line Items]
Repayment of short-term borrowings		$ 20,000	$ 0
Short-term borrowings		501,500	$ 99,958			$ 246,500
Term Loan Agreement \| Intermountain Gas Company
Short-Term Debt [Line Items]
Repayment of short-term borrowings		$ 20,000
Short-term borrowings					$ 125,000
Ratio of total debt to total capitalization as specified in debt covenants					65%
Term Loan Agreement \| Subsequent Event [Member] \| Intermountain Gas Company
Short-Term Debt [Line Items]
Repayment of short-term borrowings	$ 30,000
Term Loan Agreement \| Subsequent Event [Member] \| MDU Resources Group [Member]
Short-Term Debt [Line Items]
Short-term borrowings				$ 75,000
Ratio of total debt to total capitalization as specified in debt covenants				65%

Subsequent Events (Details 2)

Subsequent Events (Details 2) - USD ($) $ in Thousands	Apr. 25, 2023	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Long-term debt outstanding [Line Items]
Long-term debt		$ 2,847,068	$ 2,841,425	$ 2,747,763
Senior Notes
Long-term debt outstanding [Line Items]
Long-term debt		$ 2,258,500	$ 2,258,500	$ 2,275,000
Senior Notes \| Subsequent Event [Member] \| Knife River Holding Company
Long-term debt outstanding [Line Items]
Long-term debt	$ 425,000
Long-Term Debt, Percentage Bearing Fixed Interest, Percentage Rate	7.75%

Subsequent Events (Details 3)

Subsequent Events (Details 3) - Subsequent Event [Member]	May 03, 2023
Subsequent Events [Line Items]
Percent of Shares, Retained, in conjunction with spin off	10%
Knife River Holding Company
Subsequent Events [Line Items]
Percent of Shares Distributed in conjunction with spin off	90%