MDU Resources (MDU) 10-K 24 Feb 23 2022 FY Annual report Financial data

Cover page

Cover page - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 16, 2023	Jun. 30, 2022
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Correction of previously issued statements	false
Required compensation recovery	false
Entity Shell Company	false
Entity Public Float			$ 5,488,436,473
Entity Common Stock, Shares Outstanding		203,623,893
Entity Central Index Key	0000067716
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2022
Audit Information [Abstract]
Auditor Name	Deloitte & Touche LLP
Auditor Firm ID	34
Auditor Location	Minneapolis, Minnesota

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating revenues:
Revenues	$ 6,973,864	$ 5,680,733	$ 5,532,750
Operating expenses:
Operation and maintenance:	4,978,857	4,078,623	4,028,262
Purchased natural gas sold	757,883	483,118	390,269
Depreciation, depletion and amortization	327,826	299,214	285,100
Taxes, other than income	243,338	211,454	217,253
Electric fuel and purchased power	92,007	74,105	66,941
Operating expenses	6,399,911	5,146,514	4,987,825
Operating income	573,953	534,219	544,925
Other income	7,379	26,416	26,711
Interest expense	119,273	93,984	96,519
Income before income taxes	462,059	466,651	475,117
Income taxes	94,783	88,920	84,590
Income from continuing operations	367,276	377,731	390,527
Discontinued operations, net of tax	213	400	(322)
Net income	$ 367,489	$ 378,131	$ 390,205
Earnings per share - basic:
Income from continuing operations	$ 1.81	$ 1.87	$ 1.95
Discontinued operations, net of tax	0	0	0
Earnings per share - basic	1.81	1.87	1.95
Earnings per share - diluted:
Income from continuing operations	1.81	1.87	1.95
Discontinued operations, net of tax	0	0	0
Earnings per share - diluted	$ 1.81	$ 1.87	$ 1.95
Weighted average common shares outstanding - basic	203,358	202,076	200,502
Weighted Average Number of Shares Outstanding, Diluted	203,462	202,383	200,571
Regulated Operation
Operating revenues:
Revenues	$ 1,735,759	$ 1,390,343	$ 1,249,146
Operating expenses:
Operation and maintenance:	374,708	366,586	353,184
Income from continuing operations	137,605	143,085	135,103
Nonregulated Operation
Operating revenues:
Revenues	5,238,105	4,290,390	4,283,604
Operating expenses:
Operation and maintenance:	4,604,149	3,712,037	3,675,078
Income from continuing operations	$ 229,671	$ 234,646	$ 255,424

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net income	$ 367,489	$ 378,131	$ 390,205
Other comprehensive income (loss):
Reclassification adjustment for loss on derivative instruments included in net income, tax	177	145	145
Reclassification adjustment for loss on derivative instruments included in net income, net of tax	413	446	446
Postretirement liability adjustment:
Postretirement liability gains (losses) arising during the period, tax	3,965	1,626	(2,606)
Postretirment liability gains (losses) arising during the period, net of tax	12,007	4,876	(8,395)
Amortization of postretirement liability losses included in net periodic benefit credit, tax	597	615	630
Amortization of postretirement liability losses included in net periodic benefit credit, net of tax	1,819	1,870	1,922
Reclassification of postretirement liability adjustment from regulatory asset, tax	(1,086)	0	0
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	(3,265)	0	0
Postretirement liability adjustment	10,561	6,746	(6,473)
Net unrealized (loss) gain on available-for-sale investments:
Net unrealized loss on available-for-sale investments arising during the period, tax	(177)	(67)	0
Net unrealized loss on available-for-sale investments arising during the period, net of tax	(667)	(252)	(1)
Reclassification adjustment for loss on available-for-sale investments included in net income, tax	31	36	14
Reclassification adjustment for loss on available-for-sale investments included in net income, net of tax	114	134	52
Net unrealized (loss) gain on available-for-sale investments	(553)	(118)	51
Other comprehensive income (loss)	10,421	7,074	(5,976)
Comprehensive income attributable to common stockholders	$ 377,910	$ 385,205	$ 384,229

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 80,517	$ 54,161
Receivables, net	1,305,642	946,741
Inventories	387,525	335,609
Current regulatory assets	165,092	118,691
Prepayments and other current assets	72,972	95,741
Total current assets	2,011,748	1,550,943
Noncurrent assets:
Property, plant and equipment	9,364,038	8,972,849
Less accumulated depreciation, depletion and amortization	3,272,493	3,216,461
Net property, plant and equipment	6,091,545	5,756,388
Goodwill	763,500	765,386
Other intangible assets, net	17,532	22,578
Regulatory assets	329,659	357,851
Investments	161,913	175,476
Operating lease right-of-use assets	119,375	124,138
Other	165,509	157,675
Total noncurrent assets	7,649,033	7,359,492
Total assets	9,660,781	8,910,435
Current liabilities:
Short-term borrowings	246,500	0
Long-term debt due within one year	78,031	148,053
Accounts payable	657,168	478,933
Taxes payable	70,810	80,372
Dividends payable	45,245	44,229
Accrued compensation	88,662	81,904
Operating lease liabilities due within one year	34,516	35,368
Regulatory liabilities due within one year	26,440	16,303
Other accrued liabilities	232,231	207,078
Total current liabilities	1,479,603	1,092,240
Noncurrent liabilities:
Long-term debt	2,763,394	2,593,847
Deferred income taxes	631,303	591,962
Asset retirement obligations	405,885	458,061
Regulatory liabilities	448,454	428,790
Operating lease liabilities	85,534	89,253
Other	259,479	273,408
Total noncurrent liabilities	4,594,049	4,435,321
Commitments and contingencies
Stockholders' equity:
Common stock	204,163	203,889
Other paid-in capital	1,466,037	1,461,205
Retained earnings	1,951,138	1,762,410
Accumulated other comprehensive loss	(30,583)	(41,004)
Treasury stock at cost - 538,921 shares	(3,626)	(3,626)
Total stockholders' equity	3,587,129	3,382,874
Total liabilities and stockholders' equity	$ 9,660,781	$ 8,910,435
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Par Value Per Share	$ 1	$ 1
Common Stock, Shares, Issued	204,162,814	203,889,661
Treasury Stock, Common, Shares	538,921	538,921
MDU Resources Group, Inc. [Member]
Current assets:
Cash and cash equivalents	$ 19,486	$ 6,159
Receivables, net	4,410	6,120
Prepayments and other current assets	3,237	2,528
Total current assets	80,418	64,503
Noncurrent assets:
Investments	50,206	55,686
Operating lease right-of-use assets	72	114
Other	2,068	26,558
Total noncurrent assets	3,646,768	3,458,259
Total assets	3,727,186	3,522,762
Current liabilities:
Accounts payable	2,354	2,546
Taxes payable	572	1,672
Dividends payable	45,246	44,229
Accrued compensation	4,312	4,098
Operating lease liabilities due within one year	42	52
Other accrued liabilities	17,907	7,309
Total current liabilities	74,835	66,039
Noncurrent liabilities:
Operating lease liabilities	30	62
Other	65,192	73,787
Total noncurrent liabilities	65,222	73,849
Commitments and contingencies
Stockholders' equity:
Common stock	204,163	203,889
Other paid-in capital	1,466,037	1,461,205
Retained earnings	1,951,138	1,762,410
Accumulated other comprehensive loss	(30,583)	(41,004)
Treasury stock at cost - 538,921 shares	(3,626)	(3,626)
Total stockholders' equity	3,587,129	3,382,874
Total liabilities and stockholders' equity	$ 3,727,186	$ 3,522,762
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Par Value Per Share	$ 1	$ 1
Common Stock, Shares, Issued	204,162,814	203,889,661
Treasury Stock, Common, Shares	538,921	538,921

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common stock	Other paid-in capital	Retained earnings	Total accumulated other comprehensive loss	Treasury stock
Balance (in shares) at Dec. 31, 2019		200,922,790
Treasury stock (in shares) at Dec. 31, 2019						(538,921)
Balance at Dec. 31, 2019	$ 2,847,246	$ 200,923	$ 1,355,404	$ 1,336,647	$ (42,102)	$ (3,626)
Net income	390,205			390,205
Other comprehensive income (loss)	(5,976)				(5,976)
Dividends declared on common stock	(168,489)			(168,489)
Employee stock-based compensation	13,096		13,096
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(388)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(362)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)		26,406
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings		$ 26
Issuance of common stock (in shares)		112,002
Issuance of common stock	3,385	$ 112	3,273
Balance (in shares) at Dec. 31, 2020		201,061,198
Balance at Dec. 31, 2020	3,079,105	$ 201,061	1,371,385	1,558,363	(48,078)	$ (3,626)
Treasury stock (in shares) at Dec. 31, 2020						(538,921)
Net income	378,131			378,131
Other comprehensive income (loss)	7,074				7,074
Dividends declared on common stock	(174,084)			(174,084)
Employee stock-based compensation	14,709		14,709
Repurchase of common stock (in shares)						(392,294)
Repurchase of common stock	(6,701)					$ (6,701)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(10,828)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)						392,294
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						$ 6,701
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(4,127)
Issuance of common stock (in shares)		2,828,463
Issuance of common stock	$ 88,767	$ 2,828	85,939
Balance (in shares) at Dec. 31, 2021	203,889,661	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 (in shares) at Dec. 31, 2021						(538,921)
Net income	367,489			367,489
Other comprehensive income (loss)	10,421				10,421
Dividends declared on common stock	(178,761)			(178,761)
Employee stock-based compensation	10,254		10,254
Repurchase of common stock (in shares)						(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 (in shares)						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 (in shares)		273,153
Issuance of common stock	$ 7,155	$ 274	6,881
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 (in shares) at Dec. 31, 2022						(538,921)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net income	$ 367,489	$ 378,131	$ 390,205
Discontinued operations, net of tax	213	400	(322)
Income from continuing operations	367,276	377,731	390,527
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	327,826	299,214	285,100
Deferred income taxes	23,326	60,250	(1,801)
Provision for credit losses	6,133	1,085	10,576
Amortization of debt issuance costs	1,461	1,333	2,162
Employee stock-based compensation costs	10,254	14,709	13,096
Pension and postretirement benefit plan net periodic benefit credit	(6,018)	(4,900)	(3,001)
Unrealized losses (gains) on investments	12,732	(7,728)	(14,563)
Gains on sales of assets	(20,723)	(13,056)	(15,350)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(363,314)	(60,024)	(2,780)
Inventories	(46,588)	(42,302)	(7,221)
Other current assets	(9,360)	(71,964)	31,601
Accounts payable	186,285	15,247	15,955
Other current liabilities	27,011	(17,650)	35,591
Pension and postretirement benefit plan contributions	(507)	(476)	(434)
Other noncurrent changes	(5,944)	(55,367)	30,291
Net cash provided by continuing operations	509,850	496,102	769,749
Net cash provided by (used in) discontinued operations	214	(325)	(1,375)
Net cash provided by operating activities	510,064	495,777	768,374
Investing activities:
Capital expenditures	(656,588)	(659,425)	(558,007)
Acquisitions, net of cash acquired	1,745	(237,718)	(105,979)
Net proceeds from sale or disposition of property and other	22,439	15,238	35,557
Investments	(6,477)	(3,973)	(1,814)
Net cash used in investing activities	(638,881)	(885,878)	(630,243)
Financing activities:
Issuance of short-term borrowings	246,500	50,000	75,000
Repayment of short-term borrowings	0	(100,000)	(25,000)
Issuance of long-term debt	361,650	554,027	117,450
Repayment of long-term debt	(261,674)	(24,979)	(148,634)
Debt issuance costs	(1,936)	(918)	(477)
Proceeds from issuance of common stock	(149)	88,767	3,385
Dividends paid	(176,915)	(171,354)	(166,405)
Repurchase of common stock	(7,399)	(6,701)	0
Tax withholding on stock-based compensation	(4,904)	(4,127)	(362)
Net cash provided by (used in) financing activities	155,173	384,715	(145,043)
Increase (decrease) in cash and cash equivalents	26,356	(5,386)	(6,912)
Cash and cash equivalents - beginning of year	54,161	59,547	66,459
Cash and cash equivalents - end of year	$ 80,517	$ 54,161	$ 59,547

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure	Basis of Presentation The abbreviations and acronyms used throughout are defined following the Notes to Consolidated Financial Statements. The consolidated financial statements of the Company include the accounts of the following businesses: electric, natural gas distribution, pipeline, construction materials and contracting, construction services and other. The electric and natural gas distribution businesses, as well as a portion of the pipeline business, are regulated. Construction materials and contracting, construction services and the other businesses, as well as a portion of the pipeline business, are non-regulated. For further descriptions of the Company's businesses, see Note 17. On August 4, 2022, the Company announced its board of directors unanimously approved a plan to pursue the separation of Knife River from the Company. The separation is planned as a tax-free spinoff transaction to the Company’s stockholders for U.S. federal income tax purposes. As the next step of the Company’s strategic planning, 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 to achieve this future structure, the board authorized management to commence a strategic review process of MDU Construction Services. Discontinued operations include the supporting activities of Fidelity and the assets and liabilities of the Company's discontinued operations have been classified as held for sale and are included in prepayments and other current assets, noncurrent assets - other and other accrued liabilities on the Consolidated Balance Sheets and are not material to the financial statements for any period presented. The results and supporting activities are shown in income (loss) 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. Management has also evaluated the impact of events occurring after December 31, 2022, up to the date of issuance of these consolidated financial statements on February 24, 2023, that would require recognition or disclosure in the financial statements. Principles of consolidation The consolidated financial statements were prepared in accordance with GAAP and include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation, except for certain transactions related to the Company's regulated operations in accordance with GAAP. For more information on intercompany revenues, see Note 17. The statements also include the Company's ownership interests in the assets, liabilities and expenses of jointly owned electric transmission and generating facilities. See Note 19 for additional information. Use of estimates The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Estimates are used for items such as long-lived assets and goodwill; fair values of acquired assets and liabilities under the acquisition method of accounting; aggregate reserves; property depreciable lives; tax provisions; revenue recognized using the cost-to-cost measure of progress for contracts; expected credit losses; environmental and other loss contingencies; regulatory assets expected to be recovered in rates charged to customers; costs on construction contracts; unbilled revenues; actuarially determined benefit costs; asset retirement obligations; lease classification; present value of right-of-use assets and lease liabilities; and the valuation of stock-based compensation. As additional information becomes available, or actual amounts are determinable, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.

Accounting Policies

Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Significant Accounting Policies New accounting standards The following table provides a brief description of the accounting pronouncements applicable to the Company and the potential impact on its financial statements and or disclosures: Standard Description Effective date Impact on financial statements/disclosures Recently adopted accounting standards ASU 2021-10 - Government Assistance In November 2021, the FASB issued guidance on modifying the disclosure requirements to increase the transparency of government assistance including disclosure of the types of assistance, an entity's accounting for the assistance and the effect of the assistance on an entity's financial statements. January 1, 2022 The Company determined the guidance did not have a material impact on its disclosures for the year ended December 31, 2022. 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 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. Cash and cash equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Revenue recognition 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. The electric and natural gas distribution segments generate revenue from the sales of electric and natural gas products and services, which includes retail and transportation services. These segments establish a customer's retail or transportation service account based on the customer's application/contract for service, which indicates approval of a contract for service. The contract identifies an obligation to provide service in exchange for delivering or standing ready to deliver the identified commodity; and the customer is obligated to pay for the service as provided in the applicable tariff. The product sales are based on a fixed rate that includes a base and per-unit rate, which are included in approved tariffs as determined by state or federal regulatory agencies. The quantity of the commodity consumed or transported determines the total per-unit revenue. The service provided, along with the product consumed or transported, are a single performance obligation because both are required in combination to successfully transfer the contracted product or service to the customer. Revenues are recognized over time as customers receive and consume the products and services. The method of measuring progress toward the completion of the single performance obligation is on a per-unit output method basis, with revenue recognized based on the direct measurement of the value to the customer of the goods or services transferred to date. For contracts governed by the Company’s utility tariffs, amounts are billed monthly with the amount due between 15 and 22 days of receipt of the invoice depending on the applicable state’s tariff. For other contracts not governed by tariff, payment terms are net 30 days. At this time, the segment has no material obligations for returns, refunds or other similar obligations. The pipeline segment generates revenue from providing natural gas transportation and underground storage services, as well as other energy-related services to both third parties and internal customers, largely the natural gas distribution segment. The pipeline segment establishes a contract with a customer based upon the customer’s request for firm or interruptible natural gas transportation or storage service(s). The contract identifies an obligation for the segment to provide the requested service(s) in exchange for consideration from the customer over a specified term. Depending on the type of service(s) requested and contracted, the service provided may include transporting or storing an identified quantity of natural gas and/or standing ready to deliver or store an identified quantity of natural gas. Natural gas transportation and storage revenues are based on fixed rates, which may include reservation fees and/or per-unit commodity rates. The services provided by the segment are generally treated as single performance obligations satisfied over time simultaneous to when the service is provided and revenue is recognized. Rates for the segment’s regulated services are based on its FERC approved tariff or customer negotiated rates, and rates for its non-regulated services are negotiated with its customers and set forth in the contract. For contracts governed by the company’s tariff, amounts are billed on or before the ninth business day of the following month and the amount is due within 12 days of receipt of the invoice. For other contracts not governed by the tariff, payment terms are net 30 days. At this time, the segment has no material obligations for returns, refunds or other similar obligations. The construction materials and contracting segment generates revenue from contracting services and construction materials sales. This segment focuses on the vertical integration of its contracting services with its construction materials to support the aggregate-based product lines. This segment provides contracting services to a customer when a contract has been signed by both the customer and a representative of the segment obligating a service to be provided in exchange for the consideration identified in the contract. The nature of the services this segment provides generally include integrating a set of services and related construction materials into a single project to create a distinct bundle of goods and services, which the Company has determined are single performance obligations. The transaction price includes the fixed consideration required pursuant to the original contract price together with any additional consideration, to which the Company expects to be entitled to, associated with executed change orders plus the estimate of variable consideration to which the Company expects to be entitled, subject to the following constraint. The nature of this segment's contracts gives rise to several types of variable consideration. Examples of variable consideration include: liquidated damages; performance bonuses or incentives and penalties; claims; unpriced change orders; and index pricing. The variable amounts usually arise upon achievement of certain performance metrics or change in project scope. The Company estimates the amount of revenue to be recognized on variable consideration using one of the two prescribed estimation methods, the expected value method or the most likely amount method, depending on which method best predicts the most likely amount of consideration the Company expects to be entitled to or expects to incur. Assumptions as to the occurrence of future events and the likelihood and amount of variable consideration are made during the contract performance period. Estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on the assessment of anticipated performance and all information (historical, current and forecasted) that is reasonably available to management. The Company only includes variable consideration in the estimated transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur or when the uncertainty associated with the variable consideration is resolved. Changes in circumstances could impact management's estimates made in determining the value of variable consideration recorded. When determining if the variable consideration is constrained, the Company considers if factors exist that could increase the likelihood or the magnitude of a potential reversal of revenue. The Company updates its estimate of the transaction price each reporting period and the effect of variable consideration on the transaction price is recognized as an adjustment to revenue on a cumulative catch-up basis. Contract revenue is recognized over time using an input method based on the cost-to-cost measure of progress on a project. This is the preferred method of measuring revenue because the costs incurred have been determined to represent the best indication of the overall progress toward the transfer of such goods or services promised to a customer. Under the cost-to-cost measure of progress, the costs incurred are compared with total estimated costs of a performance obligation. Revenues are recorded proportionately to the costs incurred. The percentage of completion is determined on a performance obligation basis. This segment also sells construction materials to third parties and internal customers. The contract for material sales is the use of a sales order or an invoice, which includes the pricing and payment terms. All material contracts contain a single performance obligation for the delivery of a single distinct product or a distinct separately identifiable bundle of products and services. Revenue is recognized at a point in time when the performance obligation has been satisfied with the delivery of the products or services. The warranties associated with the sales are those consistent with a standard warranty that the product meets certain specifications for quality or those required by law. For most contracts, amounts billed to customers are due within 30 days of receipt. There are no material obligations for returns, refunds or other similar obligations. The construction services segment generates revenue from specialty contracting services which also includes the sale of construction equipment and other supplies. This segment provides specialty contracting services to a customer when a contract has been signed by both the customer and a representative of the segment obligating a service to be provided in exchange for the consideration identified in the contract. The nature of the services this segment provides generally includes multiple promised goods and services in a single project to create a distinct bundle of goods and services, which the Company has determined are single performance obligations. The transaction price includes the fixed consideration required pursuant to the original contract price together with any additional consideration, to which the Company expects to be entitled to, associated with executed change orders plus the estimate of variable consideration to which the Company expects to be entitled, subject to the following constraint. The nature of the segment's contracts gives rise to several types of variable consideration. Examples of variable consideration include: liquidated damages; performance bonuses or incentives and penalties; claims; unpriced change orders; and index pricing. The variable amounts usually arise upon achievement of certain performance metrics or change in project scope. The Company estimates the amount of revenue to be recognized on variable consideration using one of the two prescribed estimation methods, the expected value method or the most likely amount method, depending on which method best predicts the most likely amount of consideration the Company expects to be entitled to or expects to incur. Assumptions as to the occurrence of future events and the likelihood and amount of variable consideration are made during the contract performance period. Estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on the assessment of anticipated performance and all information (historical, current, and forecasted) that is reasonably available to management. The Company only includes variable consideration in the estimated transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur or when the uncertainty associated with the variable consideration is resolved. Changes in circumstances could impact management's estimates made in determining the value of variable consideration recorded. When determining if the variable consideration is constrained, the Company considers if factors exist that could increase the likelihood or the magnitude of a potential reversal of revenue. The Company updates its estimate of the transaction price each reporting period and the effect of variable consideration on the transaction price is recognized as an adjustment to revenue on a cumulative catch-up basis. Contract revenue is recognized over time using the input method based on the measurement of progress on a project. This is the preferred method of measuring revenue because the costs incurred have been determined to represent the best indication of the overall progress toward the transfer of such goods or services promised to a customer. Under the cost-to-cost measure of progress, the costs incurred are compared with total estimated costs of a performance obligation. Revenues are recorded proportionately to the costs incurred. This segment also sells construction equipment and other supplies to third parties and internal customers. The contract for these sales is the use of a sales order or invoice, which includes the pricing and payment terms. All such contracts include a single performance obligation for the delivery of a single distinct product or a distinct separately identifiable bundle of products and services. Revenue is recognized at a point in time when the performance obligation has been satisfied with the delivery of the products or services. The warranties associated with the sales are those consistent with a standard warranty that the product meets certain specifications for quality or those required by law. For most contracts, amounts billed to customers are due within 30 days of receipt. There are no material obligations for returns, refunds or other similar obligations. The Company recognizes all other revenues when services are rendered or goods are delivered. Legal costs The Company expenses external legal fees as they are incurred. Business combinations For all business combinations, the Company preliminarily allocates the purchase price of the acquisitions to the assets acquired and liabilities assumed based on their estimated fair values as of the acquisition dates and are considered provisional until final fair values are determined or the measurement period has passed. The Company expects to record adjustments as it accumulates the information needed to estimate the fair value of assets acquired and liabilities assumed, including working capital balances, estimated fair value of identifiable intangible assets, property, plant and equipment, total consideration and goodwill. The excess of the purchase price over the aggregate fair values is recorded as goodwill. The Company calculated the fair value of the assets acquired in 2022 and 2021 using a market or cost approach (or a combination of both). Fair values for some of the assets were determined based on Level 3 inputs including estimated future cash flows, discount rates, growth rates, sales projections, retention rates and terminal values, all of which require significant management judgment and are susceptible to change. The discount rate used in calculating the fair value of common stock issued in a business combination is determined by using a Black-Scholes-Merton model. The model uses Level 2 inputs including risk-free interest rate, volatility range and dividend yield. The final fair value of the net assets acquired may result in adjustments to the assets and liabilities, including goodwill, and will be made as soon as practical, but no later than 12 months from the respective acquisition dates. Any subsequent measurement period adjustments are not expected to have a material impact on the Company's results of operations. Receivables and allowance for expected credit losses Receivables consist primarily of trade and contracting services receivables from the sale of goods and services net of expected credit losses. 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 $45.6 million and $44.8 million at December 31, 2022 and 2021, 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, 2020 $ 899 $ 2,571 $ 2 $ 6,164 $ 5,722 $ 15,358 Current expected credit loss provision* 1,099 2,188 — 68 (2,250) 1,105 Less write-offs charged against the allowance 2,139 4,072 — 826 1,032 8,069 Credit loss recoveries collected 410 819 — — 93 1,322 At December 31, 2021 269 1,506 2 5,406 2,533 9,716 Current expected credit loss provision 1,325 4,084 — 538 186 6,133 Less write-offs charged against the allowance 1,625 4,913 — 467 625 7,630 Credit loss recoveries collected 406 938 — — 68 1,412 At December 31, 2022 $ 375 $ 1,615 $ 2 $ 5,477 $ 2,162 $ 9,631 * Includes impacts from businesses acquired. Receivables also consist of accrued unbilled revenue representing revenues recognized in excess of amounts billed. Accrued unbilled revenue at MDU Energy Capital was $181.8 million and $144.9 million at December 31, 2022 and 2021, respectively. Amounts representing balances billed but not paid by customers under retainage provisions in contracts at December 31 were as follows: 2022 2021 (In thousands) Short-term retainage* $ 120,333 $ 70,600 Long-term retainage** 19,511 10,742 Total retainage $ 139,844 $ 81,342 * Expected to be paid within 12 months or less and included in receivables, net. ** Included in noncurrent assets - other. 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 at December 31 consisted of: 2022 2021 (In thousands) Aggregates held for resale $ 199,110 $ 184,363 Asphalt oil 68,609 57,002 Materials and supplies 40,056 30,629 Merchandise for resale 40,296 28,501 Natural gas in storage (current) 22,533 18,867 Other 16,921 16,247 Total $ 387,525 $ 335,609 The remainder of natural gas in storage, which largely represents the cost of gas required to maintain pressure levels for normal operating purposes, was included in noncurrent assets - other and was $47.5 million at both December 31, 2022 and 2021. Property, plant and equipment Additions to property, plant and equipment are recorded at cost. Aggregate mining development costs are capitalized and classified as land improvements and depreciated over the lower of the estimated life of the reserves or the life of the associated improvement. The Company begins capitalizing development costs at a point when reserves are determined to be proven or probable and economically mineable. Capitalization of these costs cease when production commences. The cost of acquiring reserves in connection with a business combination are valued at fair value. When regulated assets are retired, or otherwise disposed of in the ordinary course of business, the original cost of the asset is charged to accumulated depreciation. With respect to the retirement or disposal of all other assets, the resulting gains or losses are recognized as a component of income. The Company is permitted to capitalize AFUDC on regulated construction projects and to include such amounts in rate base when the related facilities are placed in service. In addition, the Company capitalizes interest, when applicable, on certain contracting services projects associated with its other operations. The amount of AFUDC for the years ended December 31 was as follows: 2022 2021 2020 (In thousands) AFUDC - borrowed $ 2,236 $ 2,833 $ 2,640 AFUDC - equity $ 2,165 $ 6,961 $ 1,270 Generally, property, plant and equipment are depreciated on a straight-line basis over the average useful lives of the assets, except for depletable aggregate reserves, which are depleted based on the units-of-production method. The Company uses proven and probable aggregate reserves as the denominator in its units-of production calculation. Exploration costs are expensed as incurred in operation and maintenance expense and production costs are either expensed or capitalized to inventory. The Company collects removal costs for certain plant assets in regulated utility rates. These amounts are recorded as regulatory liabilities on the Consolidated Balance Sheets. Impairment of long-lived assets, excluding goodwill The Company reviews the carrying values of its long-lived assets, including mining and related assets, whenever events or changes in circumstances indicate that such carrying values may not be recoverable. The Company tests long-lived assets for impairment at a level significantly lower than that of goodwill impairment testing. Long-lived assets or groups of assets that are evaluated for impairment at the lowest level of largely independent identifiable cash flows at an individual operation or group of operations collectively serving a local market. The determination of whether an impairment has occurred is based on an estimate of undiscounted future cash flows attributable to the assets, compared to the carrying value of the assets. If impairment has occurred, the amount of the impairment recognized is determined by estimating the fair value of the assets and recording a loss if the carrying value is greater than the fair value. The impairments are recorded in operation and maintenance expense on the Consolidated Statements of Income. No impairment losses were recorded in 2022, 2021 or 2020. Unforeseen events and changes in circumstances could require the recognition of impairment losses at some future date. Regulatory assets and liabilities The Company's regulated businesses are subject to various state and federal agency regulations. The accounting policies followed by these businesses are generally subject to the Uniform System of Accounts of the FERC as well as the provisions of ASC 980 - Regulated Operations . These accounting policies differ in some respects from those used by the Company's non-regulated businesses. The Company's regulated businesses account for certain income and expense items under the provisions of regulatory accounting, which requires these businesses to defer as regulatory assets or liabilities certain items that would have otherwise been reflected as expense or income, respectively. The Company records regulatory assets or liabilities at the time the Company determines the amounts to be recoverable in current or future rates. Regulatory assets and liabilities are being amortized consistently with the regulatory treatment established by the FERC and the applicable state public service commission. See Note 6 for more information regarding the nature and amounts of these regulatory deferrals. Natural gas costs recoverable or refundable through rate adjustments Under the terms of certain orders of the applicable state public service commissions, the Company is deferring natural gas commodity, transportation and storage costs that are greater or less than amounts presently being recovered through its existing rate schedules. Such orders generally provide that these amounts are recoverable or refundable through rate adjustments. Natural gas costs refundable through rate adjustments were $1.0 million and $6.7 million at December 31, 2022 and 2021, respectively, which were included in regulatory liabilities due within one year on the Consolidated Balance Sheets. Natural gas costs recoverable through rate adjustments were $141.3 million and $91.6 million at December 31, 2022 and 2021, respectively, which were included in current regulatory assets and noncurrent assets - regulatory assets on the Consolidated Balance Sheets. Goodwill Goodwill represents the excess of the purchase price over the fair value of identifiable net tangible and intangible assets acquired in a business combination. Goodwill is required to be tested for impairment annually, which the Company completes in the fourth quarter, or more frequently if events or changes in circumstances indicate that goodwill may be impaired. The Company has determined that the reporting units for its goodwill impairment test are its operating segments, or components of an operating segment, that constitute a business for which discrete financial information is available and for which segment management regularly reviews the operating results. For more information on the Company's operating segments, see Note 17. Goodwill impairment, if any, is measured by comparing the fair value of each reporting unit to its carrying value. If the fair value of a reporting unit exceeds its carrying value, the goodwill of the reporting unit is not impaired. If the carrying value of a reporting unit exceeds its fair value, the Company must record an impairment loss for the amount that the carrying value of the reporting unit, including goodwill, exceeds the fair value of the reporting unit. For the years ended December 31, 2022, 2021 and 2020, there were no impairment losses recorded. Investments The Company's investments include the cash surrender value of life insurance policies, insurance contracts, mortgage-backed securities and U.S. Treasury securities. The Company measures its investment in the insurance contracts at fair value with any unrealized gains and losses recorded on the Consolidated Statements of Income. The Company has not elected the fair value option for its mortgage-backed securities and U.S. Treasury securities and, as a result, the unrealized gains and losses on these investments are recorded in accumulated other comprehensive loss. For more information, see Notes 8 and 18. Government Assistance The Company accounts for government assistance received for capital projects by reducing the cost of the project by the amount of assistance received. The Company records government assistance received as taxable income and writes-up the tax basis of the asset to include the amount of the assistance received. Government assistance received for the years ended December 31, 2022, 2021 and 2020, was immaterial. 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. GAAP provides a framework for identifying VIEs and determining when a company should include the assets, liabilities, noncontrolling interest and results of activities of a VIE in its consolidated financial statements. A VIE should be consolidated if a party with an ownership, contractual or other financial interest in the VIE (a variable interest holder) has the power to direct the VIE's most significant activities and the obligation to absorb losses or right to receive benefits of the VIE that could be significant to the VIE. A variable interest holder that consolidates the VIE is called the primary beneficiary. Upon consolidation, the primary beneficiary generally must initially record all of the VIE's assets, liabilities and noncontrolling interests at fair value and subsequently account for the VIE as if it were consolidated. The Company's evaluation of whether it qualifies as the primary beneficiary of a VIE involves significant judgments, estimates and assumptions and includes a qualitative analysis of the activities that most significantly impact the VIE's economic performance and whether the Company has the power to direct those activities, the design of the entity, the rights of the parties and the purpose of the arrangement. Joint ventures The Company accounts for unconsolidated joint ventures using either the equity method or proportionate consolidation. The Company currently holds interests between 25 percent and 50 percent in joint ventures formed primarily for the purpose of pooling resources on construction contracts. Proportionate consolidation is used for joint ventures that include unincorporated legal entities and activities of the joint venture which are construction-related. For those joint ventures accounted for under proportionate consolidation, only the Company’s pro rata share of assets, liabilities, revenues and expenses are included in the Company’s balance sheet and results of operations. For those joint ventures accounted for using proportionate consolidation, the Company recorded in its Consolidated Statements of Income $14.8 million, $14.7 million, and $69.7 million of revenue for the years ended December 31, 2022, 2021 and 2020, respectively, and $3.0 million, $4.7 million and $20.6 million of operating income for the years ended December 31, 2022, 2021 and 2020, respectively. At December 31, 2022 and 2021, the C

Revenue from Contract with Cust

Revenue from Contract with Customer	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Revenue from contracts from 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. As part of the adoption of ASC 606 - Revenue from Contracts with Customers , the Company elected the practical expedient to recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that the Company otherwise would have recognized is 12 months or less. Disaggregation In the following table, 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. Year ended December 31, 2022 Electric Natural gas distribution Pipeline Construction materials and contracting Construction services Other Total (In thousands) Residential utility sales $ 138,634 $ 718,191 $ — $ — $ — $ — $ 856,825 Commercial utility sales 146,182 453,802 — — — — 599,984 Industrial utility sales 43,766 41,710 — — — — 85,476 Other utility sales 7,597 — — — — — 7,597 Natural gas transportation — 48,886 129,290 — — — 178,176 Natural gas storage — — 14,583 — — — 14,583 Contracting services — — — 1,187,721 — — 1,187,721 Construction materials — — — 1,940,890 — — 1,940,890 Internal sales — — — (593,882) — — (593,882) Electrical & mechanical specialty contracting — — — — 1,988,729 — 1,988,729 Transmission & distribution specialty contracting — — — — 662,705 — 662,705 Other 45,608 13,617 11,450 — 436 17,605 88,716 Intersegment eliminations (494) (555) (59,012) (1,016) (5,494) (17,605) (84,176) Revenues from contracts with customers 381,293 1,275,651 96,311 2,533,713 2,646,376 — 6,933,344 Other revenues (4,714) (2,402) 256 — 47,380 — 40,520 Total external operating revenues $ 376,579 $ 1,273,249 $ 96,567 $ 2,533,713 $ 2,693,756 $ — $ 6,973,864 Year ended December 31, 2021 Electric Natural gas distribution Pipeline Construction materials and contracting Construction services Other Total (In thousands) Residential utility sales $ 126,841 $ 544,721 $ — $ — $ — $ — $ 671,562 Commercial utility sales 137,556 328,285 — — — — 465,841 Industrial utility sales 41,757 30,964 — — — — 72,721 Other utility sales 7,051 — — — — — 7,051 Natural gas transportation — 48,408 114,001 — — — 162,409 Natural gas storage — — 14,680 — — — 14,680 Contracting services — — — 1,017,471 — — 1,017,471 Construction materials — — — 1,712,503 — — 1,712,503 Internal sales — — — (501,044) — — (501,044) Electrical & mechanical specialty contracting — — — — 1,324,419 — 1,324,419 Transmission & distribution specialty contracting — — — — 677,074 — 677,074 Other 42,902 10,567 13,667 — 557 13,714 81,407 Intersegment eliminations (543) (576) (59,678) (624) (2,555) (13,630) (77,606) Revenues from contracts with customers 355,564 962,369 82,670 2,228,306 1,999,495 84 5,628,488 Other revenues (6,525) 8,995 188 — 49,587 — 52,245 Total external operating revenues $ 349,039 $ 971,364 $ 82,858 $ 2,228,306 $ 2,049,082 $ 84 $ 5,680,733 Year ended December 31, 2020 Electric Natural gas distribution Pipeline Construction materials and contracting Construction services Other Total (In thousands) Residential utility sales $ 122,663 $ 476,388 $ — $ — $ — $ — $ 599,051 Commercial utility sales 131,477 277,873 — — — — 409,350 Industrial utility sales 36,744 26,243 — — — — 62,987 Other utility sales 6,634 — — — — — 6,634 Natural gas transportation — 45,546 111,686 — — — 157,232 Natural gas gathering — — 4,865 — — — 4,865 Natural gas storage — — 14,918 — — — 14,918 Contracting services — — — 1,069,665 — — 1,069,665 Construction materials — — — 1,659,152 — — 1,659,152 Internal sales — — — (550,815) — — (550,815) Electrical & mechanical specialty contracting — — — — 1,397,124 — 1,397,124 Transmission & distribution specialty contracting — — — — 649,486 — 649,486 Other 32,452 10,753 12,216 — 1,541 11,903 68,865 Intersegment eliminations (491) (534) (58,531) (417) (5,038) (11,958) (76,969) Revenues from contracts with customers 329,479 836,269 85,154 2,177,585 2,043,113 (55) 5,471,545 Other revenues 2,059 11,382 192 — 47,572 — 61,205 Total external operating revenues $ 331,538 $ 847,651 $ 85,346 $ 2,177,585 $ 2,090,685 $ (55) $ 5,532,750 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 contracting services 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: December 31, 2022 December 31, 2021 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 185,289 $ 125,742 $ 59,547 Receivables, net Contract liabilities - current (208,204) (179,140) (29,064) Accounts payable Contract liabilities - noncurrent (6) (118) 112 Noncurrent liabilities - other Net contract liabilities $ (22,921) $ (53,516) $ 30,595 December 31, 2021 December 31, 2020 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 125,742 $ 104,345 $ 21,397 Receivables, net Contract liabilities - current (179,140) (158,603) (20,537) Accounts payable Contract liabilities - noncurrent (118) (52) (66) Noncurrent liabilities - other Net contract liabilities $ (53,516) $ (54,310) $ 794 The Company recognized $173.8 million and $155.0 million in revenue for the years ended December 31, 2022 and 2021, respectively, which was previously included in contract liabilities at December 31, 2021 and 2020, respectively. The Company recognized a net increase in revenues of $57.9 million and $66.3 million for the years ended December 31, 2022 and 2021, 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 construction contracts have an original duration of less than two years. The remaining performance obligations at the pipeline segment include firm transportation and storage contracts with fixed pricing and fixed volumes. The Company has applied the practical expedient that 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.

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
Business combination disclosure	Business Combinations The following acquisitions were accounted for as business combinations in accordance with ASC 805 - Business Combinations. The results of the business combinations have been included in the Company's Consolidated Financial Statements beginning on the acquisition date. Pro forma financial amounts reflecting the effects of the business combinations are not presented, as none of these business combinations, individually or in the aggregate, were material to the Company's financial position or results of operations. The 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. In 2022 and 2021, the construction materials and contracting segment's acquisitions included: • Allied Concrete and Supply Co., a producer of ready-mixed concrete in California, acquired in December 2022. At December 31, 2022, the purchase price allocation was preliminary and will be finalized within 12 months of the acquisition date. • Baker Rock Resources and Oregon Mainline Paving, two construction materials companies located around the Portland, Oregon metro area, acquired in November 2021. As of September 30, 2022, the purchase price allocation was settled with no material adjustments to the provisional accounting. • Mt. Hood Rock, a construction aggregates business in Oregon, acquired in April 2021. As of March 31, 2022, the purchase price allocation was settled with no material adjustments to the provisional accounting. 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 has been 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. The total purchase price for acquisitions that occurred in 2021 was $236.1 million, subject to certain adjustments, with cash acquired totaling $900,000. The purchase price includes consideration paid of $235.2 million. The amounts allocated to the aggregated assets acquired and liabilities assumed during 2021 were as follows: $17.0 million to current assets; $179.8 million to property, plant and equipment; $50.6 million to goodwill; $2.2 million to other intangible assets; $8.7 million to current liabilities; $2.5 million to noncurrent liabilities - other; and $3.2 million to deferred tax liabilities. The intangible assets include non-compete agreements, customer relationships, and trade names. The intangible assets fair value is based on various income approach methods, including, multi-period excess earnings, relief-from-royalty and the with and without method. The amortizable intangible assets are being amortized using a straight-line method over a weighted average period of 5.5 years. During the first quarter of 2022, measurement period adjustments were made to the previously reported provisional amounts, which decreased goodwill and increased property, plant and equipment by $2.1 million. The Company issued debt to finance these acquisitions. Costs incurred for acquisitions are included in operation and maintenance expense on the Consolidated Statements of Income and were immaterial for the years ended December 31, 2022, 2021 and 2020.

Property, Plant, and Equipment

Property, Plant, and Equipment	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure	Property, Plant and Equipment Property, plant and equipment at December 31 was as follows: 2022 2021 Weighted (Dollars in thousands, where applicable) Regulated: Electric: Generation $ 938,614 $ 1,056,632 48 Distribution 489,351 474,037 47 Transmission 616,611 562,080 65 Construction in progress 87,003 62,781 — Other 145,034 140,117 14 Natural gas distribution: Distribution 2,569,921 2,427,779 52 Transmission 104,769 107,721 61 Storage 42,318 34,997 37 General 204,993 197,653 13 Construction in progress 55,759 21,741 — Other 230,299 225,272 15 Pipeline: Transmission 951,187 673,344 46 Storage 55,383 57,670 53 Construction in progress 34,655 263,640 — Other 59,917 50,477 19 Non-regulated: Pipeline: Construction in progress 49 18 — Other 6,950 6,719 10 Construction materials and contracting: Land 150,809 149,066 — Buildings and improvements 165,833 149,262 21 Machinery, vehicles and equipment 1,492,506 1,414,260 12 Construction in progress 88,163 50,425 — Aggregate reserves 592,097 584,683 * Construction services: Land 8,234 6,513 — Buildings and improvements 50,776 39,039 24 Machinery, vehicles and equipment 179,459 166,739 7 Other 6,643 13,467 4 Other: Land 2,648 2,648 — Other 34,057 34,069 7 Less accumulated depreciation, depletion and amortization 3,272,493 3,216,461 Net property, plant and equipment $ 6,091,545 $ 5,756,388 * Depleted on the units-of-production method based on proven and probable aggregate reserves.

Regulatory assets and liabiliti

Regulatory assets and liabilities	12 Months Ended
	Dec. 31, 2022
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 as of December 31: Estimated Recovery or Refund Period * 2022 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 141,306 $ 86,371 Conservation programs Up to 1 year 8,544 8,225 Cost recovery mechanisms Up to 1 year 4,019 4,536 Decoupling Up to 1 year 1,801 9,131 Other Up to 1 year 9,422 10,428 165,092 118,691 Noncurrent: Pension and postretirement benefits ** 143,349 142,681 Cost recovery mechanisms Up to 10 years 67,171 44,870 Plant costs/asset retirement obligations Over plant lives 44,462 63,116 Manufactured gas plant sites remediation - 26,624 26,053 Plant to be retired - 21,525 50,070 Taxes recoverable from customers Over plant lives 12,330 12,339 Long-term debt refinancing costs Up to 38 years 3,188 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years — 5,186 Other Up to 16 years 11,010 9,742 329,659 357,851 Total regulatory assets $ 494,751 $ 476,542 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year $ 4,929 $ — Conservation programs Up to 1 year 4,126 12 Taxes refundable to customers Up to 1 year 3,937 3,841 Refundable fuel & electric costs Up to 1 year 3,253 713 Natural gas costs refundable through rate adjustments Up to 1 year 955 6,700 Other Up to 1 year 9,240 5,037 26,440 16,303 Noncurrent: Plant removal and decommissioning costs Over plant lives 208,650 168,152 Taxes refundable to customers Over plant lives 203,222 215,421 Cost recovery mechanisms Up to 19 years 14,025 2,919 Accumulated deferred investment tax credit Up to 19 years 13,594 12,696 Pension and postretirement benefits ** 7,376 20,434 Other Up to 15 years 1,587 9,168 448,454 428,790 Total regulatory liabilities $ 474,894 $ 445,093 Net regulatory position $ 19,857 $ 31,449 * 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. As of December 31, 2022 and 2021, approximately $242.5 million and $296.6 million, respectively, of regulatory assets were not earning a rate of return but are expected to be recovered from customers in future rates. These assets are largely comprised of the unfunded portion of pension and postretirement benefits, asset retirement obligations, accelerated depreciation on plant retirement and the estimated future cost of manufactured gas plant site remediation. In the last half of 2021 and in 2022, the Company has experienced higher natural gas costs due to increase in demand outpacing the supply along with the impact of global events. This increase in natural gas costs experienced in certain jurisdictions has been partially offset by the recovery of prior period natural gas costs being recovered over a period longer than the normal one-year period. 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, as previously discussed. 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 removed from the balance sheet and included in the statement of income or accumulated other comprehensive loss in the period in which the discontinuance of regulatory accounting occurs.

Goodwill and other intangible a

Goodwill and other intangible assets	12 Months Ended
	Dec. 31, 2022
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, 2022 Goodwill Measurement Period 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 Balance at January 1, 2021 Goodwill Acquired Measurement Period Balance at December 31, 2021 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 226,003 50,640 (217) 276,426 Construction services 143,224 — — 143,224 Total $ 714,963 $ 50,640 $ (217) $ 765,386 Other amortizable intangible assets at December 31 were as follows: 2022 2021 (In thousands) Customer relationships $ 28,990 $ 29,740 Less accumulated amortization 13,724 10,650 15,266 19,090 Noncompete agreements 4,591 4,591 Less accumulated amortization 3,529 2,856 1,062 1,735 Other 5,280 12,601 Less accumulated amortization 4,076 10,848 1,204 1,753 Total $ 17,532 $ 22,578 The previous tables include goodwill and intangible assets associated with the business combinations completed during 2022 and 2021. For more information related to these business combinations, see Note 4. Amortization expense for amortizable intangible assets for the years ended December 31, 2022, 2021 and 2020, was $5.0 million, $5.1 million and $9.0 million, respectively. The amounts of estimated amortization expense for identifiable intangible assets as of December 31, 2022, were: 2023 2024 2025 2026 2027 Thereafter (In thousands) Amortization expense $ 4,591 $ 4,249 $ 2,200 $ 1,782 $ 1,759 $ 2,951 At October 31, 2022, the fair value substantially exceeded the carrying value at the Company's reporting units with goodwill, with the exception of the natural gas distribution reporting unit. The Company's annual impairment testing indicated the natural gas distribution reporting units fair value is not substantially in excess of its carrying value ("cushion"). Based on the Company's assessment, the estimated fair value of the natural gas distribution reporting unit exceeded its carrying value, which includes $345.7 million of goodwill, by approximately 8 percent as of October 31, 2022. The decrease in the natural gas distribution reporting unit's cushion from the prior year was primarily attributable to the risk adjusted cost of capital increasing from 5.0 percent in 2021 to 6.4 percent 2022, which directly correlates with the treasury rates at the date of the test. The natural gas distribution reporting unit is at risk of future impairment if projected operating results are not met or other inputs into the fair value measurement model change.

Fair value measurements

Fair value measurements	12 Months Ended
	Dec. 31, 2022
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 the Company's 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 $98.0 million and $109.6 million at December 31, 2022 and 2021, respectively, are classified as investments on the Consolidated Balance Sheets. The net unrealized losses on these investments for the year ended December 31, 2022, were $14.1 million. The net unrealized gains on these investments for the years ended December 31, 2021 and 2020, were $7.2 million and $13.1 million, respectively. 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: 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 December 31, 2021 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,702 $ 51 $ 47 $ 8,706 U.S. Treasury securities 2,407 — 11 2,396 Total $ 11,109 $ 51 $ 58 $ 11,102 The Company's assets measured at fair value on a recurring basis were as follows: Fair Value Measurements at December 31, 2022, Using Quoted Prices 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 Measurements at December 31, 2021, Using Quoted Prices Significant Significant Balance at December 31, 2021 (In thousands) Assets: Money market funds $ — $ 10,190 $ — $ 10,190 Insurance contracts* — 109,603 — 109,603 Available-for-sale securities: Mortgage-backed securities — 8,706 — 8,706 U.S. Treasury securities — 2,396 — 2,396 Total assets measured at fair value $ — $ 130,895 $ — $ 130,895 * 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, 7 percent in common stock of small-cap companies, 5 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 is 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 a fair value assessment of the assets acquired and liabilities assumed in the business combinations that occurred during 2022 and 2021. For more information on these Level 2 and Level 3 fair value measurements, see Notes 2 and 4. 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 at December 31 was as follows: 2022 2021 (In thousands) Carrying Amount $ 2,841,425 $ 2,741,900 Fair Value $ 2,469,625 $ 2,984,866 The carrying amounts of the Company's remaining financial instruments included in current assets and current liabilities approximate their fair values.

Debt

Debt	12 Months Ended
	Dec. 31, 2022
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 respective debt instruments, 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 December 31, 2022. In the event the subsidiaries do not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued. The following table summarizes the outstanding revolving credit facilities of the Company's subsidiaries: Company Facility Facility Amount Outstanding at December 31, 2022 Amount Outstanding at December 31, 2021 Letters of Credit at December 31, 2022 Expiration (In millions) Montana-Dakota Utilities Co. Commercial paper/Revolving credit agreement (a) $ 175.0 $ 117.5 $ 64.9 $ — 12/19/24 Cascade Natural Gas Corporation Revolving credit agreement $ 100.0 (b) $ 44.4 $ 71.0 $ 2.2 (c) 11/30/27 Intermountain Gas Company Revolving credit agreement $ 100.0 (d) $ 85.6 $ 56.5 $ — 10/13/27 Centennial Energy Holdings, Inc. Commercial paper/Revolving credit agreement (e) $ 600.0 $ 298.0 $ 385.4 $ — 12/19/24 (a) The commercial paper program is supported by a revolving credit agreement with various banks (provisions allow for increased borrowings, at the option of Montana-Dakota on stated conditions, up to a maximum of $225.0 million). At December 31, 2022 and 2021, there were no amounts outstanding under the revolving credit agreement. (b) Certain provisions allow for increased borrowings, up to a maximum of $125.0 million. (c) Outstanding letter(s) of credit reduce the amount available under the credit agreement. (d) Certain provisions allow for increased borrowings, up to a maximum of $125.0 million. (e) The commercial paper program is supported by a revolving credit agreement with various banks (provisions allow for increased borrowings, at the option of Centennial on stated conditions, up to a maximum of $700.0 million). At December 31, 2022 and 2021, there were no amounts outstanding under the revolving credit agreement. The 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 their 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 MDU Energy Capital On October 21, 2022, MDU Energy Capital entered into a $11.5 million term loan agreement with a SOFR-based variable interest rate and a maturity date of July 21, 2023. The agreement contains customary covenants and provisions, including a covenant of MDU Energy Capital not to permit, at any time, the ratio of total debt to total capitalization to be greater than 70 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. 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. On December 19, 2022, Centennial entered into a $135.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of December 18, 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 December 31, 2022 2022 2021 (In thousands) Senior Notes due on dates ranging from May 15, 2023 to June 15, 2062 4.32 % $ 2,258,500 $ 2,125,000 Commercial paper supported by revolving credit agreements 5.13 % 415,500 450,300 Credit agreements due on October 13, 2027 and November 30, 2027 6.31 % 130,000 127,500 Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 7.32 % 35,000 35,000 Term Loan Agreement due on September 3, 2032 3.64 % 7,000 7,700 Other notes due on dates ranging from March 1, 2024 to January 1, 2061 1.00 % 2,253 2,564 Less unamortized debt issuance costs 6,542 6,090 Less discount 286 74 Total long-term debt 2,841,425 2,741,900 Less current maturities 78,031 148,053 Net long-term debt $ 2,763,394 $ 2,593,847 Montana-Dakota Montana-Dakota's revolving credit agreement supports its commercial paper program. Commercial paper borrowings under this agreement are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued commercial paper borrowings. The credit agreement contains customary covenants and provisions, including covenants of Montana-Dakota not to permit, as of the end of any fiscal quarter, the ratio of funded debt to total capitalization (determined on a consolidated basis) to be greater than 65 percent. Other covenants include limitations on the sale of certain assets and on the making of certain loans and investments. Montana-Dakota's ratio of total debt to total capitalization at December 31, 2022, was 51 percent. Cascade On November 30, 2022, Cascade amended and restated its revolving credit agreement to extend the maturity date to November 30, 2027. Any borrowings under the revolving credit agreement are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued borrowings. The credit 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. Other covenants include restrictions on the sale of certain assets, limitations on indebtedness and the making of certain investments. On June 15, 2022, Cascade issued $50.0 million of senior notes under a note purchase agreement with maturity dates ranging from June 15, 2032 to June 15, 2052, at a weighted average interest rate of 4.50 percent. The agreement contains customary covenants and provisions, including a covenant of Cascade not to permit, at any time, the ratio of debt to total capitalization to be greater than 65 percent. Other covenants include restrictions on the sale of certain assets, limitations on indebtedness and the making of certain investments. Cascade's ratio of total debt to total capitalization at December 31, 2022, was 50 percent. Intermountain On October 13, 2022, Intermountain amended and restated its revolving credit agreement to increase the borrowing capacity to $100.0 million and extend the maturity date to October 13, 2027. Any borrowings under the revolving credit agreement are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued borrowings. The credit 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. Other covenants include restrictions on the sale of certain assets, limitations on indebtedness and the making of certain investments. On June 15, 2022, Intermountain issued $40.0 million of senior notes under a note purchase agreement with maturity dates ranging from June 15, 2052 to June 15, 2062, at a weighted average interest rate of 4.68 percent. The agreement contains customary covenants and provisions, including a covenant of Intermountain not to permit, at any time, the ratio of debt to total capitalization to be greater than 65 percent. Other covenants include restrictions on the sale of certain assets, limitations on indebtedness and the making of certain investments. Intermountain's ratio of total debt to total capitalization at December 31, 2022, was 57 percent. Centennial Centennial's revolving credit agreement supports its commercial paper program. Commercial paper borrowings under this agreement are classified as long-term debt as they are intended to be refinanced on a long-term basis through continued commercial paper borrowings. Centennial's revolving credit agreement contains customary covenants and provisions, including a covenant of Centennial not to permit, as of the end of any fiscal quarter, the ratio of total consolidated debt to total consolidated capitalization to be greater than 65 percent. Other covenants include restricted payments, restrictions on the sale of certain assets, limitations on subsidiary indebtedness, minimum consolidated net worth, limitations on priority debt and the making of certain loans and investments. On March 23, 2022, Centennial issued $150.0 million of senior notes under a note purchase agreement with maturity dates ranging from March 23, 2032 to March 23, 2034, at a weighted average interest rate of 3.71 percent. The agreement contains customary covenants and provisions, including a covenant of Centennial not to permit, at any time, the ratio of debt to total capitalization to be greater than 60 percent. Other covenants include restrictions on the sale of certain assets, limitations on indebtedness and the making of certain investments. Centennial's ratio of total debt to total capitalization, as defined by its debt covenants, at December 31, 2022, was 46 percent. Certain of Centennial's financing agreements contain cross-default provisions. These provisions state that if Centennial or any subsidiary of Centennial fails to make any payment with respect to any indebtedness or contingent obligation, in excess of a specified amount, under any agreement that causes such indebtedness to be due prior to its stated maturity or the contingent obligation to become payable, the applicable agreements will be in default. WBI Energy Transmission On December 22, 2022, WBI Energy Transmission amended its uncommitted note purchase and private shelf agreement to increase capacity to $350.0 million with an expiration date of December 22, 2025. On December 22, 2022, WBI Energy Transmission issued $40.0 million in senior notes under the private shelf agreement with a maturity date of December 22, 2030, at an interest rate of 6.67 percent. WBI Energy Transmission had $235.0 million of notes outstanding at December 31, 2022, which reduced the remaining capacity under this uncommitted private shelf agreement to $115.0 million. This agreement contains customary covenants and provisions, including a covenant of WBI Energy Transmission not to permit, as of the end of any fiscal quarter, the ratio of total debt to total capitalization to be greater than 55 percent. Other covenants include a limitation on priority debt, restrictions on the sale of certain assets and the making of certain investments. WBI Energy Transmission's ratio of total debt to total capitalization at December 31, 2022, was 40 percent. Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs and discount, for the five years and thereafter following December 31, 2022, were as follows: 2023 2024 2025 2026 2027 Thereafter (In thousands) Long-term debt maturities $ 78,031 $ 476,923 $ 177,802 $ 140,802 $ 230,802 $ 1,743,893

Leases

Leases	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Leases of Lessee Disclosure	Leases Most of the leases the Company enters into are for equipment, buildings, easements and vehicles as part of their ongoing operations. The Company also leases certain equipment to third parties through its utility and construction services segments. The Company determines if an arrangement contains a lease at inception of a contract and accounts for all leases in accordance with ASC 842 - Leases. The recognition of leases requires the Company to make estimates and assumptions that affect the lease classification and the assets and liabilities recorded. The accuracy of lease assets and liabilities reported on the Consolidated Financial Statements depends on, among other things, management's estimates of interest rates used to discount the lease assets and liabilities to their present value, as well as the lease terms based on the unique facts and circumstances of each lease. Lessee accounting The leases the Company has entered into as part of its ongoing operations are considered operating leases and are recognized on the Consolidated Balance Sheets as operating lease right-of-use assets, current operating lease liabilities and noncurrent liabilities - operating lease liabilities. The corresponding lease costs are included in operation and maintenance expense on the Consolidated Statements of Income. Generally, the leases for vehicles and equipment have a term of five years or less and buildings and easements have a longer term of up to 35 years or more. To date, the Company does not have any residual value guarantee amounts probable of being owed to a lessor, financing leases or material agreements with related parties. The following tables provide information on the Company's operating leases at and for the years ended December 31: 2022 2021 2020 (In thousands) Lease costs: Short-term lease cost $ 160,318 $ 132,449 $ 135,376 Operating lease cost 44,956 46,622 45,319 Variable lease cost 1,739 1,516 1,319 $ 207,013 $ 180,587 $ 182,014 2022 2021 2020 (Dollars in thousands) Weighted average remaining lease term 2.83 years 2.67 years 2.73 years Weighted average discount rate 4.05 % 3.54 % 4.03 % Cash paid for amounts included in the measurement of lease liabilities $ 44,512 $ 43,489 $ 45,043 The reconciliation of future undiscounted cash flows to operating lease liabilities presented on the Consolidated Balance Sheet at December 31, 2022, was as follows: (In thousands) 2023 $ 38,927 2024 27,825 2025 18,741 2026 11,191 2027 7,297 Thereafter 39,963 Total 143,944 Less discount 23,894 Total operating lease liabilities $ 120,050
Leases of Lessor Disclosure	Lessor accounting 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 $ 47.9 million 50.1 million

Asset retirement obligations

Asset retirement obligations	12 Months Ended
	Dec. 31, 2022
Asset Retirement Obligation [Abstract]
Asset retirement obligations	Asset Retirement Obligations The Company records obligations related to retirement costs of natural gas distribution lines, natural gas transmission lines, natural gas storage wells, decommissioning of certain electric generating facilities, reclamation of certain aggregate properties, special handling and disposal of hazardous materials at certain electric generating facilities, natural gas distribution facilities and buildings, and certain other obligations as asset retirement obligations. A reconciliation of the Company's liability, which the current portion is included in other accrued liabilities on the Consolidated Balance Sheets, for the years ended December 31 was as follows: 2022 2021 (In thousands) Balance at beginning of year $ 468,686 $ 446,919 Liabilities incurred 5,972 12,454 Liabilities acquired — 1,805 Liabilities settled (9,646) (15,155) Accretion expense* 23,188 21,214 Revisions in estimates (77,692) 1,449 Balance at end of year $ 410,508 $ 468,686 * Includes $21.8 million and $19.6 million in 2022 and 2021, respectively, recorded to regulatory assets. The 2022 revisions in estimates consist principally of updated asset retirement obligation costs associated with natural gas distribution and transmission lines at the natural gas distribution segment. The Company believes that largely all expenses related to asset retirement obligations at the Company's regulated operations will be recovered in rates over time and, accordingly, defers such expenses as regulatory assets. For more information on the Company's regulatory assets and liabilities, see Note 6.

Equity

Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Stockholders' Equity Note Disclosure	Equity The Company depends on earnings and dividends from its subsidiaries to pay dividends on common stock. The Company has paid quarterly dividends for 85 consecutive years with an increase in the dividend amount for the last 32 consecutive years. For the years ended December 31, 2022, 2021 and 2020, dividends declared on common stock were $.8750, $.8550 and $.8350 per common share, respectively. Dividends on common stock are paid quarterly to the stockholders of record less than 30 days prior to the distribution date. For the years ended December 31, 2022, 2021 and 2020, the dividends declared to common stockholders were $177.9 million, $173.0 million and $167.4 million, respectively. The declaration and payment of dividends of the Company is at the sole discretion of the board of directors. In addition, the Company's subsidiaries are generally restricted to paying dividends out of capital accounts or net assets. The following discusses the most restrictive limitations. Pursuant to a covenant under its revolving credit agreement, Centennial may only declare or pay distributions if, as of the last day of any fiscal quarter, the ratio of Centennial's average consolidated indebtedness as of the last day of such fiscal quarter and each of the preceding three fiscal quarters to Centennial's Consolidated trailing 12 month EBITDA does not exceed 3.5 to 1. In addition, certain credit agreements and regulatory limitations of the Company's subsidiaries also contain restrictions on dividend payments. The most restrictive limitation requires the Company's subsidiaries not to permit the ratio of funded debt to capitalization to be greater than 60 percent. Based on this limitation, approximately $1.9 billion of the net assets of the Company's subsidiaries, which represents common stockholders' equity including retained earnings, would be restricted from use for dividend payments at December 31, 2022. The Company currently has a shelf registration statement on file with the SEC, under which the Company may issue and sell any combination of common stock and debt securities. The Company may sell such securities if warranted by market conditions and the Company's capital requirements. Any public offer and sale of such securities will be made only by means of a prospectus meeting the requirements of the Securities Act and the rules and regulations thereunder. In August 2020, the Company amended the Distribution Agreement dated February 22, 2019, with J.P. Morgan Securities LLC and MUFG Securities Americas Inc., as sales agents. This agreement, as amended, allows the offering, issuance and sale of up to 6.4 million shares of the Company's common stock in connection with an “at-the-market” offering. The common stock may be offered for sale, from time to time, in accordance with the terms and conditions of the agreement. As of December 31, 2022, the Company had capacity to issue up to 3.6 million additional shares of common stock under the "at-the-market" offering program. Details of the Company's "at-the-market" offering activity for the years ended December 31 was as follows: 2022 2021 (In millions) Shares issued — 2.8 Net proceeds * $ (0.1) $ 88.8 ** * Net proceeds include issuance costs of $149,000 and $1.2 million for ** Net proceeds were used for capital expenditures. The K-Plan provides participants the option to invest in the Company's common stock. For the years ended December 31, 2022, 2021 and 2020, the K-Plan purchased shares of common stock on the open market or issued original issue common stock of the Company. At December 31, 2022, there were 7.2 million shares of common stock reserved for original issuance under the K-Plan.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Stock-based compensation	Stock-Based CompensationThe Company has stock-based compensation plans under which it is currently authorized to grant restricted stock and other stock awards. As of December 31, 2022, there were 3.4 million remaining shares available to grant under these plans. The Company either purchases shares on the open market or issues new shares of common stock to satisfy the vesting of stock-based awards. Total stock-based compensation expense (after tax) was $8.7 million, $12.0 million and $10.8 million in 2022, 2021 and 2020, respectively. The Company uses the straight-line amortization method to recognize compensation expense related to restricted stock, which only has a service condition. The Company recognizes compensation expense related to performance awards with market-based performance metrics on a straight-line basis over the requisite service period. As of December 31, 2022, total remaining unrecognized compensation expense related to stock-based compensation was approximately $12.5 million (before income taxes) which will be amortized over a weighted average period of 1.6 years. Stock awards Non-employee directors receive shares of common stock in addition to and in lieu of cash payment for directors' fees. There were 40,800 shares with a fair value of $1.2 million, 41,925 shares with a fair value of $1.2 million and 45,273 shares with a fair value of $1.1 million issued to non-employee directors during the years ended December 31, 2022, 2021 and 2020, respectively. Restricted stock awards In February 2022 and 2021, key employees were granted restricted stock awards under the long-term performance-based incentive plan. The shares vest over three years, contingent on continued employment. Compensation expense is recognized over the vesting period. At December 31, 2022, the number of outstanding shares granted was 188,499 with a weighted average grant-date fair value of $27.54 per share. Performance share awards Since 2003, key employees of the Company have been granted performance share awards each year under the long-term performance-based incentive plan authorized by the Company's compensation committee. The compensation committee has the authority to select the recipients of awards, determine the type and size of awards, and establish certain terms and conditions of award grants. Share awards are generally earned over a three-year vesting period and tied to financial metrics. Upon vesting, participants receive dividends that accumulate during the vesting period. Target grants of performance shares outstanding at December 31, 2022, were as follows: Grant Date Performance Target Grant February 2021 2021-2023 281,129 February 2022 2022-2024 284,416 Under the market condition for these performance share awards, participants may earn from zero to 200 percent of the apportioned target grant of shares based on the Company's total stockholder return relative to that of the selected peer group. Compensation expense is based on the grant-date fair value as determined by Monte Carlo simulation. The blended volatility term structure ranges are comprised of 50 percent historical volatility and 50 percent implied volatility. Risk-free interest rates were based on U.S. Treasury security rates in effect as of the grant date. Assumptions used for grants applicable to the market condition for certain performance shares issued in 2022, 2021 and 2020 were: 2022 2021 2020 Weighted average grant-date fair value $36.25 $37.96 $40.75 Blended volatility range 24.07% - 31.41% 35.37% - 46.35% 15.30% - 15.97% Risk-free interest rate range .71% - 1.68% .02% - .20% 1.45% - 1.62% Weighted average discounted dividends per share $2.93 $3.16 $2.91 Under the performance conditions for these performance share awards, participants may earn from zero to 200 percent of the apportioned target grant of shares. The performance conditions are based on the Company's compound annual growth rate in earnings from continuing operations before interest, taxes, depreciation, depletion and amortization and the Company's compound annual growth rate in earnings from continuing operations. The weighted average grant-date fair value per share for the performance shares applicable to these performance conditions issued in 2022, 2021 and 2020 was $27.73, $27.35 and $31.63, respectively. The fair value of the performance shares that vested during the years ended December 31, 2022, 2021 and 2020, was $7.6 million, $13.7 million and $9.7 million, respectively. A summary of the status of the performance share awards for the year ended December 31, 2022, was as follows: Number of Weighted Nonvested at beginning of period 555,047 $ 34.40 Granted 284,416 31.99 Performance shares earned/unearned (22,750) 31.63 Less: Vested 251,168 36.60 Nonvested at end of period 565,545 $ 32.32

Accumulated other comprehensive

Accumulated other comprehensive loss	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Accumulated other comprehensive loss	Accumulated Other Comprehensive Loss The Company's accumulated other comprehensive loss is comprised of losses on derivative instruments qualifying as hedges, postretirement liability adjustments and gain (loss) on available-for-sale investments. The after-tax changes in the components of accumulated other comprehensive loss were as follows: Net Post- Net Total (In thousands) At December 31, 2020 $ (984) $ (47,207) $ 113 $ (48,078) Other comprehensive income (loss) before reclassifications — 4,876 (252) 4,624 Amounts reclassified from accumulated other comprehensive loss 446 1,870 134 2,450 Net current-period other comprehensive income (loss) 446 6,746 (118) 7,074 At December 31, 2021 (538) (40,461) (5) (41,004) Other comprehensive income (loss) before reclassifications — 12,007 (667) 11,340 Amounts reclassified to accumulated other comprehensive loss from a regulatory asset — (3,265) — (3,265) Amounts reclassified from accumulated other comprehensive loss 413 1,819 114 2,346 Net current-period other comprehensive income (loss) 413 10,561 (553) 10,421 At December 31, 2022 $ (125) $ (29,900) $ (558) $ (30,583) The following amounts were reclassified out of accumulated other comprehensive loss into net income. The amounts presented in parentheses indicate a decrease to net income on the Consolidated Statements of Income. The reclassifications for the years ended December 31 were as follows: 2022 2021 Location on Consolidated (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (590) $ (591) Interest expense 177 145 Income taxes (413) (446) Amortization of postretirement liability losses included in net periodic benefit credit (2,416) (2,485) Other income 597 615 Income taxes (1,819) (1,870) Reclassification adjustment on available-for-sale investments included in net income (145) (170) Other income 31 36 Income taxes (114) (134) Total reclassifications $ (2,346) $ (2,450)

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income taxes	Income Taxes The components of income before income taxes from continuing operations for each of the years ended December 31 were as follows: 2022 2021 2020 (In thousands) United States $ 462,059 $ 466,651 $ 474,856 Foreign — — 261 Income before income taxes from continuing operations $ 462,059 $ 466,651 $ 475,117 Income tax expense (benefit) from continuing operations for the years ended December 31 was as follows: 2022 2021 2020 (In thousands) Current: Federal $ 50,747 $ 17,121 $ 65,006 State 20,710 11,549 21,234 Foreign — — 151 71,457 28,670 86,391 Deferred: Income taxes: Federal 17,820 45,885 (3,735) State 4,608 12,610 (625) Investment tax credit - net 898 1,755 2,559 23,326 60,250 (1,801) Total income tax expense $ 94,783 $ 88,920 $ 84,590 Components of deferred tax assets and deferred tax liabilities at December 31 were as follows: 2022 2021 (In thousands) Deferred tax assets: Postretirement $ 41,298 $ 45,752 Compensation-related 35,196 37,917 Operating lease liabilities 25,718 26,710 Asset retirement obligations 9,687 8,696 Legal and environmental contingencies 8,526 8,603 Customer advances 7,615 7,683 Payroll tax deferral — 6,940 Other 51,472 39,960 Total deferred tax assets 179,512 182,261 Deferred tax liabilities: Basis differences on property, plant and equipment 608,528 585,095 Postretirement 47,340 48,302 Purchased gas adjustment 33,567 21,136 Operating lease right-of-use-assets 25,472 26,570 Intangible assets 23,007 21,074 Other 60,078 59,934 Total deferred tax liabilities 797,992 762,111 Valuation allowance 12,823 12,112 Net deferred income tax liability $ 631,303 $ 591,962 As of December 31, 2022 and 2021, the Company had various state income tax net operating loss carryforwards of $176.0 million and $164.8 million, respectively, and federal and state income tax credit carryforwards, excluding alternative minimum tax credit carryforwards, of $35.7 million and $35.6 million, respectively. The state credits include various regulatory investment tax credits of approximately $35.1 million and $35.0 million at December 31, 2022 and 2021, respectively. The state income tax credit carryforwards are due to expire between 2024 and 2036. Changes in tax regulations or assumptions regarding current and future taxable income could require additional valuation allowances in the future. The following table reconciles the change in the net deferred income tax liability from December 31, 2021, to December 31, 2022, to deferred income tax expense: 2022 (In thousands) Change in net deferred income tax liability from the preceding table $ 39,341 Deferred taxes associated with other comprehensive loss (3,507) Excess deferred income tax amortization (9,008) Other (3,500) Deferred income tax expense for the period $ 23,326 Total income tax expense differs from the amount computed by applying the statutory federal income tax rate to income before taxes. The reasons for this difference were as follows: Years ended December 31, 2022 2021 2020 Amount % Amount % Amount % (Dollars in thousands) Computed tax at federal statutory rate $ 97,032 21.0 $ 97,997 21.0 $ 99,775 21.0 Increases (reductions) resulting from: State income taxes, net of federal income tax 19,126 4.1 19,496 4.2 17,845 3.8 Federal renewable energy credit (15,343) (3.3) (13,914) (3.0) (16,009) (3.4) Tax compliance and uncertain tax positions 1,080 .2 (477) (.1) (3,543) (.7) Nonqualified benefit plans 2,827 .6 (1,881) (.4) (2,443) (.5) Excess deferred income tax amortization (9,008) (1.9) (10,295) (2.2) (12,517) (2.6) Other (931) (.2) (2,006) (.4) 1,482 .2 Total income tax expense $ 94,783 20.5 $ 88,920 19.1 $ 84,590 17.8 The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction, and various state, local and foreign jurisdictions. The Company is no longer subject to U.S. federal or non-U.S. income tax examinations by tax authorities for years ending prior to 2019. With few exceptions, as of December 31, 2022, the Company is no longer subject to state and local income tax examinations by tax authorities for years ending prior to 2019. For the years ended December 31, 2022, 2021 and 2020, total reserves for uncertain tax positions were not material. The Company recognizes interest and penalties accrued relative to unrecognized tax benefits in income tax expense.

Cash flow information

Cash flow information	12 Months Ended
	Dec. 31, 2022
Supplemental Cash Flow Information [Abstract]
Cash flow information	Cash Flow Information Cash expenditures for interest and income taxes for the years ended December 31 were as follows: 2022 2021 2020 (In thousands) Interest, net* $ 83,118 $ 91,165 $ 88,681 Income taxes paid, net** $ 26,503 $ 71,079 $ 65,536 * AFUDC - borrowed was $2.2 million, $2.8 million and $2.6 million for the years ended December 31, 2022, 2021 and 2020, respectively. ** Income taxes paid, including discontinued operations, were $26.4 million, $70.9 million and $59.4 million for the years ended December 31, 2022, 2021 and 2020, respectively. Noncash investing and financing transactions at December 31 were as follows: 2022 2021 2020 (In thousands) Property, plant and equipment additions in accounts payable $ 49,602 $ 57,605 $ 26,082 Right-of-use assets obtained in exchange for new operating lease liabilities $ 50,921 $ 55,987 $ 54,356 Debt assumed in connection with a business combination $ — $ 10 $ — Accrual for holdback payment related to a business combination $ 70 $ — $ 2,500 Stock issued in connection with a business combination $ 7,304 $ — $ —

Business segment data

Business segment data	12 Months Ended
	Dec. 31, 2022
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. Information on the Company's segments as of December 31 and for the years then ended was as follows: 2022 2021 2020 (In thousands) External operating revenues: Regulated operations: Electric $ 376,579 $ 349,039 $ 331,538 Natural gas distribution 1,273,249 971,364 847,651 Pipeline 85,931 69,940 69,957 1,735,759 1,390,343 1,249,146 Non-regulated operations: Pipeline 10,636 12,918 15,389 Construction materials and contracting 2,533,713 2,228,306 2,177,585 Construction services 2,693,756 2,049,082 2,090,685 Other — 84 (55) 5,238,105 4,290,390 4,283,604 Total external operating revenues $ 6,973,864 $ 5,680,733 $ 5,532,750 2022 2021 2020 (In thousands) Intersegment operating revenues: Regulated operations: Electric $ 494 $ 543 $ 491 Natural gas distribution 555 576 534 Pipeline 58,368 58,989 57,977 59,417 60,108 59,002 Non-regulated operations: Pipeline 644 689 554 Construction materials and contracting 1,016 624 417 Construction services 5,494 2,555 5,038 Other 17,605 13,630 11,958 24,759 17,498 17,967 Total Intersegment operating revenues $ 84,176 $ 77,606 $ 76,969 Depreciation, depletion and amortization: Electric $ 67,802 $ 66,750 $ 62,998 Natural gas distribution 89,466 86,065 84,580 Pipeline 26,857 20,569 21,669 Construction materials and contracting 117,798 100,974 89,626 Construction services 21,468 20,270 23,523 Other 4,435 4,586 2,704 Total depreciation, depletion and amortization $ 327,826 $ 299,214 $ 285,100 Operating income (loss): Electric $ 79,655 $ 66,335 $ 63,434 Natural gas distribution 91,889 89,173 73,082 Pipeline 55,466 48,078 49,436 Construction materials and contracting 194,295 191,077 214,498 Construction services 164,644 145,754 147,644 Other (11,996) (6,198) (3,169) Total operating income $ 573,953 $ 534,219 $ 544,925 Interest expense: Electric $ 28,526 $ 26,712 $ 26,699 Natural gas distribution 42,126 37,265 36,798 Pipeline 11,318 7,010 7,622 Construction materials and contracting 30,121 19,218 20,577 Construction services 6,354 3,540 4,095 Other 1,465 342 883 Intersegment eliminations (637) (103) (155) Total interest expense $ 119,273 $ 93,984 $ 96,519 Income tax expense (benefit): Electric $ (5,420) $ (7,626) $ (11,636) Natural gas distribution 7,805 8,366 5,746 Pipeline 10,212 9,594 7,650 Construction materials and contracting 42,601 43,459 47,431 Construction services 40,788 35,426 35,797 Other (1,203) (299) (398) Total income tax expense $ 94,783 $ 88,920 $ 84,590 2022 2021 2020 (In thousands) Net income (loss): Regulated operations: Electric $ 57,077 $ 51,906 $ 55,601 Natural gas distribution 45,171 51,596 44,049 Pipeline 35,357 39,583 35,453 137,605 143,085 135,103 Non-regulated operations: Pipeline (69) 1,313 1,559 Construction materials and contracting 116,220 129,755 147,325 Construction services 124,781 109,402 109,721 Other (11,261) (5,824) (3,181) 229,671 234,646 255,424 Income from continuing operations 367,276 377,731 390,527 Discontinued operations, net of tax 213 400 (322) Net income $ 367,489 $ 378,131 $ 390,205 Capital expenditures: Electric $ 133,970 $ 82,427 $ 114,676 Natural gas distribution 240,064 170,411 193,048 Pipeline 61,923 234,803 62,224 Construction materials and contracting 181,917 417,524 191,635 Construction services 36,413 29,140 83,651 Other 2,272 1,501 3,045 Total capital expenditures (a) $ 656,559 $ 935,806 $ 648,279 Assets: Electric (b) $ 1,856,258 $ 1,810,695 $ 2,123,693 Natural gas distribution (b) 3,214,452 2,929,519 2,302,770 Pipeline 961,893 913,945 703,377 Construction materials and contracting 2,268,970 2,161,653 1,798,493 Construction services 1,126,323 845,262 818,662 Other (c) 232,885 249,361 306,377 Total assets $ 9,660,781 $ 8,910,435 $ 8,053,372 Property, plant and equipment: Electric (b) $ 2,276,613 $ 2,295,646 $ 2,323,403 Natural gas distribution (b) 3,208,060 3,015,164 2,868,853 Pipeline 1,108,141 1,051,868 821,697 Construction materials and contracting 2,489,408 2,347,696 2,028,476 Construction services 245,111 225,758 220,796 Other 36,705 36,717 37,545 Less accumulated depreciation, depletion and amortization 3,272,493 3,216,461 3,133,831 Net property, plant and equipment $ 6,091,545 $ 5,756,388 $ 5,166,939 (a) Capital expenditures for 2022, 2021 and 2020 include noncash transactions such as capital expenditure-related accounts payable, the issuance of the Company's equity securities in connection with an acquisition, AFUDC and accrual of holdback payments in connection with acquisitions totaling $1.7 million, $38.7 million and $(15.7) million, respectively. (b) Includes allocations of common utility property. (c) Includes assets not directly assignable to a business (i.e. cash and cash equivalents, certain accounts receivable, certain investments and other miscellaneous current and deferred assets). A reconciliation of reportable segment operating revenues and assets to consolidated operating revenues and assets is as follows: 2022 2021 2020 (In thousands) Operating revenues reconciliation: Total reportable segment operating revenues $ 7,040,435 $ 5,744,625 $ 5,597,816 Other revenue 17,605 13,714 11,903 Elimination of intersegment operating revenues (84,176) (77,606) (76,969) Total consolidated operating revenues $ 6,973,864 $ 5,680,733 $ 5,532,750 Asset reconciliation: Total reportable segment assets $ 9,491,679 $ 8,717,563 $ 7,816,848 Other assets 1,353,614 1,184,956 947,740 Elimination of intersegment receivables (1,184,512) (992,084) (711,216) Total consolidated assets $ 9,660,781 $ 8,910,435 $ 8,053,372

Employee benefit plans

Employee benefit plans	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans Pension and other postretirement benefit plans The Company has noncontributory qualified defined benefit pension plans and other postretirement benefit plans for certain eligible employees. The Company uses a measurement date of December 31 for all of its pension and postretirement benefit plans. Prior to 2013, defined benefit pension plan benefits and accruals for all nonunion and certain union plans were frozen and on June 30, 2015, the remaining union plan was frozen. These employees were eligible to receive additional defined contribution plan benefits. Effective January 1, 2010, eligibility to receive retiree medical benefits was modified at certain of the Company's businesses. Employees who had attained age 55 with 10 years of continuous service by December 31, 2010, were provided the option to choose between a pre-65 comprehensive medical plan coupled with a Medicare supplement or a specified company funded Retiree Reimbursement Account, regardless of when they retire. All other eligible employees must meet the new eligibility criteria of age 60 and 10 years of continuous service at the time they retire to be eligible for a specified company funded Retiree Reimbursement Account. Employees hired after December 31, 2009, will not be eligible for retiree medical benefits at certain of the Company's businesses. In 2012, the Company modified health care coverage for certain retirees. Effective January 1, 2013, post-65 coverage was replaced by a fixed-dollar subsidy for retirees and spouses to be used to purchase individual insurance through a healthcare exchange. Changes in benefit obligation and plan assets and amounts recognized in the Consolidated Balance Sheets at December 31 were as follows: Pension Benefits Other 2022 2021 2022 2021 Change in benefit obligation: (In thousands) Benefit obligation at beginning of year $ 411,497 $ 437,360 $ 73,460 $ 86,155 Service cost — — 1,416 1,600 Interest cost 10,522 9,819 1,896 1,862 Plan participants' contributions — — 569 641 Actuarial gain (85,303) (12,140) (18,401) (12,802) Benefits paid (24,672) (23,542) (4,009) (3,996) Benefit obligation at end of year 312,044 411,497 54,931 73,460 Change in net plan assets: Fair value of plan assets at beginning of year 373,109 383,834 100,158 101,639 Actual return on plan assets (77,975) 12,817 (20,893) 1,398 Employer contribution — — 501 476 Plan participants' contributions — — 569 641 Benefits paid (24,672) (23,542) (4,009) (3,996) Fair value of net plan assets at end of year 270,462 373,109 76,326 100,158 Funded status - (under) over $ (41,582) $ (38,388) $ 21,395 $ 26,698 Amounts recognized in the Consolidated Balance Sheets at December 31: Noncurrent assets - other $ — $ — $ 36,325 $ 45,863 Other accrued liabilities — — 1,044 544 Noncurrent liabilities - other 41,582 38,388 13,886 18,621 Benefit obligation (liabilities) assets - net amount recognized $ (41,582) $ (38,388) $ 21,395 $ 26,698 Amounts recognized in accumulated other comprehensive loss: Actuarial loss (gain) $ 32,378 $ 25,976 $ (2,923) $ 2,367 Prior service credit — — (289) (290) Total $ 32,378 $ 25,976 $ (3,212) $ 2,077 Amounts recognized in regulatory assets or liabilities: Actuarial loss (gain) $ 141,207 $ 142,166 $ (1,439) $ (14,727) Prior service credit — — (3,796) (5,193) Total $ 141,207 $ 142,166 $ (5,235) $ (19,920) Employer contributions and benefits paid in the preceding table include only those amounts contributed directly to, or paid directly from, plan assets. Amounts related to regulated operations are recorded as regulatory assets or liabilities and are expected to be reflected in rates charged to customers over time. For more information on regulatory assets and liabilities, see Note 6. In 2022 and 2021, the actuarial gain recognized in the benefit obligation was primarily the result of an increase in the discount rate. For more information on the discount rates, see the table below. Unrecognized pension actuarial gains and losses in excess of 10 percent of the greater of the projected benefit obligation or the market-related value of assets are amortized over the average life expectancy of plan participants for frozen plans. The market-related value of assets is determined using a five-year average of assets. The pension plans all have accumulated benefit obligations in excess of plan assets. The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for these plans at December 31 were as follows: 2022 2021 (In thousands) Projected benefit obligation $ 312,044 $ 411,497 Accumulated benefit obligation $ 312,044 $ 411,497 Fair value of plan assets $ 270,462 $ 373,109 The components of net periodic benefit cost (credit), other than the service cost component, are included in other income on the Consolidated Statements of Income. Prior service credit is amortized on a straight-line basis over the average remaining service period of active participants. These components related to the Company's pension and other postretirement benefit plans for the years ended December 31 were as follows: Pension Benefits Other 2022 2021 2020 2022 2021 2020 Components of net periodic benefit credit: (In thousands) Service cost $ — $ — $ — $ 1,416 $ 1,600 $ 1,532 Interest cost 10,522 9,819 12,093 1,896 1,862 2,437 Expected return on assets (19,455) (19,576) (19,949) (5,288) (5,098) (5,019) Amortization of prior service credit — — — (1,398) (1,398) (1,398) Recognized net actuarial loss (gain) 6,683 8,017 7,172 (219) 24 287 Net periodic benefit credit, including amount capitalized (2,250) (1,740) (684) (3,593) (3,010) (2,161) Less amount capitalized — — — 175 150 156 Net periodic benefit cost credit (2,250) (1,740) (684) (3,768) (3,160) (2,317) Other changes in plan assets and benefit obligations recognized in accumulated comprehensive loss: Net (gain) loss 2,369 (265) 934 (4,141) (2,811) (259) Amortization of actuarial loss (1,310) (1,286) (1,155) (281) (135) (306) Amortization of prior service credit — — — 125 100 101 Reclassification of postretirement liability adjustment from regulatory asset 5,343 — — (992) — — Total recognized in accumulated other comprehensive loss 6,402 (1,551) (221) (5,289) (2,846) (464) Other changes in plan assets and benefit obligations recognized in regulatory assets or liabilities: Net (gain) loss 9,757 (5,116) 4,546 11,920 (6,292) (3,793) Amortization of actuarial gain (loss) (5,373) (6,731) (6,017) 500 110 19 Amortization of prior service credit — — — 1,273 1,298 1,297 Reclassification of postretirement liability adjustment from regulatory asset (5,343) — — 992 — — Total recognized in regulatory assets or liabilities (959) (11,847) (1,471) 14,685 (4,884) (2,477) Total recognized in net periodic benefit credit, accumulated other comprehensive loss and regulatory assets or liabilities $ 3,193 $ (15,138) $ (2,376) $ 5,628 $ (10,890) $ (5,258) Weighted average assumptions used to determine benefit obligations at December 31 were as follows: Pension Benefits Other 2022 2021 2022 2021 Discount rate 5.06 % 2.64 % 5.07 % 2.66 % Expected return on plan assets 6.50 % 6.00 % 6.00 % 5.50 % Rate of compensation increase N/A N/A 3.00 % 3.00 % Weighted average assumptions used to determine net periodic benefit cost (credit) for the years ended December 31 were as follows: Pension Benefits Other 2022 2021 2022 2021 Discount rate 2.64 % 2.30 % 2.66 % 2.30 % Expected return on plan assets 6.00 % 6.00 % 5.50 % 5.50 % Rate of compensation increase N/A N/A 3.00 % 3.00 % The expected rate of return on pension plan assets is based on a targeted asset allocation range determined by the funded ratio of the plan. As of December 31, 2022, the expected rate of return on pension plan assets is based on the targeted asset allocation range of 40 percent to 50 percent equity securities and 50 percent to 60 percent fixed-income securities and the expected rate of return from these asset categories. The expected rate of return on other postretirement plan assets is based on the targeted asset allocation range of 10 percent to 20 percent equity securities and 80 percent to 90 percent fixed-income securities and the expected rate of return from these asset categories. The expected return on plan assets for other postretirement benefits reflects insurance-related investment costs. Health care rate assumptions for the Company's other postretirement benefit plans as of December 31 were as follows: 2022 2021 Health care trend rate assumed for next year 7.5 % 7.0 % Health care cost trend rate - ultimate 4.5 % 4.5 % Year in which ultimate trend rate achieved 2033 2031 The Company's other postretirement benefit plans include health care and life insurance benefits for certain retirees. The plans underlying these benefits may require contributions by the retiree depending on such retiree's age and years of service at retirement or the date of retirement. The Company contributes a flat dollar amount to the monthly premiums which is updated annually on January 1. The Company does not expect to contribute to its defined benefit pension plans in 2023 due to an additional $20.0 million contributed to the plans in 2019 creating prefunding credits to be used in future years. The Company expects to contribute approximately $595,000 to its postretirement benefit plans in 2023. The following benefit payments, which reflect future service, as appropriate, and expected Medicare Part D subsidies at December 31, 2022, are as follows: Years Pension Other Expected (In thousands) 2023 $ 24,936 $ 4,275 $ 62 2024 24,882 4,371 53 2025 24,749 4,456 46 2026 24,605 4,509 39 2027 24,387 4,523 31 2028-2032 114,850 16,917 93 Outside investment managers manage the Company's pension and postretirement assets. The Company's investment policy with respect to pension and other postretirement assets is to make investments solely in the interest of the participants and beneficiaries of the plans and for the exclusive purpose of providing benefits accrued and defraying the reasonable expenses of administration. The Company strives to maintain investment diversification to assist in minimizing the risk of large losses. The Company's policy guidelines allow for investment of funds in cash equivalents, fixed-income securities and equity securities. The guidelines prohibit investment in commodities and futures contracts, equity private placement, employer securities, leveraged or derivative securities, options, direct real estate investments, precious metals, venture capital and limited partnerships. The guidelines also prohibit short selling and margin transactions. The Company's practice is to periodically review and rebalance asset categories based on its targeted asset allocation percentage policy. 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 pension plans' assets are determined using the market approach. The carrying value of the pension plans' Level 2 cash equivalents approximates fair value and is determined using observable inputs in active markets or the net asset value of shares held at year end, which is determined using other observable inputs including pricing from outside sources. The estimated fair value of the pension plans' Level 1 and Level 2 equity securities are based on the closing price reported on the active market on which the individual securities are traded or other known sources including pricing from outside sources. The estimated fair value of the pension plans' Level 1 and Level 2 collective and mutual funds are based on the net asset value of shares held at year end, based on either published market quotations on active markets or other known sources including pricing from outside sources. The estimated fair value of the pension plans' Level 2 corporate and municipal bonds is determined using other observable inputs, including benchmark yields, reported trades, broker/dealer quotes, bids, offers, future cash flows and other reference data. The estimated fair value of the pension plans' Level 1 U.S. Government securities are valued based on quoted prices on an active market. The estimated fair value of the pension plans' Level 2 U.S. Government securities are valued mainly using other observable inputs, including benchmark yields, reported trades, broker/dealer quotes, bids, offers, to be announced prices, future cash flows and other reference data. The estimated fair value of the pension plans' Level 2 pooled separate accounts are determined using observable inputs in active markets or the net asset value of shares held at year end, or other observable inputs. Some of these securities are valued using pricing from outside sources. All investments measured at net asset value in the tables that follow are invested in commingled funds, separate accounts or common collective trusts which do not have publicly quoted prices. The fair value of the commingled funds, separate accounts and common collective trusts are determined based on the net asset value of the underlying investments. The fair value of the underlying investments held by the commingled funds, separate accounts and common collective trusts is generally based on quoted prices in active markets. 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 fair value of the Company's pension plans' assets (excluding cash) by class were as follows: Fair Value Measurements Quoted Prices Significant Significant Balance at December 31, 2022 (In thousands) Assets: Cash equivalents $ — $ 8,170 $ — $ 8,170 Equity securities: U.S. companies 7,388 — — 7,388 International companies — 467 — 467 Collective and mutual funds (a) 121,072 33,371 — 154,443 Corporate bonds — 81,363 — 81,363 Municipal bonds — 5,904 — 5,904 U.S. Government securities 3,044 880 — 3,924 Pooled separate accounts (b) — 3,241 — 3,241 Investments measured at net asset value (c) — — — 5,562 Total assets measured at fair value $ 131,504 $ 133,396 $ — $ 270,462 (a) Collective and mutual funds invest approximately 29 percent in corporate bonds, 24 percent in common stock of large-cap U.S. companies, 16 percent in common stock of international companies, 7 percent cash and cash equivalents, 7 percent in U.S. Government securities and 17 percent in other investments. (b) Pooled separate accounts are invested 100 percent in cash and cash equivalents. (c) In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets. Fair Value Measurements Quoted Prices Significant Significant Balance at December 31, 2021 (In thousands) Assets: Cash equivalents $ — $ 4,637 $ — $ 4,637 Equity securities: U.S. companies 7,483 — — 7,483 International companies — 1,279 — 1,279 Collective and mutual funds (a) 167,093 41,383 — 208,476 Corporate bonds — 125,167 — 125,167 Municipal bonds — 7,507 — 7,507 U.S. Government securities 7,113 1,902 — 9,015 Pooled separate accounts (b) — 3,088 — 3,088 Investments measured at net asset value (c) — — — 6,457 Total assets measured at fair value $ 181,689 $ 184,963 $ — $ 373,109 (a) Collective and mutual funds invest approximately 37 percent in corporate bonds, 19 percent in common stock of international companies, 16 percent in common stock of large-cap U.S. companies, 9 percent in U.S. Government securities and 19 percent in other investments. (b) Pooled separate accounts are invested 100 percent in cash and cash equivalents. (c) In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets. The estimated fair values of the Company's other postretirement benefit plans' assets are determined using the market approach. The estimated fair value of the other postretirement benefit plans' Level 2 cash equivalents is valued at the net asset value of shares held at year end, based on published market quotations on active markets, or using other known sources including pricing from outside sources. The estimated fair value of the other postretirement benefit plans' Level 1 and Level 2 equity securities is based on the closing price reported on the active market on which the individual securities are traded or other known sources including pricing from outside sources . The estimated fair value of the other postretirement benefit plans' Level 2 insurance contract is 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 fair value of the Company's other postretirement benefit plans' assets (excluding cash) by asset class were as follows: Fair Value Measurements Quoted Prices Significant Significant Balance at December 31, 2022 (In thousands) Assets: Cash equivalents $ — $ 4,196 $ — $ 4,196 Equity securities: U.S. companies 2,572 — — 2,572 Collective and mutual funds (a) 5 5 — 10 Insurance contract (b) — 69,548 — 69,548 Total assets measured at fair value $ 2,577 $ 73,749 $ — $ 76,326 (a) Collective and mutual funds invest approximately 29 percent in corporate bonds, 24 percent in common stock of large-cap U.S. companies,16 percent in common stock of international companies, 7 percent in cash and cash equivalents,7 percent in U.S. Government securities and 17 percent in other investments. (b) The insurance contract invests approximately 69 percent in corporate bonds, 13 percent in U.S. Government securities, 14 percent in common stock of large-cap U.S. companies and 4 percent in common stock of small-cap U.S. companies. Fair Value Measurements Quoted Prices Significant Significant Balance at December 31, 2021 (In thousands) Assets: Cash equivalents $ — $ 4,281 $ — $ 4,281 Equity securities: U.S. companies 2,332 — — 2,332 International companies — 1 — 1 Collective and mutual funds (a) 4 90 — 94 Insurance contract (b) — 93,447 — 93,447 Investments measured at net asset value (c) — — — 3 Total assets measured at fair value $ 2,336 $ 97,819 $ — $ 100,158 (a) Collective and mutual funds invest approximately 37 percent in corporate bonds, 19 percent in common stock of international companies, 16 percent in common stock of large-cap U.S. companies, 9 percent in U.S. Government securities and 19 percent in other investments. (b) The insurance contract invests approximately 58 percent in corporate bonds, 13 percent in common stock of large-cap U.S. companies, 13 percent in U.S. Government securities, 5 percent in common stock of small-cap U.S. companies and 11 percent in other investments. (c) In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets. Nonqualified 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 that generally provide for defined benefit payments at age 65 following the employee's retirement or, upon death, to their beneficiaries for a 15-year period. In February 2016, the Company froze the unfunded, nonqualified defined benefit plans to new participants and eliminated benefit increases. Vesting for participants not fully vested was retained. The projected benefit obligation and accumulated benefit obligation for these plans at December 31 were as follows: 2022 2021 (In thousands) Projected benefit obligation $ 74,730 $ 92,918 Accumulated benefit obligation $ 74,730 $ 92,918 The components of net periodic benefit cost are included in other income on the Consolidated Statements of Income. These components related to the Company's nonqualified defined benefit plans for the years ended December 31 were as follows: 2022 2021 2020 (In thousands) Components of net periodic benefit cost: Service cost $ — $ — $ 58 Interest cost 2,142 1,912 2,606 Recognized net actuarial loss 950 1,164 1,192 Net periodic benefit cost $ 3,092 $ 3,076 $ 3,856 Weighted average assumptions used at December 31 were as follows: 2022 2021 Benefit obligation discount rate 4.97 % 2.39 % Benefit obligation rate of compensation increase N/A N/A Net periodic benefit cost discount rate 2.39 % 1.97 % Net periodic benefit cost rate of compensation increase N/A N/A The amount of future benefit payments for the unfunded, nonqualified defined benefit plans at December 31, 2022, are expected to aggregate as follows: 2023 2024 2025 2026 2027 2028-2032 (In thousands) Nonqualified benefits $ 6,651 $ 7,183 $ 7,430 $ 7,537 $ 7,420 $ 29,930 In 2012, the Company established a nonqualified defined contribution plan for certain key management employees. In 2020, the plan was frozen to new participants and no new Company contributions will be made to the plan after December 31, 2020. Vesting for participants not fully vested was retained. A new nonqualified defined contribution plan was adopted in 2020, effective January 1, 2021, to replace the plan originally established in 2012 with similar provisions. Expenses incurred under these plans for 2022, 2021 and 2020 were $3.3 million, $2.4 million and $1.8 million, respectively. The amount of investments that the Company anticipates using to satisfy obligations under these plans at December 31 was as follows: 2022 2021 (In thousands) Investments Insurance contracts* $ 98,041 $ 109,603 Life insurance** 38,448 38,356 Other 7,361 10,190 Total investments $ 143,850 $ 158,149 * For more information on the insurance contracts, see Note 8. ** Investments of life insurance are carried on plan participants (payable upon the employee's death). Defined contribution plans The Company sponsors a defined contribution plan for eligible employees and the costs incurred under this plan were $46.4 million in 2022, $45.4 million in 2021 and $50.1 million in 2020. Multiemployer plans The Company contributes to a number of MEPPs under the terms of collective-bargaining agreements that cover its union-represented employees. The risks of participating in these multiemployer plans are different from single-employer plans in the following aspects: • Assets contributed to the MEPP by one employer may be used to provide benefits to employees of other participating employers • If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers • If the Company chooses to stop participating in some of its MEPPs, the Company may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability The Company's participation in these plans is outlined in the following table. Unless otherwise noted, the most recent Pension Protection Act zone status available in 2022 and 2021 is for the plan's year-end at December 31, 2021, and December 31, 2020, respectively. The zone status is based on information that the Company received from the plan and is certified by the plan's actuary. Among other factors, plans in the red zone are generally less than 65 percent funded, plans in the yellow zone are between 65 percent and 80 percent funded, and plans in the green zone are at least 80 percent funded. EIN/Pension Plan Number Pension Protection Act Zone Status FIP/RP Status Pending/Implemented Contributions Surcharge Imposed Expiration Date Pension Fund 2022 2021 2022 2021 2020 (In thousands) Edison Pension Plan 936061681-001 Green Green No $ 18,750 $ 18,331 $ 16,121 No 12/31/2023 IBEW Local 212 Pension Trust 316127280-001 Green as of 4/30/2021 Green as of 4/30/2021 No 1,622 1,733 1,521 No 6/1/2025 IBEW Local 357 Pension Plan A 886023284-001 Green Green No 12,876 6,485 9,913 No 5/31/2024 IBEW Local 82 Pension Plan 316127268-001 Green as of 6/30/2022 Green as of 6/30/2021 No 1,854 1,353 1,373 No 12/3/2023 IBEW Local 648 Pension Plan 316134845-001 Yellow as of 2/28/2022 Yellow as of 02/28/2021 Implemented 915 706 526 No 9/1/2024 IBEW Local 683 Pension Fund Pension Plan 341442087-001 Green Green No 3,362 1,238 1,240 No 5/26/2024 Idaho Plumbers and Pipefitters Pension Plan 826010346-001 Green as of 5/31/2022 Green as of 5/31/2021 No 1,613 1,528 1,370 No 3/31/2023 National Electrical Benefit Fund 530181657-001 Green Green No 18,060 14,361 14,484 No 5/31/2022- 5/31/2027 * Pension and Retirement Plan of Plumbers and Pipefitters Local 525 886003864-001 Green as of 6/30/2022 Green as of 6/30/2021 No 6,304 4,345 6,266 No 9/30/2024 Pension Trust Fund for Operating Engineers 946090764-001 Yellow Yellow Implemented 2,484 2,495 2,680 No 3/31/2023- 6/15/2026 Sheet Metal Workers Pension Plan of Southern CA, AZ, and NV 956052257-001 Green Yellow Implemented 3,400 2,615 3,255 No 6/30/2024 Western Conference of Teamsters Pension Plan 916145047-001 Green Green No 3,127 3,006 3,025 No 12/31/2023- 12/31/2025 Other funds 26,909 24,192 23,670 Total contributions $ 101,276 $ 82,388 $ 85,444 * Plan includes contributions required by collective bargaining agreements which have expired but contain provisions automatically renewing their terms in the absence of a subsequent negotiated agreement. The Company was listed in the plans' Forms 5500 as providing more than 5 percent of the total contributions for the following plans and plan years: Pension Fund Year Contributions to Plan Exceeded More Than 5 Percent Edison Pension Plan 2021 and 2020 IBEW Local 82 Pension Plan 2021 and 2020 IBEW Local 124 Pension Trust Fund 2021 and 2020 IBEW Local 212 Pension Trust Fund 2021 and 2020 IBEW Local 357 Pension Plan A 2021 and 2020 IBEW Local 648 Pension Plan 2021 and 2020 IBEW Local 683 Pension Fund Pension Plan 2021 and 2020 IBEW Local Union No 226 Open End Pension Fund 2020 Idaho Plumbers and Pipefitters Pension Plan 2021 and 2020 International Union of Operating Engineers Local 701 Pension Trust Fund 2021 and 2020 Minnesota Teamsters Construction Division Pension Fund 2021 and 2020 Pension and Retirement Plan of Plumbers and Pipefitters Local 525 2021 and 2020 Southwest Marine Pension Trust 2021 and 2020 The Company also contributes to a number of multiemployer other postretirement plans under the terms of collective-bargaining agreements that cover its union-represented employees. These plans provide benefits such as health insurance, disability insurance and life insurance to retired union employees. Many of the multiemployer other postretirement plans are combined with active multiemployer health and welfare plans. The Company's total contributions to its multiemployer other postretirement plans, which also includes contributions to active multiemployer health and welfare plans, were $81.0 million, $66.1 million and $63.8 million for the years ended December 31, 2022, 2021 and 2020, respectively. Amounts contributed in 2022, 2021 and 2020 to defined contribution multiemployer plans were $67.9 million, $54.8 million and $54.2 million, respectively.

Jointly owned facilities

Jointly owned facilities	12 Months Ended
	Dec. 31, 2022
Regulated Operations [Abstract]
Jointly owned facilities	Jointly Owned Facilities The consolidated financial statements include the Company's ownership interests in three coal-fired electric generating facilities (Big Stone Station, Coyote Station and Wygen III) and one major transmission line (BSSE). Each owner of the jointly owned facilities is responsible for financing its investment. The Company's share of the jointly owned facilities operating expenses was reflected in the appropriate categories of operating expenses (electric fuel and purchased power; operation and maintenance; and taxes, other than income) in the Consolidated Statements of Income. At December 31, the Company's share of the cost of utility plant in service, construction work in progress and related accumulated depreciation for the jointly owned facilities was as follows: Ownership Percentage 2022 2021 (In thousands) Big Stone Station: 22.7 % Utility plant in service $ 157,699 $ 157,259 Construction work in progress 231 571 Less accumulated depreciation 48,590 47,293 $ 109,340 $ 110,537 BSSE: 50.0 % Utility plant in service $ 107,260 $ 107,424 Construction work in progress — — Less accumulated depreciation 6,182 4,506 $ 101,078 $ 102,918 Coyote Station: 25.0 % Utility plant in service $ 158,274 $ 157,764 Construction work in progress 1,807 784 Less accumulated depreciation 111,203 109,202 $ 48,878 $ 49,346 Wygen III: 25.0 % Utility plant in service $ 66,238 $ 66,357 Construction work in progress 273 108 Less accumulated depreciation 12,477 11,383 $ 54,034 $ 55,082

Regulatory matters

Regulatory matters	12 Months Ended
	Dec. 31, 2022
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. 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 is for an increase of $11.3 million annually or 3.2 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. The IPUC has up to seven months to issue a decision on the request, which is currently pending. Intermountain defers the difference between the actual cost of gas spent to serve customers and the amount approved to be recovered from customers and annually prepares a true-up pursuant to the purchased gas adjustment tariff. On December 27, 2022, Intermountain filed an application with the IPUC for an out-of-cycle cost of gas adjustment requesting an increase in rates of approximately $56.5 million annually or approximately 17.1 percent above current rates. The primary reason for the requested increase was to mitigate the under-collection balance due to the significant increase in the commodity price for natural gas. On January 30, 2023, the request was approved with rates effective February 1, 2023. MNPUC Great Plains defers the difference between the actual cost of gas spent to serve customers and that recovered from customers on a monthly basis. Annually, Great Plains prepares a true-up pursuant to the purchased gas adjustment tariff. On August 30, 2021, the MNPUC issued an order to allow Great Plains recovery of an out-of-cycle cost of gas adjustment of $8.8 million over a period of 27 months. The order was effective September 1, 2021, and was subject to a prudence review by the MNPUC. The requested increase was for the February 2021 extreme cold weather, primarily in the central United States, and market conditions surrounding the natural gas commodity market. On October 19, 2022, the MNPUC issued a final order disallowing $845,000 of the gas costs. These costs, which were deferred as a regulatory asset in natural gas costs recoverable through rate adjustments, were then recorded to expense as they were no longer recoverable from customers. On November 8, 2022, Great Plains filed a request for reconsideration, which was denied by the MNPUC on January 6, 2023. On June 1, 2022, Great Plains filed an application with the MNPUC for a decrease in its depreciation and amortization rates of approximately $1.2 million annually or a decrease from a combined rate of 4.5 percent to 2.8 percent. Great Plains requested the rates be retroactive to January 1, 2022. On November 8, 2022, the MNPUC approved a decrease of $1.0 million annually with rates retroactive to January 1, 2022. 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. The requested increase is primarily to recover investments made since the last rate case, including the Heskett 4 gas turbine, 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, which is expected to be in service in the summer of 2023. The matter is pending before the NDPSC with a hearing scheduled for May 1, 2023. Montana-Dakota has a renewable resource cost adjustment rate tariff that allows for annual adjustments for recent projected capital costs and related expenses for projects determined to be recoverable under the tariff. On November 1, 2022, Montana-Dakota filed an annual update to its renewable resource cost adjustment requesting to recover a revenue requirement of approximately $17.9 million annually, which was revised to $17.0 million annually on January 31, 2023. The update reflects a decrease of approximately $1.0 million from the revenues currently included in rates. On February 22, 2023, this matter was approved by the NDPSC with rates effective March 1, 2023. 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 proposes a similar remedy through the tariff to recover the excess amounts refunded to customers while this tariff has been in place, and revises 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. FERC On September 1, 2022, Montana-Dakota filed an update to its transmission formula rate under the MISO tariff for its multi-value project and network upgrade charges for $15.4 million, which was effective January 1, 2023. 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 will be in effect no later than August 1, 2023.

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and 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 December 31, 2022 and 2021, the Company accrued liabilities which have not been discounted of $32.9 million and $37.0 million, respectively. At December 31, 2022 and 2021, the Company also recorded corresponding insurance receivables of $10.4 million and $14.1 million, respectively, and regulatory assets of $20.9 million and $21.2 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 Portland Harbor Site In December 2000, Knife River - Northwest was named by the EPA as a PRP in connection with the cleanup of the riverbed site adjacent to a commercial property site acquired by Knife River - Northwest from Georgia-Pacific West, Inc. along the Willamette River. The riverbed site is part of the Portland, Oregon, Harbor Superfund Site where the EPA wants responsible parties to share in the costs of cleanup. The EPA entered into a consent order with certain other PRPs referred to as the Lower Willamette Group for a remedial investigation and feasibility study. The Lower Willamette Group has indicated that it has incurred over $115.0 million in investigation related costs. Knife River - Northwest has joined with approximately 100 other PRPs, including the Lower Willamette Group members, in a voluntary process to establish an allocation of costs for the site. Costs to be allocated would include costs incurred by the Lower Willamette Group as well as costs to implement and fund remediation of the site. In January 2017, the EPA issued a Record of Decision adopting a selected remedy which is expected to take 13 years to complete with a then estimated present value of approximately $1 billion. Corrective action will not be taken until remedial design/remedial action plans are approved by the EPA. In 2020, the EPA encouraged certain PRPs to enter into consent agreements to perform remedial design covering the entire site and proposed dividing the site into multiple subareas for remedial design. Certain PRPs executed consent agreements for remedial design work and certain others were issued unilateral administrative orders to perform design work. Knife River - Northwest is not subject to either a voluntary agreement or unilateral order to perform remedial design work. In February 2021, the EPA announced that 100 percent of the site's area requiring active cleanup is in the remedial design process. Site-wide remediation activities are not expected to commence for a number of years. Knife River - Northwest was also notified that the Portland Harbor Natural Resource Trustee Council intends to perform an injury assessment to natural resources resulting from the release of hazardous substances at the site. It is not possible to estimate the costs of natural resource damages until an assessment is completed and allocations are undertaken. At this time, Knife River - Northwest does not believe it is a responsible party and has notified Georgia-Pacific West, Inc., that it intends to seek indemnity for liabilities incurred in relation to the above matters pursuant to the terms of their sale agreement. The Company believes it is not probable that it will incur any material environmental remediation costs or damages in relation to the above referenced matter. Manufactured Gas Plant Sites Claims have been made against Cascade for cleanup of environmental contamination at manufactured gas plant sites operated by Cascade's predecessors and a similar claim has been made against Montana-Dakota for a site operated by Montana-Dakota and its predecessors. Any accruals related to these claims are reflected in regulatory assets. For more information, see Note 6. Demand has been made of Montana-Dakota to participate in investigation and remediation of environmental contamination at a site in Missoula, Montana. The site operated as a former manufactured gas plant from approximately 1907 to 1938 when it was converted to a butane-air plant that operated until 1956. Montana-Dakota or its predecessors owned or controlled the site for a period of the time it operated as a manufactured gas plant and Montana-Dakota operated the butane-air plant from 1940 to 1951, at which time it sold the plant. There are no documented wastes or by-products resulting from the mixing or distribution of butane-air gas. Preliminary assessment of a portion of the site provided a recommended remedial alternative for that portion of approximately $560,000. However, the recommended remediation would not address any potential contamination to adjacent parcels that may be impacted from historic operations of the manufactured gas plant. An environmental assessment was started in 2020, which is estimated to cost approximately $1.8 million. The environmental assessment report is expected to be submitted to the MTDEQ in 2024. Montana-Dakota and another party agreed to voluntarily investigate and remediate the site and that Montana-Dakota will pay two-thirds of the costs for further investigation and remediation of the site. Montana-Dakota has accrued costs of $725,000 for the remediation and investigation costs, and has incurred costs of $922,000 as of December 31, 2022. Montana-Dakota received notice from a prior insurance carrier that it will participate in payment of defense costs incurred in relation to the claim. On December 9, 2021, Montana Dakota filed an application with the MTPSC for deferred accounting treatment for costs associated with the investigation and remediation of the site. The MTPSC approved the application for deferred accounting treatment as requested on July 26, 2022. A claim was made against Cascade for contamination at the Bremerton Gasworks Superfund Site in Bremerton, Washington, which was received in 1997. A preliminary investigation has found soil and groundwater at the site contain impacts requiring further investigation and cleanup. The EPA conducted a Targeted Brownfields Assessment of the site and released a report summarizing the results of that assessment in August 2009. The assessment confirmed that impacts have affected soil and groundwater at the site, as well as sediments in the adjacent Port Washington Narrows. In April 2010, the Washington DOE issued notice it considered Cascade a PRP for hazardous substances at the site. In May 2012, the EPA added the site to the National Priorities List of Superfund sites. Cascade entered into an administrative settlement agreement and consent order with the EPA regarding the scope and schedule for a remedial investigation and feasibility study for the site. Current estimates for the cost to complete the remedial investigation and feasibility study are approximately $12.1 million of which $9.9 million has been incurred as of December 31, 2022. Based on the site investigation, preliminary remediation alternative costs were provided by consultants in August 2020. The preliminary information received through the completion of the data report allowed for the projection of possible costs for a variety of site configurations, remedial measures and potential natural resource damage claims of between $13.6 million and $71.0 million. At December 31, 2022, Cascade has accrued $2.2 million for the remedial investigation and feasibility study, as well as $17.5 million for remediation of this site. The accrual for remediation costs will be reviewed and adjusted, if necessary, after the completion of the feasibility study. In April 2010, Cascade filed a petition with the WUTC for authority to defer the costs incurred in relation to the environmental remediation of this site. The WUTC approved the petition in September 2010, subject to conditions set forth in the order. A claim was made against Cascade for impacts at a site in Bellingham, Washington. Cascade received notice from a party in May 2008 that Cascade may be a PRP, along with other parties, for impacts from a manufactured gas plant owned by Cascade and its predecessor from about 1946 to 1962. Other PRPs reached an agreed order and work plan with the Washington DOE for completion of a remedial investigation and feasibility study for the site. A feasibility study prepared for one of the PRPs in March 2018 identifies five cleanup action alternatives for the site with estimated costs ranging from $8.0 million to $20.4 million with a selected preferred alternative having an estimated total cost of $9.3 million. The other PRPs developed a cleanup action plan and completed public review in 2020. The development of the remediation design is underway, with the Draft Pre-Remedial Design Investigation Data Report submitted to Washington Ecology in early 2023. The remedy construction is expected to occur following the approval of the final design. Cascade believes its proportional share of any liability will be relatively small in comparison to other PRPs. The plant manufactured gas from coal between approximately 1890 and 1946. In 1946, shortly after Cascade's predecessor acquired the plant, the plant converted to a propane-air gas facility. There are no documented wastes or by-products resulting from the mixing or distribution of propane-air gas. Cascade has recorded an accrual for this site for an amount that is not material. The Company has received notices from and entered into agreements with certain of its insurance carriers that they will participate in the defense for certain contamination claims subject to full and complete reservations of rights and defenses to insurance coverage. To the extent these claims are not covered by insurance, the Company intends to seek recovery of remediation costs through its natural gas rates charged to customers. Purchase commitments The Company has entered into various commitments largely consisting of contracts for natural gas and coal supply; purchased power; natural gas transportation and storage; asphalt oil supply; royalties; information technology; and construction materials. Certain of these contracts are subject to variability in volume and price. The commitment terms vary in length, up to 37 years. The commitments under these contracts as of December 31, 2022, were: 2023 2024 2025 2026 2027 Thereafter (In thousands) Purchase commitments $ 712,875 $ 258,074 $ 158,152 $ 103,677 $ 81,619 $ 676,489 These commitments were not reflected in the Company's consolidated financial statements. Amounts purchased under various commitments for the years ended December 31, 2022, 2021 and 2020, were $1.0 billion, $849.3 million and $666.0 million, respectively. 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 December 31, 2022, the fixed maximum amounts guaranteed under these agreements aggregated $341.8 million. Certain of the guarantees also have no fixed maximum amounts specified. The amounts of scheduled expiration of the maximum amounts guaranteed under these agreements aggregate to $51.3 million in 2023; $148.4 million in 2024; $126.8 million in 2025; $1.3 million in 2026; $800,000 in 2027; $1.7 million thereafter; and $11.5 million, which has no scheduled maturity date. There were no amounts outstanding under the previously mentioned guarantees at December 31, 2022. 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 December 31, 2022, the fixed maximum amounts guaranteed under these letters of credit aggregated $30.0 million. The amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $29.5 million in 2023 and $500,000 in 2024. There were no amounts outstanding under the previously mentioned letters of credit at December 31, 2022. 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 December 31, 2022. 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 December 31, 2022, approximately $1.3 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 December 31, 2022, 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 $29.5 million.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events On January 20, 2023, Cascade entered into a $150.0 million term loan agreement with a SOFR-based variable 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. On January 20, 2023, Intermountain entered into a $125.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of January 19, 2024. 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.

Schedule I-Condensed Financial

Schedule I-Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2022
Condensed Financial Information Disclosure [Abstract]
Schedule I-Condensed Financial Information of Registrant	Condensed Financial Information of Registrant (Unconsolidated) Condensed Statements of Income and Comprehensive Income Years ended December 31, 2022 2021 2020 (In thousands) Operating revenues $ — $ — $ — Operating expenses 14,323 — — Operating loss (14,323) — — Other income — — — Interest expense — — — Loss before income taxes (14,323) — — Income taxes (1,623) — — Equity in earnings of subsidiaries from continuing operations 379,976 377,731 390,527 Income from continuing operations 367,276 377,731 390,527 Equity in earnings (loss) of subsidiaries from discontinued operations 213 400 (322) Net income $ 367,489 $ 378,131 $ 390,205 Comprehensive income $ 377,910 $ 385,205 $ 384,229 The accompanying notes are an integral part of these condensed financial statements. Condensed Balance Sheets December 31, 2022 2021 (In thousands, except shares and per share amounts) Assets Current assets: Cash and cash equivalents $ 19,486 $ 6,159 Receivables, net 4,410 6,120 Accounts receivable from subsidiaries 53,285 49,696 Prepayments and other current assets 3,237 2,528 Total current assets 80,418 64,503 Noncurrent assets Investments 50,206 55,686 Investment in subsidiaries 3,581,754 3,368,537 Deferred income taxes 12,668 7,364 Operating lease right-of-use assets 72 114 Other 2,068 26,558 Total noncurrent assets 3,646,768 3,458,259 Total assets $ 3,727,186 $ 3,522,762 Liabilities and Stockholders' Equity Current liabilities: Accounts payable $ 2,354 $ 2,546 Accounts payable to subsidiaries 4,402 6,133 Taxes payable 572 1,672 Dividends payable 45,246 44,229 Accrued compensation 4,312 4,098 Operating lease liabilities due within one year 42 52 Other accrued liabilities 17,907 7,309 Total current liabilities 74,835 66,039 Noncurrent liabilities: Operating lease liabilities 30 62 Other 65,192 73,787 Total noncurrent liabilities 65,222 73,849 Commitments and contingencies Stockholders' equity: Common stock Authorized - 500,000,000 shares, $1.00 par value Shares issued - 204,162,814 at December 31, 2022 and 203,889,661 at December 31, 2021 204,163 203,889 Other paid-in capital 1,466,037 1,461,205 Retained earnings 1,951,138 1,762,410 Accumulated other comprehensive loss (30,583) (41,004) Treasury stock at cost - 538,921 shares (3,626) (3,626) Total stockholders' equity 3,587,129 3,382,874 Total liabilities and stockholders' equity $ 3,727,186 $ 3,522,762 The accompanying notes are an integral part of these condensed financial statements. Condensed Statements of Cash Flows Years ended December 31, 2022 2021 2020 (In thousands) Net cash provided by operating activities $ 242,199 $ 187,297 $ 226,642 Investing activities: Investments in and advances to subsidiaries (45,000) (102,000) (67,000) Investments (885) (391) (4) Net cash used in investing activities (45,885) (102,391) (67,004) Financing activities: Proceeds from issuance of common stock (149) 88,767 3,385 Dividends paid (176,915) (171,354) (166,405) Repurchase of common stock (3,525) (2,992) — Tax withholding on stock-based compensation (2,398) (1,949) (163) Net cash used in financing activities (182,987) (87,528) (163,183) Increase (decrease) in cash and cash equivalents 13,327 (2,622) (3,545) Cash and cash equivalents - beginning of year 6,159 8,781 12,326 Cash and cash equivalents - end of year $ 19,486 $ 6,159 $ 8,781 The accompanying notes are an integral part of these condensed financial statements. Note 1 - Summary of Significant Accounting Policies Basis of presentation The condensed financial information reported in Schedule I is being presented to comply with Rule 12-04 of Regulation S-X. The information is unconsolidated and is presented for the parent company only, MDU Resources Group, Inc. (the Company) as of and for the years ended December 31, 2022, 2021 and 2020. In Schedule I, investments in subsidiaries are presented under the equity method of accounting where the assets and liabilities of the subsidiaries are not consolidated. The investments in net assets of the subsidiaries are recorded on the Condensed Balance Sheets. The income from subsidiaries is reported as equity in earnings of subsidiaries on the Condensed Statements of Income. The material cash inflows on the Condensed Statements of Cash Flows are primarily from the dividends and other payments received from its subsidiaries and the proceeds raised from the issuance of equity securities. The consolidated financial statements of the Company reflect certain businesses as discontinued operations. These statements should be read in conjunction with the consolidated financial statements and notes thereto of the Company. Earnings per common share Please refer to the Consolidated Statements of Income of the registrant for earnings per common share. In addition, see Item 8 - Note 2 for information on the computation of earnings per common share. Note 2 - Debt At December 31, 2022, the Company had no long-term debt maturities. For more information on debt, see Item 8 - Note 9. Note 3 - Dividends The Company depends on earnings and dividends from its subsidiaries to pay dividends on common stock. Cash dividends paid to the Company by subsidiaries were $242.1 million, $188.1 million and $228.4 million for the years ended December 31, 2022, 2021 and 2020, respectively.

Basis of Presentation (Policies

Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of presentation	The abbreviations and acronyms used throughout are defined following the Notes to Consolidated Financial Statements. The consolidated financial statements of the Company include the accounts of the following businesses: electric, natural gas distribution, pipeline, construction materials and contracting, construction services and other. The electric and natural gas distribution businesses, as well as a portion of the pipeline business, are regulated. Construction materials and contracting, construction services and the other businesses, as well as a portion of the pipeline business, are non-regulated. For further descriptions of the Company's businesses, see Note 17. On August 4, 2022, the Company announced its board of directors unanimously approved a plan to pursue the separation of Knife River from the Company. The separation is planned as a tax-free spinoff transaction to the Company’s stockholders for U.S. federal income tax purposes. As the next step of the Company’s strategic planning, 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 to achieve this future structure, the board authorized management to commence a strategic review process of MDU Construction Services. Discontinued operations include the supporting activities of Fidelity and the assets and liabilities of the Company's discontinued operations have been classified as held for sale and are included in prepayments and other current assets, noncurrent assets - other and other accrued liabilities on the Consolidated Balance Sheets and are not material to the financial statements for any period presented. The results and supporting activities are shown in income (loss) 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. Management has also evaluated the impact of events occurring after December 31, 2022, up to the date of issuance of these consolidated financial statements on February 24, 2023, that would require recognition or disclosure in the financial statements.
Consolidation, Policy	Principles of consolidation The consolidated financial statements were prepared in accordance with GAAP and include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation, except for certain transactions related to the Company's regulated operations in accordance with GAAP. For more information on intercompany revenues, see Note 17. The statements also include the Company's ownership interests in the assets, liabilities and expenses of jointly owned electric transmission and generating facilities. See Note 19 for additional information.
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, at the date of the financial statements, as well as the reported amounts of revenues and expenses during the reporting period. Estimates are used for items such as long-lived assets and goodwill; fair values of acquired assets and liabilities under the acquisition method of accounting; aggregate reserves; property depreciable lives; tax provisions; revenue recognized using the cost-to-cost measure of progress for contracts; expected credit losses; environmental and other loss contingencies; regulatory assets expected to be recovered in rates charged to customers; costs on construction contracts; unbilled revenues; actuarially determined benefit costs; asset retirement obligations; lease classification; present value of right-of-use assets and lease liabilities; and the valuation of stock-based compensation. As additional information becomes available, or actual amounts are determinable, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.

Accounting Policies (Policies)

Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [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 financial statements and or disclosures: Standard Description Effective date Impact on financial statements/disclosures Recently adopted accounting standards ASU 2021-10 - Government Assistance In November 2021, the FASB issued guidance on modifying the disclosure requirements to increase the transparency of government assistance including disclosure of the types of assistance, an entity's accounting for the assistance and the effect of the assistance on an entity's financial statements. January 1, 2022 The Company determined the guidance did not have a material impact on its disclosures for the year ended December 31, 2022. 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 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.
Cash and cash equivalents	Cash and cash equivalents The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents.
Revenue recognition	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. The electric and natural gas distribution segments generate revenue from the sales of electric and natural gas products and services, which includes retail and transportation services. These segments establish a customer's retail or transportation service account based on the customer's application/contract for service, which indicates approval of a contract for service. The contract identifies an obligation to provide service in exchange for delivering or standing ready to deliver the identified commodity; and the customer is obligated to pay for the service as provided in the applicable tariff. The product sales are based on a fixed rate that includes a base and per-unit rate, which are included in approved tariffs as determined by state or federal regulatory agencies. The quantity of the commodity consumed or transported determines the total per-unit revenue. The service provided, along with the product consumed or transported, are a single performance obligation because both are required in combination to successfully transfer the contracted product or service to the customer. Revenues are recognized over time as customers receive and consume the products and services. The method of measuring progress toward the completion of the single performance obligation is on a per-unit output method basis, with revenue recognized based on the direct measurement of the value to the customer of the goods or services transferred to date. For contracts governed by the Company’s utility tariffs, amounts are billed monthly with the amount due between 15 and 22 days of receipt of the invoice depending on the applicable state’s tariff. For other contracts not governed by tariff, payment terms are net 30 days. At this time, the segment has no material obligations for returns, refunds or other similar obligations. The pipeline segment generates revenue from providing natural gas transportation and underground storage services, as well as other energy-related services to both third parties and internal customers, largely the natural gas distribution segment. The pipeline segment establishes a contract with a customer based upon the customer’s request for firm or interruptible natural gas transportation or storage service(s). The contract identifies an obligation for the segment to provide the requested service(s) in exchange for consideration from the customer over a specified term. Depending on the type of service(s) requested and contracted, the service provided may include transporting or storing an identified quantity of natural gas and/or standing ready to deliver or store an identified quantity of natural gas. Natural gas transportation and storage revenues are based on fixed rates, which may include reservation fees and/or per-unit commodity rates. The services provided by the segment are generally treated as single performance obligations satisfied over time simultaneous to when the service is provided and revenue is recognized. Rates for the segment’s regulated services are based on its FERC approved tariff or customer negotiated rates, and rates for its non-regulated services are negotiated with its customers and set forth in the contract. For contracts governed by the company’s tariff, amounts are billed on or before the ninth business day of the following month and the amount is due within 12 days of receipt of the invoice. For other contracts not governed by the tariff, payment terms are net 30 days. At this time, the segment has no material obligations for returns, refunds or other similar obligations. The construction materials and contracting segment generates revenue from contracting services and construction materials sales. This segment focuses on the vertical integration of its contracting services with its construction materials to support the aggregate-based product lines. This segment provides contracting services to a customer when a contract has been signed by both the customer and a representative of the segment obligating a service to be provided in exchange for the consideration identified in the contract. The nature of the services this segment provides generally include integrating a set of services and related construction materials into a single project to create a distinct bundle of goods and services, which the Company has determined are single performance obligations. The transaction price includes the fixed consideration required pursuant to the original contract price together with any additional consideration, to which the Company expects to be entitled to, associated with executed change orders plus the estimate of variable consideration to which the Company expects to be entitled, subject to the following constraint. The nature of this segment's contracts gives rise to several types of variable consideration. Examples of variable consideration include: liquidated damages; performance bonuses or incentives and penalties; claims; unpriced change orders; and index pricing. The variable amounts usually arise upon achievement of certain performance metrics or change in project scope. The Company estimates the amount of revenue to be recognized on variable consideration using one of the two prescribed estimation methods, the expected value method or the most likely amount method, depending on which method best predicts the most likely amount of consideration the Company expects to be entitled to or expects to incur. Assumptions as to the occurrence of future events and the likelihood and amount of variable consideration are made during the contract performance period. Estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on the assessment of anticipated performance and all information (historical, current and forecasted) that is reasonably available to management. The Company only includes variable consideration in the estimated transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur or when the uncertainty associated with the variable consideration is resolved. Changes in circumstances could impact management's estimates made in determining the value of variable consideration recorded. When determining if the variable consideration is constrained, the Company considers if factors exist that could increase the likelihood or the magnitude of a potential reversal of revenue. The Company updates its estimate of the transaction price each reporting period and the effect of variable consideration on the transaction price is recognized as an adjustment to revenue on a cumulative catch-up basis. Contract revenue is recognized over time using an input method based on the cost-to-cost measure of progress on a project. This is the preferred method of measuring revenue because the costs incurred have been determined to represent the best indication of the overall progress toward the transfer of such goods or services promised to a customer. Under the cost-to-cost measure of progress, the costs incurred are compared with total estimated costs of a performance obligation. Revenues are recorded proportionately to the costs incurred. The percentage of completion is determined on a performance obligation basis. This segment also sells construction materials to third parties and internal customers. The contract for material sales is the use of a sales order or an invoice, which includes the pricing and payment terms. All material contracts contain a single performance obligation for the delivery of a single distinct product or a distinct separately identifiable bundle of products and services. Revenue is recognized at a point in time when the performance obligation has been satisfied with the delivery of the products or services. The warranties associated with the sales are those consistent with a standard warranty that the product meets certain specifications for quality or those required by law. For most contracts, amounts billed to customers are due within 30 days of receipt. There are no material obligations for returns, refunds or other similar obligations. The construction services segment generates revenue from specialty contracting services which also includes the sale of construction equipment and other supplies. This segment provides specialty contracting services to a customer when a contract has been signed by both the customer and a representative of the segment obligating a service to be provided in exchange for the consideration identified in the contract. The nature of the services this segment provides generally includes multiple promised goods and services in a single project to create a distinct bundle of goods and services, which the Company has determined are single performance obligations. The transaction price includes the fixed consideration required pursuant to the original contract price together with any additional consideration, to which the Company expects to be entitled to, associated with executed change orders plus the estimate of variable consideration to which the Company expects to be entitled, subject to the following constraint. The nature of the segment's contracts gives rise to several types of variable consideration. Examples of variable consideration include: liquidated damages; performance bonuses or incentives and penalties; claims; unpriced change orders; and index pricing. The variable amounts usually arise upon achievement of certain performance metrics or change in project scope. The Company estimates the amount of revenue to be recognized on variable consideration using one of the two prescribed estimation methods, the expected value method or the most likely amount method, depending on which method best predicts the most likely amount of consideration the Company expects to be entitled to or expects to incur. Assumptions as to the occurrence of future events and the likelihood and amount of variable consideration are made during the contract performance period. Estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on the assessment of anticipated performance and all information (historical, current, and forecasted) that is reasonably available to management. The Company only includes variable consideration in the estimated transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur or when the uncertainty associated with the variable consideration is resolved. Changes in circumstances could impact management's estimates made in determining the value of variable consideration recorded. When determining if the variable consideration is constrained, the Company considers if factors exist that could increase the likelihood or the magnitude of a potential reversal of revenue. The Company updates its estimate of the transaction price each reporting period and the effect of variable consideration on the transaction price is recognized as an adjustment to revenue on a cumulative catch-up basis. Contract revenue is recognized over time using the input method based on the measurement of progress on a project. This is the preferred method of measuring revenue because the costs incurred have been determined to represent the best indication of the overall progress toward the transfer of such goods or services promised to a customer. Under the cost-to-cost measure of progress, the costs incurred are compared with total estimated costs of a performance obligation. Revenues are recorded proportionately to the costs incurred. This segment also sells construction equipment and other supplies to third parties and internal customers. The contract for these sales is the use of a sales order or invoice, which includes the pricing and payment terms. All such contracts include a single performance obligation for the delivery of a single distinct product or a distinct separately identifiable bundle of products and services. Revenue is recognized at a point in time when the performance obligation has been satisfied with the delivery of the products or services. The warranties associated with the sales are those consistent with a standard warranty that the product meets certain specifications for quality or those required by law. For most contracts, amounts billed to customers are due within 30 days of receipt. There are no material obligations for returns, refunds or other similar obligations. The Company recognizes all other revenues when services are rendered or goods are delivered.
Legal costs	The Company expenses external legal fees as they are incurred.
Business combinations policy	For all business combinations, the Company preliminarily allocates the purchase price of the acquisitions to the assets acquired and liabilities assumed based on their estimated fair values as of the acquisition dates and are considered provisional until final fair values are determined or the measurement period has passed. The Company expects to record adjustments as it accumulates the information needed to estimate the fair value of assets acquired and liabilities assumed, including working capital balances, estimated fair value of identifiable intangible assets, property, plant and equipment, total consideration and goodwill. The excess of the purchase price over the aggregate fair values is recorded as goodwill. The Company calculated the fair value of the assets acquired in 2022 and 2021 using a market or cost approach (or a combination of both). Fair values for some of the assets were determined based on Level 3 inputs including estimated future cash flows, discount rates, growth rates, sales projections, retention rates and terminal values, all of which require significant management judgment and are susceptible to change. The discount rate used in calculating the fair value of common stock issued in a business combination is determined by using a Black-Scholes-Merton model. The model uses Level 2 inputs including risk-free interest rate, volatility range and dividend yield. The final fair value of the net assets acquired may result in adjustments to the assets and liabilities, including goodwill, and will be made as soon as practical, but no later than 12 months from the respective acquisition dates. Any subsequent measurement period adjustments are not expected to have a material impact on the Company's results of operations.
Accounts receivable and allowance for doubtful accounts	Receivables consist primarily of trade and contracting services receivables from the sale of goods and services net of expected credit losses. The Company's trade receivables are all due in 12 months or less.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.
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.
Property, Plant and Equipment, Policy	Additions to property, plant and equipment are recorded at cost. Aggregate mining development costs are capitalized and classified as land improvements and depreciated over the lower of the estimated life of the reserves or the life of the associated improvement. The Company begins capitalizing development costs at a point when reserves are determined to be proven or probable and economically mineable. Capitalization of these costs cease when production commences. The cost of acquiring reserves in connection with a business combination are valued at fair value. When regulated assets are retired, or otherwise disposed of in the ordinary course of business, the original cost of the asset is charged to accumulated depreciation. With respect to the retirement or disposal of all other assets, the resulting gains or losses are recognized as a component of income. The Company is permitted to capitalize AFUDC on regulated construction projects and to include such amounts in rate base when the related facilities are placed in service. In addition, the Company capitalizes interest, when applicable, on certain contracting services projects associated with its other operations.
Impairment or Disposal of Long-Lived Assets, Including Intangible Assets, Policy	The Company reviews the carrying values of its long-lived assets, including mining and related assets, whenever events or changes in circumstances indicate that such carrying values may not be recoverable. The Company tests long-lived assets for impairment at a level significantly lower than that of goodwill impairment testing. Long-lived assets or groups of assets that are evaluated for impairment at the lowest level of largely independent identifiable cash flows at an individual operation or group of operations collectively serving a local market. The determination of whether an impairment has occurred is based on an estimate of undiscounted future cash flows attributable to the assets, compared to the carrying value of the assets. If impairment has occurred, the amount of the impairment recognized is determined by estimating the fair value of the assets and recording a loss if the carrying value is greater than the fair value.
Regulatory assets and liabilities	The Company's regulated businesses are subject to various state and federal agency regulations. The accounting policies followed by these businesses are generally subject to the Uniform System of Accounts of the FERC as well as the provisions of ASC 980 - Regulated Operations . These accounting policies differ in some respects from those used by the Company's non-regulated businesses. The Company's regulated businesses account for certain income and expense items under the provisions of regulatory accounting, which requires these businesses to defer as regulatory assets or liabilities certain items that would have otherwise been reflected as expense or income, respectively. The Company records regulatory assets or liabilities at the time the Company determines the amounts to be recoverable in current or future rates. Regulatory assets and liabilities are being amortized consistently with the regulatory treatment established by the FERC and the applicable state public service commission. See Note 6 for more information regarding the nature and amounts of these regulatory deferrals.
Natural gas costs recoverable or refundable through rate adjustments	Under the terms of certain orders of the applicable state public service commissions, the Company is deferring natural gas commodity, transportation and storage costs that are greater or less than amounts presently being recovered through its existing rate schedules. Such orders generally provide that these amounts are recoverable or refundable through rate adjustments
Goodwill	Goodwill represents the excess of the purchase price over the fair value of identifiable net tangible and intangible assets acquired in a business combination. Goodwill is required to be tested for impairment annually, which the Company completes in the fourth quarter, or more frequently if events or changes in circumstances indicate that goodwill may be impaired.
Investment, Policy	The Company's investments include the cash surrender value of life insurance policies, insurance contracts, mortgage-backed securities and U.S. Treasury securities. The Company measures its investment in the insurance contracts at fair value with any unrealized gains and losses recorded on the Consolidated Statements of Income. The Company has not elected the fair value option for its mortgage-backed securities and U.S. Treasury securities and, as a result, the unrealized gains and losses on these investments are recorded in accumulated other comprehensive loss. For more information, see Notes 8 and 18
Government Assistance	The Company accounts for government assistance received for capital projects by reducing the cost of the project by the amount of assistance received. The Company records government assistance received as taxable income and writes-up the tax basis of the asset to include the amount of the assistance received.
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. GAAP provides a framework for identifying VIEs and determining when a company should include the assets, liabilities, noncontrolling interest and results of activities of a VIE in its consolidated financial statements. A VIE should be consolidated if a party with an ownership, contractual or other financial interest in the VIE (a variable interest holder) has the power to direct the VIE's most significant activities and the obligation to absorb losses or right to receive benefits of the VIE that could be significant to the VIE. A variable interest holder that consolidates the VIE is called the primary beneficiary. Upon consolidation, the primary beneficiary generally must initially record all of the VIE's assets, liabilities and noncontrolling interests at fair value and subsequently account for the VIE as if it were consolidated. The Company's evaluation of whether it qualifies as the primary beneficiary of a VIE involves significant judgments, estimates and assumptions and includes a qualitative analysis of the activities that most significantly impact the VIE's economic performance and whether the Company has the power to direct those activities, the design of the entity, the rights of the parties and the purpose of the arrangement.
Joint ventures	The Company accounts for unconsolidated joint ventures using either the equity method or proportionate consolidation. The Company currently holds interests between 25 percent and 50 percent in joint ventures formed primarily for the purpose of pooling resources on construction contracts. Proportionate consolidation is used for joint ventures that include unincorporated legal entities and activities of the joint venture which are construction-related. For those joint ventures accounted for under proportionate consolidation, only the Company’s pro rata share of assets, liabilities, revenues and expenses are included in the Company’s balance sheet and results of operations.
Derivative Instruments	The Company enters into commodity price derivative contracts in order to minimize the price volatility associated with customer natural gas costs at its natural gas distribution segment. These derivatives are not designated as hedging instruments and are recorded in the Consolidated Balance Sheets at fair value. Changes in the fair value of these derivatives along with any contract settlements are recorded each period in regulatory assets or liabilities in accordance with regulatory accounting. The Company does not enter into any derivatives for trading or other speculative purposes.
Leases	Lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The Company recognizes leases with an original lease term of 12 months or less in income on a straight-line basis over the term of the lease and does not recognize a corresponding right-of-use asset or lease liability. The Company determines the lease term based on the non-cancelable and cancelable periods in each contract. The non-cancelable period consists of the term of the contract that is legally enforceable and cannot be canceled by either party without incurring a significant penalty. The cancelable period is determined by various factors that are based on who has the right to cancel a contract. If only the lessor has the right to cancel the contract, the Company will assume the contract will continue. If the lessee is the only party that has the right to cancel the contract, the Company looks to asset, entity and market-based factors. If both the lessor and the lessee have the right to cancel the contract, the Company assumes the contract will not continue. The discount rate used to calculate the present value of the lease liabilities is based upon the implied rate within each contract. If the rate is unknown or cannot be determined, the Company uses an incremental borrowing rate, which is determined by the length of the contract, asset class and the Company's borrowing rates, as of the commencement date of the contract.
Asset retirement obligation	The Company records the fair value of a liability for an asset retirement obligation in the period in which it is incurred. When the liability is initially recorded, the Company capitalizes a cost by increasing the carrying amount of the related long-lived asset. Over time, the liability is accreted to its present value each period and the capitalized cost is depreciated over the useful life of the related asset. Upon settlement of the liability, the Company either settles the obligation for the recorded amount or incurs a gain or loss at its non-regulated operations or incurs a regulatory asset or liability at its regulated operations.
Stock-based compensation	The Company determines compensation expense for stock-based awards based on the estimated fair values at the grant date and recognizes the related compensation expense over the vesting period. The Company uses the straight-line amortization method to recognize compensation expense related to restricted stock, which only has a service condition. This method recognizes stock compensation expense on a straight-line basis over the requisite service period for the entire award. The Company recognizes compensation expense related to performance awards that vest based on performance metrics and service conditions on a straight-line basis over the service period. Inception-to-date expense is adjusted based upon the determination of the potential achievement of the performance target at each reporting date. The Company recognizes compensation expense related to performance awards with market-based performance metrics on a straight-line basis over the requisite service period.The Company records the compensation expense for performance share awards using an estimated forfeiture rate. The estimated forfeiture rate is calculated based on an average of actual historical forfeitures. The Company also performs an analysis of any known factors at the time of the calculation to identify any necessary adjustments to the average historical forfeiture rate. At the time actual forfeitures become more than estimated forfeitures, the Company records compensation expense using actual forfeitures
Earnings (loss) per common share	Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the year. 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 year, plus the effect of nonvested performance share awards and restricted stock units.
Income Tax, Policy	The Company provides deferred federal and state income taxes on all temporary differences between the book and tax basis of the Company's assets and liabilities by using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. Excess deferred income tax balances associated with the Company's rate-regulated activities have been recorded as regulatory liabilities. These regulatory liabilities are expected to be reflected as a reduction in future rates charged to customers in accordance with applicable regulatory procedures. The Company uses the deferral method of accounting for investment tax credits and amortizes the credits on regulated electric and natural gas distribution plant over various periods that conform to the ratemaking treatment prescribed by the applicable state public service commissions.
Income tax uncertainties	The Company records uncertain tax positions in accordance with accounting guidance on accounting for income taxes on the basis of a two-step process in which (1) the Company determines whether it is more-likely-than-not that the tax position will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, the Company recognizes the largest amount of the tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. Tax positions that do not meet the more-likely-than-not criteria are reflected as a tax liability. The Company recognizes interest and penalties accrued related to unrecognized tax benefits in income taxes.

Revenue from Contract with Cu_2

Revenue from Contract with Customer (Policies)	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	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. As part of the adoption of ASC 606 - Revenue from Contracts with Customers , the Company elected the practical expedient to recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that the Company otherwise would have recognized is 12 months or less.

Accumulated other comprehensi_2

Accumulated other comprehensive loss (Policies)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Accumulated other comprehensive loss (Policy)	The Company's accumulated other comprehensive loss is comprised of losses on derivative instruments qualifying as hedges, postretirement liability adjustments and gain (loss) on available-for-sale investments.

Business segment data (Policies

Business segment data (Policies)	12 Months Ended
	Dec. 31, 2022
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.

Commitment and Contingencies (P

Commitment and Contingencies (Policies)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies, Policy	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.

Accounting Policies (Tables)

Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Financing 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, 2020 $ 899 $ 2,571 $ 2 $ 6,164 $ 5,722 $ 15,358 Current expected credit loss provision* 1,099 2,188 — 68 (2,250) 1,105 Less write-offs charged against the allowance 2,139 4,072 — 826 1,032 8,069 Credit loss recoveries collected 410 819 — — 93 1,322 At December 31, 2021 269 1,506 2 5,406 2,533 9,716 Current expected credit loss provision 1,325 4,084 — 538 186 6,133 Less write-offs charged against the allowance 1,625 4,913 — 467 625 7,630 Credit loss recoveries collected 406 938 — — 68 1,412 At December 31, 2022 $ 375 $ 1,615 $ 2 $ 5,477 $ 2,162 $ 9,631
Contract receivable retainage	Amounts representing balances billed but not paid by customers under retainage provisions in contracts at December 31 were as follows: 2022 2021 (In thousands) Short-term retainage* $ 120,333 $ 70,600 Long-term retainage** 19,511 10,742 Total retainage $ 139,844 $ 81,342 * Expected to be paid within 12 months or less and included in receivables, net. ** Included in noncurrent assets - other.
Inventories	Inventories at December 31 consisted of: 2022 2021 (In thousands) Aggregates held for resale $ 199,110 $ 184,363 Asphalt oil 68,609 57,002 Materials and supplies 40,056 30,629 Merchandise for resale 40,296 28,501 Natural gas in storage (current) 22,533 18,867 Other 16,921 16,247 Total $ 387,525 $ 335,609
AFUDC and interest capitailized	The amount of AFUDC for the years ended December 31 was as follows: 2022 2021 2020 (In thousands) AFUDC - borrowed $ 2,236 $ 2,833 $ 2,640 AFUDC - equity $ 2,165 $ 6,961 $ 1,270
Schedule of earnings per share reconciliation	A reconciliation of the weighted average common shares outstanding used in the basic and diluted earnings per share calculations follows: 2022 2021 2020 (In thousands) Weighted average common shares outstanding - basic 203,358 202,076 200,502 Effect of dilutive performance share awards 104 307 69 Weighted average common shares outstanding - diluted 203,462 202,383 200,571 Shares excluded from the calculation of diluted earnings per share 14 — 164

Revenue from contracts with cus

Revenue from contracts with customers (Tables)	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Disaggregation of revenue	Disaggregation In the following table, 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. Year ended December 31, 2022 Electric Natural gas distribution Pipeline Construction materials and contracting Construction services Other Total (In thousands) Residential utility sales $ 138,634 $ 718,191 $ — $ — $ — $ — $ 856,825 Commercial utility sales 146,182 453,802 — — — — 599,984 Industrial utility sales 43,766 41,710 — — — — 85,476 Other utility sales 7,597 — — — — — 7,597 Natural gas transportation — 48,886 129,290 — — — 178,176 Natural gas storage — — 14,583 — — — 14,583 Contracting services — — — 1,187,721 — — 1,187,721 Construction materials — — — 1,940,890 — — 1,940,890 Internal sales — — — (593,882) — — (593,882) Electrical & mechanical specialty contracting — — — — 1,988,729 — 1,988,729 Transmission & distribution specialty contracting — — — — 662,705 — 662,705 Other 45,608 13,617 11,450 — 436 17,605 88,716 Intersegment eliminations (494) (555) (59,012) (1,016) (5,494) (17,605) (84,176) Revenues from contracts with customers 381,293 1,275,651 96,311 2,533,713 2,646,376 — 6,933,344 Other revenues (4,714) (2,402) 256 — 47,380 — 40,520 Total external operating revenues $ 376,579 $ 1,273,249 $ 96,567 $ 2,533,713 $ 2,693,756 $ — $ 6,973,864 Year ended December 31, 2021 Electric Natural gas distribution Pipeline Construction materials and contracting Construction services Other Total (In thousands) Residential utility sales $ 126,841 $ 544,721 $ — $ — $ — $ — $ 671,562 Commercial utility sales 137,556 328,285 — — — — 465,841 Industrial utility sales 41,757 30,964 — — — — 72,721 Other utility sales 7,051 — — — — — 7,051 Natural gas transportation — 48,408 114,001 — — — 162,409 Natural gas storage — — 14,680 — — — 14,680 Contracting services — — — 1,017,471 — — 1,017,471 Construction materials — — — 1,712,503 — — 1,712,503 Internal sales — — — (501,044) — — (501,044) Electrical & mechanical specialty contracting — — — — 1,324,419 — 1,324,419 Transmission & distribution specialty contracting — — — — 677,074 — 677,074 Other 42,902 10,567 13,667 — 557 13,714 81,407 Intersegment eliminations (543) (576) (59,678) (624) (2,555) (13,630) (77,606) Revenues from contracts with customers 355,564 962,369 82,670 2,228,306 1,999,495 84 5,628,488 Other revenues (6,525) 8,995 188 — 49,587 — 52,245 Total external operating revenues $ 349,039 $ 971,364 $ 82,858 $ 2,228,306 $ 2,049,082 $ 84 $ 5,680,733 Year ended December 31, 2020 Electric Natural gas distribution Pipeline Construction materials and contracting Construction services Other Total (In thousands) Residential utility sales $ 122,663 $ 476,388 $ — $ — $ — $ — $ 599,051 Commercial utility sales 131,477 277,873 — — — — 409,350 Industrial utility sales 36,744 26,243 — — — — 62,987 Other utility sales 6,634 — — — — — 6,634 Natural gas transportation — 45,546 111,686 — — — 157,232 Natural gas gathering — — 4,865 — — — 4,865 Natural gas storage — — 14,918 — — — 14,918 Contracting services — — — 1,069,665 — — 1,069,665 Construction materials — — — 1,659,152 — — 1,659,152 Internal sales — — — (550,815) — — (550,815) Electrical & mechanical specialty contracting — — — — 1,397,124 — 1,397,124 Transmission & distribution specialty contracting — — — — 649,486 — 649,486 Other 32,452 10,753 12,216 — 1,541 11,903 68,865 Intersegment eliminations (491) (534) (58,531) (417) (5,038) (11,958) (76,969) Revenues from contracts with customers 329,479 836,269 85,154 2,177,585 2,043,113 (55) 5,471,545 Other revenues 2,059 11,382 192 — 47,572 — 61,205 Total external operating revenues $ 331,538 $ 847,651 $ 85,346 $ 2,177,585 $ 2,090,685 $ (55) $ 5,532,750
Contract balances	The changes in contract assets and liabilities were as follows: December 31, 2022 December 31, 2021 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 185,289 $ 125,742 $ 59,547 Receivables, net Contract liabilities - current (208,204) (179,140) (29,064) Accounts payable Contract liabilities - noncurrent (6) (118) 112 Noncurrent liabilities - other Net contract liabilities $ (22,921) $ (53,516) $ 30,595 December 31, 2021 December 31, 2020 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 125,742 $ 104,345 $ 21,397 Receivables, net Contract liabilities - current (179,140) (158,603) (20,537) Accounts payable Contract liabilities - noncurrent (118) (52) (66) Noncurrent liabilities - other Net contract liabilities $ (53,516) $ (54,310) $ 794

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment at December 31 was as follows: 2022 2021 Weighted (Dollars in thousands, where applicable) Regulated: Electric: Generation $ 938,614 $ 1,056,632 48 Distribution 489,351 474,037 47 Transmission 616,611 562,080 65 Construction in progress 87,003 62,781 — Other 145,034 140,117 14 Natural gas distribution: Distribution 2,569,921 2,427,779 52 Transmission 104,769 107,721 61 Storage 42,318 34,997 37 General 204,993 197,653 13 Construction in progress 55,759 21,741 — Other 230,299 225,272 15 Pipeline: Transmission 951,187 673,344 46 Storage 55,383 57,670 53 Construction in progress 34,655 263,640 — Other 59,917 50,477 19 Non-regulated: Pipeline: Construction in progress 49 18 — Other 6,950 6,719 10 Construction materials and contracting: Land 150,809 149,066 — Buildings and improvements 165,833 149,262 21 Machinery, vehicles and equipment 1,492,506 1,414,260 12 Construction in progress 88,163 50,425 — Aggregate reserves 592,097 584,683 * Construction services: Land 8,234 6,513 — Buildings and improvements 50,776 39,039 24 Machinery, vehicles and equipment 179,459 166,739 7 Other 6,643 13,467 4 Other: Land 2,648 2,648 — Other 34,057 34,069 7 Less accumulated depreciation, depletion and amortization 3,272,493 3,216,461 Net property, plant and equipment $ 6,091,545 $ 5,756,388 * Depleted on the units-of-production method based on proven and probable aggregate reserves.

Regulatory assets and liabili_2

Regulatory assets and liabilities (Tables)	12 Months Ended
	Dec. 31, 2022
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory assets	The following table summarizes the individual components of unamortized regulatory assets and liabilities as of December 31: Estimated Recovery or Refund Period * 2022 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 141,306 $ 86,371 Conservation programs Up to 1 year 8,544 8,225 Cost recovery mechanisms Up to 1 year 4,019 4,536 Decoupling Up to 1 year 1,801 9,131 Other Up to 1 year 9,422 10,428 165,092 118,691 Noncurrent: Pension and postretirement benefits ** 143,349 142,681 Cost recovery mechanisms Up to 10 years 67,171 44,870 Plant costs/asset retirement obligations Over plant lives 44,462 63,116 Manufactured gas plant sites remediation - 26,624 26,053 Plant to be retired - 21,525 50,070 Taxes recoverable from customers Over plant lives 12,330 12,339 Long-term debt refinancing costs Up to 38 years 3,188 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years — 5,186 Other Up to 16 years 11,010 9,742 329,659 357,851 Total regulatory assets $ 494,751 $ 476,542 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year $ 4,929 $ — Conservation programs Up to 1 year 4,126 12 Taxes refundable to customers Up to 1 year 3,937 3,841 Refundable fuel & electric costs Up to 1 year 3,253 713 Natural gas costs refundable through rate adjustments Up to 1 year 955 6,700 Other Up to 1 year 9,240 5,037 26,440 16,303 Noncurrent: Plant removal and decommissioning costs Over plant lives 208,650 168,152 Taxes refundable to customers Over plant lives 203,222 215,421 Cost recovery mechanisms Up to 19 years 14,025 2,919 Accumulated deferred investment tax credit Up to 19 years 13,594 12,696 Pension and postretirement benefits ** 7,376 20,434 Other Up to 15 years 1,587 9,168 448,454 428,790 Total regulatory liabilities $ 474,894 $ 445,093 Net regulatory position $ 19,857 $ 31,449 * 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 as of December 31: Estimated Recovery or Refund Period * 2022 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 141,306 $ 86,371 Conservation programs Up to 1 year 8,544 8,225 Cost recovery mechanisms Up to 1 year 4,019 4,536 Decoupling Up to 1 year 1,801 9,131 Other Up to 1 year 9,422 10,428 165,092 118,691 Noncurrent: Pension and postretirement benefits ** 143,349 142,681 Cost recovery mechanisms Up to 10 years 67,171 44,870 Plant costs/asset retirement obligations Over plant lives 44,462 63,116 Manufactured gas plant sites remediation - 26,624 26,053 Plant to be retired - 21,525 50,070 Taxes recoverable from customers Over plant lives 12,330 12,339 Long-term debt refinancing costs Up to 38 years 3,188 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years — 5,186 Other Up to 16 years 11,010 9,742 329,659 357,851 Total regulatory assets $ 494,751 $ 476,542 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year $ 4,929 $ — Conservation programs Up to 1 year 4,126 12 Taxes refundable to customers Up to 1 year 3,937 3,841 Refundable fuel & electric costs Up to 1 year 3,253 713 Natural gas costs refundable through rate adjustments Up to 1 year 955 6,700 Other Up to 1 year 9,240 5,037 26,440 16,303 Noncurrent: Plant removal and decommissioning costs Over plant lives 208,650 168,152 Taxes refundable to customers Over plant lives 203,222 215,421 Cost recovery mechanisms Up to 19 years 14,025 2,919 Accumulated deferred investment tax credit Up to 19 years 13,594 12,696 Pension and postretirement benefits ** 7,376 20,434 Other Up to 15 years 1,587 9,168 448,454 428,790 Total regulatory liabilities $ 474,894 $ 445,093 Net regulatory position $ 19,857 $ 31,449 * 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.

Goodwill and other intangible_2

Goodwill and other intangible assets (Tables)	12 Months Ended
	Dec. 31, 2022
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, 2022 Goodwill Measurement Period 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 Balance at January 1, 2021 Goodwill Acquired Measurement Period Balance at December 31, 2021 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 226,003 50,640 (217) 276,426 Construction services 143,224 — — 143,224 Total $ 714,963 $ 50,640 $ (217) $ 765,386
Other amortizable intangible assets	Other amortizable intangible assets at December 31 were as follows: 2022 2021 (In thousands) Customer relationships $ 28,990 $ 29,740 Less accumulated amortization 13,724 10,650 15,266 19,090 Noncompete agreements 4,591 4,591 Less accumulated amortization 3,529 2,856 1,062 1,735 Other 5,280 12,601 Less accumulated amortization 4,076 10,848 1,204 1,753 Total $ 17,532 $ 22,578
Estimated amortization expense	The amounts of estimated amortization expense for identifiable intangible assets as of December 31, 2022, were: 2023 2024 2025 2026 2027 Thereafter (In thousands) Amortization expense $ 4,591 $ 4,249 $ 2,200 $ 1,782 $ 1,759 $ 2,951

Fair value measurements (Tables

Fair value measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Debt Securities, Available-for-sale	Details of available-for-sale securities were as follows: 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 December 31, 2021 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,702 $ 51 $ 47 $ 8,706 U.S. Treasury securities 2,407 — 11 2,396 Total $ 11,109 $ 51 $ 58 $ 11,102
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 December 31, 2022, Using Quoted Prices 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 Measurements at December 31, 2021, Using Quoted Prices Significant Significant Balance at December 31, 2021 (In thousands) Assets: Money market funds $ — $ 10,190 $ — $ 10,190 Insurance contracts* — 109,603 — 109,603 Available-for-sale securities: Mortgage-backed securities — 8,706 — 8,706 U.S. Treasury securities — 2,396 — 2,396 Total assets measured at fair value $ — $ 130,895 $ — $ 130,895 * 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, 7 percent in common stock of small-cap companies, 5 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 at December 31 was as follows: 2022 2021 (In thousands) Carrying Amount $ 2,841,425 $ 2,741,900 Fair Value $ 2,469,625 $ 2,984,866

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Outstanding credit facilities	The following table summarizes the outstanding revolving credit facilities of the Company's subsidiaries: Company Facility Facility Amount Outstanding at December 31, 2022 Amount Outstanding at December 31, 2021 Letters of Credit at December 31, 2022 Expiration (In millions) Montana-Dakota Utilities Co. Commercial paper/Revolving credit agreement (a) $ 175.0 $ 117.5 $ 64.9 $ — 12/19/24 Cascade Natural Gas Corporation Revolving credit agreement $ 100.0 (b) $ 44.4 $ 71.0 $ 2.2 (c) 11/30/27 Intermountain Gas Company Revolving credit agreement $ 100.0 (d) $ 85.6 $ 56.5 $ — 10/13/27 Centennial Energy Holdings, Inc. Commercial paper/Revolving credit agreement (e) $ 600.0 $ 298.0 $ 385.4 $ — 12/19/24 (a) The commercial paper program is supported by a revolving credit agreement with various banks (provisions allow for increased borrowings, at the option of Montana-Dakota on stated conditions, up to a maximum of $225.0 million). At December 31, 2022 and 2021, there were no amounts outstanding under the revolving credit agreement. (b) Certain provisions allow for increased borrowings, up to a maximum of $125.0 million. (c) Outstanding letter(s) of credit reduce the amount available under the credit agreement. (d) Certain provisions allow for increased borrowings, up to a maximum of $125.0 million. (e) The commercial paper program is supported by a revolving credit agreement with various banks (provisions allow for increased borrowings, at the option of Centennial on stated conditions, up to a maximum of $700.0 million). At December 31, 2022 and 2021, there were no amounts outstanding under the revolving credit agreement.
Long term debt outstanding	Long-term debt outstanding was as follows: Weighted Average Interest Rate at December 31, 2022 2022 2021 (In thousands) Senior Notes due on dates ranging from May 15, 2023 to June 15, 2062 4.32 % $ 2,258,500 $ 2,125,000 Commercial paper supported by revolving credit agreements 5.13 % 415,500 450,300 Credit agreements due on October 13, 2027 and November 30, 2027 6.31 % 130,000 127,500 Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 7.32 % 35,000 35,000 Term Loan Agreement due on September 3, 2032 3.64 % 7,000 7,700 Other notes due on dates ranging from March 1, 2024 to January 1, 2061 1.00 % 2,253 2,564 Less unamortized debt issuance costs 6,542 6,090 Less discount 286 74 Total long-term debt 2,841,425 2,741,900 Less current maturities 78,031 148,053 Net long-term debt $ 2,763,394 $ 2,593,847
Schedule of debt maturities	Long-term debt maturities, which excludes unamortized debt issuance costs and discount, for the five years and thereafter following December 31, 2022, were as follows: 2023 2024 2025 2026 2027 Thereafter (In thousands) Long-term debt maturities $ 78,031 $ 476,923 $ 177,802 $ 140,802 $ 230,802 $ 1,743,893

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Lease, Cost	The following tables provide information on the Company's operating leases at and for the years ended December 31: 2022 2021 2020 (In thousands) Lease costs: Short-term lease cost $ 160,318 $ 132,449 $ 135,376 Operating lease cost 44,956 46,622 45,319 Variable lease cost 1,739 1,516 1,319 $ 207,013 $ 180,587 $ 182,014 2022 2021 2020 (Dollars in thousands) Weighted average remaining lease term 2.83 years 2.67 years 2.73 years Weighted average discount rate 4.05 % 3.54 % 4.03 % Cash paid for amounts included in the measurement of lease liabilities $ 44,512 $ 43,489 $ 45,043
Lessee, Operating Lease, Liability, Maturity	The reconciliation of future undiscounted cash flows to operating lease liabilities presented on the Consolidated Balance Sheet at December 31, 2022, was as follows: (In thousands) 2023 $ 38,927 2024 27,825 2025 18,741 2026 11,191 2027 7,297 Thereafter 39,963 Total 143,944 Less discount 23,894 Total operating lease liabilities $ 120,050

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2022
Asset Retirement Obligation [Abstract]
Reconciliation of the company's asset retirement obligation	A reconciliation of the Company's liability, which the current portion is included in other accrued liabilities on the Consolidated Balance Sheets, for the years ended December 31 was as follows: 2022 2021 (In thousands) Balance at beginning of year $ 468,686 $ 446,919 Liabilities incurred 5,972 12,454 Liabilities acquired — 1,805 Liabilities settled (9,646) (15,155) Accretion expense* 23,188 21,214 Revisions in estimates (77,692) 1,449 Balance at end of year $ 410,508 $ 468,686 * Includes $21.8 million and $19.6 million in 2022 and 2021, respectively, recorded to regulatory assets.

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Schedule of Stock by Class	Details of the Company's "at-the-market" offering activity for the years ended December 31 was as follows: 2022 2021 (In millions) Shares issued — 2.8 Net proceeds * $ (0.1) $ 88.8 ** * Net proceeds include issuance costs of $149,000 and $1.2 million for ** Net proceeds were used for capital expenditures.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Target grants performance share	Target grants of performance shares outstanding at December 31, 2022, were as follows: Grant Date Performance Target Grant February 2021 2021-2023 281,129 February 2022 2022-2024 284,416
Schedule of share-based payment award, performance shares, valuation assumptions	Assumptions used for grants applicable to the market condition for certain performance shares issued in 2022, 2021 and 2020 were: 2022 2021 2020 Weighted average grant-date fair value $36.25 $37.96 $40.75 Blended volatility range 24.07% - 31.41% 35.37% - 46.35% 15.30% - 15.97% Risk-free interest rate range .71% - 1.68% .02% - .20% 1.45% - 1.62% Weighted average discounted dividends per share $2.93 $3.16 $2.91
Summary of the status of the performance share awards	A summary of the status of the performance share awards for the year ended December 31, 2022, was as follows: Number of Weighted Nonvested at beginning of period 555,047 $ 34.40 Granted 284,416 31.99 Performance shares earned/unearned (22,750) 31.63 Less: Vested 251,168 36.60 Nonvested at end of period 565,545 $ 32.32

Accumulated other comprehensi_3

Accumulated other comprehensive loss (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Accumulated comprehensive loss	The after-tax changes in the components of accumulated other comprehensive loss were as follows: Net Post- Net Total (In thousands) At December 31, 2020 $ (984) $ (47,207) $ 113 $ (48,078) Other comprehensive income (loss) before reclassifications — 4,876 (252) 4,624 Amounts reclassified from accumulated other comprehensive loss 446 1,870 134 2,450 Net current-period other comprehensive income (loss) 446 6,746 (118) 7,074 At December 31, 2021 (538) (40,461) (5) (41,004) Other comprehensive income (loss) before reclassifications — 12,007 (667) 11,340 Amounts reclassified to accumulated other comprehensive loss from a regulatory asset — (3,265) — (3,265) Amounts reclassified from accumulated other comprehensive loss 413 1,819 114 2,346 Net current-period other comprehensive income (loss) 413 10,561 (553) 10,421 At December 31, 2022 $ (125) $ (29,900) $ (558) $ (30,583)
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 parentheses indicate a decrease to net income on the Consolidated Statements of Income. The reclassifications for the years ended December 31 were as follows: 2022 2021 Location on Consolidated (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (590) $ (591) Interest expense 177 145 Income taxes (413) (446) Amortization of postretirement liability losses included in net periodic benefit credit (2,416) (2,485) Other income 597 615 Income taxes (1,819) (1,870) Reclassification adjustment on available-for-sale investments included in net income (145) (170) Other income 31 36 Income taxes (114) (134) Total reclassifications $ (2,346) $ (2,450)

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Components of income before income taxes	The components of income before income taxes from continuing operations for each of the years ended December 31 were as follows: 2022 2021 2020 (In thousands) United States $ 462,059 $ 466,651 $ 474,856 Foreign — — 261 Income before income taxes from continuing operations $ 462,059 $ 466,651 $ 475,117
Income tax expense	Income tax expense (benefit) from continuing operations for the years ended December 31 was as follows: 2022 2021 2020 (In thousands) Current: Federal $ 50,747 $ 17,121 $ 65,006 State 20,710 11,549 21,234 Foreign — — 151 71,457 28,670 86,391 Deferred: Income taxes: Federal 17,820 45,885 (3,735) State 4,608 12,610 (625) Investment tax credit - net 898 1,755 2,559 23,326 60,250 (1,801) Total income tax expense $ 94,783 $ 88,920 $ 84,590
Deferred tax assets and deferred tax liabilities	Components of deferred tax assets and deferred tax liabilities at December 31 were as follows: 2022 2021 (In thousands) Deferred tax assets: Postretirement $ 41,298 $ 45,752 Compensation-related 35,196 37,917 Operating lease liabilities 25,718 26,710 Asset retirement obligations 9,687 8,696 Legal and environmental contingencies 8,526 8,603 Customer advances 7,615 7,683 Payroll tax deferral — 6,940 Other 51,472 39,960 Total deferred tax assets 179,512 182,261 Deferred tax liabilities: Basis differences on property, plant and equipment 608,528 585,095 Postretirement 47,340 48,302 Purchased gas adjustment 33,567 21,136 Operating lease right-of-use-assets 25,472 26,570 Intangible assets 23,007 21,074 Other 60,078 59,934 Total deferred tax liabilities 797,992 762,111 Valuation allowance 12,823 12,112 Net deferred income tax liability $ 631,303 $ 591,962
Schedule of change in net deferred income tax liability reconciliation	The following table reconciles the change in the net deferred income tax liability from December 31, 2021, to December 31, 2022, to deferred income tax expense: 2022 (In thousands) Change in net deferred income tax liability from the preceding table $ 39,341 Deferred taxes associated with other comprehensive loss (3,507) Excess deferred income tax amortization (9,008) Other (3,500) Deferred income tax expense for the period $ 23,326
Reconciliation of income tax expense (benefit) at statutory federal rate versus actual rate	Total income tax expense differs from the amount computed by applying the statutory federal income tax rate to income before taxes. The reasons for this difference were as follows: Years ended December 31, 2022 2021 2020 Amount % Amount % Amount % (Dollars in thousands) Computed tax at federal statutory rate $ 97,032 21.0 $ 97,997 21.0 $ 99,775 21.0 Increases (reductions) resulting from: State income taxes, net of federal income tax 19,126 4.1 19,496 4.2 17,845 3.8 Federal renewable energy credit (15,343) (3.3) (13,914) (3.0) (16,009) (3.4) Tax compliance and uncertain tax positions 1,080 .2 (477) (.1) (3,543) (.7) Nonqualified benefit plans 2,827 .6 (1,881) (.4) (2,443) (.5) Excess deferred income tax amortization (9,008) (1.9) (10,295) (2.2) (12,517) (2.6) Other (931) (.2) (2,006) (.4) 1,482 .2 Total income tax expense $ 94,783 20.5 $ 88,920 19.1 $ 84,590 17.8

Cash flow information (Tables)

Cash flow information (Tables)	12 Months Ended
	Dec. 31, 2022
Supplemental Cash Flow Information [Abstract]
Cash expenditures for interest and income taxes and noncash investing transactions	Cash expenditures for interest and income taxes for the years ended December 31 were as follows: 2022 2021 2020 (In thousands) Interest, net* $ 83,118 $ 91,165 $ 88,681 Income taxes paid, net** $ 26,503 $ 71,079 $ 65,536 * AFUDC - borrowed was $2.2 million, $2.8 million and $2.6 million for the years ended December 31, 2022, 2021 and 2020, respectively. ** Income taxes paid, including discontinued operations, were $26.4 million, $70.9 million and $59.4 million for the years ended December 31, 2022, 2021 and 2020, respectively. Noncash investing and financing transactions at December 31 were as follows: 2022 2021 2020 (In thousands) Property, plant and equipment additions in accounts payable $ 49,602 $ 57,605 $ 26,082 Right-of-use assets obtained in exchange for new operating lease liabilities $ 50,921 $ 55,987 $ 54,356 Debt assumed in connection with a business combination $ — $ 10 $ — Accrual for holdback payment related to a business combination $ 70 $ — $ 2,500 Stock issued in connection with a business combination $ 7,304 $ — $ —

Business segment data (Tables)

Business segment data (Tables)	12 Months Ended
	Dec. 31, 2022
Segment Reporting [Abstract]
Information on the Company's businesses	Information on the Company's segments as of December 31 and for the years then ended was as follows: 2022 2021 2020 (In thousands) External operating revenues: Regulated operations: Electric $ 376,579 $ 349,039 $ 331,538 Natural gas distribution 1,273,249 971,364 847,651 Pipeline 85,931 69,940 69,957 1,735,759 1,390,343 1,249,146 Non-regulated operations: Pipeline 10,636 12,918 15,389 Construction materials and contracting 2,533,713 2,228,306 2,177,585 Construction services 2,693,756 2,049,082 2,090,685 Other — 84 (55) 5,238,105 4,290,390 4,283,604 Total external operating revenues $ 6,973,864 $ 5,680,733 $ 5,532,750 2022 2021 2020 (In thousands) Intersegment operating revenues: Regulated operations: Electric $ 494 $ 543 $ 491 Natural gas distribution 555 576 534 Pipeline 58,368 58,989 57,977 59,417 60,108 59,002 Non-regulated operations: Pipeline 644 689 554 Construction materials and contracting 1,016 624 417 Construction services 5,494 2,555 5,038 Other 17,605 13,630 11,958 24,759 17,498 17,967 Total Intersegment operating revenues $ 84,176 $ 77,606 $ 76,969 Depreciation, depletion and amortization: Electric $ 67,802 $ 66,750 $ 62,998 Natural gas distribution 89,466 86,065 84,580 Pipeline 26,857 20,569 21,669 Construction materials and contracting 117,798 100,974 89,626 Construction services 21,468 20,270 23,523 Other 4,435 4,586 2,704 Total depreciation, depletion and amortization $ 327,826 $ 299,214 $ 285,100 Operating income (loss): Electric $ 79,655 $ 66,335 $ 63,434 Natural gas distribution 91,889 89,173 73,082 Pipeline 55,466 48,078 49,436 Construction materials and contracting 194,295 191,077 214,498 Construction services 164,644 145,754 147,644 Other (11,996) (6,198) (3,169) Total operating income $ 573,953 $ 534,219 $ 544,925 Interest expense: Electric $ 28,526 $ 26,712 $ 26,699 Natural gas distribution 42,126 37,265 36,798 Pipeline 11,318 7,010 7,622 Construction materials and contracting 30,121 19,218 20,577 Construction services 6,354 3,540 4,095 Other 1,465 342 883 Intersegment eliminations (637) (103) (155) Total interest expense $ 119,273 $ 93,984 $ 96,519 Income tax expense (benefit): Electric $ (5,420) $ (7,626) $ (11,636) Natural gas distribution 7,805 8,366 5,746 Pipeline 10,212 9,594 7,650 Construction materials and contracting 42,601 43,459 47,431 Construction services 40,788 35,426 35,797 Other (1,203) (299) (398) Total income tax expense $ 94,783 $ 88,920 $ 84,590 2022 2021 2020 (In thousands) Net income (loss): Regulated operations: Electric $ 57,077 $ 51,906 $ 55,601 Natural gas distribution 45,171 51,596 44,049 Pipeline 35,357 39,583 35,453 137,605 143,085 135,103 Non-regulated operations: Pipeline (69) 1,313 1,559 Construction materials and contracting 116,220 129,755 147,325 Construction services 124,781 109,402 109,721 Other (11,261) (5,824) (3,181) 229,671 234,646 255,424 Income from continuing operations 367,276 377,731 390,527 Discontinued operations, net of tax 213 400 (322) Net income $ 367,489 $ 378,131 $ 390,205 Capital expenditures: Electric $ 133,970 $ 82,427 $ 114,676 Natural gas distribution 240,064 170,411 193,048 Pipeline 61,923 234,803 62,224 Construction materials and contracting 181,917 417,524 191,635 Construction services 36,413 29,140 83,651 Other 2,272 1,501 3,045 Total capital expenditures (a) $ 656,559 $ 935,806 $ 648,279 Assets: Electric (b) $ 1,856,258 $ 1,810,695 $ 2,123,693 Natural gas distribution (b) 3,214,452 2,929,519 2,302,770 Pipeline 961,893 913,945 703,377 Construction materials and contracting 2,268,970 2,161,653 1,798,493 Construction services 1,126,323 845,262 818,662 Other (c) 232,885 249,361 306,377 Total assets $ 9,660,781 $ 8,910,435 $ 8,053,372 Property, plant and equipment: Electric (b) $ 2,276,613 $ 2,295,646 $ 2,323,403 Natural gas distribution (b) 3,208,060 3,015,164 2,868,853 Pipeline 1,108,141 1,051,868 821,697 Construction materials and contracting 2,489,408 2,347,696 2,028,476 Construction services 245,111 225,758 220,796 Other 36,705 36,717 37,545 Less accumulated depreciation, depletion and amortization 3,272,493 3,216,461 3,133,831 Net property, plant and equipment $ 6,091,545 $ 5,756,388 $ 5,166,939 (a) Capital expenditures for 2022, 2021 and 2020 include noncash transactions such as capital expenditure-related accounts payable, the issuance of the Company's equity securities in connection with an acquisition, AFUDC and accrual of holdback payments in connection with acquisitions totaling $1.7 million, $38.7 million and $(15.7) million, respectively. (b) Includes allocations of common utility property. (c) Includes assets not directly assignable to a business (i.e. cash and cash equivalents, certain accounts receivable, certain investments and other miscellaneous current and deferred assets).
Reconciliation of Revenue from Segments to Consolidated	A reconciliation of reportable segment operating revenues and assets to consolidated operating revenues and assets is as follows: 2022 2021 2020 (In thousands) Operating revenues reconciliation: Total reportable segment operating revenues $ 7,040,435 $ 5,744,625 $ 5,597,816 Other revenue 17,605 13,714 11,903 Elimination of intersegment operating revenues (84,176) (77,606) (76,969) Total consolidated operating revenues $ 6,973,864 $ 5,680,733 $ 5,532,750 Asset reconciliation: Total reportable segment assets $ 9,491,679 $ 8,717,563 $ 7,816,848 Other assets 1,353,614 1,184,956 947,740 Elimination of intersegment receivables (1,184,512) (992,084) (711,216) Total consolidated assets $ 9,660,781 $ 8,910,435 $ 8,053,372
Reconciliation of Assets from Segment to Consolidated	A reconciliation of reportable segment operating revenues and assets to consolidated operating revenues and assets is as follows: 2022 2021 2020 (In thousands) Operating revenues reconciliation: Total reportable segment operating revenues $ 7,040,435 $ 5,744,625 $ 5,597,816 Other revenue 17,605 13,714 11,903 Elimination of intersegment operating revenues (84,176) (77,606) (76,969) Total consolidated operating revenues $ 6,973,864 $ 5,680,733 $ 5,532,750 Asset reconciliation: Total reportable segment assets $ 9,491,679 $ 8,717,563 $ 7,816,848 Other assets 1,353,614 1,184,956 947,740 Elimination of intersegment receivables (1,184,512) (992,084) (711,216) Total consolidated assets $ 9,660,781 $ 8,910,435 $ 8,053,372

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Schedule of amounts recognized in balance sheet	Changes in benefit obligation and plan assets and amounts recognized in the Consolidated Balance Sheets at December 31 were as follows: Pension Benefits Other 2022 2021 2022 2021 Change in benefit obligation: (In thousands) Benefit obligation at beginning of year $ 411,497 $ 437,360 $ 73,460 $ 86,155 Service cost — — 1,416 1,600 Interest cost 10,522 9,819 1,896 1,862 Plan participants' contributions — — 569 641 Actuarial gain (85,303) (12,140) (18,401) (12,802) Benefits paid (24,672) (23,542) (4,009) (3,996) Benefit obligation at end of year 312,044 411,497 54,931 73,460 Change in net plan assets: Fair value of plan assets at beginning of year 373,109 383,834 100,158 101,639 Actual return on plan assets (77,975) 12,817 (20,893) 1,398 Employer contribution — — 501 476 Plan participants' contributions — — 569 641 Benefits paid (24,672) (23,542) (4,009) (3,996) Fair value of net plan assets at end of year 270,462 373,109 76,326 100,158 Funded status - (under) over $ (41,582) $ (38,388) $ 21,395 $ 26,698 Amounts recognized in the Consolidated Balance Sheets at December 31: Noncurrent assets - other $ — $ — $ 36,325 $ 45,863 Other accrued liabilities — — 1,044 544 Noncurrent liabilities - other 41,582 38,388 13,886 18,621 Benefit obligation (liabilities) assets - net amount recognized $ (41,582) $ (38,388) $ 21,395 $ 26,698 Amounts recognized in accumulated other comprehensive loss: Actuarial loss (gain) $ 32,378 $ 25,976 $ (2,923) $ 2,367 Prior service credit — — (289) (290) Total $ 32,378 $ 25,976 $ (3,212) $ 2,077 Amounts recognized in regulatory assets or liabilities: Actuarial loss (gain) $ 141,207 $ 142,166 $ (1,439) $ (14,727) Prior service credit — — (3,796) (5,193) Total $ 141,207 $ 142,166 $ (5,235) $ (19,920)
The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for the pension plans with accumulated benefit obligations in excess of plan assets	The pension plans all have accumulated benefit obligations in excess of plan assets. The projected benefit obligation, accumulated benefit obligation and fair value of plan assets for these plans at December 31 were as follows: 2022 2021 (In thousands) Projected benefit obligation $ 312,044 $ 411,497 Accumulated benefit obligation $ 312,044 $ 411,497 Fair value of plan assets $ 270,462 $ 373,109 The projected benefit obligation and accumulated benefit obligation for these plans at December 31 were as follows: 2022 2021 (In thousands) Projected benefit obligation $ 74,730 $ 92,918 Accumulated benefit obligation $ 74,730 $ 92,918
Components of net periodic benefit cost	The components of net periodic benefit cost (credit), other than the service cost component, are included in other income on the Consolidated Statements of Income. Prior service credit is amortized on a straight-line basis over the average remaining service period of active participants. These components related to the Company's pension and other postretirement benefit plans for the years ended December 31 were as follows: Pension Benefits Other 2022 2021 2020 2022 2021 2020 Components of net periodic benefit credit: (In thousands) Service cost $ — $ — $ — $ 1,416 $ 1,600 $ 1,532 Interest cost 10,522 9,819 12,093 1,896 1,862 2,437 Expected return on assets (19,455) (19,576) (19,949) (5,288) (5,098) (5,019) Amortization of prior service credit — — — (1,398) (1,398) (1,398) Recognized net actuarial loss (gain) 6,683 8,017 7,172 (219) 24 287 Net periodic benefit credit, including amount capitalized (2,250) (1,740) (684) (3,593) (3,010) (2,161) Less amount capitalized — — — 175 150 156 Net periodic benefit cost credit (2,250) (1,740) (684) (3,768) (3,160) (2,317) Other changes in plan assets and benefit obligations recognized in accumulated comprehensive loss: Net (gain) loss 2,369 (265) 934 (4,141) (2,811) (259) Amortization of actuarial loss (1,310) (1,286) (1,155) (281) (135) (306) Amortization of prior service credit — — — 125 100 101 Reclassification of postretirement liability adjustment from regulatory asset 5,343 — — (992) — — Total recognized in accumulated other comprehensive loss 6,402 (1,551) (221) (5,289) (2,846) (464) Other changes in plan assets and benefit obligations recognized in regulatory assets or liabilities: Net (gain) loss 9,757 (5,116) 4,546 11,920 (6,292) (3,793) Amortization of actuarial gain (loss) (5,373) (6,731) (6,017) 500 110 19 Amortization of prior service credit — — — 1,273 1,298 1,297 Reclassification of postretirement liability adjustment from regulatory asset (5,343) — — 992 — — Total recognized in regulatory assets or liabilities (959) (11,847) (1,471) 14,685 (4,884) (2,477) Total recognized in net periodic benefit credit, accumulated other comprehensive loss and regulatory assets or liabilities $ 3,193 $ (15,138) $ (2,376) $ 5,628 $ (10,890) $ (5,258) The components of net periodic benefit cost are included in other income on the Consolidated Statements of Income. These components related to the Company's nonqualified defined benefit plans for the years ended December 31 were as follows: 2022 2021 2020 (In thousands) Components of net periodic benefit cost: Service cost $ — $ — $ 58 Interest cost 2,142 1,912 2,606 Recognized net actuarial loss 950 1,164 1,192 Net periodic benefit cost $ 3,092 $ 3,076 $ 3,856
Weighted average assumptions used to determine benefit obligations and net periodic benefit costs	Weighted average assumptions used to determine benefit obligations at December 31 were as follows: Pension Benefits Other 2022 2021 2022 2021 Discount rate 5.06 % 2.64 % 5.07 % 2.66 % Expected return on plan assets 6.50 % 6.00 % 6.00 % 5.50 % Rate of compensation increase N/A N/A 3.00 % 3.00 % Weighted average assumptions used to determine net periodic benefit cost (credit) for the years ended December 31 were as follows: Pension Benefits Other 2022 2021 2022 2021 Discount rate 2.64 % 2.30 % 2.66 % 2.30 % Expected return on plan assets 6.00 % 6.00 % 5.50 % 5.50 % Rate of compensation increase N/A N/A 3.00 % 3.00 % Weighted average assumptions used at December 31 were as follows: 2022 2021 Benefit obligation discount rate 4.97 % 2.39 % Benefit obligation rate of compensation increase N/A N/A Net periodic benefit cost discount rate 2.39 % 1.97 % Net periodic benefit cost rate of compensation increase N/A N/A
Health care rate assumptions for the Company's other postretirement benefit plans	Health care rate assumptions for the Company's other postretirement benefit plans as of December 31 were as follows: 2022 2021 Health care trend rate assumed for next year 7.5 % 7.0 % Health care cost trend rate - ultimate 4.5 % 4.5 % Year in which ultimate trend rate achieved 2033 2031
Benefit payments expected to be paid	The following benefit payments, which reflect future service, as appropriate, and expected Medicare Part D subsidies at December 31, 2022, are as follows: Years Pension Other Expected (In thousands) 2023 $ 24,936 $ 4,275 $ 62 2024 24,882 4,371 53 2025 24,749 4,456 46 2026 24,605 4,509 39 2027 24,387 4,523 31 2028-2032 114,850 16,917 93 The amount of future benefit payments for the unfunded, nonqualified defined benefit plans at December 31, 2022, are expected to aggregate as follows: 2023 2024 2025 2026 2027 2028-2032 (In thousands) Nonqualified benefits $ 6,651 $ 7,183 $ 7,430 $ 7,537 $ 7,420 $ 29,930
The fair value of the pension and postretirement net plan assets by class	The fair value of the Company's pension plans' assets (excluding cash) by class were as follows: Fair Value Measurements Quoted Prices Significant Significant Balance at December 31, 2022 (In thousands) Assets: Cash equivalents $ — $ 8,170 $ — $ 8,170 Equity securities: U.S. companies 7,388 — — 7,388 International companies — 467 — 467 Collective and mutual funds (a) 121,072 33,371 — 154,443 Corporate bonds — 81,363 — 81,363 Municipal bonds — 5,904 — 5,904 U.S. Government securities 3,044 880 — 3,924 Pooled separate accounts (b) — 3,241 — 3,241 Investments measured at net asset value (c) — — — 5,562 Total assets measured at fair value $ 131,504 $ 133,396 $ — $ 270,462 (a) Collective and mutual funds invest approximately 29 percent in corporate bonds, 24 percent in common stock of large-cap U.S. companies, 16 percent in common stock of international companies, 7 percent cash and cash equivalents, 7 percent in U.S. Government securities and 17 percent in other investments. (b) Pooled separate accounts are invested 100 percent in cash and cash equivalents. (c) In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets. Fair Value Measurements Quoted Prices Significant Significant Balance at December 31, 2021 (In thousands) Assets: Cash equivalents $ — $ 4,637 $ — $ 4,637 Equity securities: U.S. companies 7,483 — — 7,483 International companies — 1,279 — 1,279 Collective and mutual funds (a) 167,093 41,383 — 208,476 Corporate bonds — 125,167 — 125,167 Municipal bonds — 7,507 — 7,507 U.S. Government securities 7,113 1,902 — 9,015 Pooled separate accounts (b) — 3,088 — 3,088 Investments measured at net asset value (c) — — — 6,457 Total assets measured at fair value $ 181,689 $ 184,963 $ — $ 373,109 (a) Collective and mutual funds invest approximately 37 percent in corporate bonds, 19 percent in common stock of international companies, 16 percent in common stock of large-cap U.S. companies, 9 percent in U.S. Government securities and 19 percent in other investments. (b) Pooled separate accounts are invested 100 percent in cash and cash equivalents. (c) In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets. The fair value of the Company's other postretirement benefit plans' assets (excluding cash) by asset class were as follows: Fair Value Measurements Quoted Prices Significant Significant Balance at December 31, 2022 (In thousands) Assets: Cash equivalents $ — $ 4,196 $ — $ 4,196 Equity securities: U.S. companies 2,572 — — 2,572 Collective and mutual funds (a) 5 5 — 10 Insurance contract (b) — 69,548 — 69,548 Total assets measured at fair value $ 2,577 $ 73,749 $ — $ 76,326 (a) Collective and mutual funds invest approximately 29 percent in corporate bonds, 24 percent in common stock of large-cap U.S. companies,16 percent in common stock of international companies, 7 percent in cash and cash equivalents,7 percent in U.S. Government securities and 17 percent in other investments. (b) The insurance contract invests approximately 69 percent in corporate bonds, 13 percent in U.S. Government securities, 14 percent in common stock of large-cap U.S. companies and 4 percent in common stock of small-cap U.S. companies. Fair Value Measurements Quoted Prices Significant Significant Balance at December 31, 2021 (In thousands) Assets: Cash equivalents $ — $ 4,281 $ — $ 4,281 Equity securities: U.S. companies 2,332 — — 2,332 International companies — 1 — 1 Collective and mutual funds (a) 4 90 — 94 Insurance contract (b) — 93,447 — 93,447 Investments measured at net asset value (c) — — — 3 Total assets measured at fair value $ 2,336 $ 97,819 $ — $ 100,158 (a) Collective and mutual funds invest approximately 37 percent in corporate bonds, 19 percent in common stock of international companies, 16 percent in common stock of large-cap U.S. companies, 9 percent in U.S. Government securities and 19 percent in other investments. (b) The insurance contract invests approximately 58 percent in corporate bonds, 13 percent in common stock of large-cap U.S. companies, 13 percent in U.S. Government securities, 5 percent in common stock of small-cap U.S. companies and 11 percent in other investments. (c) In accordance with ASC 820 - Fair Value Measurements, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Consolidated Balance Sheets. The amount of investments that the Company anticipates using to satisfy obligations under these plans at December 31 was as follows: 2022 2021 (In thousands) Investments Insurance contracts* $ 98,041 $ 109,603 Life insurance** 38,448 38,356 Other 7,361 10,190 Total investments $ 143,850 $ 158,149 * For more information on the insurance contracts, see Note 8. ** Investments of life insurance are carried on plan participants (payable upon the employee's death).
Schedule of Multiemployer Plans [Table Text Block]	EIN/Pension Plan Number Pension Protection Act Zone Status FIP/RP Status Pending/Implemented Contributions Surcharge Imposed Expiration Date Pension Fund 2022 2021 2022 2021 2020 (In thousands) Edison Pension Plan 936061681-001 Green Green No $ 18,750 $ 18,331 $ 16,121 No 12/31/2023 IBEW Local 212 Pension Trust 316127280-001 Green as of 4/30/2021 Green as of 4/30/2021 No 1,622 1,733 1,521 No 6/1/2025 IBEW Local 357 Pension Plan A 886023284-001 Green Green No 12,876 6,485 9,913 No 5/31/2024 IBEW Local 82 Pension Plan 316127268-001 Green as of 6/30/2022 Green as of 6/30/2021 No 1,854 1,353 1,373 No 12/3/2023 IBEW Local 648 Pension Plan 316134845-001 Yellow as of 2/28/2022 Yellow as of 02/28/2021 Implemented 915 706 526 No 9/1/2024 IBEW Local 683 Pension Fund Pension Plan 341442087-001 Green Green No 3,362 1,238 1,240 No 5/26/2024 Idaho Plumbers and Pipefitters Pension Plan 826010346-001 Green as of 5/31/2022 Green as of 5/31/2021 No 1,613 1,528 1,370 No 3/31/2023 National Electrical Benefit Fund 530181657-001 Green Green No 18,060 14,361 14,484 No 5/31/2022- 5/31/2027 * Pension and Retirement Plan of Plumbers and Pipefitters Local 525 886003864-001 Green as of 6/30/2022 Green as of 6/30/2021 No 6,304 4,345 6,266 No 9/30/2024 Pension Trust Fund for Operating Engineers 946090764-001 Yellow Yellow Implemented 2,484 2,495 2,680 No 3/31/2023- 6/15/2026 Sheet Metal Workers Pension Plan of Southern CA, AZ, and NV 956052257-001 Green Yellow Implemented 3,400 2,615 3,255 No 6/30/2024 Western Conference of Teamsters Pension Plan 916145047-001 Green Green No 3,127 3,006 3,025 No 12/31/2023- 12/31/2025 Other funds 26,909 24,192 23,670 Total contributions $ 101,276 $ 82,388 $ 85,444 * Plan includes contributions required by collective bargaining agreements which have expired but contain provisions automatically renewing their terms in the absence of a subsequent negotiated agreement. The Company was listed in the plans' Forms 5500 as providing more than 5 percent of the total contributions for the following plans and plan years: Pension Fund Year Contributions to Plan Exceeded More Than 5 Percent Edison Pension Plan 2021 and 2020 IBEW Local 82 Pension Plan 2021 and 2020 IBEW Local 124 Pension Trust Fund 2021 and 2020 IBEW Local 212 Pension Trust Fund 2021 and 2020 IBEW Local 357 Pension Plan A 2021 and 2020 IBEW Local 648 Pension Plan 2021 and 2020 IBEW Local 683 Pension Fund Pension Plan 2021 and 2020 IBEW Local Union No 226 Open End Pension Fund 2020 Idaho Plumbers and Pipefitters Pension Plan 2021 and 2020 International Union of Operating Engineers Local 701 Pension Trust Fund 2021 and 2020 Minnesota Teamsters Construction Division Pension Fund 2021 and 2020 Pension and Retirement Plan of Plumbers and Pipefitters Local 525 2021 and 2020 Southwest Marine Pension Trust 2021 and 2020

Jointly owned facilities (Table

Jointly owned facilities (Tables)	12 Months Ended
	Dec. 31, 2022
Regulated Operations [Abstract]
Company's share of the cost of utility plant in service and related accumulated depreciation for the stations	At December 31, the Company's share of the cost of utility plant in service, construction work in progress and related accumulated depreciation for the jointly owned facilities was as follows: Ownership Percentage 2022 2021 (In thousands) Big Stone Station: 22.7 % Utility plant in service $ 157,699 $ 157,259 Construction work in progress 231 571 Less accumulated depreciation 48,590 47,293 $ 109,340 $ 110,537 BSSE: 50.0 % Utility plant in service $ 107,260 $ 107,424 Construction work in progress — — Less accumulated depreciation 6,182 4,506 $ 101,078 $ 102,918 Coyote Station: 25.0 % Utility plant in service $ 158,274 $ 157,764 Construction work in progress 1,807 784 Less accumulated depreciation 111,203 109,202 $ 48,878 $ 49,346 Wygen III: 25.0 % Utility plant in service $ 66,238 $ 66,357 Construction work in progress 273 108 Less accumulated depreciation 12,477 11,383 $ 54,034 $ 55,082

Commitment and Contingencies Di

Commitment and Contingencies Disclosure (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Purchase commitments	The commitment terms vary in length, up to 37 years. The commitments under these contracts as of December 31, 2022, were: 2023 2024 2025 2026 2027 Thereafter (In thousands) Purchase commitments $ 712,875 $ 258,074 $ 158,152 $ 103,677 $ 81,619 $ 676,489

Accounting Policies - Receivabl

Accounting Policies - Receivables Past Due 90 Days (Details 1) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Accounts Receivable, Noncurrent, 90 Days or More Past Due, Still Accruing	$ 45.6	$ 44.8

Accounting Policies - CECL Tabl

Accounting Policies - CECL Table (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Accounts Receivable, Credit Loss Expense (Reversal)	$ 6,133	$ 1,085	$ 10,576
Trade Accounts Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	9,631	9,716	15,358
Accounts Receivable, Credit Loss Expense (Reversal)	6,133	1,105
Accounts Receivable, Allowance for Credit Loss, Writeoff	7,630	8,069
Accounts Receivable, Allowance for Credit Loss, Recovery	1,412	1,322
Electric | Trade Accounts Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	375	269	899
Accounts Receivable, Credit Loss Expense (Reversal)	1,325	1,099
Accounts Receivable, Allowance for Credit Loss, Writeoff	1,625	2,139
Accounts Receivable, Allowance for Credit Loss, Recovery	406	410
Natural gas distribution | Trade Accounts Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	1,615	1,506	2,571
Accounts Receivable, Credit Loss Expense (Reversal)	4,084	2,188
Accounts Receivable, Allowance for Credit Loss, Writeoff	4,913	4,072
Accounts Receivable, Allowance for Credit Loss, Recovery	938	819
Pipeline | Trade Accounts Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	2	2	2
Accounts Receivable, Credit Loss Expense (Reversal)	0	0
Accounts Receivable, Allowance for Credit Loss, Writeoff	0	0
Accounts Receivable, Allowance for Credit Loss, Recovery	0	0
Construction materials and contracting | Trade Accounts Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	5,477	5,406	6,164
Accounts Receivable, Credit Loss Expense (Reversal)	538	68
Accounts Receivable, Allowance for Credit Loss, Writeoff	467	826
Accounts Receivable, Allowance for Credit Loss, Recovery	0	0
Construction services | Trade Accounts Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for doubtful accounts	2,162	2,533	$ 5,722
Accounts Receivable, Credit Loss Expense (Reversal)	186	(2,250)
Accounts Receivable, Allowance for Credit Loss, Writeoff	625	1,032
Accounts Receivable, Allowance for Credit Loss, Recovery	$ 68	$ 93

Accounting Policies - Accrued U

Accounting Policies - Accrued Unbilled Revenue (Details 3) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Accrued unbilled revenue at MDU Energy Capital	$ 181.8	$ 144.9

Accounting Policies - Retainage

Accounting Policies - Retainage (Details 4) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Contract Receivable Retainage, Next Twelve Months	$ 120,333	$ 70,600
Contract Receivable Retainage, after Next Twelve Months	19,511	10,742
Contract Receivable Retainage	$ 139,844	$ 81,342

Accounting Policies - Inventory

Accounting Policies - Inventory (Details 5) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Inventory and natural gas in storage [Line Items]
Aggregates held for resale	$ 199,110	$ 184,363
Asphalt oil	68,609	57,002
Materials and supplies	40,056	30,629
Merchandise for resale	40,296	28,501
Natural gas in storage (current)	22,533	18,867
Other	16,921	16,247
Total	387,525	335,609
Natural gas in storage (noncurrent)	$ 47,500	$ 47,500

Accounting Policies - PPE (Deta

Accounting Policies - PPE (Details 6) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, plant and equipment [Line Items]
Allowance for Funds Used During Construction, Capitalized Interest	$ 2,236	$ 2,833	$ 2,640
Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity	$ 2,165	$ 6,961	$ 1,270

Accounting Policies - Impairmen

Accounting Policies - Impairment of Long-Lived Assets (Details 7) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Impairment of Long-Lived Assets to be Disposed of	$ 0	$ 0	$ 0

Natural Gas Costs Recoverable o

Natural Gas Costs Recoverable or Refundable through Rate Adjustments (Details 8) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Natural gas costs refundable	$ 1	$ 6.7
Natural gas costs recoverable	$ 141.3	$ 91.6

Accounting Policies - Goodwill

Accounting Policies - Goodwill (Details 9) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Goodwill, Impairment Loss	$ 0	$ 0	$ 0

Government Assistance (Details)

Government Assistance (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Grant
Government Assistance [Line Items]
Government Assistance, Amount	$ 0	$ 0	$ 0

Accounting Policies - Joint Ven

Accounting Policies - Joint Ventures (Details 10) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Revenues	$ 6,973,864,000	$ 5,680,733,000	$ 5,532,750,000
Operating income	573,953,000	534,219,000	544,925,000
Receivables	1,305,642,000	946,741,000
Joint Venture, Proportionate Consolidation
Schedule of Equity Method Investments [Line Items]
Revenues	14,800,000	14,700,000	69,700,000
Joint Venture, Proportionate Consolidation
Schedule of Equity Method Investments [Line Items]
Operating income	3,000,000	4,700,000	20,600,000
Receivables	2,400,000	14,300,000
Joint Venture, Equity Method Investment
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	1,300,000	1,300,000
Income (Loss) from Equity Method Investments	$ 5,400,000	$ 892,000	$ (32,000)
Minimum | Joint Venture, Equity Method Investment
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	25%
Maximum | Joint Venture, Equity Method Investment
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50%

Accounting Policies - Derivativ

Accounting Policies - Derivatives (Details 11) - MMBTU	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Commodity Contract [Member] | Not Designated as Hedging Instrument, Economic Hedge [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	0	450,000

Accounting Policies - EPS (Deta

Accounting Policies - EPS (Details 12) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Weighted average common shares outstanding - basic	203,358	202,076	200,502
Effect of dilutive performance share awards	104	307	69
Weighted average common shares outstanding - diluted	203,462	202,383	200,571
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	14	0	164

Accounting Policies - Income Ta

Accounting Policies - Income Taxes (Details 13)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Threshold of likelihood of tax positions being realized upon ultimate settlement with a taxing authority	50%

Disaggregation of revenue (Deta

Disaggregation of revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 6,973,864	$ 5,680,733	$ 5,532,750
Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(84,176)	(77,606)	(76,969)
Internal sales
Disaggregation of Revenue [Line Items]
Revenues	(593,882)	(501,044)	(550,815)
Natural gas transportation
Disaggregation of Revenue [Line Items]
Revenues	178,176	162,409	157,232
Natural Gas Gathering [Member]
Disaggregation of Revenue [Line Items]
Revenues			4,865
Natural gas storage
Disaggregation of Revenue [Line Items]
Revenues	14,583	14,680	14,918
Contracting services
Disaggregation of Revenue [Line Items]
Revenues	1,187,721	1,017,471	1,069,665
Construction materials
Disaggregation of Revenue [Line Items]
Revenues	1,940,890	1,712,503	1,659,152
Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Revenues	1,988,729	1,324,419	1,397,124
Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Revenues	662,705	677,074	649,486
Other
Disaggregation of Revenue [Line Items]
Revenues	88,716	81,407	68,865
Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Revenues	6,933,344	5,628,488	5,471,545
Other revenues
Disaggregation of Revenue [Line Items]
Revenues	40,520	52,245	61,205
Residential utility sales
Disaggregation of Revenue [Line Items]
Revenues	856,825	671,562	599,051
Commercial utility sales
Disaggregation of Revenue [Line Items]
Revenues	599,984	465,841	409,350
Industrial utility sales
Disaggregation of Revenue [Line Items]
Revenues	85,476	72,721	62,987
Other utility sales
Disaggregation of Revenue [Line Items]
Revenues	7,597	7,051	6,634
Electric
Disaggregation of Revenue [Line Items]
Revenues	376,579	349,039	331,538
Electric | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(494)	(543)	(491)
Electric | Other
Disaggregation of Revenue [Line Items]
Revenues	45,608	42,902	32,452
Electric | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Revenues	381,293	355,564	329,479
Electric | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	(4,714)	(6,525)	2,059
Electric | Residential utility sales
Disaggregation of Revenue [Line Items]
Revenues	138,634	126,841	122,663
Electric | Commercial utility sales
Disaggregation of Revenue [Line Items]
Revenues	146,182	137,556	131,477
Electric | Industrial utility sales
Disaggregation of Revenue [Line Items]
Revenues	43,766	41,757	36,744
Electric | Other utility sales
Disaggregation of Revenue [Line Items]
Revenues	7,597	7,051	6,634
Natural gas distribution
Disaggregation of Revenue [Line Items]
Revenues	1,273,249	971,364	847,651
Natural gas distribution | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(555)	(576)	(534)
Natural gas distribution | Natural gas transportation
Disaggregation of Revenue [Line Items]
Revenues	48,886	48,408	45,546
Natural gas distribution | Other
Disaggregation of Revenue [Line Items]
Revenues	13,617	10,567	10,753
Natural gas distribution | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Revenues	1,275,651	962,369	836,269
Natural gas distribution | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	(2,402)	8,995	11,382
Natural gas distribution | Residential utility sales
Disaggregation of Revenue [Line Items]
Revenues	718,191	544,721	476,388
Natural gas distribution | Commercial utility sales
Disaggregation of Revenue [Line Items]
Revenues	453,802	328,285	277,873
Natural gas distribution | Industrial utility sales
Disaggregation of Revenue [Line Items]
Revenues	41,710	30,964	26,243
Natural gas distribution | Other utility sales
Disaggregation of Revenue [Line Items]
Revenues	0	0	0
Pipeline
Disaggregation of Revenue [Line Items]
Revenues	96,567	82,858	85,346
Pipeline | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(59,012)	(59,678)	(58,531)
Pipeline | Natural gas transportation
Disaggregation of Revenue [Line Items]
Revenues	129,290	114,001	111,686
Pipeline | Natural Gas Gathering [Member]
Disaggregation of Revenue [Line Items]
Revenues			4,865
Pipeline | Natural gas storage
Disaggregation of Revenue [Line Items]
Revenues	14,583	14,680	14,918
Pipeline | Other
Disaggregation of Revenue [Line Items]
Revenues	11,450	13,667	12,216
Pipeline | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Revenues	96,311	82,670	85,154
Pipeline | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	256	188	192
Construction materials and contracting
Disaggregation of Revenue [Line Items]
Revenues	2,533,713	2,228,306	2,177,585
Construction materials and contracting | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(1,016)	(624)	(417)
Construction materials and contracting | Internal sales
Disaggregation of Revenue [Line Items]
Revenues	(593,882)	(501,044)	(550,815)
Construction materials and contracting | Contracting services
Disaggregation of Revenue [Line Items]
Revenues	1,187,721	1,017,471	1,069,665
Construction materials and contracting | Construction materials
Disaggregation of Revenue [Line Items]
Revenues	1,940,890	1,712,503	1,659,152
Construction materials and contracting | Other
Disaggregation of Revenue [Line Items]
Revenues	0	0	0
Construction materials and contracting | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Revenues	2,533,713	2,228,306	2,177,585
Construction materials and contracting | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	0	0	0
Construction services
Disaggregation of Revenue [Line Items]
Revenues	2,693,756	2,049,082	2,090,685
Construction services | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(5,494)	(2,555)	(5,038)
Construction services | Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Revenues	1,988,729	1,324,419	1,397,124
Construction services | Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Revenues	662,705	677,074	649,486
Construction services | Other
Disaggregation of Revenue [Line Items]
Revenues	436	557	1,541
Construction services | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Revenues	2,646,376	1,999,495	2,043,113
Construction services | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	47,380	49,587	47,572
Other
Disaggregation of Revenue [Line Items]
Revenues	0	84	(55)
Other | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(17,605)	(13,630)	(11,958)
Other | Other
Disaggregation of Revenue [Line Items]
Revenues	17,605	13,714	11,903
Other | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Revenues	0	84	(55)
Other | Other revenues
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0

Contract balances (Details 2)

Contract balances (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Contract assets	$ 185,289	$ 125,742	$ 104,345
Change in contract assets	59,547	21,397
Contract liabilities - current	(208,204)	(179,140)	(158,603)
Change in contract liabilities - current	(29,064)	(20,537)
Contract liabilities - noncurrent	(6)	(118)	(52)
Change in contract liabilities - noncurrent	112	(66)
Net contract liabilities	(22,921)	(53,516)	$ (54,310)
Change in net contract assets (liabilities)	30,595	794
Amounts included in contract liability at the beginning of the period	173,800	155,000
Amounts from performance obligations satisfied in prior periods	$ 57,900	$ 66,300

Revenue from contracts with c_2

Revenue from contracts with customers Remaining performance obligations (Details 3) $ in Millions	Dec. 31, 2022 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	$ 3,500
Remaining performance obligation, expected timing of satisfaction, start date: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	$ 2,700
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Remaining performance obligation, expected timing of satisfaction, start date: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	$ 411.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	13 months
Remaining performance obligation, expected timing of satisfaction, start date: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	$ 429.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	25 months

Business Combinations (Details)

Business Combinations (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill	$ 763,500,000	$ 765,386,000	$ 714,963,000
2022 Acquisition
Business Acquisition [Line Items]
Gross Aggregate Consideration	8,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	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, Recognized Identifiable Assets Acquired and Liabilities Assumed, 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 - Assets

Business Combinations - Assets Acquired & Liabilities Assumed (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill	$ 765,386,000	$ 763,500,000	$ 714,963,000
2021 Acquisition
Business Acquisition [Line Items]
Gross Aggregate Consideration	236,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	900,000
Business Combination, Consideration Transferred	235,200,000
Business Combination, Current Assets	17,000,000
Business Combination, Property, Plant, and Equipment	179,800,000
Goodwill	50,600,000
Business Combination, Other Intangible Assets	2,200,000
Business Combination, Current Liabilities	8,700,000
Business Combination, Noncurrent Liabilities	2,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities	$ 3,200,000
Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life	5 years 6 months
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets	$ 2,100,000

Business Combinations - Acquisi

Business Combinations - Acquisition Costs Incurred (Details 3) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Expense
Business Acquisition [Line Items]
Business Acquisition Costs Incurred	$ 0	$ 0	$ 0

Property, Plant, and Equipmen_2

Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 9,364,038	$ 8,972,849
Less accumulated depreciation, depletion and amortization	3,272,493	3,216,461	$ 3,133,831
Net property, plant and equipment	6,091,545	5,756,388	5,166,939
Electric
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	2,276,613	2,295,646	2,323,403
Natural gas distribution
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	3,208,060	3,015,164	2,868,853
Pipeline
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	1,108,141	1,051,868	821,697
Construction materials and contracting
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	2,489,408	2,347,696	2,028,476
Construction services
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	245,111	225,758	220,796
Other
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	36,705	36,717	$ 37,545
Regulated Operation | Electric | Electric Generation Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 938,614	1,056,632
Weighted average depreciable life in years	48 years
Regulated Operation | Electric | Electric Distribution
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 489,351	474,037
Weighted average depreciable life in years	47 years
Regulated Operation | Electric | Electric Transmission
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 616,611	562,080
Weighted average depreciable life in years	65 years
Regulated Operation | Electric | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 87,003	62,781
Regulated Operation | Electric | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 145,034	140,117
Weighted average depreciable life in years	14 years
Regulated Operation | Natural gas distribution | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 55,759	21,741
Regulated Operation | Natural gas distribution | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 230,299	225,272
Weighted average depreciable life in years	15 years
Regulated Operation | Natural gas distribution | Gas Distribution [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,569,921	2,427,779
Weighted average depreciable life in years	52 years
Regulated Operation | Natural gas distribution | Gas Transmission [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 104,769	107,721
Weighted average depreciable life in years	61 years
Regulated Operation | Natural gas distribution | Natural gas storage
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 42,318	34,997
Weighted average depreciable life in years	37 years
Regulated Operation | Natural gas distribution | General
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 204,993	197,653
Weighted average depreciable life in years	13 years
Regulated Operation | Pipeline | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 34,655	263,640
Regulated Operation | Pipeline | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 59,917	50,477
Weighted average depreciable life in years	19 years
Regulated Operation | Pipeline | Gas Transmission [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 951,187	673,344
Weighted average depreciable life in years	46 years
Regulated Operation | Pipeline | Natural gas storage
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 55,383	57,670
Weighted average depreciable life in years	53 years
Nonregulated Operation | Pipeline | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 49	18
Nonregulated Operation | Pipeline | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 6,950	6,719
Weighted average depreciable life in years	10 years
Nonregulated Operation | Construction materials and contracting | Construction in Progress
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 88,163	50,425
Nonregulated Operation | Construction materials and contracting | Land [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	150,809	149,066
Nonregulated Operation | Construction materials and contracting | Building and Building Improvements [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 165,833	149,262
Weighted average depreciable life in years	21 years
Nonregulated Operation | Construction materials and contracting | Machinery, vehicles and equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,492,506	1,414,260
Weighted average depreciable life in years	12 years
Nonregulated Operation | Construction materials and contracting | Aggregate reserves [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 592,097	584,683
Nonregulated Operation | Construction services | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 6,643	13,467
Weighted average depreciable life in years	4 years
Nonregulated Operation | Construction services | Land [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 8,234	6,513
Nonregulated Operation | Construction services | Building and Building Improvements [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 50,776	39,039
Weighted average depreciable life in years	24 years
Nonregulated Operation | Construction services | Machinery, vehicles and equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 179,459	166,739
Weighted average depreciable life in years	7 years
Nonregulated Operation | Other | Other Capitalized Property Plant and Equipment
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 34,057	34,069
Weighted average depreciable life in years	7 years
Nonregulated Operation | Other | Land [Member]
Property, plant and equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,648	$ 2,648

Regulatory assets (Details)

Regulatory assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Current regulatory assets	$ 165,092	$ 118,691
Regulatory assets	329,659	357,851
Total regulatory assets	494,751	476,542
Regulatory assets not earning a rate of return	242,500	296,600
Natural gas costs recoverable through rate adjustments
Regulatory Assets [Line Items]
Current regulatory assets	141,306	86,371
Regulatory assets	$ 0	5,186
Natural gas costs recoverable through rate adjustments | Minimum
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 1 year
Natural gas costs recoverable through rate adjustments | Maximum
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 2 years
Conservation programs
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 1 year
Current regulatory assets	$ 8,544	8,225
Cost recovery mechanisms
Regulatory Assets [Line Items]
Current regulatory assets	4,019	4,536
Regulatory assets	$ 67,171	44,870
Cost recovery mechanisms | Minimum
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 1 year
Cost recovery mechanisms | Maximum
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 10 years
Decoupling
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 1 year
Current regulatory assets	$ 1,801	9,131
Other regulatory assets
Regulatory Assets [Line Items]
Current regulatory assets	9,422	10,428
Regulatory assets	$ 11,010	9,742
Other regulatory assets | Minimum
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 1 year
Other regulatory assets | Maximum
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 16 years
Pension and postretirement benefits
Regulatory Assets [Line Items]
Regulatory asset, recovery period	**
Regulatory assets	$ 143,349	142,681
Plant costs/asset retirement obligation costs
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Over plant lives
Regulatory assets	$ 44,462	63,116
Manufactured gas plant sites remediation
Regulatory Assets [Line Items]
Regulatory asset, recovery period	-
Regulatory assets	$ 26,624	26,053
Plants to be retired
Regulatory Assets [Line Items]
Regulatory asset, recovery period	-
Regulatory assets	$ 21,525	50,070
Taxes recoverable from customers
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Over plant lives
Regulatory assets	$ 12,330	12,339
Long-term debt refinancing costs
Regulatory Assets [Line Items]
Regulatory asset, recovery period	Up to 38 years
Regulatory assets	$ 3,188	$ 3,794

Regulatory liabilities (Details

Regulatory liabilities (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	$ 26,440	$ 16,303
Regulatory liabilities	448,454	428,790
Total regulatory liabilities	474,894	445,093
Net Regulatory Position	$ 19,857	31,449
Electric fuel and purchased power deferral
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 1 year
Regulatory liabilities due within one year	$ 4,929	0
Conservation programs
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 1 year
Regulatory liabilities due within one year	$ 4,126	12
Taxes refundable to customers
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	3,937	3,841
Regulatory liabilities	$ 203,222	215,421
Taxes refundable to customers | Minimum
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 1 year
Taxes refundable to customers | Maximum
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Over plant lives
Refundable Fuel and Electric Costs
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 1 year
Regulatory liabilities due within one year	$ 3,253	713
Natural gas costs refundable through rate adjustments
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 1 year
Regulatory liabilities due within one year	$ 955	6,700
Other regulatory liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	9,240	5,037
Regulatory liabilities	$ 1,587	9,168
Other regulatory liabilities | Minimum
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 1 year
Other regulatory liabilities | Maximum
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 15 years
Plant removal and decommissioning costs
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Over plant lives
Regulatory liabilities	$ 208,650	168,152
Cost recovery mechanisms
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 19 years
Regulatory liabilities	$ 14,025	2,919
Accumulated deferred investment tax credit
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	Up to 19 years
Regulatory liabilities	$ 13,594	12,696
Pension and postretirement benefits
Regulatory Liabilities [Line Items]
Regulatory liability, refund period	**
Regulatory liabilities	$ 7,376	$ 20,434

Goodwill rollforward (Details)

Goodwill rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Roll Forward]
Balance at beginning of period	$ 765,386	$ 714,963
Goodwill acquired during the year	238	50,640
Measurement period adjustments	(2,124)	(217)
Balance at end of period	763,500	765,386
Natural gas distribution
Goodwill [Roll Forward]
Balance at beginning of period	345,736	345,736
Goodwill acquired during the year	0	0
Measurement period adjustments	0	0
Balance at end of period	345,736	345,736
Construction materials and contracting
Goodwill [Roll Forward]
Balance at beginning of period	276,426	226,003
Goodwill acquired during the year	238	50,640
Measurement period adjustments	(2,124)	(217)
Balance at end of period	274,540	276,426
Construction services
Goodwill [Roll Forward]
Balance at beginning of period	143,224	143,224
Goodwill acquired during the year	0	0
Measurement period adjustments	0	0
Balance at end of period	$ 143,224	$ 143,224

Other intangible assets (Detail

Other intangible assets (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 17,532	$ 22,578
Amortization of intangible assets	5,000	5,100	$ 9,000
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	28,990	29,740
Intangible assets, less accumulated amortization	13,724	10,650
Intangible assets, net (excluding goodwill)	15,266	19,090
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	4,591	4,591
Intangible assets, less accumulated amortization	3,529	2,856
Intangible assets, net (excluding goodwill)	1,062	1,735
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	5,280	12,601
Intangible assets, less accumulated amortization	4,076	10,848
Intangible assets, net (excluding goodwill)	$ 1,204	$ 1,753

Future amortization expense (De

Future amortization expense (Details 3) $ in Thousands	Dec. 31, 2022 USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2023	$ 4,591
2024	4,249
2025	2,200
2026	1,782
2027	1,759
Thereafter	$ 2,951

Goodwill impairment testing res

Goodwill impairment testing results (Details 4) - USD ($) $ in Thousands	Dec. 31, 2022	Oct. 31, 2022	Dec. 31, 2021	Oct. 31, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill	$ 763,500		$ 765,386		$ 714,963
Natural gas distribution
Goodwill [Line Items]
Goodwill	$ 345,736		$ 345,736		$ 345,736
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount		8%
Risk Adjusted Cost of Capital, Percent		6.40%		5%

Fair value measurements insuran

Fair value measurements insurance contracts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Investments used to satisfy nonqualified benefit plans obligations	$ 98	$ 109.6
Net unrealized gain (loss) on investments used to satisfy obligations under nonqualified benefit plans	$ (14.1)	$ 7.2	$ 13.1

Available-for-sale securities (

Available-for-sale securities (Details 2) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Abstract]
Cost	$ 11,536	$ 11,109
Gross Unrealized Gains	2	51
Gross Unrealized Losses	708	58
Fair Value	10,830	11,102
Mortgage-backed securities
Debt Securities, Available-for-sale [Abstract]
Cost	8,928	8,702
Gross Unrealized Gains	2	51
Gross Unrealized Losses	636	47
Fair Value	8,294	8,706
U.S. Treasury securities
Debt Securities, Available-for-sale [Abstract]
Cost	2,608	2,407
Gross Unrealized Gains	0	0
Gross Unrealized Losses	72	11
Fair Value	$ 2,536	$ 2,396

Fair value measurements (Detail

Fair value measurements (Details 3) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Concentration risks, percentage [Abstract]
Percentage in fixed-income investments	63%	61%
Percentage investment in common stock of large-cap companies	15%	17%
Percentage investment in common stock of mid-cap companies	8%	8%
Percentage investment in common stock of small-cap companies	6%	7%
Percentage investment in target date investments	6%	5%
Percentage investment in cash and cash equivalents	2%	2%
Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 116,232	$ 130,895
Fair value, measurements, recurring | Money market funds
Fair value measurements [Line Items]
Assets, fair value disclosure	7,361	10,190
Fair value, measurements, recurring | Insurance contracts*
Fair value measurements [Line Items]
Assets, fair value disclosure	98,041	109,603
Fair value, measurements, recurring | Mortgage-backed securities
Fair value measurements [Line Items]
Assets, fair value disclosure	8,294	8,706
Fair value, measurements, recurring | U.S. Treasury securities
Fair value measurements [Line Items]
Assets, fair value disclosure	2,536	2,396
Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	116,232	130,895
Fair value, inputs, level 2 | Fair value, measurements, recurring | Money market funds
Fair value measurements [Line Items]
Assets, fair value disclosure	7,361	10,190
Fair value, inputs, level 2 | Fair value, measurements, recurring | Insurance contracts*
Fair value measurements [Line Items]
Assets, fair value disclosure	98,041	109,603
Fair value, inputs, level 2 | Fair value, measurements, recurring | Mortgage-backed securities
Fair value measurements [Line Items]
Assets, fair value disclosure	8,294	8,706
Fair value, inputs, level 2 | Fair value, measurements, recurring | U.S. Treasury securities
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 2,536	$ 2,396

Fair value measurements (Deta_2

Fair value measurements (Details 5) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 2,841,425	$ 2,741,900
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	2,841,425	2,741,900
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 2,469,625	$ 2,984,866

Credit facilities (Details)

Credit facilities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Line of credit facility and other debt [Abstract]
Letters of credit at end of period	$ 0
Long-term debt | Commercial paper revolving credit agreement | Montana-Dakota Utilities Co. [Member]
Line of credit facility and other debt [Abstract]
Facility limit, maximum borrowing capacity	175,000,000
Amount outstanding, end of period	117,500,000	$ 64,900,000
Letters of credit at end of period	$ 0
Expiration date	Dec. 19, 2024
Long-term debt | Commercial paper revolving credit agreement | Centennial Energy Holdings, Inc.
Line of credit facility and other debt [Abstract]
Facility limit, maximum borrowing capacity	$ 600,000,000
Amount outstanding, end of period	298,000,000	385,400,000
Letters of credit at end of period	$ 0
Expiration date	Dec. 19, 2024
Long-term debt | Revolving credit facility | Montana-Dakota Utilities Co. [Member]
Line of credit facility and other debt [Abstract]
Amount outstanding, end of period	$ 0
Option to increase borrowings, maximum amount	225,000,000
Long-term debt | Revolving credit facility | Cascade Natural Gas Corporation
Line of credit facility and other debt [Abstract]
Facility limit, maximum borrowing capacity	100,000,000
Amount outstanding, end of period	44,400,000	71,000,000
Letters of credit at end of period	$ 2,200,000
Expiration date	Nov. 30, 2027
Option to increase borrowings, maximum amount	$ 125,000,000
Long-term debt | Revolving credit facility | Intermountain Gas Company
Line of credit facility and other debt [Abstract]
Facility limit, maximum borrowing capacity	100,000,000
Amount outstanding, end of period	85,600,000	$ 56,500,000
Letters of credit at end of period	$ 0
Expiration date	Oct. 13, 2027
Option to increase borrowings, maximum amount	$ 125,000,000
Long-term debt | Revolving credit facility | Centennial Energy Holdings, Inc.
Line of credit facility and other debt [Abstract]
Amount outstanding, end of period	0
Option to increase borrowings, maximum amount	$ 700,000,000

Short-term Debt (Details 2)

Short-term Debt (Details 2) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 19, 2022	Oct. 21, 2022	Mar. 18, 2022	Dec. 31, 2021
Short-term Debt [Line Items]
Short-term borrowings	$ 246,500				$ 0
Term Loan Agreement [Member] | MDU Energy Capital
Short-term Debt [Line Items]
Short-term borrowings			$ 11,500
Ratio of total debt to total capitalization as specified in debt covenants			70%
Term Loan Agreement [Member] | Centennial Energy Holdings, Inc.
Short-term Debt [Line Items]
Short-term borrowings		$ 135,000		$ 100,000
Ratio of total debt to total capitalization as specified in debt covenants		65%		65%

Long-term debt outstanding (Det

Long-term debt outstanding (Details 3) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,841,425	$ 2,741,900
Long-term debt due within one year	78,031	148,053
Long-term debt	$ 2,763,394	2,593,847
Senior Notes
Long-term debt outstanding [Line Items]
Weighted average interest rate	4.32%
Long-term debt	$ 2,258,500	2,125,000
Commercial paper
Long-term debt outstanding [Line Items]
Weighted average interest rate	5.13%
Long-term debt	$ 415,500	450,300
Credit Agreements
Long-term debt outstanding [Line Items]
Weighted average interest rate	6.31%
Long-term debt	$ 130,000	127,500
Medium-term notes
Long-term debt outstanding [Line Items]
Weighted average interest rate	7.32%
Long-term debt	$ 35,000	35,000
Term Loan Agreements
Long-term debt outstanding [Line Items]
Weighted average interest rate	3.64%
Long-term debt	$ 7,000	7,700
Other notes
Long-term debt outstanding [Line Items]
Weighted average interest rate	1%
Long-term debt	$ 2,253	2,564
Long-term debt
Long-term debt outstanding [Line Items]
Unamortized debt issuance costs	6,542	6,090
Discount	$ 286	$ 74

Long-term borrowings (Details 4

Long-term borrowings (Details 4) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 22, 2022	Oct. 13, 2022	Jun. 15, 2022	Mar. 23, 2022	Dec. 31, 2021
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,841,425					$ 2,741,900
Montana-Dakota Utilities Co. [Member]
Long-term debt outstanding [Line Items]
Ratio of total debt to total capitalization	51%
Cascade Natural Gas [Member]
Long-term debt outstanding [Line Items]
Ratio of total debt to total capitalization	50%
Intermountain Gas Company
Long-term debt outstanding [Line Items]
Ratio of total debt to total capitalization	57%
Intermountain Gas Company | Revolving credit facility | Long-term debt
Long-term debt outstanding [Line Items]
Facility limit, maximum borrowing capacity	$ 100,000
Centennial Energy Holdings, Inc.
Long-term debt outstanding [Line Items]
Ratio of total debt to total capitalization	46%
WBI Energy Transmission, Inc.
Long-term debt outstanding [Line Items]
Ratio of total debt to total capitalization	40%
Senior Notes
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,258,500					$ 2,125,000
Weighted average interest rate	4.32%
Senior Notes | Cascade Natural Gas [Member]
Long-term debt outstanding [Line Items]
Long-term debt				$ 50,000
Weighted average interest rate				4.50%
Ratio of total debt to total capitalization as specified in debt covenants				65%
Senior Notes | Intermountain Gas Company
Long-term debt outstanding [Line Items]
Long-term debt				$ 40,000
Weighted average interest rate				4.68%
Ratio of total debt to total capitalization as specified in debt covenants				65%
Senior Notes | Centennial Energy Holdings, Inc.
Long-term debt outstanding [Line Items]
Long-term debt					$ 150,000
Weighted average interest rate					3.71%
Ratio of total debt to total capitalization as specified in debt covenants					60%
Senior Notes | WBI Energy Transmission, Inc.
Long-term debt outstanding [Line Items]
Long-term debt	$ 235,000	$ 40,000
Weighted average interest rate		6.67%
Ratio of total debt to total capitalization as specified in debt covenants	55%
Long-term private shelf agreement issuance capacity		$ 350,000
Remaining capacity under uncommitted private shelf agreement	$ 115,000
Revolving credit facility | Montana-Dakota Utilities Co. [Member]
Long-term debt outstanding [Line Items]
Ratio of funded debt to total capitalization as specified in debt covenants	65%
Revolving credit facility | Cascade Natural Gas [Member]
Long-term debt outstanding [Line Items]
Ratio of total debt to total capitalization as specified in debt covenants	65%
Revolving credit facility | Intermountain Gas Company
Long-term debt outstanding [Line Items]
Ratio of total debt to total capitalization as specified in debt covenants	65%
Facility limit, maximum borrowing capacity			$ 100,000
Revolving credit facility | Centennial Energy Holdings, Inc.
Long-term debt outstanding [Line Items]
Ratio of total debt to total capitalization as specified in debt covenants	65%

Schedule of debt maturities (De

Schedule of debt maturities (Details 5) $ in Thousands	Dec. 31, 2022 USD ($)
Long-term debt maturities [Line Items]
2023	$ 78,031
2024	476,923
2025	177,802
2026	140,802
2027	230,802
Thereafter	$ 1,743,893

Lease costs (Details)

Lease costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Short-term lease cost	$ 160,318	$ 132,449	$ 135,376
Operating lease cost	44,956	46,622	45,319
Variable lease cost	1,739	1,516	1,319
Total lease costs	$ 207,013	$ 180,587	$ 182,014
Weighted average remaining lease term	2 years 9 months 29 days	2 years 8 months 1 day	2 years 8 months 23 days
Weighted average discount rate	4.05%	3.54%	4.03%
Cash paid for amounts included in the measurement of lease liabilities	$ 44,512	$ 43,489	$ 45,043

Operating lease liabilities und

Operating lease liabilities undiscounted cash flows maturity schedule (Details 2) $ in Thousands	Dec. 31, 2022 USD ($)
Leases [Abstract]
2023	$ 38,927
2024	27,825
2025	18,741
2026	11,191
2027	7,297
Thereafter	39,963
Total	143,944
Less discount	23,894
Total operating lease liabilities	$ 120,050

Lessor accounting (Details 3)

Lessor accounting (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating Lease, Lease Income	$ 47.9	$ 50.1
Lessor, Operating Lease, Payments to be Received, Next Twelve Months	$ 9.7
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenues	Revenues

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Asset retirement obligation [Roll Forward]
Balance at beginning of year	$ 468,686	$ 446,919
Liabilities incurred	5,972	12,454
Liabilities acquired	0	1,805
Liabilities settled	(9,646)	(15,155)
Accretion expense*	23,188	21,214
Revisions in estimates	(77,692)	1,449
Balance at end of year	410,508	468,686
Plant costs/asset retirement obligation costs
Asset retirement obligation [Roll Forward]
Accretion expense, including asset retirement obligations	$ 21,800	$ 19,600

Common stock (Details)

Common stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Dividends declared per common share	$ 0.8750	$ 0.8550	$ 0.8350
Dividends declared to common stockholders	$ 178,761	$ 174,084	$ 168,489
Credit agreement limitation on company's subsidiaries ratio of funded debt to capitalization	60%
Company's subsidiaries net assets restricted from use for dividend payments	$ 1,900,000
Common stock
Dividends declared to common stockholders	$ 177,900	$ 173,000	$ 167,400
Centennial [Member]
Maximum distributions to the company as a ratio of average consolidated indebtedness to consolidated EBITDA	350%

Common stock Common stock issua

Common stock Common stock issuance (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Shares, Issued	204,162,814	203,889,661
Proceeds from Issuance of Common Stock	$ (149,000)	$ 88,767,000	$ 3,385,000
At-the-market offering
Class of Stock [Line Items]
Common Stock, Shares Authorized	6,400,000
Common Stock, Shares, Issued	0	2,800,000
Common Stock, Authorized Shares Remaining	3,600,000
Proceeds from Issuance of Common Stock	$ (100,000)	$ 88,800,000
Payments of Stock Issuance Costs	$ 149,000	$ 1,200,000
K-Plan
Class of Stock [Line Items]
Common Stock, Authorized Shares Remaining	7,200,000

Preferred Stock (Details 3)

Preferred Stock (Details 3) - Preferred Stock [Member] - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Preferred stock, shares authorized	2,000,000
Preferred stock, par value per share	$ 100
Preferred stock, shares oustanding	0	0

Stock based compensation plans

Stock based compensation plans (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Payment Arrangement [Abstract]
Share-based compensation arrangement, number of shares available for grant	3.4
Share-based compensation expense, net of tax	$ 8.7	$ 12	$ 10.8
Share-based compensation nonvested awards total compensation cost not yet recognized	$ 12.5
Share-based compensation, nonvested awards, total compensation cost not yet recognized, period for recognition	1 year 7 months 6 days

Stock awards (Details 2)

Stock awards (Details 2) - Board of Directors - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based compensation arrangement by share-based payment award [Line Items]
Share-based Compensation Arrangement Shares Issued in Period	40,800	41,925	45,273
Share-based Compensation Arrangement, Value	$ 1.2	$ 1.2	$ 1.1

Restricted stock awards (Detail

Restricted stock awards (Details 3) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target grant of shares under performance awards | shares	188,499
Weighted average grant-date fair value | $ / shares	$ 27.54

Performance share awards (Detai

Performance share awards (Details 4) - Performance shares [Member] - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based compensation arrangement by share-based payment award [Line Items]
Weighted average grant-date fair value	$ 31.99
Fair value of vested shares	$ 7,600,000	$ 13,700,000	$ 9,700,000
Share-based compensation arrangement by share-based payment award, options, outstanding [Roll Forward]
Nonvested at beginning of period	555,047
Nonvested at beginning of period	$ 34.40
Granted	284,416
Weighted average grant-date fair value	$ 31.99
Performance shares earned/unearned	(22,750)
Performance shares earned/unearned	$ 31.63
Vested	251,168
Vested	$ 36.60
Nonvested at end of period	565,545	555,047
Nonvested at end of period	$ 32.32	$ 34.40
Grant Date February 2021
Share-based compensation arrangement by share-based payment award [Line Items]
Target grant of shares under performance awards	281,129
Grant Date February 2022
Share-based compensation arrangement by share-based payment award [Line Items]
Target grant of shares under performance awards	284,416
Market Condition [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Historical volatility rate	50%
Implied volatility rate	50%
Weighted average grant-date fair value	$ 36.25	$ 37.96	$ 40.75
Expected volatility rate, minimum	24.07%	35.37%	15.30%
Expected volatility rate, maximum	31.41%	46.35%	15.97%
Risk-free interest rate, minimum	0.71%	0.02%	1.45%
Risk-free interest rate, maximum	1.68%	0.20%	1.62%
Weighted average discounted dividends per share	$ 2.93	$ 3.16	$ 2.91
Share-based compensation arrangement by share-based payment award, options, outstanding [Roll Forward]
Weighted average grant-date fair value	$ 36.25	$ 37.96	$ 40.75
Market Condition [Member] | Minimum
Share-based compensation arrangement by share-based payment award [Line Items]
Participant target grant of shares, percentage rate range	0%
Market Condition [Member] | Maximum
Share-based compensation arrangement by share-based payment award [Line Items]
Participant target grant of shares, percentage rate range	200%
Performance Condition [Member]
Share-based compensation arrangement by share-based payment award [Line Items]
Weighted average grant-date fair value	$ 27.73	27.35	31.63
Share-based compensation arrangement by share-based payment award, options, outstanding [Roll Forward]
Weighted average grant-date fair value	$ 27.73	$ 27.35	$ 31.63
Performance Condition [Member] | Minimum
Share-based compensation arrangement by share-based payment award [Line Items]
Participant target grant of shares, percentage rate range	0%
Performance Condition [Member] | Maximum
Share-based compensation arrangement by share-based payment award [Line Items]
Participant target grant of shares, percentage rate range	200%

Accumulated other comprehensi_4

Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated other comprehensive loss [Roll Forward]
Balance	$ 3,382,874
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	(3,265)	$ 0	$ 0
Other comprehensive income (loss)	10,421	7,074	(5,976)
Balance	3,587,129	3,382,874
Net unrealized gain (loss) on derivative instruments qualifying as hedges
Accumulated other comprehensive loss [Roll Forward]
Balance	(538)	(984)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	0
Amounts reclassified from accumulated other comprehensive loss	413	446
Other comprehensive income (loss)	413	446
Balance	(125)	(538)	(984)
Postretirement liability adjustment
Accumulated other comprehensive loss [Roll Forward]
Balance	(40,461)	(47,207)
Other comprehensive income (loss) before reclassifications	12,007	4,876
Amounts reclassified from accumulated other comprehensive loss	1,819	1,870
Other comprehensive income (loss)	10,561	6,746
Balance	(29,900)	(40,461)	(47,207)
Net unrealized gain (loss) on available-for-sale investments
Accumulated other comprehensive loss [Roll Forward]
Balance	(5)	113
Other comprehensive income (loss) before reclassifications	(667)	(252)
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	0
Amounts reclassified from accumulated other comprehensive loss	114	134
Other comprehensive income (loss)	(553)	(118)
Balance	(558)	(5)	113
Total accumulated other comprehensive loss
Accumulated other comprehensive loss [Roll Forward]
Balance	(41,004)	(48,078)
Other comprehensive income (loss) before reclassifications	11,340	4,624
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	(3,265)
Amounts reclassified from accumulated other comprehensive loss	2,346	2,450
Other comprehensive income (loss)	10,421	7,074	(5,976)
Balance	$ (30,583)	$ (41,004)	$ (48,078)

Reclassification out of accumul

Reclassification out of accumulated other comprehensive loss (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Loss [Line Items]
Interest expense	$ (119,273)	$ (93,984)	$ (96,519)
Income taxes	(94,783)	(88,920)	(84,590)
Other income	7,379	26,416	26,711
Net income	367,489	378,131	$ 390,205
Reclassification out of accumulated other comprehensive loss
Reclassification Adjustment out of Accumulated Other Comprehensive Loss [Line Items]
Net income	(2,346)	(2,450)
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	(590)	(591)
Income taxes	177	145
Net income	(413)	(446)
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	597	615
Other income	(2,416)	(2,485)
Net income	(1,819)	(1,870)
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	31	36
Other income	(145)	(170)
Net income	$ (114)	$ (134)

Components of income before inc

Components of income before income taxes from continuing operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
United States	$ 462,059	$ 466,651	$ 474,856
Foreign	0	0	261
Income before income taxes	$ 462,059	$ 466,651	$ 475,117

Income tax expense (benefit) (D

Income tax expense (benefit) (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ 50,747	$ 17,121	$ 65,006
State	20,710	11,549	21,234
Foreign	0	0	151
Current income taxes	71,457	28,670	86,391
Deferred:
Federal	17,820	45,885	(3,735)
State	4,608	12,610	(625)
Investment tax credit - net	898	1,755	2,559
Deferred income taxes	23,326	60,250	(1,801)
Income taxes	$ 94,783	$ 88,920	$ 84,590

Components of deferred tax asse

Components of deferred tax assets and liabilities (Details 3) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Postretirement	$ 41,298	$ 45,752
Compensation-related	35,196	37,917
Operating lease liabilities	25,718	26,710
Asset retirement obligations	9,687	8,696
Legal and environmental contingencies	8,526	8,603
Customer advances	7,615	7,683
Payroll tax deferral	0	6,940
Other	51,472	39,960
Total deferred tax assets	179,512	182,261
Deferred tax liabilities:
Basis differences on property, plant and equipment	608,528	585,095
Postretirement	47,340	48,302
Purchased gas adjustment	33,567	21,136
Operating lease right-of-use-assets	25,472	26,570
Intangible assets	23,007	21,074
Other	60,078	59,934
Total deferred tax liabilities	797,992	762,111
Valuation allowance	12,823	12,112
Net deferred income tax liability	$ 631,303	$ 591,962

Carryforwards (Details 4)

Carryforwards (Details 4) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
State and local jurisdiction
Carryforwards [Line Items]
Operating loss carryforwards	$ 176	$ 164.8
Investment tax credit carryforward, amount	35.1	35
Federal and State Taxing Authority
Carryforwards [Line Items]
Tax credit carryforward, amount	$ 35.7	$ 35.6

Deferred tax reconciliation (De

Deferred tax reconciliation (Details 5) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Change in net deferred income tax liability from the preceding table	$ 39,341
Deferred taxes associated with other comprehensive loss	(3,507)
Excess deferred income tax amortization	(9,008)
Other	(3,500)
Deferred income taxes	$ 23,326	$ 60,250	$ (1,801)

Income tax expense (benefit) st

Income tax expense (benefit) statutory rate versus actual rate (Details 6) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Computed tax at federal statutory rate
Computed tax at federal statutory rate	$ 97,032	$ 97,997	$ 99,775
Federal statutory rate	21%	21%	21%
Increases (reductions) resulting from:
State income taxes, net of federal income tax	$ 19,126	$ 19,496	$ 17,845
State income tax, rate	4.10%	4.20%	3.80%
Federal renewable energy credit	$ (15,343)	$ (13,914)	$ (16,009)
Federal renewable energy credit, rate	(3.30%)	(3.00%)	(3.40%)
Tax compliance and uncertain tax positions	$ 1,080	$ (477)	$ (3,543)
Tax compliance and uncertain tax positions, rate	0.20%	(0.10%)	(0.70%)
Nonqualified benefit plans	$ 2,827	$ (1,881)	$ (2,443)
Effective Income Tax Rate Nonqualified benefit plans	0.60%	(0.40%)	(0.50%)
Excess deferred income tax amortization	$ (9,008)	$ (10,295)	$ (12,517)
Excess deferred income tax amortization, rate	(1.90%)	(2.20%)	(2.60%)
Other	$ (931)	$ (2,006)	$ 1,482
Other, rate	(0.20%)	(0.40%)	0.20%
Income taxes	$ 94,783	$ 88,920	$ 84,590
Total income tax expense, rate	20.50%	19.10%	17.80%

Cash flow information (Details)

Cash flow information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Interest, net*	$ 83,118	$ 91,165	$ 88,681
Income taxes paid, net**	26,503	71,079	65,536
AFUDC borrowed	2,200	2,800	2,600
Property, plant and equipment additions in accounts payable	49,602	57,605	26,082
Right-of-use assets obtained in exchange for new operating lease liabilities	50,921	55,987	54,356
Debt assumed in connection with a business combination	0	10	0
Accrual for holdback payment related to a business combination	70	0	2,500
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	7,304	0	0
Continuing and discontinued operations
Income taxes paid, net**	$ 26,400	$ 70,900	$ 59,400

Business segment data (Details)

Business segment data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Business segment data [Line Items]
Revenues	$ 6,973,864	$ 5,680,733	$ 5,532,750
Depreciation, depletion and amortization	327,826	299,214	285,100
Operating income (loss)	573,953	534,219	544,925
Interest expense	119,273	93,984	96,519
Income taxes	94,783	88,920	84,590
Income from continuing operations	367,276	377,731	390,527
Discontinued operations, net of tax	213	400	(322)
Net income	367,489	378,131	390,205
Capital expenditures	656,559	935,806	648,279
Total assets	9,660,781	8,910,435	8,053,372
Property, Plant and Equipment, Gross	9,364,038	8,972,849
Less accumulated depreciation, depletion and amortization	3,272,493	3,216,461	3,133,831
Net property, plant and equipment	6,091,545	5,756,388	5,166,939
Additional information [Abstract]
Net noncash acquisitions, capital expenditure-related accounts payable and AFUDC	1,700	38,700	(15,700)
Electric
Business segment data [Line Items]
Revenues	376,579	349,039	331,538
Depreciation, depletion and amortization	67,802	66,750	62,998
Operating income (loss)	79,655	66,335	63,434
Interest expense	28,526	26,712	26,699
Income taxes	(5,420)	(7,626)	(11,636)
Capital expenditures	133,970	82,427	114,676
Total assets	1,856,258	1,810,695	2,123,693
Property, Plant and Equipment, Gross	2,276,613	2,295,646	2,323,403
Natural gas distribution
Business segment data [Line Items]
Revenues	1,273,249	971,364	847,651
Depreciation, depletion and amortization	89,466	86,065	84,580
Operating income (loss)	91,889	89,173	73,082
Interest expense	42,126	37,265	36,798
Income taxes	7,805	8,366	5,746
Capital expenditures	240,064	170,411	193,048
Total assets	3,214,452	2,929,519	2,302,770
Property, Plant and Equipment, Gross	3,208,060	3,015,164	2,868,853
Pipeline
Business segment data [Line Items]
Revenues	96,567	82,858	85,346
Depreciation, depletion and amortization	26,857	20,569	21,669
Operating income (loss)	55,466	48,078	49,436
Interest expense	11,318	7,010	7,622
Income taxes	10,212	9,594	7,650
Capital expenditures	61,923	234,803	62,224
Total assets	961,893	913,945	703,377
Property, Plant and Equipment, Gross	1,108,141	1,051,868	821,697
Construction materials and contracting
Business segment data [Line Items]
Revenues	2,533,713	2,228,306	2,177,585
Depreciation, depletion and amortization	117,798	100,974	89,626
Operating income (loss)	194,295	191,077	214,498
Interest expense	30,121	19,218	20,577
Income taxes	42,601	43,459	47,431
Capital expenditures	181,917	417,524	191,635
Total assets	2,268,970	2,161,653	1,798,493
Property, Plant and Equipment, Gross	2,489,408	2,347,696	2,028,476
Construction services
Business segment data [Line Items]
Revenues	2,693,756	2,049,082	2,090,685
Depreciation, depletion and amortization	21,468	20,270	23,523
Operating income (loss)	164,644	145,754	147,644
Interest expense	6,354	3,540	4,095
Income taxes	40,788	35,426	35,797
Capital expenditures	36,413	29,140	83,651
Total assets	1,126,323	845,262	818,662
Property, Plant and Equipment, Gross	245,111	225,758	220,796
Other
Business segment data [Line Items]
Revenues	0	84	(55)
Depreciation, depletion and amortization	4,435	4,586	2,704
Operating income (loss)	(11,996)	(6,198)	(3,169)
Interest expense	1,465	342	883
Income taxes	(1,203)	(299)	(398)
Capital expenditures	2,272	1,501	3,045
Total assets	232,885	249,361	306,377
Property, Plant and Equipment, Gross	36,705	36,717	37,545
Intersegment Eliminations
Business segment data [Line Items]
Revenues	(84,176)	(77,606)	(76,969)
Interest expense	(637)	(103)	(155)
Total assets	(1,184,512)	(992,084)	(711,216)
Intersegment Eliminations | Electric
Business segment data [Line Items]
Revenues	(494)	(543)	(491)
Intersegment Eliminations | Natural gas distribution
Business segment data [Line Items]
Revenues	(555)	(576)	(534)
Intersegment Eliminations | Pipeline
Business segment data [Line Items]
Revenues	(59,012)	(59,678)	(58,531)
Intersegment Eliminations | Construction materials and contracting
Business segment data [Line Items]
Revenues	(1,016)	(624)	(417)
Intersegment Eliminations | Construction services
Business segment data [Line Items]
Revenues	(5,494)	(2,555)	(5,038)
Intersegment Eliminations | Other
Business segment data [Line Items]
Revenues	(17,605)	(13,630)	(11,958)
Total Intersegment operating revenues
Business segment data [Line Items]
Revenues	84,176	77,606	76,969
Regulated Operation
Business segment data [Line Items]
Revenues	1,735,759	1,390,343	1,249,146
Income from continuing operations	137,605	143,085	135,103
Regulated Operation | Electric
Business segment data [Line Items]
Revenues	376,579	349,039	331,538
Income from continuing operations	57,077	51,906	55,601
Regulated Operation | Natural gas distribution
Business segment data [Line Items]
Revenues	1,273,249	971,364	847,651
Income from continuing operations	45,171	51,596	44,049
Regulated Operation | Pipeline
Business segment data [Line Items]
Revenues	85,931	69,940	69,957
Income from continuing operations	35,357	39,583	35,453
Regulated Operation | Intersegment Eliminations
Business segment data [Line Items]
Revenues	59,417	60,108	59,002
Regulated Operation | Intersegment Eliminations | Electric
Business segment data [Line Items]
Revenues	494	543	491
Regulated Operation | Intersegment Eliminations | Natural gas distribution
Business segment data [Line Items]
Revenues	555	576	534
Regulated Operation | Intersegment Eliminations | Pipeline
Business segment data [Line Items]
Revenues	58,368	58,989	57,977
Nonregulated Operation
Business segment data [Line Items]
Revenues	5,238,105	4,290,390	4,283,604
Income from continuing operations	229,671	234,646	255,424
Nonregulated Operation | Pipeline
Business segment data [Line Items]
Revenues	10,636	12,918	15,389
Income from continuing operations	(69)	1,313	1,559
Nonregulated Operation | Construction materials and contracting
Business segment data [Line Items]
Revenues	2,533,713	2,228,306	2,177,585
Income from continuing operations	116,220	129,755	147,325
Nonregulated Operation | Construction services
Business segment data [Line Items]
Revenues	2,693,756	2,049,082	2,090,685
Income from continuing operations	124,781	109,402	109,721
Nonregulated Operation | Other
Business segment data [Line Items]
Revenues	0	84	(55)
Income from continuing operations	(11,261)	(5,824)	(3,181)
Nonregulated Operation | Intersegment Eliminations
Business segment data [Line Items]
Revenues	24,759	17,498	17,967
Nonregulated Operation | Intersegment Eliminations | Pipeline
Business segment data [Line Items]
Revenues	644	689	554
Nonregulated Operation | Intersegment Eliminations | Construction materials and contracting
Business segment data [Line Items]
Revenues	1,016	624	417
Nonregulated Operation | Intersegment Eliminations | Construction services
Business segment data [Line Items]
Revenues	5,494	2,555	5,038
Nonregulated Operation | Intersegment Eliminations | Other
Business segment data [Line Items]
Revenues	$ 17,605	$ 13,630	$ 11,958

Business segment data operating

Business segment data operating revenues reconciliation (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 6,973,864	$ 5,680,733	$ 5,532,750
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	7,040,435	5,744,625	5,597,816
Corporate, Non-Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	17,605	13,714	11,903
Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ (84,176)	$ (77,606)	$ (76,969)

Business segment data operati_2

Business segment data operating assets reconciliation (Details 3) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 9,660,781	$ 8,910,435	$ 8,053,372
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	9,491,679	8,717,563	7,816,848
Corporate, Non-Segment
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	1,353,614	1,184,956	947,740
Intersegment Eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ (1,184,512)	$ (992,084)	$ (711,216)

Change in benefit obligations a

Change in benefit obligations and plan assets (Details) - Qualified Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Underfunded Plan | Pension Benefits
Change in benefit obligation:
Benefit obligation at beginning of year	$ 411,497	$ 437,360
Service cost	0	0	$ 0
Interest cost	10,522	9,819	12,093
Plan participants' contributions	0	0
Actuarial gain	(85,303)	(12,140)
Benefits paid	(24,672)	(23,542)
Benefit obligation at end of year	312,044	411,497	437,360
Change in net plan assets:
Fair value of plan assets at beginning of year	373,109	383,834
Actual return on plan assets	(77,975)	12,817
Employer contribution	0	0
Plan participants' contributions	0	0
Benefits paid	(24,672)	(23,542)
Fair value of net plan assets at end of year	270,462	373,109	383,834
Funded status - (under) over	(41,582)	(38,388)
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent assets - other	0	0
Other accrued liabilities	0	0
Noncurrent liabilities - other	41,582	38,388
Benefit obligation (liabilities) assets - net amount recognized	(41,582)	(38,388)
Amounts recognized in accumulated other comprehensive loss:
Actuarial loss (gain)	32,378	25,976
Prior service credit	0	0
Total	32,378	25,976
Amounts recognized in regulatory assets or liabilities:
Actuarial loss (gain)	141,207	142,166
Prior service credit	0	0
Total	141,207	142,166
Overfunded Plan | Other Postretirement Benefits
Change in benefit obligation:
Benefit obligation at beginning of year	73,460	86,155
Service cost	1,416	1,600	1,532
Interest cost	1,896	1,862	2,437
Plan participants' contributions	569	641
Actuarial gain	(18,401)	(12,802)
Benefits paid	(4,009)	(3,996)
Benefit obligation at end of year	54,931	73,460	86,155
Change in net plan assets:
Fair value of plan assets at beginning of year	100,158	101,639
Actual return on plan assets	(20,893)	1,398
Employer contribution	501	476
Plan participants' contributions	569	641
Benefits paid	(4,009)	(3,996)
Fair value of net plan assets at end of year	76,326	100,158	$ 101,639
Funded status - (under) over	21,395	26,698
Amounts recognized in the Consolidated Balance Sheets at December 31:
Noncurrent assets - other	36,325	45,863
Other accrued liabilities	1,044	544
Noncurrent liabilities - other	13,886	18,621
Benefit obligation (liabilities) assets - net amount recognized	21,395	26,698
Amounts recognized in accumulated other comprehensive loss:
Actuarial loss (gain)	(2,923)	2,367
Prior service credit	(289)	(290)
Total	(3,212)	2,077
Amounts recognized in regulatory assets or liabilities:
Actuarial loss (gain)	(1,439)	(14,727)
Prior service credit	(3,796)	(5,193)
Total	$ (5,235)	$ (19,920)

Benefit obligations in excess o

Benefit obligations in excess of plan assets (Details 2) - Qualified Plan - Pension Benefits - Underfunded Plan - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 312,044	$ 411,497
Accumulated benefit obligation	312,044	411,497
Fair value of plan assets	$ 270,462	$ 373,109

Components of net periodic bene

Components of net periodic benefit cost (Details 3) - Qualified Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Underfunded Plan | Pension Benefits
Components of net periodic benefit credit:
Service cost	$ 0	$ 0	$ 0
Interest cost	10,522	9,819	12,093
Expected return on assets	(19,455)	(19,576)	(19,949)
Amortization of prior service credit	0	0	0
Recognized net actuarial loss (gain)	6,683	8,017	7,172
Net periodic benefit credit, including amount capitalized	(2,250)	(1,740)	(684)
Less amount capitalized	0	0	0
Net periodic benefit cost (credit)	(2,250)	(1,740)	(684)
Other changes in plan assets and benefit obligations recognized in accumulated comprehensive loss:
Net (gain) loss	2,369	(265)	934
Amortization of actuarial loss	(1,310)	(1,286)	(1,155)
Amortization of prior service credit	0	0	0
Reclassification of postretirement liability adjustment from regulatory asset	5,343	0	0
Total recognized in accumulated other comprehensive loss	6,402	(1,551)	(221)
Other changes in plan assets and benefit obligations recognized in regulatory assets or liabilities:
Net (gain) loss	9,757	(5,116)	4,546
Amortization of actuarial gain (loss)	(5,373)	(6,731)	(6,017)
Amortization of prior service credit	0	0	0
Reclassification of postretirement liability adjustment from regulatory asset to OCI	(5,343)	0	0
Total recognized in regulatory assets or liabilities	(959)	(11,847)	(1,471)
Total recognized in net periodic benefit credit, accumulated other comprehensive loss and regulatory assets or liabilities	3,193	(15,138)	(2,376)
Overfunded Plan | Other Postretirement Benefits
Components of net periodic benefit credit:
Service cost	1,416	1,600	1,532
Interest cost	1,896	1,862	2,437
Expected return on assets	(5,288)	(5,098)	(5,019)
Amortization of prior service credit	(1,398)	(1,398)	(1,398)
Recognized net actuarial loss (gain)	(219)	24	287
Net periodic benefit credit, including amount capitalized	(3,593)	(3,010)	(2,161)
Less amount capitalized	175	150	156
Net periodic benefit cost (credit)	(3,768)	(3,160)	(2,317)
Other changes in plan assets and benefit obligations recognized in accumulated comprehensive loss:
Net (gain) loss	(4,141)	(2,811)	(259)
Amortization of actuarial loss	(281)	(135)	(306)
Amortization of prior service credit	125	100	101
Reclassification of postretirement liability adjustment from regulatory asset	(992)	0	0
Total recognized in accumulated other comprehensive loss	(5,289)	(2,846)	(464)
Other changes in plan assets and benefit obligations recognized in regulatory assets or liabilities:
Net (gain) loss	11,920	(6,292)	(3,793)
Amortization of actuarial gain (loss)	500	110	19
Amortization of prior service credit	1,273	1,298	1,297
Reclassification of postretirement liability adjustment from regulatory asset to OCI	992	0	0
Total recognized in regulatory assets or liabilities	14,685	(4,884)	(2,477)
Total recognized in net periodic benefit credit, accumulated other comprehensive loss and regulatory assets or liabilities	$ 5,628	$ (10,890)	$ (5,258)

Weighted average assumptions (D

Weighted average assumptions (Details 4) - Qualified Plan	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Underfunded Plan | Pension Benefits
Used to determine benefit obligation
Discount rate	5.06%	2.64%
Expected return on plan assets	6.50%	6%
Used to determine benefit cost
Discount rate	2.64%	2.30%
Expected return on plan assets	6%	6%
Overfunded Plan | Other Postretirement Benefits
Used to determine benefit obligation
Discount rate	5.07%	2.66%
Expected return on plan assets	6%	5.50%
Rate of compensation increase	3%	3%
Used to determine benefit cost
Discount rate	2.66%	2.30%
Expected return on plan assets	5.50%	5.50%
Rate of compensation increase	3%	3%

Investment Allocations (Details

Investment Allocations (Details 5) - Qualified Plan	Dec. 31, 2022
Underfunded Plan | Minimum | Equity securities | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	40%
Underfunded Plan | Minimum | Fixed Income Securities | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	50%
Underfunded Plan | Maximum | Equity securities | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	50%
Underfunded Plan | Maximum | Fixed Income Securities | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	60%
Overfunded Plan | Minimum | Equity securities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	10%
Overfunded Plan | Minimum | Fixed Income Securities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	80%
Overfunded Plan | Maximum | Equity securities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	20%
Overfunded Plan | Maximum | Fixed Income Securities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	90%

Health care rate assumptions an

Health care rate assumptions and cost trend rate (Details 6) - Overfunded Plan - Qualified Plan - Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Health care trend rate assumed for next year	7.50%	7%
Health care cost trend rate - ultimate	4.50%	4.50%
Year in which ultimate trend rate achieved	2033	2031

Estimated future benefit paymen

Estimated future benefit payments and subsidies (Details 7) - Qualified Plan - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2022
Underfunded Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		$ 0
Defined Benefit Plan, Plan Assets, Additional Contributions by Employer	$ 20,000,000
2023		24,936,000
2024		24,882,000
2025		24,749,000
2026		24,605,000
2027		24,387,000
2028-2032		114,850,000
Overfunded Plan | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year		595,000
2023		4,275,000
2024		4,371,000
2025		4,456,000
2026		4,509,000
2027		4,523,000
2028-2032		16,917,000
2023		62,000
2024		53,000
2025		46,000
2026		39,000
2027		31,000
2028-2032		$ 93,000

Fair value - pension (Details 8

Fair value - pension (Details 8) - Qualified Plan - Underfunded Plan - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at end of year	$ 270,462	$ 373,109	$ 383,834
Defined Benefit Plan, Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 8,170	4,637
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Percentage	7%
Pension investments in insurance contracts	100%
Defined Benefit Plan, Equity Securities, US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 7,388	7,483
Defined Benefit Plan, Equity Securities, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 467	$ 1,279
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Percentage	16%	19%
Collective and mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 154,443	$ 208,476
Corporate debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 81,363	$ 125,167
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Percentage	29%	37%
Municipal bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 5,904	$ 7,507
U.S. Government securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 3,924	$ 9,015
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Percentage	7%	9%
Pooled Separate Accounts
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 3,241	$ 3,088
Total assets measured at fair value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at end of year	$ 270,462	$ 373,109
Defined Benefit Plan, Equity Securities, US, Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Percentage	24%	16%
Other Investments
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Percentage	17%	19%
Quoted Prices in Active Markets for Identical Assets  (Level 1) | Defined Benefit Plan, Equity Securities, US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 7,388	$ 7,483
Quoted Prices in Active Markets for Identical Assets  (Level 1) | Collective and mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	121,072	167,093
Quoted Prices in Active Markets for Identical Assets  (Level 1) | U.S. Government securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	3,044	7,113
Quoted Prices in Active Markets for Identical Assets  (Level 1) | Total assets measured at fair value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at end of year	131,504	181,689
Significant Other Observable Inputs  (Level 2) | Defined Benefit Plan, Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	8,170	4,637
Significant Other Observable Inputs  (Level 2) | Defined Benefit Plan, Equity Securities, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	467	1,279
Significant Other Observable Inputs  (Level 2) | Collective and mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	33,371	41,383
Significant Other Observable Inputs  (Level 2) | Corporate debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	81,363	125,167
Significant Other Observable Inputs  (Level 2) | Municipal bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	5,904	7,507
Significant Other Observable Inputs  (Level 2) | U.S. Government securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	880	1,902
Significant Other Observable Inputs  (Level 2) | Pooled Separate Accounts
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	3,241	3,088
Significant Other Observable Inputs  (Level 2) | Total assets measured at fair value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at end of year	133,396	184,963
Fair Value Measured at Net Asset Value Per Share | Collective and mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 5,562	$ 6,457

Fair value - other postretireme

Fair value - other postretirement (Details 9) - Other Postretirement Benefits - Qualified Plan - Overfunded Plan - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at end of year	$ 76,326	$ 100,158	$ 101,639
Defined Benefit Plan, Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 4,196	4,281
Postretirement Investments in Collective and Mutual Funds	7%
Defined Benefit Plan, Equity Securities, US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 2,572	2,332
Defined Benefit Plan, Equity Securities, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount		$ 1
Postretirement Investments in Collective and Mutual Funds	16%	19%
Collective and mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 10	$ 94
Insurance investment contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	69,548	93,447
Total assets measured at fair value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at end of year	$ 76,326	$ 100,158
Corporate debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement Investments in Collective and Mutual Funds	29%	37%
Postretirement Investments in Insurance Contracts	69%	58%
Defined Benefit Plan, Equity Securities, US, Large Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement Investments in Collective and Mutual Funds	24%	16%
Postretirement Investments in Insurance Contracts	14%	13%
Defined Benefit Plan, Equity Securities, US, Small Cap [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement Investments in Insurance Contracts	4%	5%
U.S. Government securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Postretirement Investments in Collective and Mutual Funds	7%	9%
Postretirement Investments in Insurance Contracts	13%	13%
Other Investments
Defined Benefit Plan Disclosure [Line Items]
Postretirement Investments in Collective and Mutual Funds	17%	19%
Postretirement Investments in Insurance Contracts		11%
Quoted Prices in Active Markets for Identical Assets  (Level 1) | Defined Benefit Plan, Equity Securities, US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	$ 2,572	$ 2,332
Quoted Prices in Active Markets for Identical Assets  (Level 1) | Collective and mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	5	4
Quoted Prices in Active Markets for Identical Assets  (Level 1) | Total assets measured at fair value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at end of year	2,577	2,336
Significant Other Observable Inputs  (Level 2) | Defined Benefit Plan, Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	4,196	4,281
Significant Other Observable Inputs  (Level 2) | Defined Benefit Plan, Equity Securities, Non-US [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount		1
Significant Other Observable Inputs  (Level 2) | Collective and mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	5	90
Significant Other Observable Inputs  (Level 2) | Insurance investment contract [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount	69,548	93,447
Significant Other Observable Inputs  (Level 2) | Total assets measured at fair value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of net plan assets at end of year	$ 73,749	97,819
Fair Value Measured at Net Asset Value Per Share | Collective and mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Investment within Plan Asset Category, Amount		$ 3

Nonqualified Benefit Plans Bene

Nonqualified Benefit Plans Benefit Obligations (Details 10) - Unfunded Plan - Nonqualified Plan - Supplemental Employee Retirement Plan - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 74,730	$ 92,918
Accumulated benefit obligation	$ 74,730	$ 92,918

Nonqualified Benefit Plans Comp

Nonqualified Benefit Plans Components of NPBC (Details 11) - Unfunded Plan - Nonqualified Plan - Supplemental Employee Retirement Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 0	$ 58
Interest cost	2,142	1,912	2,606
Recognized net actuarial loss	950	1,164	1,192
Net periodic benefit cost	$ 3,092	$ 3,076	$ 3,856

Nonqualified Benefit Plans Weig

Nonqualified Benefit Plans Weighted Average Assumptions (Details 12) - Unfunded Plan - Nonqualified Plan - Supplemental Employee Retirement Plan	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation discount rate	4.97%	2.39%
Net periodic benefit cost discount rate	2.39%	1.97%

Nonqualified Benefit Plans Futu

Nonqualified Benefit Plans Future Benefit Payments (Details 13) - Unfunded Plan - Nonqualified Plan - Supplemental Employee Retirement Plan $ in Thousands	Dec. 31, 2022 USD ($)
Defined Benefit Plan Disclosure [Line Items]
2023	$ 6,651
2024	7,183
2025	7,430
2026	7,537
2027	7,420
2028-2032	$ 29,930

Nonqualified Benefit Plans Cont

Nonqualified Benefit Plans Contributions (Details 14) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Unfunded Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Nonqualified Defined Contribution Plan, Cost	$ 3.3	$ 2.4	$ 1.8

Nonqualified Benefit Plans Inve

Nonqualified Benefit Plans Investments (Details 15) - Unfunded Plan - Supplemental Employee Retirement Plan - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Investments in nonqualified benefit plans	$ 143,850	$ 158,149
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Investments in nonqualified benefit plans	98,041	109,603
Life insurance carried on plan participants
Defined Benefit Plan Disclosure [Line Items]
Investments in nonqualified benefit plans	38,448	38,356
Other Investments
Defined Benefit Plan Disclosure [Line Items]
Investments in nonqualified benefit plans	$ 7,361	$ 10,190

Defined Contribution Benefit Pl

Defined Contribution Benefit Plans Contribution (Details 16) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Contribution Plan
Defined Benefit Plan Disclosure [Line Items]
Nonqualified Defined Contribution Plan, Cost	$ 46.4	$ 45.4	$ 50.1

Multiemployer Plans Zones (Deta

Multiemployer Plans Zones (Details 17)	12 Months Ended
	Dec. 31, 2022
Maximum
Multiemployer Plans [Line Items]
Multiemployer plan red zone status funded percentage	65%
Mulitiemployer plan yellow status funded percentage	80%
Minimum
Multiemployer Plans [Line Items]
Multiemployer plan yellow zone status funded percentage	65%
Multiemployer plan green zone status funded percentage	80%

Multiemployer Plans Participati

Multiemployer Plans Participation by Plan (Details 18) - Pension Benefits - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Insignificant, Employer Contribution, Cost	$ 26,909	$ 24,192	$ 23,670
Multiemployer Plan, Employer Contribution, Cost	$ 101,276	$ 82,388	85,444
Edison Pension Plan
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	936061681
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 18,750	$ 18,331	16,121
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Dec. 31, 2023
IBEW Local 212 Pension Trust
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	316127280
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 1,622	$ 1,733	1,521
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Jun. 01, 2025
Multiemployer Plan, Pension, Significant, Certified Zone Status, Date	Apr. 30, 2021	Apr. 30, 2021
IBEW Local 357 Pension Plan A
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	886023284
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 12,876	$ 6,485	9,913
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	May 31, 2024
IBEW Local 82 Pension Plan
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	316127268
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 1,854	$ 1,353	1,373
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Dec. 03, 2023
Multiemployer Plan, Pension, Significant, Certified Zone Status, Date	Jun. 30, 2022	Jun. 30, 2021
IBEW Local 648 Pension Plan
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	316134845
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Yellow	Yellow
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	Implemented
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 915	$ 706	526
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Sep. 01, 2024
Multiemployer Plan, Pension, Significant, Certified Zone Status, Date	Feb. 28, 2022	Feb. 28, 2021
IBEW Local 683 Pension Fund Pension Plan
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	341442087
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 3,362	$ 1,238	1,240
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	May 26, 2024
Idaho Plumbers and Pipefitters Pension Plan
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	826010346
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 1,613	$ 1,528	1,370
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Mar. 31, 2023
Multiemployer Plan, Pension, Significant, Certified Zone Status, Date	May 31, 2022	May 31, 2021
National Electrical Benefit Fund
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	530181657
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 18,060	$ 14,361	14,484
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
National Electrical Benefit Fund | Minimum
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	May 31, 2022
National Electrical Benefit Fund | Maximum
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	May 31, 2027
Pension and Retirement Plan of Plumbers and Pipefitters Local 525
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	886003864
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 6,304	$ 4,345	6,266
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Sep. 30, 2024
Multiemployer Plan, Pension, Significant, Certified Zone Status, Date	Jun. 30, 2022	Jun. 30, 2021
Pension Trust Fund for Operating Engineers
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	946090764
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Yellow	Yellow
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	Implemented
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 2,484	$ 2,495	2,680
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Pension Trust Fund for Operating Engineers | Minimum
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Mar. 31, 2023
Pension Trust Fund for Operating Engineers | Maximum
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Jun. 15, 2026
Sheet Metal Workers Pension Plan of Southern CA, AZ, and NV
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	956052257
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Yellow
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	Implemented
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 3,400	$ 2,615	3,255
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Jun. 30, 2024
Western Conference of Teamsters Pension Plan
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Employer Identification Number	916145047
Multiemployer Plan, Pension, Significant, Plan Number	001
Multiemployer Plan, Pension, Significant, Certified Zone Status [Fixed List]	Green	Green
Multiemployer Plan, Pension, Significant, Funding Improvement or Rehabilitation Plan, Implementation Status [Fixed List]	No
Multiemployer Plan, Pension, Significant, Employer Contribution, Cost	$ 3,127	$ 3,006	$ 3,025
Multiemployer Plan, Pension, Significant, Surcharge [Fixed List]	No
Western Conference of Teamsters Pension Plan | Minimum
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Dec. 31, 2023
Western Conference of Teamsters Pension Plan | Maximum
Multiemployer Plans [Line Items]
Multiemployer Plan, Pension, Significant, Collective-Bargaining Arrangement, Expiration Date	Dec. 31, 2025

Multiemployer Plan Contribution

Multiemployer Plan Contributions (Details 19) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Multiemployer Plans, Defined Contribution [Member]
Multiemployer Plans [Line Items]
Multiemployer Plan, Employer Contribution, Cost	$ 67.9	$ 54.8	$ 54.2
Other Postretirement Benefits
Multiemployer Plans [Line Items]
Multiemployer Plan, Employer Contribution, Cost	$ 81	$ 66.1	$ 63.8

Jointly owned facilities (Detai

Jointly owned facilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Jointly owned electricity generation plant | Big Stone Station
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	22.70%
Utility plant in service	$ 157,699	$ 157,259
Construction work in progress	231	571
Less accumulated depreciation	48,590	47,293
Utility plant in services net	$ 109,340	110,537
Jointly owned electricity generation plant | Coyote Station
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	25%
Utility plant in service	$ 158,274	157,764
Construction work in progress	1,807	784
Less accumulated depreciation	111,203	109,202
Utility plant in services net	$ 48,878	49,346
Jointly owned electricity generation plant | Wygen III
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	25%
Utility plant in service	$ 66,238	66,357
Construction work in progress	273	108
Less accumulated depreciation	12,477	11,383
Utility plant in services net	$ 54,034	55,082
Jointly Owned Electricity Transmission and Distribution System | BSSE
Jointly Owned Utility Plant Interests [Line Items]
Proportionate ownership share	50%
Utility plant in service	$ 107,260	107,424
Construction work in progress	0	0
Less accumulated depreciation	6,182	4,506
Utility plant in services net	$ 101,078	$ 102,918

IPUC (Details)

IPUC (Details) - Intermountain Gas Company - Gas Distribution [Member] - IPUC - USD ($) $ in Millions	Feb. 01, 2023	Dec. 01, 2022
Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 56.5
Public Utilities, Approved Rate Increase (Decrease), Percentage	17.10%
Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 11.3
Public Utilities, Requested Rate Increase (Decrease), Percentage		3.20%

MNPUC (Details 2)

MNPUC (Details 2) - MNPUC [Member] - Gas Distribution [Member] - Great Plains Natural Gas Co. [Member] - USD ($)	Jan. 06, 2023	Nov. 08, 2022	Jun. 01, 2022	Sep. 01, 2021
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount				$ 8,800,000
Depreciation and Amortization Requested Rate Increase (Decrease), Amount			$ (1,200,000)
Depreciation and Amortization, Rate, Percent			4.50%
Depreciation and Amortization, Requested Rate, Percent			2.80%
Depreciation and Amortization Approved Rate Increase (Decrease), Amount		$ (1,000,000)
Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Disallowed Gas Costs (Increase) Decrease	$ 845,000

MTPSC (Details 3)

MTPSC (Details 3) - Pending Rate Case [Member] - Montana-Dakota Utilities Co. [Member] - Electric - MTPSC - USD ($) $ in Millions	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%
Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Interim Rate Increase (Decrease), Amount	$ 1.7
Public Utilities, Interim Rate Increase (Decrease), Percentage	2.70%

NDPSC (Details 4)

NDPSC (Details 4) - Electric - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - USD ($)	Mar. 01, 2023	Nov. 01, 2022	Jul. 14, 2022	May 16, 2022
Public Utilities, General Disclosures [Line Items]
Requested Renewable Resource Cost Adjustment Rate Tariff		$ 17,900,000
Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Renewable Resource Cost Adjustment Rate Tariff	$ 17,000,000
Public Utilities, Approved Rate Increase (Decrease), Amount	$ (1,000,000)
Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 25,400,000
Public Utilities, Requested Rate Increase (Decrease), Percentage				12.30%
Public Utilities, Interim Rate Increase (Decrease), Amount			$ 10,900,000
Public Utilities, Interim Rate Increase (Decrease), Percentage			5.30%

WUTC (Details 5)

WUTC (Details 5) $ in Millions	Jan. 23, 2023 USD ($)
Gas Distribution [Member] | WUTC [Member] | Cascade Natural Gas [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Denied Rate Increase (Decrease), Amount	$ 3.3

FERC (Details 6)

FERC (Details 6) $ in Millions	Jan. 01, 2023 USD ($)
MISO [Member] | Montana-Dakota Utilities Co. [Member] | Electric | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Transmission Formula Revenue Requirement	$ 15.4

Litigation (Details)

Litigation (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Loss Contingencies [Line Items]
Potential liabilities related to litigation and environmental matters	$ 32.9	$ 37
Loss Contingency, Receivable	10.4	14.1
Loss Contingency, Regulated	$ 20.9	$ 21.2

Enviromental matters (Details 2

Enviromental matters (Details 2)	12 Months Ended
	Dec. 31, 2022 USD ($)
Portland Harbor Site
Site Contingency [Line Items]
Environmental matters investigative costs	$ 115,000,000
Environmental matters, estimated costs	1,000,000,000
Missoula, MT manufactured gas plant site
Site Contingency [Line Items]
Total estimated costs for site remediation	560,000
Environmental Matters Estimated Investigative Costs	1,800,000
Environmental matters accrual for site remediation	725,000
Incurred Costs For Site Remedial Investigation	922,000
Bremerton, WA manufactured gas plant site
Site Contingency [Line Items]
Environmental matters accrual for site remediation	17,500,000
Total estimated costs for site remedial investigation and feasibility study	12,100,000
Incurred costs for site remedial investigation and feasibility study	9,900,000
Environmental matters accrual of investigative costs	2,200,000
Bellingham, WA manufactured gas plant site
Site Contingency [Line Items]
Site contingency, loss exposure not accrued, preferred alternative estimate	9,300,000
Minimum | Bremerton, WA manufactured gas plant site
Site Contingency [Line Items]
Site contingency, loss exposure not accrued, best estimate	13,600,000
Minimum | Bellingham, WA manufactured gas plant site
Site Contingency [Line Items]
Site contingency, loss exposure not accrued, best estimate	8,000,000
Maximum | Bremerton, WA manufactured gas plant site
Site Contingency [Line Items]
Site contingency, loss exposure not accrued, best estimate	71,000,000
Maximum | Bellingham, WA manufactured gas plant site
Site Contingency [Line Items]
Site contingency, loss exposure not accrued, best estimate	$ 20,400,000

Purchase commitments (Details 3

Purchase commitments (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Long-term Purchase Commitment [Line Items]
Commitment term	37 years
Amounts purchased under various commitments	$ 1,000,000	$ 849,300	$ 666,000
Inventories
Purchase commitments due
2023	712,875
2024	258,074
2025	158,152
2026	103,677
2027	81,619
Purchase Obligation, to be Paid, after Year Five	$ 676,489

Guarantees (Details 4)

Guarantees (Details 4)	Dec. 31, 2022 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 341,800,000
Fixed maximum amounts guaranteed by year 2023	51,300,000
Fixed maximum amounts guaranteed by year 2024	148,400,000
Fixed maximum amounts guaranteed by year 2025	126,800,000
Fixed maximum amounts guaranteed by year 2026	1,300,000
Fixed maximum amounts guaranteed by year 2027	800,000
Fixed maximum amounts guaranteed, thereafter	1,700,000
No scheduled maturity date	11,500,000
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit	30,000,000
Letters of credit set to expire - 2023	29,500,000
Letters of credit set to expire - 2024	500,000
Outstanding letters of credit	0
Amount of surety bonds outstanding	$ 1,300,000,000

Variable interest entities (Det

Variable interest entities (Details 5) $ in Millions	Dec. 31, 2022 USD ($)
Fuel contract
Variable Interest Entities [Line Items]
Variable interest entity, reporting entity involvement, maximum loss exposure, amount	$ 29.5

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Thousands	Jan. 20, 2023	Dec. 31, 2022	Dec. 31, 2021
Subsequent Event [Line Items]
Long-term debt		$ 2,841,425	$ 2,741,900
Term Loan Agreement [Member] | Cascade Natural Gas [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Long-term debt	$ 150,000
Ratio of total debt to total capitalization as specified in debt covenants	65%
Term Loan Agreement [Member] | Intermountain Gas Company | Subsequent Event [Member]
Subsequent Event [Line Items]
Long-term debt	$ 125,000
Ratio of total debt to total capitalization as specified in debt covenants	65%

Condensed Statements of Income

Condensed Statements of Income and Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 6,973,864	$ 5,680,733	$ 5,532,750
Operating expenses	6,399,911	5,146,514	4,987,825
Operating income	573,953	534,219	544,925
Other income	7,379	26,416	26,711
Interest expense	119,273	93,984	96,519
Income before income taxes	462,059	466,651	475,117
Income taxes	94,783	88,920	84,590
Income from continuing operations	367,276	377,731	390,527
Comprehensive income	377,910	385,205	384,229
MDU Resources Group, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0	0
Operating expenses	14,323	0	0
Operating income	(14,323)	0	0
Other income	0	0	0
Interest expense	0	0	0
Income before income taxes	(14,323)	0	0
Income taxes	(1,623)	0	0
Equity in earnings of subsidiaries from continuing operations	379,976	377,731	390,527
Income from continuing operations	367,276	377,731	390,527
Equity in earnings (loss) of subsidiaries from discontinued operations	213	400	(322)
Net income	367,489	378,131	390,205
Comprehensive income	$ 377,910	$ 385,205	$ 384,229

Condensed Balance Sheets (Detai

Condensed Balance Sheets (Details 2) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 80,517	$ 54,161	$ 59,547	$ 66,459
Receivables, net	1,305,642	946,741
Prepayments and other current assets	72,972	95,741
Assets, Current	2,011,748	1,550,943
Noncurrent Assets
Investments	161,913	175,476
Operating lease right-of-use assets	119,375	124,138
Other	165,509	157,675
Total noncurrent assets	7,649,033	7,359,492
Total assets	9,660,781	8,910,435	8,053,372
Current liabilities:
Accounts payable	657,168	478,933
Taxes payable	70,810	80,372
Dividends payable	45,245	44,229
Accrued compensation	88,662	81,904
Operating lease liabilities due within one year	34,516	35,368
Other accrued liabilities	232,231	207,078
Total current liabilities	1,479,603	1,092,240
Noncurrent liabilities:
Operating lease liabilities	85,534	89,253
Other	259,479	273,408
Total noncurrent liabilities	4,594,049	4,435,321
Commitments and contingencies
Commitments and Contingencies
Stockholders' equity:
Common stock	204,163	203,889
Other paid-in capital	1,466,037	1,461,205
Retained earnings	1,951,138	1,762,410
Accumulated other comprehensive loss	(30,583)	(41,004)
Treasury stock at cost - 538,921 shares	(3,626)	(3,626)
Stockholders' Equity Attributable to Parent	3,587,129	3,382,874
Total liabilities and stockholders' equity	$ 9,660,781	$ 8,910,435
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Par or Stated Value Per Share	$ 1	$ 1
Common Stock, Shares, Issued	204,162,814	203,889,661
Treasury Stock, Common, Shares	538,921	538,921
MDU Resources Group, Inc. [Member]
Current assets:
Cash and cash equivalents	$ 19,486	$ 6,159	$ 8,781	$ 12,326
Receivables, net	4,410	6,120
Accounts receivable from subsidiaries	53,285	49,696
Prepayments and other current assets	3,237	2,528
Assets, Current	80,418	64,503
Noncurrent Assets
Investments	50,206	55,686
Investment in subsidiaries	3,581,754	3,368,537
Deferred income taxes	12,668	7,364
Operating lease right-of-use assets	72	114
Other	2,068	26,558
Total noncurrent assets	3,646,768	3,458,259
Total assets	3,727,186	3,522,762
Current liabilities:
Accounts payable	2,354	2,546
Accounts payable to subsidiaries	4,402	6,133
Taxes payable	572	1,672
Dividends payable	45,246	44,229
Accrued compensation	4,312	4,098
Operating lease liabilities due within one year	42	52
Other accrued liabilities	17,907	7,309
Total current liabilities	74,835	66,039
Noncurrent liabilities:
Operating lease liabilities	30	62
Other	65,192	73,787
Total noncurrent liabilities	65,222	73,849
Commitments and contingencies
Commitments and Contingencies
Stockholders' equity:
Common stock	204,163	203,889
Other paid-in capital	1,466,037	1,461,205
Retained earnings	1,951,138	1,762,410
Accumulated other comprehensive loss	(30,583)	(41,004)
Treasury stock at cost - 538,921 shares	(3,626)	(3,626)
Stockholders' Equity Attributable to Parent	3,587,129	3,382,874
Total liabilities and stockholders' equity	$ 3,727,186	$ 3,522,762
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Par or Stated Value Per Share	$ 1	$ 1
Common Stock, Shares, Issued	204,162,814	203,889,661
Treasury Stock, Common, Shares	538,921	538,921

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$ 510,064	$ 495,777	$ 768,374
Investments	(6,477)	(3,973)	(1,814)
Net cash used in investing activities	(638,881)	(885,878)	(630,243)
Proceeds from issuance of common stock	(149)	88,767	3,385
Dividends paid	(176,915)	(171,354)	(166,405)
Repurchase of common stock	(7,399)	(6,701)	0
Tax withholding on stock-based compensation	(4,904)	(4,127)	(362)
Net cash used in financing activities	155,173	384,715	(145,043)
Increase (decrease) in cash and cash equivalents	26,356	(5,386)	(6,912)
Cash and cash equivalents - beginning of year	54,161	59,547	66,459
Cash and cash equivalents - end of year	80,517	54,161	59,547
MDU Resources Group, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	242,199	187,297	226,642
Investments in and advances to subsidiaries	(45,000)	(102,000)	(67,000)
Investments	(885)	(391)	(4)
Net cash used in investing activities	(45,885)	(102,391)	(67,004)
Proceeds from issuance of common stock	(149)	88,767	3,385
Dividends paid	(176,915)	(171,354)	(166,405)
Repurchase of common stock	(3,525)	(2,992)	0
Tax withholding on stock-based compensation	(2,398)	(1,949)	(163)
Net cash used in financing activities	(182,987)	(87,528)	(163,183)
Increase (decrease) in cash and cash equivalents	13,327	(2,622)	(3,545)
Cash and cash equivalents - beginning of year	6,159	8,781	12,326
Cash and cash equivalents - end of year	$ 19,486	$ 6,159	$ 8,781

Notes to Condensed Financial St

Notes to Condensed Financial Statements (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
MDU Resources Group, Inc. [Member]
Condensed Financial Statements, Captions [Line Items]
Cash dividends paid to parent company by consolidated subsidiaries	$ 242.1	$ 188.1	$ 228.4