MDU Resources (MDU) 10-Q 3 Aug 23 2023 Q2 Quarterly report Financial data

Cover page

Cover page - shares	6 Months Ended
	Jun. 30, 2023	Aug. 01, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
Document Transition Report	false
Entity File Number	1-03480
Entity Registrant Name	MDU RESOURCES GROUP INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	30-1133956
Entity Address, Address Line One	1200 West Century Avenue
Entity Address, Address Line Two	P.O. Box 5650
Entity Address, City or Town	Bismarck
Entity Address, State or Province	ND
Entity Address, Postal Zip Code	58506-5650
City Area Code	701
Local Phone Number	530-1000
Title of 12(b) Security	Common Stock, par value $1.00 per share
Trading Symbol	MDU
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity common stock, shares outstanding		203,638,373
Entity Central Index Key	0000067716
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Amendment Flag	false

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating revenues:
Operating revenues:	$ 1,091,126	$ 1,009,749	$ 2,521,224	$ 2,116,864
Operating expenses:
Operation and maintenance:	769,593	709,517	1,566,138	1,310,073
Purchased natural gas sold	115,866	115,312	486,881	382,665
Depreciation, depletion and amortization	53,498	55,006	105,730	106,779
Taxes, other than income	49,706	45,480	117,133	99,057
Electric fuel and purchased power	20,432	21,929	44,789	48,290
Total operating expenses	1,009,095	947,244	2,320,671	1,946,864
Operating income	82,031	62,505	200,553	170,000
Unrealized Gain (Loss) on investment in Knife River	140,020	0	140,020	0
Other income (expense)	9,959	(2,209)	20,333	(3,253)
Interest expense	26,459	19,187	50,412	38,079
Income before income taxes	205,551	41,109	310,494	128,668
Income taxes	57,918	5,347	78,986	24,140
Income from continuing operations	147,633	35,762	231,508	104,528
Discontinued operations, net of tax	(16,941)	34,905	(62,464)	(2,098)
Net income	$ 130,692	$ 70,667	$ 169,044	$ 102,430
Earnings per share - basic:
Income from continuing operations	$ 0.72	$ 0.18	$ 1.14	$ 0.51
Discontinued operations, net of tax	(0.08)	0.17	(0.31)	(0.01)
Earnings per share - basic	0.64	0.35	0.83	0.50
Earnings per share - diluted:
Income from continuing operations	0.72	0.18	1.14	0.51
Discontinued operations, net of tax	(0.08)	0.17	(0.31)	(0.01)
Earnings per share - diluted	$ 0.64	$ 0.35	$ 0.83	$ 0.50
Weighted average common shares outstanding - basic	203,635	203,351	203,630	203,351
Weighted average common shares outstanding - diluted	203,877	203,401	203,894	203,396
Regulated operation
Operating revenues:
Operating revenues:	$ 340,492	$ 323,616	$ 1,014,423	$ 877,233
Operating expenses:
Operation and maintenance:	95,483	94,422	197,522	192,247
Income from continuing operations	21,832	4,429	86,296	60,047
Nonregulated operation
Operating revenues:
Operating revenues:	750,634	686,133	1,506,801	1,239,631
Operating expenses:
Operation and maintenance:	674,110	615,095	1,368,616	1,117,826
Income from continuing operations	$ 125,801	$ 31,333	$ 145,212	$ 44,481

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Net income	$ 130,692	$ 70,667	$ 169,044	$ 102,430
Other comprehensive income (loss):
Reclassification adjustment for loss on derivative instruments included in net income, tax	6	36	17	72
Reclassification adjustment for loss on derivative instruments included in net income, net of tax	47	111	81	223
Postretirement liability adjustment:
Amortization of postretirement liability losses included in net periodic benefit credit, tax	131	148	165	312
Amortization of postretirement liability losses included in net periodic benefit credit, net of tax	387	461	487	906
other comprehensive (income) loss, reclassification adjustment to aoci, postretirement liabiltiy adjustment from regulatory asset, tax	0	(1,086)	0	(1,086)
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset, net of tax	0	(3,265)	0	(3,265)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	387	(2,804)	487	(2,359)
Net unrealized gain (loss) on available-for-sale investments:
Net unrealized gain (loss) on available-for-sale investments arising during the period, tax	(22)	(34)	(4)	(119)
Net unrealized gain (loss) on available-for-sale investments arising during the period, net of tax	(84)	(128)	(14)	(448)
Reclassification adjustment for loss on available-for-sale investments included in net income, tax	3	7	6	15
Reclassification adjustment for loss on available-for-sale investments included in net income, net of tax	13	25	26	57
Net unrealized gain (loss) on available-for-sale investments	(71)	(103)	12	(391)
Other comprehensive income	363	(2,796)	580	(2,527)
Comprehensive income attributable to common stockholders	$ 131,055	$ 67,871	$ 169,624	$ 99,903

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Current assets:
Cash and cash equivalents	$ 50,780	$ 70,428	$ 53,663
Receivables, net	934,173	1,064,340	760,696
Current regulatory assets	193,162	165,092	102,535
Inventories	60,154	64,248	50,977
Prepayments and other current assets	60,502	55,123	82,533
Investment in Knife River	246,063	0	0
Current assets of discontinued operations	0	583,218	798,665
Total current assets	1,544,834	2,002,449	1,849,069
Noncurrent assets:
Property, plant and equipment	7,083,229	6,874,630	6,692,019
Less accumulated depreciation, depletion and amortization	2,160,439	2,098,298	2,067,811
Net property, plant and equipment	4,922,790	4,776,332	4,624,208
Goodwill	488,960	488,960	488,960
Other intangible assets, net	3,049	4,102	5,213
Regulatory assets	345,185	329,659	347,061
Investments	139,569	128,827	127,847
Operating lease right-of-use assets	74,553	73,502	69,869
Other	165,910	161,900	170,709
Noncurrent assets of discontinued operations	0	1,685,751	1,636,027
Total noncurrent assets	6,140,016	7,649,033	7,469,894
Total assets	7,684,850	9,651,482	9,318,963
Current liabilities:
Short-term borrowings	345,000	38,500	0
Long-term debt due within one year	1,319	47,819	86,319
Accounts payable	399,339	525,560	394,317
Taxes payable	60,284	62,308	97,471
Dividends payable	45,310	45,245	44,229
Accrued compensation	66,555	59,470	69,538
Operating lease liabilities due within one year	22,666	21,307	19,960
Regulatory liabilities due within one year	48,057	26,440	17,884
Other accrued liabilities	143,235	156,031	138,479
Current liabilities of discontinued operations	0	487,624	502,317
Total current liabilities	1,131,765	1,470,304	1,370,514
Noncurrent liabilities:
Long-term debt	2,246,103	2,317,848	2,003,881
Deferred income taxes	515,661	455,499	428,249
Asset retirement obligations	380,058	372,870	440,216
Regulatory liabilities	455,877	448,454	433,019
Operating lease liabilities	52,328	52,871	50,625
Other	196,865	180,603	178,204
Noncurrent liabilities of discontinued operations	0	765,904	1,027,445
Total noncurrent liabilities	3,846,892	4,594,049	4,561,639
Commitments and contingencies
Stockholders' equity:
Common stock	203,638	204,163	203,889
Other paid-in capital	1,460,735	1,466,037	1,454,131
Retained earnings	1,059,517	1,951,138	1,775,947
Accumulated other comprehensive loss	(17,697)	(30,583)	(43,531)
Treasury Stock, Common, Value	0	3,626	3,626
Total stockholders' equity	2,706,193	3,587,129	3,386,810
Total liabilities and stockholders' equity	$ 7,684,850	$ 9,651,482	$ 9,318,963
Common Stock, Shares Authorized	500,000,000	500,000,000	500,000,000
Common Stock, Par or Stated Value Per Share	$ 1	$ 1	$ 1
Common Stock, Shares, Issued	203,638,373	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	Accumulated other comprehensive loss	Treasury Stock, Common
Common stock balance (in shares) at Dec. 31, 2021		203,889,661
Balance at Dec. 31, 2021	$ 3,382,874	$ 203,889	$ 1,461,205	$ 1,762,410	$ (41,004)	$ (3,626)
Treasury Stock, Common, Shares at Dec. 31, 2021						(538,921)
Net income	31,763			31,763
Other comprehensive income	269				269
Dividends declared on common stock	(44,447)			(44,447)
Stock-based compensation	2,689		2,689
Repurchase of common stock						(266,821)
Repurchase of common stock	(7,399)					$ (7,399)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(12,303)
Treasury Stock, Shares, Retired						266,821
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						$ 7,399
Tax withholding on stock-based compensation	(4,904)
Issuance of common stock	(127)		(127)
Common stock balance (in shares) at Mar. 31, 2022		203,889,661
Balance at Mar. 31, 2022	3,360,718	$ 203,889	1,451,464	1,749,726	(40,735)	$ (3,626)
Treasury Stock, Common, Shares at Mar. 31, 2022						(538,921)
Common stock balance (in shares) at Dec. 31, 2021		203,889,661
Balance at Dec. 31, 2021	3,382,874	$ 203,889	1,461,205	1,762,410	(41,004)	$ (3,626)
Treasury Stock, Common, Shares at Dec. 31, 2021						(538,921)
Net income	102,430
Other comprehensive income	(2,527)
Tax withholding on stock-based compensation	$ (4,905)
Common stock balance (in shares) at Jun. 30, 2022	203,889,661	203,889,661
Balance at Jun. 30, 2022	$ 3,386,810	$ 203,889	1,454,131	1,775,947	(43,531)	$ (3,626)
Treasury Stock, Common, Shares at Jun. 30, 2022	538,921					(538,921)
Common stock balance (in shares) at Mar. 31, 2022		203,889,661
Balance at Mar. 31, 2022	$ 3,360,718	$ 203,889	1,451,464	1,749,726	(40,735)	$ (3,626)
Treasury Stock, Common, Shares at Mar. 31, 2022						(538,921)
Net income	70,667			70,667
Other comprehensive income	(2,796)				(2,796)
Dividends declared on common stock	(44,446)			(44,446)
Stock-based compensation	2,689		2,689
Issuance of common stock	$ (22)		(22)
Common stock balance (in shares) at Jun. 30, 2022	203,889,661	203,889,661
Balance at Jun. 30, 2022	$ 3,386,810	$ 203,889	1,454,131	1,775,947	(43,531)	$ (3,626)
Treasury Stock, Common, Shares at Jun. 30, 2022	538,921					(538,921)
Common stock balance (in shares) at Dec. 31, 2022	204,162,814	204,162,814
Balance at Dec. 31, 2022	$ 3,587,129	$ 204,163	1,466,037	1,951,138	(30,583)	$ (3,626)
Treasury Stock, Common, Shares at Dec. 31, 2022	538,921					(538,921)
Net income	$ 38,353			38,353
Other comprehensive income	217				217
Dividends declared on common stock	(45,574)			(45,574)
Stock-based compensation	3,108		3,108
Repurchase of common stock						(153,622)
Repurchase of common stock	(4,811)					$ (4,811)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(7,851)
Treasury Stock, Shares, Retired						153,622
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						$ 4,811
Tax withholding on stock-based compensation	(3,040)
Common stock balance (in shares) at Mar. 31, 2023		204,162,814
Balance at Mar. 31, 2023	$ 3,575,382	$ 204,163	1,461,294	1,943,917	(30,366)	$ (3,626)
Treasury Stock, Common, Shares at Mar. 31, 2023						(538,921)
Common stock balance (in shares) at Dec. 31, 2022	204,162,814	204,162,814
Balance at Dec. 31, 2022	$ 3,587,129	$ 204,163	1,466,037	1,951,138	(30,583)	$ (3,626)
Treasury Stock, Common, Shares at Dec. 31, 2022	538,921					(538,921)
Net income	$ 169,044
Other comprehensive income	$ 580
Treasury Stock, Shares, Retired	538,921
Tax withholding on stock-based compensation	$ (3,040)
Common stock balance (in shares) at Jun. 30, 2023	203,638,373	203,638,373
Balance at Jun. 30, 2023	$ 2,706,193	$ 203,638	1,460,735	1,059,517	(17,697)	$ 0
Treasury Stock, Common, Shares at Jun. 30, 2023						0
Common stock balance (in shares) at Mar. 31, 2023		204,162,814
Balance at Mar. 31, 2023	3,575,382	$ 204,163	1,461,294	1,943,917	(30,366)	$ (3,626)
Treasury Stock, Common, Shares at Mar. 31, 2023						(538,921)
Net income	130,692			130,692
Other comprehensive income	363				363
Dividends declared on common stock	(45,158)			(45,158)
Stock-based compensation	$ (927)		(927)
Treasury Stock, Shares, Retired	538,921
Separation of Knife River, Treasury Stock Retirement						538,921
Separation of Knife River	$ (954,541)	(539)		969,934	12,306	$ 3,626
Issuance of common stock (shares)	14,480
Stock Issued		$ 14
Issuance of common stock	$ 382		368
Common stock balance (in shares) at Jun. 30, 2023	203,638,373	203,638,373
Balance at Jun. 30, 2023	$ 2,706,193	$ 203,638	$ 1,460,735	$ 1,059,517	$ (17,697)	$ 0
Treasury Stock, Common, Shares at Jun. 30, 2023						0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating activities:
Net income	$ 169,044	$ 102,430
Discontinued operations, net of tax	(62,464)	(2,098)
Income from continuing operations	231,508	104,528
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	105,730	106,779
Deferred income taxes	55,478	2,439
Provision for credit losses	5,862	2,485
Amortization of debt issuance costs	792	481
Employee stock-based compensation costs	1,740	4,713
Pension and postretirement benefit plan net periodic benefit credit	(2,775)	(3,658)
Unrealized Gain (Loss) on investment in Knife River	(140,020)	0
Unrealized (gains) losses on investments	(4,885)	10,579
Gains on sales of assets	(4,887)	(2,935)
Changes in current assets and liabilities, net of acquisitions:
Receivables	124,306	(27,093)
Inventories	1,427	(4,741)
Other current assets	(27,614)	18,345
Accounts payable	(137,308)	27,113
Other current liabilities	19,090	34,858
Pension and postretirement benefit plan contributions	(17)	(54)
Other noncurrent changes	1,606	(12,449)
Net cash provided by continuing operations	230,033	261,390
Net cash used in discontinued operations	(156,932)	(142,282)
Net cash provided by operating activities	73,101	119,108
Investing activities:
Capital expenditures	(232,137)	(209,891)
Acquisitions, net of cash acquired	0	0
Net proceeds from sale or disposition of property and other	13,532	30
Investments	(2,974)	(3,072)
Net Cash Provided by (Used in) Investing Activities, Continuing Operations	(221,579)	(212,933)
Cash Provided by (Used in) Investing Activities, Discontinued Operations	(55,012)	(78,092)
Net cash used in investing activities	(276,591)	(291,025)
Financing activities:
Issuance of short-term borrowings	500,000	0
Repayment of short-term borrowings	(193,500)	0
Issuance of long-term debt	389,500	179,407
Repayment of long-term debt	(506,191)	(147,397)
Debt issuance costs	(1,864)	(320)
Net proceeds from issuance of common stock	0	(149)
Dividends paid	(90,552)	(88,457)
Repurchase of common stock	(4,811)	(7,399)
Tax withholding on stock-based compensation	(3,040)	(4,905)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations	89,542	(69,220)
Cash Provided by (Used in) Financing Activities, Discontinued Operations	94,300	254,028
Net Cash Provided by (Used in) Financing Activities, Total	183,842	184,808
Increase (decrease) in cash and cash equivalents	(19,648)	12,891
Cash and cash equivalents -- beginning of year	70,428	40,772
Cash and cash equivalents -- end of period	$ 50,780	$ 53,663

Basis of presentation

Basis of presentation	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	Basis of presentation The accompanying consolidated interim financial statements were prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Interim financial statements do not include all disclosures provided in annual financial statements and, accordingly, these financial statements should be read in conjunction with those appearing in the 2022 Annual Report. The information is unaudited but includes all adjustments that are, in the opinion of management, necessary for a fair presentation of the accompanying consolidated interim financial statements and are of a normal recurring nature. Depreciation, depletion and amortization expense is reported separately on the Consolidated Statements of Income and therefore is excluded from the other line items within operating expenses. As part of the Company's continuous review of its business, the Company announced strategic initiatives in 2022. On August 4, 2022, the Company announced that its board of directors approved a plan to pursue the separation of Knife River, the construction materials and contracting segment, from the Company. The separation was completed on May 31, 2023, and resulted in two independent, publicly traded companies, MDU Resources Group, Inc. and Knife River. The Company's board of directors approved the distribution of approximately 90 percent of the issued and outstanding shares of Knife River to the Company's stockholders. Stockholders of the Company received one share of Knife River common stock for every four shares of the Company's common stock held on May 22, 2023, the record date for the distribution. The Company retained approximately 10 percent of Knife River common stock immediately following the separation with the intent to dispose of such shares within twelve months after the separation. The separation of Knife River was a tax-free spinoff transaction to the Company’s stockholders for U.S. federal income tax purposes. The Company's consolidated financial statements and accompanying notes for the current and prior periods have been restated to present the results of operations and the assets and liabilities of Knife River as discontinued operations, other than certain corporate overhead costs of the Company historically allocated to Knife River, which are reflected in Other. Also included in discontinued operations in the Consolidated Statements of Income are the supporting activities of Fidelity and certain interest expense related to financing activity associated with the Knife River separation. Unless otherwise indicated, the amounts presented in the accompanying notes to the consolidated financial statements relate to the Company's continuing operations. For more information on discontinued operations, see Note 3. On November 3, 2022, the Company announced its intent to commence a strategic review of MDU Construction Services. Upon completing the strategic review of its wholly owned construction services business, the Company's board of directors announced on July 10, 2023, that it will pursue a tax-advantaged separation of the construction services business from the Company. The Company's board of directors believes a tax-advantaged separation of the construction services business supports the Company's goal of enhancing value for stockholders by becoming a pure-play regulated energy delivery company.

New accounting standards

New accounting standards	6 Months Ended
	Jun. 30, 2023
Accounting Standards Update and Change in Accounting Principle [Abstract]
New accounting standards	New accounting standards The following table provides a brief description of the accounting pronouncements applicable to the Company and the potential impact on its Consolidated Financial Statements and/or disclosures: Standard Description Effective date Impact on financial statements/disclosures Recently adopted accounting standards ASU 2020-04 - Reference Rate Reform In March 2020, the FASB issued optional guidance to ease the facilitation of the effects of reference rate reform on financial reporting. The guidance applies to certain contract modifications, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. Beginning January 1, 2022, LIBOR or other discontinued reference rates cannot be applied to new contracts. New contracts will incorporate a new reference rate, which includes SOFR. LIBOR or other discontinued reference rates cannot be applied to contract modifications or hedging relationships entered into or evaluated after December 31, 2022. Existing contracts referencing LIBOR or other reference rates expected to be discontinued must have identified 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 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. The Company does not expect the guidance to have a material impact on its results of operations, financial position, cash flows or disclosures.

Discontinued Operations and Dis

Discontinued Operations and Disposal Groups	6 Months Ended
	Jun. 30, 2023
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure	Discontinued operations On May 31, 2023, the Company completed the previously announced separation of Knife River, its construction materials and contracting segment, into a new publicly traded company. The separation was achieved through the Company's pro-rata distribution of approximately 90 percent of the outstanding shares of Knife River to the Company's common stockholders. To effect the separation, the Company distributed to its stockholders one share of Knife River common stock for every four shares of the Company's common stock held on May 22, 2023, the record date for the distribution, with the Company retaining approximately 10 percent of the shares of Knife River common stock immediately following the separation. The Company intends to dispose of the retained shares within twelve months after the separation. As a result of the separation, the historical assets and liabilities for Knife River have been classified as assets and liabilities of discontinued operations and the historical results of operations are shown in Discontinued operations, net of tax, other than allocated general corporate overhead costs of the Company, which do not meet the criteria for income (loss) from discontinued operations. The Company’s consolidated financial statements and accompanying notes for prior periods have been restated. For the comparative periods, Knife River's operations are only reflected through May 2023, whereas 2022 includes the full three and six months from Knife River's operations. On April 25, 2023, Knife River issued $425 million of senior notes, pursuant to an indenture, due 2031 to qualified institutional buyers. Knife River also entered into a new credit agreement which provided a revolving credit facility in an initial amount of up to $350 million and a senior secured term loan facility in an amount up to $275 million. The net proceeds from the notes offering, revolving credit facility and the term loan were used to repay $825 million of Knife River's intercompany obligations owed to Centennial. Centennial used the entirety of these proceeds from Knife River to repay a portion of its existing third-party indebtedness. As a result of the separation, the Company retained legal ownership of 538,921 shares of the Company's common stock that were historically owned by a subsidiary of Knife River and recorded in Treasury stock at cost. Following the separation, the 538,921 treasury shares were retired. The Company will provide to Knife River and Knife River will provide to the Company transition services in accordance with the TSA entered into on May 31, 2023. For the three and six months ended June 30, 2023, the Company received $599,000 and paid $277,000 related to these activities. The majority of the transition services are expected to be provided for a period of one year, however, no longer than two years after the separation. Separation costs of $41.2 million and $46.1 million, net of tax, were incurred during the three and six months ended June 30, 2023, respectively. Separation costs incurred are presented in income (loss) from discontinued operations in the Consolidated Statements of Income. These charges primarily relate to transaction and third-party support costs, one-time business separation fees and related tax charges. The Company had no assets or liabilities related to the discontinued operations of Knife River on its balance sheet as of June 30, 2023. The carrying amounts of the major classes of assets and liabilities of discontinued operations included in the Company’s Consolidated Balance Sheets were as follows: June 30, 2022 December 31, 2022 Assets (In Thousands) Current assets: Cash and cash equivalents $ 1,569 $ 790 Receivables, net 423,420 241,302 Inventories 350,457 323,277 Prepayments and other current assets 23,219 17,849 Total current assets of discontinued operations 798,665 583,218 Noncurrent assets: Net property, plant and equipment 1,264,604 1,315,213 Goodwill 274,302 274,540 Other intangible assets, net 14,827 13,430 Investments 33,400 33,086 Operating lease right-of-use assets 45,932 45,872 Other 2,962 3,610 Total noncurrent assets of discontinued operations 1,636,027 1,685,751 Total assets of discontinued operations $ 2,434,692 $ 2,268,969 Liabilities Current liabilities: Short-term borrowings $ 100,000 $ 208,000 Long-term debt due within one year 128,134 30,211 Accounts payable 174,585 122,309 Taxes payable (12,500) 8,502 Accrued compensation 28,621 29,192 Operating lease liabilities due within one year 13,666 13,210 Other accrued liabilities 69,811 76,200 Total current liabilities of discontinued operations 502,317 487,624 Noncurrent liabilities: Long-term debt 709,632 445,546 Deferred income taxes 169,484 175,804 Asset retirement obligations 27,779 33,015 Operating lease liabilities 32,266 32,663 Other 88,284 78,876 Total noncurrent liabilities of discontinued operations 1,027,445 765,904 Total liabilities of discontinued operations $ 1,529,762 $ 1,253,528 The reconciliation of the major classes of income and expense constituting pretax income (loss) from discontinued operations to the after-tax income (loss) from discontinued operations on the Consolidated Statements of Income were as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) Operating revenues $ 428,020 $ 711,227 $ 735,259 $ 1,020,726 Operating expenses 416,686 653,116 767,960 1,002,728 Operating income (loss) 11,334 58,111 (32,701) 17,998 Other income (expense) 1,889 (2,037) 2,381 (3,394) Interest expense 23,544 8,926 37,611 15,293 Income (loss) from discontinued operations before income taxes (10,321) 47,148 (67,931) (689) Income taxes 6,620 12,243 (5,467) 1,409 Income (loss) from discontinued operations $ (16,941) $ 34,905 $ (62,464) $ (2,098)

Seasonality of operations

Seasonality of operations	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Seasonality of operations	Seasonality of operationsSome of the Company's operations are highly seasonal and revenues from, and certain expenses for, such operations may fluctuate significantly among quarterly periods. Accordingly, the interim results for particular businesses, and for the Company as a whole, may not be indicative of results for the full fiscal year.

Receivables and allowance for e

Receivables and allowance for expected credit losses	6 Months Ended
	Jun. 30, 2023
Credit Loss [Abstract]
Receivables and allowance for expected credit loss	Receivables and allowance for expected credit losses Receivables consist primarily of trade receivables from the sale of goods and services, which are recorded at the invoiced amount, and contract assets, net of expected credit losses. For more information on contract assets, see Note 9. 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 $57.9 million, $27.4 million and $34.3 million at June 30, 2023 and 2022, and December 31, 2022, respectively. The Company's expected credit losses are determined through a review using historical credit loss experience; changes in asset specific characteristics; current conditions; and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly. The Company develops and documents its methodology to determine its allowance for expected credit losses at each of its reportable business segments. Risk characteristics used by the business segments may include customer mix, knowledge of customers and general economic conditions of the various local economies, among others. Specific account balances are written off when management determines the amounts to be uncollectible. Management has reviewed the balance reserved through the allowance for expected credit losses and believes it is reasonable. Details of the Company's expected credit losses were as follows: Electric Natural gas Pipeline Construction Total (In thousands) At December 31, 2022 $ 375 $ 1,615 $ 2 $ 2,162 $ 4,154 Current expected credit loss provision 615 2,324 — 826 3,765 Less write-offs charged against the allowance 667 1,225 — 51 1,943 Credit loss recoveries collected 145 229 — 1 375 At March 31, 2023 $ 468 $ 2,943 $ 2 $ 2,938 $ 6,351 Current expected credit loss provision 182 90 — 1,825 2,097 Less write-offs charged against the allowance 316 1,454 — 103 1,873 Credit loss recoveries collected 79 161 — 58 298 At June 30, 2023 $ 413 $ 1,740 $ 2 $ 4,718 $ 6,873 Electric Natural gas Pipeline Construction Total (In thousands) At December 31, 2021 $ 269 $ 1,506 $ 2 $ 2,533 $ 4,310 Current expected credit loss provision 565 1,369 — 54 1,988 Less write-offs charged against the allowance 597 932 — 71 1,600 Credit loss recoveries collected 124 180 — 28 332 At March 31, 2022 $ 361 $ 2,123 $ 2 $ 2,544 $ 5,030 Current expected credit loss provision 113 92 — 292 497 Less write-offs charged against the allowance 234 939 — 104 1,277 Credit loss recoveries collected 108 177 — — 285 At June 30, 2022 $ 348 $ 1,453 $ 2 $ 2,732 $ 4,535

Inventories and natural gas in

Inventories and natural gas in storage	6 Months Ended
	Jun. 30, 2023
Inventory Disclosure [Abstract]
Inventories and natural gas in storage	Inventories and natural gas in storage Natural gas in storage for the Company's regulated operations is generally valued at lower of cost or market using the last-in, first-out method or lower of cost or net realizable value using the average cost or first-in, first-out method. The majority of all other inventories are valued at the lower of cost or net realizable value using the average cost method. The portion of the cost of natural gas in storage expected to be used within 12 months was included in inventories. Inventories on the Consolidated Balance Sheets were as follows: June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Merchandise for resale 32,498 25,216 27,910 Natural gas in storage (current) 15,388 15,014 22,533 Materials and supplies $ 6,391 $ 6,269 $ 6,846 Other 5,877 4,478 6,959 Total $ 60,154 $ 50,977 $ 64,248

Earnings per share

Earnings per share	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Earnings per share	Earnings per share Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted earnings per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the applicable period, plus the effect of non-vested performance share awards and restricted stock units. Common stock outstanding includes issued shares less shares held in treasury. As a result of the separation, the Company retained legal ownership of 538,921 shares of the Company's common stock that were historically owned by a subsidiary of Knife River and recorded in Treasury stock at cost. Following the separation, the 538,921 treasury shares were retired. The 538,921 shares of treasury stock did not have an impact on weighted-average shares outstanding, as they were not outstanding prior to being retired. Net income was the same for both the basic and diluted earnings per share calculations. A reconciliation of the weighted average common shares outstanding used in the basic and diluted earnings per share calculations follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands, except per share amounts) Weighted average common shares outstanding - basic 203,635 203,351 203,630 203,351 Effect of dilutive performance share awards and restricted stock units 242 50 264 45 Weighted average common shares outstanding - diluted 203,877 203,401 203,894 203,396 Earnings per share - basic: Income from continuing operations .72 .18 1.14 .51 Discontinued operations, net of tax (.08) .17 (.31) (.01) Earnings per share - basic .64 .35 .83 .50 Earnings per share - diluted: Income from continuing operations 0.72 .18 1.14 .51 Discontinued operations, net of tax (.08) .17 (.31) (.01) Earnings per share - diluted .64 .35 .83 .50 Shares excluded from the calculation of diluted earnings per share — 52 — 175 Dividends declared per common share $ .2225 $ .2175 $ .4450 $ .4350

Accumulated other comprehensive

Accumulated other comprehensive loss	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Accumulated other comprehensive loss	Accumulated other comprehensive loss The after-tax changes in the components of accumulated other comprehensive loss were as follows: Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2022 $ (125) $ (29,900) $ (558) $ (30,583) Other comprehensive income before reclassifications — — 70 70 Amounts reclassified from accumulated other comprehensive loss 34 100 13 147 Net current-period other comprehensive income 34 100 83 217 At March 31, 2023 $ (91) $ (29,800) $ (475) $ (30,366) Other comprehensive income before reclassifications — — (84) (84) Amounts reclassified from accumulated other comprehensive loss 47 387 13 447 Net current-period other comprehensive income (loss) 47 387 (71) 363 Amounts reclassified related to the separation of Knife River 44 12,262 — 12,306 At June 30, 2023 $ — $ (17,151) $ (546) $ (17,697) Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2021 $ (538) $ (40,461) $ (5) $ (41,004) Other comprehensive loss before reclassifications — — (320) (320) Amounts reclassified from accumulated other comprehensive loss 112 445 32 589 Net current-period other comprehensive income (loss) 112 445 (288) 269 At March 31, 2022 $ (426) $ (40,016) $ (293) $ (40,735) Other comprehensive loss before reclassifications — — (128) (128) Amounts reclassified to accumulated other comprehensive loss from a regulatory asset — (3,265) — (3,265) Amounts reclassified from accumulated other comprehensive loss 111 461 25 597 Net current-period other comprehensive income (loss) 111 (2,804) (103) (2,796) At June 30, 2022 $ (315) $ (42,820) $ (396) $ (43,531) The following amounts were reclassified out of accumulated other comprehensive loss into net income. The amounts presented in parenthesis indicate a decrease to net income on the Consolidated Statements of Income. The reclassifications were as follows: Three Months Ended Six Months Ended Location on Consolidated June 30, June 30, 2023 2022 2023 2022 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (53) $ (147) $ (98) $ (295) Interest expense 6 36 17 72 Income taxes (47) (111) (81) (223) Amortization of postretirement liability losses included in net periodic benefit credit (518) (609) (652) (1,218) Other income 131 148 165 312 Income taxes (387) (461) (487) (906) Reclassification adjustment on available-for-sale investments included in net income (16) (32) (32) (72) Other income 3 7 6 15 Income taxes (13) (25) (26) (57) Total reclassifications $ (447) $ (597) $ (594) $ (1,186)

Revenue from contracts with cus

Revenue from contracts with customers	6 Months Ended
	Jun. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenue from contracts with customers	Revenue from contracts with customers Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes. Disaggregation In the following tables, revenue is disaggregated by the type of customer or service provided. The Company believes this level of disaggregation best depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. The table also includes a reconciliation of the disaggregated revenue by reportable segments. For more information on the Company's business segments, see Note 18. Three Months Ended June 30, 2023 Electric Natural gas Pipeline Construction Other Total (In thousands) Residential utility sales $ 30,825 $ 120,967 $ — $ — $ — $ 151,792 Commercial utility sales 38,262 71,196 — — — 109,458 Industrial utility sales 10,370 9,183 — — — 19,553 Other utility sales 1,710 — — — — 1,710 Natural gas transportation — 11,671 34,394 — — 46,065 Natural gas storage — — 3,758 — — 3,758 Electrical & mechanical specialty contracting — — — 568,307 — 568,307 Transmission & distribution specialty contracting — — — 167,485 — 167,485 Other 11,531 3,272 3,937 177 3,151 22,068 Intersegment eliminations (27) (69) (7,918) — (3,151) (11,165) Revenues from contracts with customers 92,671 216,220 34,171 735,969 — 1,079,031 Revenues out of scope (1,682) 2,775 38 10,964 — 12,095 Total external operating revenues $ 90,989 $ 218,995 $ 34,209 $ 746,933 $ — $ 1,091,126 Three Months Ended June 30, 2022 Electric Natural gas Pipeline Construction Other Total (In thousands) Residential utility sales $ 29,363 $ 116,749 $ — $ — $ — $ 146,112 Commercial utility sales 34,015 72,354 — — — 106,369 Industrial utility sales 10,923 9,009 — — — 19,932 Other utility sales 1,880 — — — — 1,880 Natural gas transportation — 11,456 31,967 — — 43,423 Natural gas storage — — 2,896 — — 2,896 Electrical & mechanical specialty contracting — — — 507,233 — 507,233 Transmission & distribution specialty contracting — — — 166,174 — 166,174 Other 10,216 3,751 2,676 109 1,456 18,208 Intersegment eliminations (34) (71) (7,787) (1,527) (1,456) (10,875) Revenues from contracts with customers 86,363 213,248 29,752 671,989 — 1,001,352 Revenues out of scope (812) (2,738) 66 11,881 — 8,397 Total external operating revenues $ 85,551 $ 210,510 $ 29,818 $ 683,870 $ — $ 1,009,749 Six Months Ended June 30, 2023 Electric Natural gas Pipeline Construction Other Total (In thousands) Residential utility sales $ 68,650 $ 448,617 $ — $ — $ — $ 517,267 Commercial utility sales 74,609 276,122 — — — 350,731 Industrial utility sales 21,133 26,021 — — — 47,154 Other utility sales 3,484 — — — — 3,484 Natural gas transportation — 25,175 69,378 — — 94,553 Natural gas storage — — 7,620 — — 7,620 Electrical & mechanical specialty contracting — — — 1,158,570 — 1,158,570 Transmission & distribution specialty contracting — — — 319,507 — 319,507 Other 23,410 7,993 5,797 209 4,723 42,132 Intersegment eliminations (55) (139) (34,188) — (4,723) (39,105) Revenues from contracts with customers 191,231 783,789 48,607 1,478,286 — 2,501,913 Revenues out of scope (4,545) 801 76 22,979 — 19,311 Total external operating revenues $ 186,686 $ 784,590 $ 48,683 $ 1,501,265 $ — $ 2,521,224 Six Months Ended June 30, 2022 Electric Natural gas Pipeline Construction Other Total (In thousands) Residential utility sales $ 66,667 $ 375,565 $ — $ — $ — $ 442,232 Commercial utility sales 69,615 235,963 — — — 305,578 Industrial utility sales 21,229 22,033 — — — 43,262 Other utility sales 3,630 — — — — 3,630 Natural gas transportation — 23,837 63,541 — — 87,378 Natural gas storage — — 6,615 — — 6,615 Electrical & mechanical specialty contracting — — — 900,041 — 900,041 Transmission & distribution specialty contracting — — — 314,640 — 314,640 Other 22,969 6,360 4,387 156 2,896 36,768 Intersegment eliminations (68) (137) (33,729) (2,353) (2,896) (39,183) Revenues from contracts with customers 184,042 663,621 40,814 1,212,484 — 2,100,961 Revenues out of scope (4,807) (2,623) 124 23,209 — 15,903 Total external operating revenues $ 179,235 $ 660,998 $ 40,938 $ 1,235,693 $ — $ 2,116,864 Contract balances The timing of revenue recognition may differ from the timing of invoicing to customers. The timing of invoicing to customers does not necessarily correlate with the timing of revenues being recognized under the cost-to-cost method of accounting. Contracts from construction work are billed as work progresses in accordance with agreed upon contractual terms. Generally, billing to the customer occurs contemporaneous to revenue recognition. A variance in timing of the billings may result in a contract asset or a contract liability. A contract asset occurs when revenues are recognized under the cost-to-cost measure of progress, which exceeds amounts billed on uncompleted contracts. Such amounts will be billed as standard contract terms allow, usually based on various measures of performance or achievement. A contract liability occurs when there are billings in excess of revenues recognized under the cost-to-cost measure of progress on uncompleted contracts. Contract liabilities decrease as revenue is recognized from the satisfaction of the related performance obligation. The changes in contract assets and liabilities were as follows: June 30, 2023 December 31, 2022 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 179,282 $ 154,144 $ 25,138 Receivables, net Contract liabilities - current (166,268) (168,361) 2,093 Accounts payable Contract liabilities - noncurrent (438) (6) (432) Noncurrent liabilities - other Net contract assets (liabilities) $ 12,576 $ (14,223) $ 26,799 The Company recognized $23.4 million and $157.9 million in revenue for the three and six months ended June 30, 2023, respectively, which was previously included in contract liabilities at December 31, 2022. The Company recognized $8.6 million and $110.4 million in revenue for the three and six months ended June 30, 2022, respectively, which was previously included in contract liabilities at December 31, 2021. The Company recognized a net increase in revenues of $23.1 million and $31.8 million for the three and six months ended June 30, 2023, respectively, from performance obligations satisfied in prior periods. The Company recognized a net increase in revenues of $24.3 million and $33.2 million for the three and six months ended June 30, 2022, respectively, from performance obligations satisfied in prior periods. Remaining performance obligations The remaining performance obligations, also referred to as backlog, at the construction services segment includes unrecognized revenues that the Company reasonably expects to be realized. These unrecognized revenues can include: projects that have a written award, a letter of intent, a notice to proceed, an agreed upon work order to perform work on mutually accepted terms and conditions and change orders or claims to the extent management believes additional contract revenues will be earned and are deemed probable of collection. Excluded from remaining performance obligations are potential orders under master service agreements. The majority of the Company's contracting services contracts have an original duration of less than two years. The remaining performance obligations at the pipeline segment include firm transportation and storage contracts with fixed pricing and fixed volumes. The Company has applied the practical expedient, which does not require additional disclosures for contracts with an original duration of less than 12 months, to certain firm transportation and non-regulated contracts. The Company's firm transportation and firm storage contracts included in the remaining performance obligations have weighted average remaining durations of approximately less than five years and two years, respectively. At June 30, 2023, the Company's remaining performance obligations were $2.5 billion. The Company expects to recognize the following revenue amounts in future periods related to these remaining performance obligations: $1.6 billion within the next 12 months or less; $384.0 million within the next 13 to 24 months; and $544.0 million in 25 months or more.

Leases

Leases	6 Months Ended
	Jun. 30, 2023
Leases [Abstract]
Lessee, Operating Leases	Leases The Company's leases primarily include operating leases for equipment, buildings, easements and vehicles. The Company leases certain equipment to third parties through its utility and construction services segments, which are considered short-term operating leases with terms of less than 12 months. The Company recognized revenue from operating leases of $11.1 million and $23.3 million for the three and six months ended June 30, 2023, respectively. The Company recognized revenue from operating leases of $12.0 million and $23.4 million for the three and six months ended June 30, 2022, respectively. At June 30, 2023, the Company had $7.9 million of lease receivables with a majority due within 12 months.

Goodwill and other intangible a

Goodwill and other intangible assets	6 Months Ended
	Jun. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and other intangible assets	Goodwill and other intangible assets The carrying amount of goodwill, which is related to the natural gas distribution and construction services segments, remained unchanged at $489.0 million at June 30, 2023 and 2022, and December 31, 2022. No impairments of goodwill have been recorded in these periods. Other amortizable intangible assets were as follows: June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Customer relationships $ 10,450 $ 10,450 $ 10,450 Less accumulated amortization 7,401 5,312 6,356 3,049 5,138 4,094 Noncompete agreements 292 552 552 Less accumulated amortization 292 477 544 — 75 8 Total $ 3,049 $ 5,213 $ 4,102 Amortization expense for amortizable intangible assets for the three and six months ended June 30, 2023, was $522,000 and $1.1 million, respectively. Amortization expense for amortizable intangible assets for the three and six months ended June 30, 2022, was $568,000 and $1.1 million, respectively. Amortization expense for identifiable intangible assets as of June 30, 2023 is estimated to be as follows: Remainder of 2023 2024 2025 2026 2027 Thereafter (In thousands) Amortization expense $ 1,045 $ 1,888 $ 116 $ — $ — $ —

Regulatory assets and liabiliti

Regulatory assets and liabilities	6 Months Ended
	Jun. 30, 2023
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Regulatory assets and liabilities The following table summarizes the individual components of unamortized regulatory assets and liabilities: Estimated Recovery or Refund Period as of June 30, 2023 * June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 170,249 $ 83,557 $ 141,306 Conservation programs Up to 1 year 10,897 7,883 8,544 Cost recovery mechanisms Up to 1 year 4,758 3,459 4,019 Other Up to 1 year 7,258 7,636 11,223 193,162 102,535 165,092 Noncurrent: Pension and postretirement benefits ** 144,448 137,582 143,349 Cost recovery mechanisms Up to 10 years 63,890 64,096 67,171 Plant costs/asset retirement obligations Over plant lives 43,855 63,334 44,462 Manufactured gas plant site remediation - 25,764 26,031 26,624 Plant to be retired - 20,858 27,628 21,525 Environmental compliance programs - 20,611 — — Taxes recoverable from customers Over plant lives 12,099 12,365 12,330 Long-term debt refinancing costs Up to 37 years 2,894 3,482 3,188 Other Up to 16 years 10,766 12,543 11,010 345,185 347,061 329,659 Total regulatory assets $ 538,347 $ 449,596 $ 494,751 Regulatory liabilities: Current: Natural gas costs refundable through rate adjustments Up to 1 year 17,820 738 955 Electric fuel and purchased power deferral Up to 1 year 8,481 4,161 4,929 Cost recovery mechanisms Up to 1 year 3,304 3,172 1,977 Conservation programs Up to 1 year 2,851 352 4,126 Taxes refundable to customers Up to 1 year 1,513 3,728 3,937 Refundable fuel and electric costs Up to 1 year 103 1,092 3,253 Other Up to 1 year 13,985 4,641 7,263 48,057 17,884 26,440 Noncurrent: Plant removal and decommissioning costs Over plant lives 216,682 172,755 208,650 Taxes refundable to customers Over plant lives 197,757 209,022 203,222 Cost recovery mechanisms Up to 19 years 18,226 10,898 14,025 Accumulated deferred investment tax credit Up to 19 years 14,398 14,009 13,594 Pension and postretirement benefits ** 7,120 19,686 7,376 Other Up to 15 years 1,694 6,649 1,587 455,877 433,019 448,454 Total regulatory liabilities $ 503,934 $ 450,903 $ 474,894 Net regulatory position $ 34,413 $ (1,307) $ 19,857 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made. At June 30, 2023 and 2022, and December 31, 2022, approximately $226.4 million, $262.9 million and $242.5 million, respectively, of regulatory assets were not earning a rate of return; however, these regulatory assets are expected to be recovered from customers in future rates. These assets are largely comprised of the unfunded portion of pension and postretirement benefits, the estimated future cost of manufactured gas plant site remediation, accelerated depreciation on plant retirement and the costs associated with environmental compliance. The Company is subject to environmental compliance regulations in certain states which require natural gas distribution companies to reduce overall GHG emissions to certain thresholds as established by each applicable state. Compliance with these standards may be achieved through increased energy efficiency and conservation measures, purchased emission allowances and offsets, purchases of community climate investment credits and purchases of low carbon fuels. Emission allowances are allocated by the respective states to the Company at no cost, of which a portion is required to be sold at auction. The Company expects the compliance costs for these regulations and the revenues from the sale of the allocated emissions allowances will be passed through to customers in rates and has, accordingly, deferred the environmental compliance obligation as a regulatory asset. In the last half of 2021 through 2022, the Company experienced high natural gas costs due to increase in demand outpacing the supply along with the impact of global events. Additionally, in December 2022 and January 2023, natural gas prices significantly increased across the Pacific Northwest from multiple price-pressuring events including wide-spread below-normal temperatures and higher natural gas consumption; reduced natural gas flows due to pipeline constraints, including maintenance in West Texas; and historically low regional natural gas storage levels. This increase in natural gas costs experienced in certain jurisdictions was partially offset by the recovery of prior period natural gas costs being recovered over a period longer than the normal one-year period. For a discussion of the Company's most recent cases by jurisdiction, see Note 21. In February 2019, the Company announced the retirement of three aging coal-fired electric generating units. The Company accelerated the depreciation related to these facilities in property, plant and equipment and recorded the difference between the accelerated depreciation, in accordance with GAAP, and the depreciation approved for rate-making purposes as regulatory assets. Requests were filed with the NDPSC and SDPUC, and subsequently approved, to offset the savings associated with the cessation of operations of these units with the amortization of the deferred regulatory assets. The Company ceased operations of Lewis & Clark Station in March 2021 and Units 1 and 2 at Heskett Station in February 2022. The Company subsequently reclassified the costs being recovered for these facilities from plant retirement to cost recovery mechanisms in the previous table and began amortizing the associated plant retirement and closure costs in the jurisdictions where requests were filed. The Company expects to recover the regulatory assets related to the plant retirements in future rates. If, for any reason, the Company's regulated businesses cease to meet the criteria for application of regulatory accounting for all or part of their operations, the regulatory assets and liabilities relating to those portions ceasing to meet such criteria would be written off and included in the statement of income or accumulated other comprehensive loss in the period in which the discontinuance of regulatory accounting occurs.

Fair value measurements

Fair value measurements	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. The fair value ASC establishes a hierarchy for grouping assets and liabilities, based on the significance of inputs. The estimated fair values of the Company's assets and liabilities measured on a recurring basis are determined using the market approach. The Company measures its investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income. The Company anticipates using these investments, which consist of insurance contracts, to satisfy its obligations under its unfunded, nonqualified defined benefit and defined contribution plans for executive officers and certain key management employees, and invests in these fixed-income and equity securities for the purpose of earning investment returns and capital appreciation. These investments, which totaled $84.1 million, $77.5 million and $78.0 million, at June 30, 2023 and 2022, and December 31, 2022, respectively, are classified as investments on the Consolidated Balance Sheets. The net unrealized gain on these investments was $1.9 million and $4.9 million for the three and six months ended June 30, 2023, respectively. The net unrealized loss on these investments was $6.7 million and $11.0 million for the three and six months ended June 30, 2022, 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: June 30, 2023 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,542 $ — $ 651 $ 7,891 U.S. Treasury securities 3,091 5 46 3,050 Total $ 11,633 $ 5 $ 697 $ 10,941 June 30, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,128 $ — $ 419 $ 7,709 U.S. Treasury securities 3,125 — 83 3,042 Total $ 11,253 $ — $ 502 $ 10,751 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 On May 31, 2023, the Company completed the Knife River separation and retained approximately 10 percent, or 5.7 million shares of Knife River common stock immediately following the separation. The Company did not retain a controlling interest in Knife River and therefore the fair value of its retained shares and subsequent fair value changes are included in assets of and results from continuing operations, respectively. At June 30, 2023, the fair value of the Company’s investment in Knife River common stock of $246.1 million was reflected in Investment in Knife River on the Consolidated Balance Sheet and was remeasured at fair value based on Knife River’s closing stock price on June 30, 2023, with an unrealized gain of $140.0 million recorded in Unrealized gain on investment in Knife River on the Consolidated Statement of Income. The Company's assets measured at fair value on a recurring basis were as follows: Fair Value Measurements at June 30, 2023, Using Quoted Prices in Significant Significant Balance at June 30, 2023 (In thousands) Assets: Investment in Knife River $ 246,063 $ — $ — $ 246,063 Money market funds — 5,737 — 5,737 Insurance contracts* — 84,099 — 84,099 Available-for-sale securities: Mortgage-backed securities — 7,891 — 7,891 U.S. Treasury securities — 3,050 — 3,050 Total assets measured at fair value $ 246,063 $ 100,777 $ — $ 346,840 * The insurance contracts invest approximately 67 percent in fixed-income investments, 14 percent in common stock of large-cap companies, 7 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 4 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at June 30, 2022, Using Quoted Prices in Significant Significant Balance at June 30, 2022 (In thousands) Assets: Money market funds $ — $ 5,976 $ — $ 5,976 Insurance contracts* — 77,529 — 77,529 Available-for-sale securities: Mortgage-backed securities — 7,709 — 7,709 U.S. Treasury securities — 3,042 — 3,042 Total assets measured at fair value $ — $ 94,256 $ — $ 94,256 * The insurance contracts invest approximately 64 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 7 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at December 31, 2022, Using Quoted Prices in Significant Significant Balance at December 31, 2022 (In thousands) Assets: Money market funds $ — $ 4,913 $ — $ 4,913 Insurance contracts* — 77,958 — 77,958 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 $ — $ 93,701 $ — $ 93,701 * The insurance contracts invest approximately 63 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. The Company's money market funds are valued at the net asset value of shares held at the end of the period, based on published market quotations on active markets, or using other known sources including pricing from outside sources. The estimated fair value of the Company's mortgage-backed securities and U.S. Treasury securities are based on comparable market transactions, other observable inputs or other sources, including pricing from outside sources. The estimated fair value of the Company's insurance contracts are based on contractual cash surrender values that are determined primarily by investments in managed separate accounts of the insurer. These amounts approximate fair value. The managed separate accounts are valued based on other observable inputs or corroborated market data. Though the Company believes the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value. The Company applies the provisions of the fair value measurement standard to its nonrecurring, non-financial measurements, including long-lived asset impairments. These assets are not measured at fair value on an ongoing basis but are subject to fair value adjustments only in certain circumstances. The Company reviews the carrying value of its long-lived assets, excluding goodwill, whenever events or changes in circumstances indicate that such carrying amounts may not be recoverable. The Company's long-term debt is not measured at fair value on the Consolidated Balance Sheets and the fair value is being provided for disclosure purposes only. The fair value was categorized as Level 2 in the fair value hierarchy and was based on discounted future cash flows using current market interest rates. The estimated fair value of the Company's Level 2 long-term debt was as follows: June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Carrying amount $ 2,247,422 $ 2,090,200 $ 2,365,667 Fair value $ 1,949,905 $ 1,940,092 $ 2,053,396 The carrying amounts of the Company's remaining financial instruments included in current assets and current liabilities approximate their fair values .

Debt

Debt	6 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Debt	Debt Due to the Knife River separation, Centennial repaid all of its outstanding debt in the second quarter of 2023, which was facilitated by the Knife River repayment and the Company entering into various new debt instruments. Refer to Note 3 for additional information related to the repayment of debt associated with the Knife River separation. Certain debt instruments of the Company and its subsidiaries contain restrictive and financial covenants and cross-default provisions. In order to borrow under the debt agreements, the Company and its subsidiaries must be in compliance with the applicable covenants and certain other conditions, all of which the Company and its subsidiaries, as applicable, were in compliance with at June 30, 2023. In the event the Company or its subsidiaries do not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued. Montana-Dakota's commercial paper program is supported by a revolving credit agreement. While the amount of commercial paper outstanding does not reduce available capacity under the respective revolving credit agreement, Montana-Dakota does not issue commercial paper in an aggregate amount exceeding the available capacity under the credit agreement. The commercial paper and revolving credit agreement 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 and its subsidiaries. Short-term debt Cascade 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. Intermountain 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. In March, April, and May 2023, Intermountain paid down $20.0 million, $30.0 million, and $30.0 million, respectively, of the outstanding balance. The agreement contains customary covenants and provisions, including a covenant of Intermountain not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. Centennial On March 18, 2022, Centennial entered into a $100.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of March 17, 2023. On March 17, 2023, Centennial amended this agreement to extend the maturity date to September 15, 2023. The agreement contained 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 included certain restrictions on the sale of certain assets, loans and investments. On May 31, 2023, Centennial repaid the full balance outstanding under the term loan agreement. O n 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 contained 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 included certain restrictions on the sale of certain assets, loans and investments. On May 31, 2023, Centennial repaid the full balance outstanding under the term loan agreement. MDU Resources Group, Inc. On May 1, 2023, the Company entered into a $75.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of November 1, 2023. The agreement contained customary covenants and provisions, including a covenant of the Company not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also included certain restrictions on the sale of certain assets, loans and investments. On May 31, 2023, the Company repaid the full balance outstanding under the term loan agreement. On May 31, 2023, the Company entered into a $150.0 million revolving credit agreement with a SOFR-based variable interest rate and a maturity date of May 29, 2024. The agreement contains customary covenants and provisions, including a covenant of the Company not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. Long-term debt Centennial On June 9, 2023, Centennial repaid the full balances outstanding on all its long-term senior note debt, which aggregated $455.0 million. MDU Resources Group, Inc . On May 31, 2023, the Company entered into a $200.0 million revolving credit agreement with a SOFR-based variable interest rate and a maturity date of May 31, 2028. 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 the Company not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. On May 31, 2023, the Company entered into a $375.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of May 31, 2025. The term loan agreement contains customary covenants and provisions, including a covenant of the Company not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. Long-term Debt Outstanding Long-term debt outstanding was as follows: Weighted Average Interest Rate at June 30, 2023 June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Senior Notes due on dates ranging from October 13, 2027 to June 15, 2062 4.33 % $ 1,757,000 $ 1,847,000 $ 1,848,500 Term Loan Agreements due on dates ranging from May 31, 2025 to September 3, 2032 6.46 % 382,000 7,700 7,000 Commercial paper supported by revolving credit agreement 5.70 % 58,900 175,020 349,050 Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 7.32 % 35,000 35,000 35,000 Credit agreements due on dates ranging from October 13, 2027 to May 31, 2028 8.35 % 20,300 29,860 130,000 Other notes due on dates ranging from January 1, 2024 to November 30, 2038 2.24 % 987 1,621 1,614 Less unamortized debt issuance costs 6,765 5,406 5,211 Less discount — 595 286 Total long-term debt 2,247,422 2,090,200 2,365,667 Less current maturities 1,319 86,319 47,819 Net long-term debt $ 2,246,103 $ 2,003,881 $ 2,317,848 Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs and discount, at June 30, 2023, were as follows: Remainder of 2023 2024 2025 2026 2027 Thereafter (In thousands) Long-term debt maturities $ 1,319 $ 119,600 $ 532,700 $ 140,700 $ 26,500 $ 1,433,368

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Income Tax Disclosure	Income taxes During the three and six months ended June 30, 2023, Income before income taxes was $205,551 and $310,494 respectively, while income tax expense was $57,918 and $78,986, respectively. The effective tax rate was 28.2 percent and 25.4 percent for the three and six months ended June 30, 2023, respectively. The effective tax rate for the current three and six month periods differed from the 2023 statutory rate of 24.9 percent primarily due to tax expense recorded related to basis differences in the Company's retained Knife River shares. During the three and six months ended June 30, 2022, Income before income taxes was $41,109 and $128,668 respectively, and income tax expense was $5,347 and $24,140, respectively. The effective tax rate was 13.0 percent and 18.8 percent for the three

Cash flow information

Cash flow information	6 Months Ended
	Jun. 30, 2023
Supplemental Cash Flow Information [Abstract]
Cash flow information	Cash flow information Cash expenditures for interest and income taxes were as follows: Six Months Ended June 30, 2023 2022 (In thousands) Interest, net* $ 54,616 $ 39,573 Income taxes paid, net** $ 17,542 $ 50 * AFUDC - borrowed was $4.9 million and $1.3 million for the six months ended June 30, 2023 and 2022, respectively. ** Income taxes paid, including discontinued operations, were $18.3 million and $16.5 million for the six months ended June 30, 2023 and 2022, respectively. Noncash investing and financing transactions were as follows: June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 24,201 $ 14,148 $ 39,158 Property, plant and equipment additions in accounts payable $ 37,076 $ 40,510 $ 35,637

Business segment data

Business segment data	6 Months Ended
	Jun. 30, 2023
Segment Reporting [Abstract]
Business segment data	Business segment data The Company's reportable segments are those that are based on the Company's method of internal reporting, which generally segregates the strategic business units due to differences in products, services and regulation. The internal reporting of these operating segments is defined based on the reporting and review process used by the Company's chief executive officer. The Company's operations are located within the United States. The electric segment generates, transmits and distributes electricity in Montana, North Dakota, South Dakota and Wyoming. The natural gas distribution segment distributes natural gas in those states, as well as in Idaho, Minnesota, Oregon and Washington. These operations also supply related value-added services. The pipeline segment provides natural gas transportation and underground storage services through a regulated pipeline system primarily in the Rocky Mountain and northern Great Plains regions of the United States. This segment also provides non-regulated cathodic protection services. The construction 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 supplying transmission and distribution 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, Fidelity and Knife River which do not meet the criteria for income (loss) from discontinued operations. Discontinued operations includes strategic initiative costs and interest on debt facilities repaid in connection with the Knife River separation and the supporting activities of Fidelity other than certain general and administrative costs and interest expense as described above. The information below follows the same accounting policies as described in Note 2 of the Notes to Consolidated Financial Statements in the 2022 Annual Report. Information on the Company's segments was as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) External operating revenues: Regulated operations: Electric $ 90,989 $ 85,551 $ 186,686 $ 179,235 Natural gas distribution 218,995 210,510 784,590 660,998 Pipeline 30,508 27,555 43,147 37,000 340,492 323,616 1,014,423 877,233 Non-regulated operations: Pipeline 3,701 2,263 5,536 3,938 Construction services 746,933 683,870 1,501,265 1,235,693 Other — — — — 750,634 686,133 1,506,801 1,239,631 Total external operating revenues $ 1,091,126 $ 1,009,749 $ 2,521,224 $ 2,116,864 Intersegment operating revenues: Regulated operations: Electric $ 27 $ 34 $ 55 $ 68 Natural gas distribution 69 71 139 137 Pipeline 7,699 7,404 33,958 33,338 7,795 7,509 34,152 33,543 Non-regulated operations: Pipeline 219 336 230 391 Construction services — 1,527 — 2,353 Other 3,151 1,503 4,723 2,896 3,370 3,366 4,953 5,640 Total intersegment operating revenues $ 11,165 $ 10,875 $ 39,105 $ 39,183 Operating income (loss): Electric $ 21,561 $ 8,325 $ 42,654 $ 23,369 Natural gas distribution 2,428 (638) 60,932 55,617 Pipeline 13,886 12,602 26,926 24,484 Construction services 54,310 46,141 89,527 75,639 Other (10,154) (3,925) (19,486) (9,109) Total operating income $ 82,031 $ 62,505 $ 200,553 $ 170,000 Net income (loss): Regulated operations: Electric $ 16,338 $ 4,601 $ 32,945 $ 15,880 Natural gas distribution (3,157) (7,498) 35,771 28,817 Pipeline 8,651 7,326 17,580 15,350 21,832 4,429 86,296 60,047 Non-regulated operations: Pipeline 286 (57) (172) (674) Construction services 41,167 35,324 69,976 57,349 Other 84,348 (3,934) 75,408 (12,194) 125,801 31,333 145,212 44,481 Income from continuing operations 147,633 35,762 231,508 104,528 Discontinued operations, net of tax (16,941) 34,905 (62,464) (2,098) Net income $ 130,692 $ 70,667 $ 169,044 $ 102,430 A reconciliation of reportable segment operating revenues to consolidated operating revenues is as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) Operating revenues reconciliation: Total reportable segment operating revenues $ 1,099,140 $ 1,019,121 $ 2,555,606 $ 2,153,151 Other revenue 3,151 1,503 4,723 2,896 Elimination of intersegment operating revenues (11,165) (10,875) (39,105) (39,183) Total consolidated operating revenues $ 1,091,126 $ 1,009,749 $ 2,521,224 $ 2,116,864

Employee benefit plans

Employee benefit plans	6 Months Ended
	Jun. 30, 2023
Retirement Benefits [Abstract]
Employee benefit plans	Employee benefit plans Pension and other postretirement plans The Company has noncontributory qualified defined benefit pension plans and other postretirement benefit plans for certain eligible employees. In connection with the previously discussed separation of Knife River on May 31, 2023, Knife River's pension plan, including the associated assets and liabilities, was transferred to Knife River and therefore is no longer reflected as part of the Company. Also in connection with the separation, a remeasurement of the Company's postretirement plan and the Company's unfunded, non-qualified defined benefit plan were performed and the applicable liabilities from the plans relating to transferring employees were transferred to Knife River. Components of net periodic benefit credit for the Company's pension benefit plans were as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) Components of net periodic benefit credit: Interest cost $ 3,380 $ 2,349 $ 7,169 $ 4,698 Expected return on assets (4,299) (4,371) (9,048) (8,742) Amortization of net actuarial loss 773 1,457 1,674 2,914 Net periodic benefit credit $ (146) $ (565) $ (205) $ (1,130) Components of net periodic benefit credit for the Company's other postretirement benefit plans were as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) Components of net periodic benefit credit: Service cost $ 136 $ 223 $ 274 $ 446 Interest cost 489 346 978 692 Expected return on assets (1,334) (1,319) (2,668) (2,638) Amortization of prior service credit (329) (330) (659) (660) Amortization of net actuarial gain (70) (142) (126) (284) Net periodic benefit credit, including amount capitalized (1,108) (1,222) (2,201) (2,444) Less amount capitalized 53 53 77 84 Net periodic benefit credit $ (1,161) $ (1,275) $ (2,278) $ (2,528) The components of net periodic benefit credit, other than the service cost component, are included in other income on the Consolidated Statements of Income. The service cost component is included in operation and maintenance expense on the Consolidated Statements of Income. Nonqualified defined benefit plans In addition to the qualified defined benefit pension plans reflected in the table at the beginning of this note, the Company also has unfunded, nonqualified defined benefit plans for executive officers and certain key management employees. The Company's net periodic benefit cost for these plans was $750,000 and $648,000 for the three months ended June 30, 2023 and 2022,

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock Based Compensation	Stock-based compensationIn connection with the completed separation of Knife River through the spinoff, the provisions of the existing compensation plans required adjustments to the number and terms of outstanding employee time-vested restricted stock units and performance share awards to preserve the intrinsic value of the awards immediately prior to the separation. The outstanding awards will continue to vest over the original vesting period, which is generally three years from the grant date. However, the performance share awards will no longer be subject to performance-based vesting conditions. The number of performance share awards were first adjusted for performance. The combined performance factors were determined based on the performance of the Company as of December 31, 2022. Outstanding awards at the time of the spinoff were converted into awards of the holder’s employer following separation. The Company recorded $204,000 of incremental compensation expense related to the conversion of the restricted stock units, which is being recognized over the remaining service period of one to three years. There was no incremental compensation expense related to the conversion of the performance share awards.

Regulatory matters

Regulatory matters	6 Months Ended
	Jun. 30, 2023
Regulated Operations [Abstract]
Regulatory Matters	Regulatory matters The Company regularly reviews the need for electric and natural gas rate changes in each of the jurisdictions in which service is provided. The Company files for rate adjustments to seek recovery of operating costs and capital investments, as well as reasonable returns as allowed by regulators. Certain regulatory proceedings and cases may also contain recurring mechanisms that can have an annual true-up. Examples of these recurring mechanisms include: infrastructure riders, transmission trackers, renewable resource cost adjustment riders, as well as weather normalization and decoupling mechanisms. The following paragraphs summarize the Company's significant open regulatory proceedings and cases by jurisdiction including updates to those reported in the 2022 Annual Report and should be read in conjunction with previous filings. The Company is unable to predict the ultimate outcome of these matters, the timing of final decisions of the various regulators and courts, or the effect on the Company's results of operations, financial position or cash flows. IPUC Intermountain filed a request with the IPUC for a natural gas general rate increase on December 1, 2022. The request was for an increase of $11.3 million annually or 3.2 percent above current rates, which was revised on March 9, 2023, to $6.8 million annually or 1.9 percent above current rates. The requested increase was primarily to recover investments made since the last rate case in 2016 and the depreciation, operation and maintenance expenses and taxes associated with the increased investments. A settlement in principle for an increase of approximately $3.1 million or 0.7 percent was filed with the IPUC on May 4, 2023. On June 30, 2023, the settlement was approved by the IPUC with rates effective July 1, 2023. MTPSC On November 4, 2022, Montana-Dakota filed an application with the MTPSC for an electric general rate increase of approximately $10.5 million annually or 15.2 percent above current rates, which was revised on March 15, 2023, to $11.5 million annually or 17.0 percent above current rates to reflect the loss of a large industrial customer. The requested increase is primarily to recover investments made since the last rate case, including Heskett Unit 4, increases in operation and maintenance expenses, and increases in property taxes. On January 24, 2023, the MTPSC approved Montana-Dakota's request for an interim increase of approximately $1.7 million or 2.7 percent above current rates, subject to refund, effective February 1, 2023. On June 12, 2023, an all-party settlement agreement was filed reflecting an annual revenue increase of $6.1 million or 9.1 percent overall. The reduction from the original filing includes a return on equity of 9.65 percent and removal of Heskett Unit 4 due to not being in service until the second half of 2023. The matter is pending before the MTPSC. NDPSC On May 16, 2022, Montana-Dakota filed an application with the NDPSC for an electric general rate increase of approximately $25.4 million annually or 12.3 percent above current rates. The requested increase is primarily to recover investments in production, transmission and distribution facilities and the associated depreciation, operation and maintenance expenses and taxes associated with the increased investment. On July 14, 2022, the NDPSC approved an interim rate increase of approximately $10.9 million annually or 5.3 percent above current rates, subject to refund, for service rendered on and after July 15, 2022. The lower interim rate increase is largely due to excluding the recovery of Heskett Unit 4 from interim rates due to not being in service until the second half of 2023. On April 26, 2023, the Company filed with the NDPSC an all-party settlement reflecting an annual revenue increase of $15.3 million or 7.4 percent overall. The reduction from the original filing includes a return on equity of 9.75 percent and maintaining depreciation expense at current levels. A hearing was held May 2, 2023. On June 6, 2023, the all-party settlement was approved by the NDPSC with rates effective July 1, 2023. On July 14, 2023, Montana-Dakota filed an application with the NDPSC to request an update to its transmission cost adjustment rider requesting to recover revenues of $2.2 million, which includes a true-up of a prior period adjustment, resulting in a decrease of $10.7 million from current rates. The request is to recover transmission-related expenses and the revenue requirement for transmission facilities not currently recovered through electric service rates. The request also reflects the inclusion of the proposed net benefit of a large customer now taking service under Rate 45, as discussed in Part I, Item 2, which accounted for approximately $7.6 million of the decrease. The request proposes the rates be effective for service rendered on and after November 1, 2023. This matter is pending before the NDPSC. WUTC On June 1, 2023, Cascade filed its annual pipeline cost recovery mechanism requesting an increase in annual revenue of approximately $3.1 million or 0.9 percent, which will be adjusted as necessary prior to the effective date. The filing includes a proposed effective date of November 1, 2023. This matter is pending before the WUTC. FERC On January 27, 2023, WBI Energy Transmission filed a general rate case with the FERC for increases in its transportation and storage services rates that also includes a Greenhouse Gas Cost Recovery Mechanism for anticipated future costs. On July 31, 2023, the Company filed motion rates with the FERC for its transportation and storage services which will be effective August 1, 2023. The motion rates are subject to refund until a rate case settlement agreement is reached or a FERC order is issued approving the final rates.

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is party to claims and lawsuits arising out of its business and that of its consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual, statutory and regulatory obligations. The Company accrues a liability for those contingencies when the incurrence of a loss is probable and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. The Company does not accrue liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, the Company discloses the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss including, but not limited to when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories. At June 30, 2023 and 2022, and December 31, 2022, the Company accrued contingent liabilities, which have not been discounted, of $20.9 million, $28.1 million and $31.9 million, respectively. At June 30, 2023 and 2022, and December 31, 2022, the Company also recorded corresponding insurance receivables of $338,000, $5.9 million and $10.0 million, respectively, and regulatory assets of $20.5 million, $20.9 million and $20.9 million, respectively, related to the accrued liabilities. The accruals are for contingencies resulting from litigation and environmental matters. This includes amounts that have been accrued for matters discussed in Environmental matters within this note. The Company will continue to monitor each matter and adjust accruals as might be warranted based on new information and further developments. Management believes that the outcomes with respect to probable and reasonably possible losses in excess of the amounts accrued, net of insurance recoveries, while uncertain, either cannot be estimated or will not have a material effect upon the Company's financial position, results of operations or cash flows. Unless otherwise required by GAAP, legal costs are expensed as they are incurred. Environmental matters The Company is a party to claims for the cleanup of environmental contamination at certain manufactured gas plant sites. There were no material changes to the Company's environmental matters that were previously reported in the 2022 Annual Report other than the removal of the Portland Harbor Site, which relates to Knife River and any potential associated liability was included in the distribution of Knife River. 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 June 30, 2023, the fixed maximum amounts guaranteed under these agreements aggregate $325.5 million. Certain of the guarantees also have no fixed maximum amounts specified. At June 30, 2023, the amounts of scheduled expiration of the maximum amounts guaranteed under these agreements aggregate to $21.6 million in 2023; $135.6 million in 2024; $165.5 million in 2025; $1.5 million in 2026; $1.0 million in 2027; and $300,000 thereafter. There were no amounts outstanding under the previously mentioned guarantees at June 30, 2023. In the event of default under these guarantee obligations, the subsidiary issuing the guarantee for that particular obligation would be required to make payments under its guarantee. Certain subsidiaries have outstanding letters of credit to third parties related to insurance policies and other agreements, some of which are guaranteed by other subsidiaries of the Company. At June 30, 2023, the fixed maximum amounts guaranteed under these letters of credit aggregated $21.0 million, with the scheduled expiration of the maximum amounts guaranteed under these letters in 2023. There were no amounts outstanding under the previously mentioned letters of credit at June 30, 2023. In the event of default under these letter of credit obligations, the subsidiary guaranteeing the letter of credit would be obligated for reimbursement of payments made under the letter of credit. In addition, Centennial 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 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 June 30, 2023. In the normal course of business, Centennial has surety bonds related to construction contracts and reclamation obligations of its subsidiaries. In the event a subsidiary of Centennial does not fulfill a bonded obligation, Centennial would be responsible to the surety bond company for completion of the bonded contract or obligation. A large portion of the surety bonds is expected to expire within the next 12 months; however, Centennial will likely continue to enter into surety bonds for its subsidiaries in the future. At June 30, 2023, approximately $707.8 million 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 June 30, 2023, the Company's exposure to loss as a result of the Company's involvement with the VIE, based on the Company's ownership percentage, was $28.5 million.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Pay vs Performance Disclosure
Net income	$ 130,692	$ 38,353	$ 70,667	$ 31,763	$ 169,044	$ 102,430

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2023
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During the three months ended June 30, 2023, no director or officer of the Company adopted or terminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K.
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Basis of presentation (Policies

Basis of presentation (Policies)	6 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of presentation	The accompanying consolidated interim financial statements were prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Interim financial statements do not include all disclosures provided in annual financial statements and, accordingly, these financial statements should be read in conjunction with those appearing in the 2022 Annual Report. The information is unaudited but includes all adjustments that are, in the opinion of management, necessary for a fair presentation of the accompanying consolidated interim financial statements and are of a normal recurring nature. Depreciation, depletion and amortization expense is reported separately on the Consolidated Statements of Income and therefore is excluded from the other line items within operating expenses.

New accounting standards (Polic

New accounting standards (Policies)	6 Months Ended
	Jun. 30, 2023
Accounting Standards Update and Change in Accounting Principle [Abstract]
New accounting standards	The following table provides a brief description of the accounting pronouncements applicable to the Company and the potential impact on its Consolidated Financial Statements and/or disclosures: Standard Description Effective date Impact on financial statements/disclosures Recently adopted accounting standards ASU 2020-04 - Reference Rate Reform In March 2020, the FASB issued optional guidance to ease the facilitation of the effects of reference rate reform on financial reporting. The guidance applies to certain contract modifications, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. Beginning January 1, 2022, LIBOR or other discontinued reference rates cannot be applied to new contracts. New contracts will incorporate a new reference rate, which includes SOFR. LIBOR or other discontinued reference rates cannot be applied to contract modifications or hedging relationships entered into or evaluated after December 31, 2022. Existing contracts referencing LIBOR or other reference rates expected to be discontinued must have identified 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 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. The Company does not expect the guidance to have a material impact on its results of operations, financial position, cash flows or disclosures.

Discontinued Operations and D_2

Discontinued Operations and Disposal Groups (Policies)	6 Months Ended
	Jun. 30, 2023
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations, Policy	As a result of the separation, the historical assets and liabilities for Knife River have been classified as assets and liabilities of discontinued operations and the historical results of operations are shown in Discontinued operations, net of tax, other than allocated general corporate overhead costs of the Company, which do not meet the criteria for income (loss) from discontinued operations. The Company’s consolidated financial statements and accompanying notes for prior periods have been restated. For the comparative periods, Knife River's operations are only reflected through May 2023, whereas 2022 includes the full three and six months from Knife River's operations.

Receivables and allowance for_2

Receivables and allowance for expected credit losses (Policies)	6 Months Ended
	Jun. 30, 2023
Credit Loss [Abstract]
Accounts receivable and allowance for doubtful accounts	Receivables consist primarily of trade receivables from the sale of goods and services, which are recorded at the invoiced amount, and contract assets, net of expected credit losses. For more information on contract assets, see Note 9. The Company's trade receivables are all due in 12 months or less.
Expected credit loss	The Company's expected credit losses are determined through a review using historical credit loss experience; changes in asset specific characteristics; current conditions; and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly. The Company develops and documents its methodology to determine its allowance for expected credit losses at each of its reportable business segments. Risk characteristics used by the business segments may include customer mix, knowledge of customers and general economic conditions of the various local economies, among others. Specific account balances are written off when management determines the amounts to be uncollectible.

Inventories and natural gas i_2

Inventories and natural gas in storage (Policies)	6 Months Ended
	Jun. 30, 2023
Inventory Disclosure [Abstract]
Inventories and natural gas in storage	Natural gas in storage for the Company's regulated operations is generally valued at lower of cost or market using the last-in, first-out method or lower of cost or net realizable value using the average cost or first-in, first-out method. The majority of all other inventories are valued at the lower of cost or net realizable value using the average cost method.

Earnings per share (Policies)

Earnings per share (Policies)	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Earnings per share	Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted earnings per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the applicable period, plus the effect of non-vested performance share awards and restricted stock units. Common stock outstanding includes issued shares less shares held in treasury.

Revenue from contracts with c_2

Revenue from contracts with customers (Policies)	6 Months Ended
	Jun. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenue from contracts with customers	Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes.

Environmental allowances and ob

Environmental allowances and obligations (Policies)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Emission Credits or Allowances, Policy	Environmental allowances and obligations The Company's natural gas distribution segment acquires environmental allowances as part of its requirement to comply with environmental regulations in certain states. Allowances are allocated by the respective states to the Company at no cost and additional allowances are required to be purchased as needed based on the requirements in the respective states. The segment records purchased and allocated environmental allowances at weighted average cost under the inventory method of accounting. Environmental allowances are included in noncurrent assets - other on the Consolidated Balance Sheets. Environmental compliance obligations, which are based on GHG emissions, are measured at the carrying value of environmental allowances held plus the estimated value of additional allowances necessary to satisfy the compliance obligation. Environmental compliance obligations are included in noncurrent liabilities - other on the Consolidated Balance Sheets. At June 30, 2023, the Company accrued $20.6 million in compliance obligations. As environmental allowances are surrendered, the segment reduces the associated environmental compliance assets and liabilities from the Consolidated Balance Sheets. The expenses associated with the Company’s environmental allowances and obligations are deferred as regulatory assets. For more information on the Company’s regulatory assets and liabilities, see Note 12.

Fair value disclosures (Policie

Fair value disclosures (Policies)	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair value measurements	The Company measures its investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income.
Investments	The Company did not elect the fair value option, which records gains and losses in income, for its available-for-sale securities, which include mortgage-backed securities and U.S. Treasury securities. These available-for-sale securities are recorded at fair value and are classified as investments on the Consolidated Balance Sheets.

Business segment data (Policies

Business segment data (Policies)	6 Months Ended
	Jun. 30, 2023
Segment Reporting [Abstract]
Business segment data	The Company's reportable segments are those that are based on the Company's method of internal reporting, which generally segregates the strategic business units due to differences in products, services and regulation. The internal reporting of these operating segments is defined based on the reporting and review process used by the Company's chief executive officer.

Stock-Based Compensation (Polic

Stock-Based Compensation (Policies)	6 Months Ended
	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Share-Based Payment Arrangement	In connection with the completed separation of Knife River through the spinoff, the provisions of the existing compensation plans required adjustments to the number and terms of outstanding employee time-vested restricted stock units and performance share awards to preserve the intrinsic value of the awards immediately prior to the separation. The outstanding awards will continue to vest over the original vesting period, which is generally three years from the grant date. However, the performance share awards will no longer be subject to performance-based vesting conditions. The number of performance share awards were first adjusted for performance. The combined performance factors were determined based on the performance of the Company as of December 31, 2022. Outstanding awards at the time of the spinoff were converted into awards of the holder’s employer following separation. The Company recorded $204,000 of incremental compensation expense related to the conversion of the restricted stock units, which is being recognized over the remaining service period of one to three years.

Contingencies (Policies)

Contingencies (Policies)	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Contingencies	The Company is party to claims and lawsuits arising out of its business and that of its consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual, statutory and regulatory obligations. The Company accrues a liability for those contingencies when the incurrence of a loss is probable and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. The Company does not accrue liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, the Company discloses the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss including, but not limited to when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories.
Variable interest entity	The Company evaluates its arrangements and contracts with other entities to determine if they are VIEs and if so, if the Company is the primary beneficiary.

Discontinued Operations and D_3

Discontinued Operations and Disposal Groups (Tables)	6 Months Ended
	Jun. 30, 2023
Discontinued Operations and Disposal Groups [Abstract]
Schedule of discontinued operations, including balance sheet and income statement	The carrying amounts of the major classes of assets and liabilities of discontinued operations included in the Company’s Consolidated Balance Sheets were as follows: June 30, 2022 December 31, 2022 Assets (In Thousands) Current assets: Cash and cash equivalents $ 1,569 $ 790 Receivables, net 423,420 241,302 Inventories 350,457 323,277 Prepayments and other current assets 23,219 17,849 Total current assets of discontinued operations 798,665 583,218 Noncurrent assets: Net property, plant and equipment 1,264,604 1,315,213 Goodwill 274,302 274,540 Other intangible assets, net 14,827 13,430 Investments 33,400 33,086 Operating lease right-of-use assets 45,932 45,872 Other 2,962 3,610 Total noncurrent assets of discontinued operations 1,636,027 1,685,751 Total assets of discontinued operations $ 2,434,692 $ 2,268,969 Liabilities Current liabilities: Short-term borrowings $ 100,000 $ 208,000 Long-term debt due within one year 128,134 30,211 Accounts payable 174,585 122,309 Taxes payable (12,500) 8,502 Accrued compensation 28,621 29,192 Operating lease liabilities due within one year 13,666 13,210 Other accrued liabilities 69,811 76,200 Total current liabilities of discontinued operations 502,317 487,624 Noncurrent liabilities: Long-term debt 709,632 445,546 Deferred income taxes 169,484 175,804 Asset retirement obligations 27,779 33,015 Operating lease liabilities 32,266 32,663 Other 88,284 78,876 Total noncurrent liabilities of discontinued operations 1,027,445 765,904 Total liabilities of discontinued operations $ 1,529,762 $ 1,253,528 The reconciliation of the major classes of income and expense constituting pretax income (loss) from discontinued operations to the after-tax income (loss) from discontinued operations on the Consolidated Statements of Income were as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) Operating revenues $ 428,020 $ 711,227 $ 735,259 $ 1,020,726 Operating expenses 416,686 653,116 767,960 1,002,728 Operating income (loss) 11,334 58,111 (32,701) 17,998 Other income (expense) 1,889 (2,037) 2,381 (3,394) Interest expense 23,544 8,926 37,611 15,293 Income (loss) from discontinued operations before income taxes (10,321) 47,148 (67,931) (689) Income taxes 6,620 12,243 (5,467) 1,409 Income (loss) from discontinued operations $ (16,941) $ 34,905 $ (62,464) $ (2,098)

Receivables and allowance for_3

Receivables and allowance for expected credit losses (Tables)	6 Months Ended
	Jun. 30, 2023
Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss	Details of the Company's expected credit losses were as follows: Electric Natural gas Pipeline Construction Total (In thousands) At December 31, 2022 $ 375 $ 1,615 $ 2 $ 2,162 $ 4,154 Current expected credit loss provision 615 2,324 — 826 3,765 Less write-offs charged against the allowance 667 1,225 — 51 1,943 Credit loss recoveries collected 145 229 — 1 375 At March 31, 2023 $ 468 $ 2,943 $ 2 $ 2,938 $ 6,351 Current expected credit loss provision 182 90 — 1,825 2,097 Less write-offs charged against the allowance 316 1,454 — 103 1,873 Credit loss recoveries collected 79 161 — 58 298 At June 30, 2023 $ 413 $ 1,740 $ 2 $ 4,718 $ 6,873 Electric Natural gas Pipeline Construction Total (In thousands) At December 31, 2021 $ 269 $ 1,506 $ 2 $ 2,533 $ 4,310 Current expected credit loss provision 565 1,369 — 54 1,988 Less write-offs charged against the allowance 597 932 — 71 1,600 Credit loss recoveries collected 124 180 — 28 332 At March 31, 2022 $ 361 $ 2,123 $ 2 $ 2,544 $ 5,030 Current expected credit loss provision 113 92 — 292 497 Less write-offs charged against the allowance 234 939 — 104 1,277 Credit loss recoveries collected 108 177 — — 285 At June 30, 2022 $ 348 $ 1,453 $ 2 $ 2,732 $ 4,535

Inventories and natural gas i_3

Inventories and natural gas in storage (Tables)	6 Months Ended
	Jun. 30, 2023
Inventory Disclosure [Abstract]
Inventories	Inventories on the Consolidated Balance Sheets were as follows: June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Merchandise for resale 32,498 25,216 27,910 Natural gas in storage (current) 15,388 15,014 22,533 Materials and supplies $ 6,391 $ 6,269 $ 6,846 Other 5,877 4,478 6,959 Total $ 60,154 $ 50,977 $ 64,248

Earnings per share (Tables)

Earnings per share (Tables)	6 Months Ended
	Jun. 30, 2023
Earnings Per Share [Abstract]
Weighted average common shares outstanding	A reconciliation of the weighted average common shares outstanding used in the basic and diluted earnings per share calculations follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands, except per share amounts) Weighted average common shares outstanding - basic 203,635 203,351 203,630 203,351 Effect of dilutive performance share awards and restricted stock units 242 50 264 45 Weighted average common shares outstanding - diluted 203,877 203,401 203,894 203,396 Earnings per share - basic: Income from continuing operations .72 .18 1.14 .51 Discontinued operations, net of tax (.08) .17 (.31) (.01) Earnings per share - basic .64 .35 .83 .50 Earnings per share - diluted: Income from continuing operations 0.72 .18 1.14 .51 Discontinued operations, net of tax (.08) .17 (.31) (.01) Earnings per share - diluted .64 .35 .83 .50 Shares excluded from the calculation of diluted earnings per share — 52 — 175 Dividends declared per common share $ .2225 $ .2175 $ .4450 $ .4350

Accumulated other comprehensi_2

Accumulated other comprehensive loss (Tables)	6 Months Ended
	Jun. 30, 2023
Equity [Abstract]
Accumulated comprehensive loss	The after-tax changes in the components of accumulated other comprehensive loss were as follows: Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2022 $ (125) $ (29,900) $ (558) $ (30,583) Other comprehensive income before reclassifications — — 70 70 Amounts reclassified from accumulated other comprehensive loss 34 100 13 147 Net current-period other comprehensive income 34 100 83 217 At March 31, 2023 $ (91) $ (29,800) $ (475) $ (30,366) Other comprehensive income before reclassifications — — (84) (84) Amounts reclassified from accumulated other comprehensive loss 47 387 13 447 Net current-period other comprehensive income (loss) 47 387 (71) 363 Amounts reclassified related to the separation of Knife River 44 12,262 — 12,306 At June 30, 2023 $ — $ (17,151) $ (546) $ (17,697) Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2021 $ (538) $ (40,461) $ (5) $ (41,004) Other comprehensive loss before reclassifications — — (320) (320) Amounts reclassified from accumulated other comprehensive loss 112 445 32 589 Net current-period other comprehensive income (loss) 112 445 (288) 269 At March 31, 2022 $ (426) $ (40,016) $ (293) $ (40,735) Other comprehensive loss before reclassifications — — (128) (128) Amounts reclassified to accumulated other comprehensive loss from a regulatory asset — (3,265) — (3,265) Amounts reclassified from accumulated other comprehensive loss 111 461 25 597 Net current-period other comprehensive income (loss) 111 (2,804) (103) (2,796) At June 30, 2022 $ (315) $ (42,820) $ (396) $ (43,531)
Reclassification out of accumulated other comprehensive loss	The following amounts were reclassified out of accumulated other comprehensive loss into net income. The amounts presented in parenthesis indicate a decrease to net income on the Consolidated Statements of Income. The reclassifications were as follows: Three Months Ended Six Months Ended Location on Consolidated June 30, June 30, 2023 2022 2023 2022 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (53) $ (147) $ (98) $ (295) Interest expense 6 36 17 72 Income taxes (47) (111) (81) (223) Amortization of postretirement liability losses included in net periodic benefit credit (518) (609) (652) (1,218) Other income 131 148 165 312 Income taxes (387) (461) (487) (906) Reclassification adjustment on available-for-sale investments included in net income (16) (32) (32) (72) Other income 3 7 6 15 Income taxes (13) (25) (26) (57) Total reclassifications $ (447) $ (597) $ (594) $ (1,186)

Revenue from contracts with c_3

Revenue from contracts with customers (Tables)	6 Months Ended
	Jun. 30, 2023
Revenue from Contract with Customer [Abstract]
Disaggregation of revenue	In the following tables, revenue is disaggregated by the type of customer or service provided. The Company believes this level of disaggregation best depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. The table also includes a reconciliation of the disaggregated revenue by reportable segments. For more information on the Company's business segments, see Note 18. Three Months Ended June 30, 2023 Electric Natural gas Pipeline Construction Other Total (In thousands) Residential utility sales $ 30,825 $ 120,967 $ — $ — $ — $ 151,792 Commercial utility sales 38,262 71,196 — — — 109,458 Industrial utility sales 10,370 9,183 — — — 19,553 Other utility sales 1,710 — — — — 1,710 Natural gas transportation — 11,671 34,394 — — 46,065 Natural gas storage — — 3,758 — — 3,758 Electrical & mechanical specialty contracting — — — 568,307 — 568,307 Transmission & distribution specialty contracting — — — 167,485 — 167,485 Other 11,531 3,272 3,937 177 3,151 22,068 Intersegment eliminations (27) (69) (7,918) — (3,151) (11,165) Revenues from contracts with customers 92,671 216,220 34,171 735,969 — 1,079,031 Revenues out of scope (1,682) 2,775 38 10,964 — 12,095 Total external operating revenues $ 90,989 $ 218,995 $ 34,209 $ 746,933 $ — $ 1,091,126 Three Months Ended June 30, 2022 Electric Natural gas Pipeline Construction Other Total (In thousands) Residential utility sales $ 29,363 $ 116,749 $ — $ — $ — $ 146,112 Commercial utility sales 34,015 72,354 — — — 106,369 Industrial utility sales 10,923 9,009 — — — 19,932 Other utility sales 1,880 — — — — 1,880 Natural gas transportation — 11,456 31,967 — — 43,423 Natural gas storage — — 2,896 — — 2,896 Electrical & mechanical specialty contracting — — — 507,233 — 507,233 Transmission & distribution specialty contracting — — — 166,174 — 166,174 Other 10,216 3,751 2,676 109 1,456 18,208 Intersegment eliminations (34) (71) (7,787) (1,527) (1,456) (10,875) Revenues from contracts with customers 86,363 213,248 29,752 671,989 — 1,001,352 Revenues out of scope (812) (2,738) 66 11,881 — 8,397 Total external operating revenues $ 85,551 $ 210,510 $ 29,818 $ 683,870 $ — $ 1,009,749 Six Months Ended June 30, 2023 Electric Natural gas Pipeline Construction Other Total (In thousands) Residential utility sales $ 68,650 $ 448,617 $ — $ — $ — $ 517,267 Commercial utility sales 74,609 276,122 — — — 350,731 Industrial utility sales 21,133 26,021 — — — 47,154 Other utility sales 3,484 — — — — 3,484 Natural gas transportation — 25,175 69,378 — — 94,553 Natural gas storage — — 7,620 — — 7,620 Electrical & mechanical specialty contracting — — — 1,158,570 — 1,158,570 Transmission & distribution specialty contracting — — — 319,507 — 319,507 Other 23,410 7,993 5,797 209 4,723 42,132 Intersegment eliminations (55) (139) (34,188) — (4,723) (39,105) Revenues from contracts with customers 191,231 783,789 48,607 1,478,286 — 2,501,913 Revenues out of scope (4,545) 801 76 22,979 — 19,311 Total external operating revenues $ 186,686 $ 784,590 $ 48,683 $ 1,501,265 $ — $ 2,521,224 Six Months Ended June 30, 2022 Electric Natural gas Pipeline Construction Other Total (In thousands) Residential utility sales $ 66,667 $ 375,565 $ — $ — $ — $ 442,232 Commercial utility sales 69,615 235,963 — — — 305,578 Industrial utility sales 21,229 22,033 — — — 43,262 Other utility sales 3,630 — — — — 3,630 Natural gas transportation — 23,837 63,541 — — 87,378 Natural gas storage — — 6,615 — — 6,615 Electrical & mechanical specialty contracting — — — 900,041 — 900,041 Transmission & distribution specialty contracting — — — 314,640 — 314,640 Other 22,969 6,360 4,387 156 2,896 36,768 Intersegment eliminations (68) (137) (33,729) (2,353) (2,896) (39,183) Revenues from contracts with customers 184,042 663,621 40,814 1,212,484 — 2,100,961 Revenues out of scope (4,807) (2,623) 124 23,209 — 15,903 Total external operating revenues $ 179,235 $ 660,998 $ 40,938 $ 1,235,693 $ — $ 2,116,864
Contract balances	The changes in contract assets and liabilities were as follows: June 30, 2023 December 31, 2022 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 179,282 $ 154,144 $ 25,138 Receivables, net Contract liabilities - current (166,268) (168,361) 2,093 Accounts payable Contract liabilities - noncurrent (438) (6) (432) Noncurrent liabilities - other Net contract assets (liabilities) $ 12,576 $ (14,223) $ 26,799

Goodwill and other intangible_2

Goodwill and other intangible assets (Tables)	6 Months Ended
	Jun. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Other amortizable intangible assets	Other amortizable intangible assets were as follows: June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Customer relationships $ 10,450 $ 10,450 $ 10,450 Less accumulated amortization 7,401 5,312 6,356 3,049 5,138 4,094 Noncompete agreements 292 552 552 Less accumulated amortization 292 477 544 — 75 8 Total $ 3,049 $ 5,213 $ 4,102
Estimated amortization expense	Amortization expense for identifiable intangible assets as of June 30, 2023 is estimated to be as follows: Remainder of 2023 2024 2025 2026 2027 Thereafter (In thousands) Amortization expense $ 1,045 $ 1,888 $ 116 $ — $ — $ —

Regulatory assets and liabili_2

Regulatory assets and liabilities (Tables)	6 Months Ended
	Jun. 30, 2023
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets	The following table summarizes the individual components of unamortized regulatory assets and liabilities: Estimated Recovery or Refund Period as of June 30, 2023 * June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 170,249 $ 83,557 $ 141,306 Conservation programs Up to 1 year 10,897 7,883 8,544 Cost recovery mechanisms Up to 1 year 4,758 3,459 4,019 Other Up to 1 year 7,258 7,636 11,223 193,162 102,535 165,092 Noncurrent: Pension and postretirement benefits ** 144,448 137,582 143,349 Cost recovery mechanisms Up to 10 years 63,890 64,096 67,171 Plant costs/asset retirement obligations Over plant lives 43,855 63,334 44,462 Manufactured gas plant site remediation - 25,764 26,031 26,624 Plant to be retired - 20,858 27,628 21,525 Environmental compliance programs - 20,611 — — Taxes recoverable from customers Over plant lives 12,099 12,365 12,330 Long-term debt refinancing costs Up to 37 years 2,894 3,482 3,188 Other Up to 16 years 10,766 12,543 11,010 345,185 347,061 329,659 Total regulatory assets $ 538,347 $ 449,596 $ 494,751 Regulatory liabilities: Current: Natural gas costs refundable through rate adjustments Up to 1 year 17,820 738 955 Electric fuel and purchased power deferral Up to 1 year 8,481 4,161 4,929 Cost recovery mechanisms Up to 1 year 3,304 3,172 1,977 Conservation programs Up to 1 year 2,851 352 4,126 Taxes refundable to customers Up to 1 year 1,513 3,728 3,937 Refundable fuel and electric costs Up to 1 year 103 1,092 3,253 Other Up to 1 year 13,985 4,641 7,263 48,057 17,884 26,440 Noncurrent: Plant removal and decommissioning costs Over plant lives 216,682 172,755 208,650 Taxes refundable to customers Over plant lives 197,757 209,022 203,222 Cost recovery mechanisms Up to 19 years 18,226 10,898 14,025 Accumulated deferred investment tax credit Up to 19 years 14,398 14,009 13,594 Pension and postretirement benefits ** 7,120 19,686 7,376 Other Up to 15 years 1,694 6,649 1,587 455,877 433,019 448,454 Total regulatory liabilities $ 503,934 $ 450,903 $ 474,894 Net regulatory position $ 34,413 $ (1,307) $ 19,857 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made.
Regulatory Liabilities	The following table summarizes the individual components of unamortized regulatory assets and liabilities: Estimated Recovery or Refund Period as of June 30, 2023 * June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 170,249 $ 83,557 $ 141,306 Conservation programs Up to 1 year 10,897 7,883 8,544 Cost recovery mechanisms Up to 1 year 4,758 3,459 4,019 Other Up to 1 year 7,258 7,636 11,223 193,162 102,535 165,092 Noncurrent: Pension and postretirement benefits ** 144,448 137,582 143,349 Cost recovery mechanisms Up to 10 years 63,890 64,096 67,171 Plant costs/asset retirement obligations Over plant lives 43,855 63,334 44,462 Manufactured gas plant site remediation - 25,764 26,031 26,624 Plant to be retired - 20,858 27,628 21,525 Environmental compliance programs - 20,611 — — Taxes recoverable from customers Over plant lives 12,099 12,365 12,330 Long-term debt refinancing costs Up to 37 years 2,894 3,482 3,188 Other Up to 16 years 10,766 12,543 11,010 345,185 347,061 329,659 Total regulatory assets $ 538,347 $ 449,596 $ 494,751 Regulatory liabilities: Current: Natural gas costs refundable through rate adjustments Up to 1 year 17,820 738 955 Electric fuel and purchased power deferral Up to 1 year 8,481 4,161 4,929 Cost recovery mechanisms Up to 1 year 3,304 3,172 1,977 Conservation programs Up to 1 year 2,851 352 4,126 Taxes refundable to customers Up to 1 year 1,513 3,728 3,937 Refundable fuel and electric costs Up to 1 year 103 1,092 3,253 Other Up to 1 year 13,985 4,641 7,263 48,057 17,884 26,440 Noncurrent: Plant removal and decommissioning costs Over plant lives 216,682 172,755 208,650 Taxes refundable to customers Over plant lives 197,757 209,022 203,222 Cost recovery mechanisms Up to 19 years 18,226 10,898 14,025 Accumulated deferred investment tax credit Up to 19 years 14,398 14,009 13,594 Pension and postretirement benefits ** 7,120 19,686 7,376 Other Up to 15 years 1,694 6,649 1,587 455,877 433,019 448,454 Total regulatory liabilities $ 503,934 $ 450,903 $ 474,894 Net regulatory position $ 34,413 $ (1,307) $ 19,857 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made.

Fair value measurements (Tables

Fair value measurements (Tables)	6 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Available-for-sale securities	Details of available-for-sale securities were as follows: June 30, 2023 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,542 $ — $ 651 $ 7,891 U.S. Treasury securities 3,091 5 46 3,050 Total $ 11,633 $ 5 $ 697 $ 10,941 June 30, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,128 $ — $ 419 $ 7,709 U.S. Treasury securities 3,125 — 83 3,042 Total $ 11,253 $ — $ 502 $ 10,751 December 31, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,928 $ 2 $ 636 $ 8,294 U.S. Treasury securities 2,608 — 72 2,536 Total $ 11,536 $ 2 $ 708 $ 10,830
Assets and liabilities measured at fair value on a recurring basis	The Company's assets measured at fair value on a recurring basis were as follows: Fair Value Measurements at June 30, 2023, Using Quoted Prices in Significant Significant Balance at June 30, 2023 (In thousands) Assets: Investment in Knife River $ 246,063 $ — $ — $ 246,063 Money market funds — 5,737 — 5,737 Insurance contracts* — 84,099 — 84,099 Available-for-sale securities: Mortgage-backed securities — 7,891 — 7,891 U.S. Treasury securities — 3,050 — 3,050 Total assets measured at fair value $ 246,063 $ 100,777 $ — $ 346,840 * The insurance contracts invest approximately 67 percent in fixed-income investments, 14 percent in common stock of large-cap companies, 7 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 4 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at June 30, 2022, Using Quoted Prices in Significant Significant Balance at June 30, 2022 (In thousands) Assets: Money market funds $ — $ 5,976 $ — $ 5,976 Insurance contracts* — 77,529 — 77,529 Available-for-sale securities: Mortgage-backed securities — 7,709 — 7,709 U.S. Treasury securities — 3,042 — 3,042 Total assets measured at fair value $ — $ 94,256 $ — $ 94,256 * The insurance contracts invest approximately 64 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 7 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at December 31, 2022, Using Quoted Prices in Significant Significant Balance at December 31, 2022 (In thousands) Assets: Money market funds $ — $ 4,913 $ — $ 4,913 Insurance contracts* — 77,958 — 77,958 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 $ — $ 93,701 $ — $ 93,701 * The insurance contracts invest approximately 63 percent in fixed-income investments, 15 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents.
Fair value of long term debt outstanding	The estimated fair value of the Company's Level 2 long-term debt was as follows: June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Carrying amount $ 2,247,422 $ 2,090,200 $ 2,365,667 Fair value $ 1,949,905 $ 1,940,092 $ 2,053,396

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Long-term debt outstanding	Long-term debt outstanding was as follows: Weighted Average Interest Rate at June 30, 2023 June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Senior Notes due on dates ranging from October 13, 2027 to June 15, 2062 4.33 % $ 1,757,000 $ 1,847,000 $ 1,848,500 Term Loan Agreements due on dates ranging from May 31, 2025 to September 3, 2032 6.46 % 382,000 7,700 7,000 Commercial paper supported by revolving credit agreement 5.70 % 58,900 175,020 349,050 Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 7.32 % 35,000 35,000 35,000 Credit agreements due on dates ranging from October 13, 2027 to May 31, 2028 8.35 % 20,300 29,860 130,000 Other notes due on dates ranging from January 1, 2024 to November 30, 2038 2.24 % 987 1,621 1,614 Less unamortized debt issuance costs 6,765 5,406 5,211 Less discount — 595 286 Total long-term debt 2,247,422 2,090,200 2,365,667 Less current maturities 1,319 86,319 47,819 Net long-term debt $ 2,246,103 $ 2,003,881 $ 2,317,848
Schedule of debt maturities	Long-term debt maturities, which excludes unamortized debt issuance costs and discount, at June 30, 2023, were as follows: Remainder of 2023 2024 2025 2026 2027 Thereafter (In thousands) Long-term debt maturities $ 1,319 $ 119,600 $ 532,700 $ 140,700 $ 26,500 $ 1,433,368

Cash flow information (Tables)

Cash flow information (Tables)	6 Months Ended
	Jun. 30, 2023
Supplemental Cash Flow Information [Abstract]
Cash expenditures for interest and income taxes and noncash investing and financing transactions	Cash expenditures for interest and income taxes were as follows: Six Months Ended June 30, 2023 2022 (In thousands) Interest, net* $ 54,616 $ 39,573 Income taxes paid, net** $ 17,542 $ 50 * AFUDC - borrowed was $4.9 million and $1.3 million for the six months ended June 30, 2023 and 2022, respectively. ** Income taxes paid, including discontinued operations, were $18.3 million and $16.5 million for the six months ended June 30, 2023 and 2022, respectively. Noncash investing and financing transactions were as follows: June 30, 2023 June 30, 2022 December 31, 2022 (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 24,201 $ 14,148 $ 39,158 Property, plant and equipment additions in accounts payable $ 37,076 $ 40,510 $ 35,637

Business segment data (Tables)

Business segment data (Tables)	6 Months Ended
	Jun. 30, 2023
Segment Reporting [Abstract]
Information on the Company's businesses	Information on the Company's segments was as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) External operating revenues: Regulated operations: Electric $ 90,989 $ 85,551 $ 186,686 $ 179,235 Natural gas distribution 218,995 210,510 784,590 660,998 Pipeline 30,508 27,555 43,147 37,000 340,492 323,616 1,014,423 877,233 Non-regulated operations: Pipeline 3,701 2,263 5,536 3,938 Construction services 746,933 683,870 1,501,265 1,235,693 Other — — — — 750,634 686,133 1,506,801 1,239,631 Total external operating revenues $ 1,091,126 $ 1,009,749 $ 2,521,224 $ 2,116,864 Intersegment operating revenues: Regulated operations: Electric $ 27 $ 34 $ 55 $ 68 Natural gas distribution 69 71 139 137 Pipeline 7,699 7,404 33,958 33,338 7,795 7,509 34,152 33,543 Non-regulated operations: Pipeline 219 336 230 391 Construction services — 1,527 — 2,353 Other 3,151 1,503 4,723 2,896 3,370 3,366 4,953 5,640 Total intersegment operating revenues $ 11,165 $ 10,875 $ 39,105 $ 39,183 Operating income (loss): Electric $ 21,561 $ 8,325 $ 42,654 $ 23,369 Natural gas distribution 2,428 (638) 60,932 55,617 Pipeline 13,886 12,602 26,926 24,484 Construction services 54,310 46,141 89,527 75,639 Other (10,154) (3,925) (19,486) (9,109) Total operating income $ 82,031 $ 62,505 $ 200,553 $ 170,000 Net income (loss): Regulated operations: Electric $ 16,338 $ 4,601 $ 32,945 $ 15,880 Natural gas distribution (3,157) (7,498) 35,771 28,817 Pipeline 8,651 7,326 17,580 15,350 21,832 4,429 86,296 60,047 Non-regulated operations: Pipeline 286 (57) (172) (674) Construction services 41,167 35,324 69,976 57,349 Other 84,348 (3,934) 75,408 (12,194) 125,801 31,333 145,212 44,481 Income from continuing operations 147,633 35,762 231,508 104,528 Discontinued operations, net of tax (16,941) 34,905 (62,464) (2,098) Net income $ 130,692 $ 70,667 $ 169,044 $ 102,430
Reconciliation of Revenue from Segments to Consolidated	A reconciliation of reportable segment operating revenues to consolidated operating revenues is as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) Operating revenues reconciliation: Total reportable segment operating revenues $ 1,099,140 $ 1,019,121 $ 2,555,606 $ 2,153,151 Other revenue 3,151 1,503 4,723 2,896 Elimination of intersegment operating revenues (11,165) (10,875) (39,105) (39,183) Total consolidated operating revenues $ 1,091,126 $ 1,009,749 $ 2,521,224 $ 2,116,864

Employee benefit plans (Tables)

Employee benefit plans (Tables)	6 Months Ended
	Jun. 30, 2023
Retirement Benefits [Abstract]
Schedule of net benefit costs	Components of net periodic benefit credit for the Company's pension benefit plans were as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) Components of net periodic benefit credit: Interest cost $ 3,380 $ 2,349 $ 7,169 $ 4,698 Expected return on assets (4,299) (4,371) (9,048) (8,742) Amortization of net actuarial loss 773 1,457 1,674 2,914 Net periodic benefit credit $ (146) $ (565) $ (205) $ (1,130) Components of net periodic benefit credit for the Company's other postretirement benefit plans were as follows: Three Months Ended Six Months Ended June 30, June 30, 2023 2022 2023 2022 (In thousands) Components of net periodic benefit credit: Service cost $ 136 $ 223 $ 274 $ 446 Interest cost 489 346 978 692 Expected return on assets (1,334) (1,319) (2,668) (2,638) Amortization of prior service credit (329) (330) (659) (660) Amortization of net actuarial gain (70) (142) (126) (284) Net periodic benefit credit, including amount capitalized (1,108) (1,222) (2,201) (2,444) Less amount capitalized 53 53 77 84 Net periodic benefit credit $ (1,161) $ (1,275) $ (2,278) $ (2,528)

Discontinued Operations and D_4

Discontinued Operations and Disposal Groups (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
	Apr. 25, 2023	Jun. 30, 2023	Jun. 30, 2023	Jun. 30, 2022	May 31, 2023	Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations Pro Rata Distribution					90%
Retained Shares Ownership Percentage					10%
Long-term debt		$ 2,247,422	$ 2,247,422	$ 2,090,200		$ 2,365,667
Repayments of Long-term Debt			$ 506,191	147,397
Treasury Stock, Shares, Retired		538,921	538,921
Restructuring and Related Cost, Incurred Cost		$ 41,200	$ 46,100
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | Knife River Corporation | Cash Received, TSA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Amount of Continuing Cash Flows after Disposal		599	599
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | Knife River Corporation | Cash Paid, TSA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Amount of Continuing Cash Flows after Disposal		277	277
Knife River Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Repayments of Long-term Debt	$ 825,000
Senior Notes
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term debt		$ 1,757,000	$ 1,757,000	$ 1,847,000		$ 1,848,500
Senior Notes | Knife River Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term debt	425,000
Revolving Credit Facility | Knife River Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term debt	350,000
Term Loan Agreement | Knife River Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Long-term debt	$ 275,000

Discontinued Operations (Detail

Discontinued Operations (Details - Balance Sheet) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Cash and Cash Equivalents		$ 790	$ 1,569
Discontinued Operation, Receivables, Net		241,302	423,420
Discontinued Operation, Inventory, Current		323,277	350,457
Discontinued Operation, Prepaid and Other Assets, Current		17,849	23,219
Discontinued Operation, Assets, Current		583,218	798,665
Discontinued Operation, Property, Plant and Equipment, Net		1,315,213	1,264,604
Discontinued Operation, Goodwill		274,540	274,302
Discontinued Operation, Intangible Assets, Net		13,430	14,827
Discontinued Operation, Long-Term Investments		33,086	33,400
Discontinued Operation, Operating Lease, Right-of-Use Asset		45,872	45,932
Discontinued Operation, Other Assets, Noncurrent		3,610	2,962
Noncurrent assets of discontinued operations	$ 0	1,685,751	1,636,027
Discontinued Operation, Total Assets		2,268,969	2,434,692
Discontinued Operation, Short-Term Debt		208,000	100,000
Discontinued Operation, Long-Term Debt, Current Maturities		30,211	128,134
Discontinued Operation, Accounts Payable		122,309	174,585
Discontinued Operation, Taxes Payable, Current		8,502	(12,500)
Discontinued Operation, Employee-related Liabilities, Current		29,192	28,621
Discontinued Operation, Operating Lease, Liability, Current		13,210	13,666
Discontinued Operation, Accrued Liabilities, Current		76,200	69,811
Current liabilities of discontinued operations	0	487,624	502,317
Discontinued Operation, Long-Term Debt, Excluding Current Maturities		445,546	709,632
Discontinued Operation, Deferred Income Tax Liabilities, Net		175,804	169,484
Discontinued Operation, Asset Retirement Obligations, Noncurrent		33,015	27,779
Discontinued Operation, Operating Lease Liability, Noncurrent		32,663	32,266
Discontinued Operation, Other Liabilities, Noncurrent		78,876	88,284
Noncurrent liabilities of discontinued operations	$ 0	765,904	1,027,445
Discontinued Operation, Total Liabilities		$ 1,253,528	$ 1,529,762

Discontinued Operations (Deta_2

Discontinued Operations (Details Income Stmt) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Revenue	$ 428,020	$ 711,227	$ 735,259	$ 1,020,726
Discontinued Operation, Operating Expense	416,686	653,116	767,960	1,002,728
Discontinued Operation, Operating Income (Loss)	11,334	58,111	(32,701)	17,998
Discontinued Operation, Other Income (Expense)	1,889	(2,037)	2,381	(3,394)
Discontinued Operation, Interest Expense	23,544	8,926	37,611	15,293
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	(10,321)	47,148	(67,931)	(689)
Discontinued Operations, Income Tax Expense (Benefit)	6,620	12,243	(5,467)	1,409
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	$ (16,941)	$ 34,905	$ (62,464)	$ (2,098)

Receivables and allowance for_4

Receivables and allowance for expected credit losses (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Credit Loss [Abstract]
Accounts Receivable, Noncurrent, 90 Days or More Past Due, Still Accruing	$ 57.9	$ 34.3	$ 27.4

Receivables and allowance for_5

Receivables and allowance for expected credit losses (Details 2) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses					$ 5,862	$ 2,485
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	$ 6,351	$ 4,154	$ 5,030	$ 4,310	4,154	4,310
Provision for credit losses	2,097	3,765	497	1,988
Less write-offs charged against the allowance	1,873	1,943	1,277	1,600
Credit loss recoveries collected	298	375	285	332
Balance	6,873	6,351	4,535	5,030	6,873	4,535
Electric | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	468	375	361	269	375	269
Provision for credit losses	182	615	113	565
Less write-offs charged against the allowance	316	667	234	597
Credit loss recoveries collected	79	145	108	124
Balance	413	468	348	361	413	348
Natural gas distribution | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2,943	1,615	2,123	1,506	1,615	1,506
Provision for credit losses	90	2,324	92	1,369
Less write-offs charged against the allowance	1,454	1,225	939	932
Credit loss recoveries collected	161	229	177	180
Balance	1,740	2,943	1,453	2,123	1,740	1,453
Pipeline | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2	2	2	2	2	2
Provision for credit losses	0	0	0	0
Less write-offs charged against the allowance	0	0	0	0
Credit loss recoveries collected	0	0	0	0
Balance	2	2	2	2	2	2
Construction services | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2,938	2,162	2,544	2,533	2,162	2,533
Provision for credit losses	1,825	826	292	54
Less write-offs charged against the allowance	103	51	104	71
Credit loss recoveries collected	58	1	0	28
Balance	$ 4,718	$ 2,938	$ 2,732	$ 2,544	$ 4,718	$ 2,732

Inventories and natural gas i_4

Inventories and natural gas in storage (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Inventory Disclosure [Abstract]
Merchandise for resale	$ 32,498	$ 27,910	$ 25,216
Natural gas in storage (current)	15,388	22,533	15,014
Materials and supplies	6,391	6,846	6,269
Other	5,877	6,959	4,478
Total	60,154	64,248	50,977
Natural gas in storage noncurrent	$ 47,400	$ 47,500	$ 47,200

Earnings per share (Details)

Earnings per share (Details) - $ / shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Weighted average common shares outstanding - basic	203,635	203,351	203,630	203,351
Effect of dilutive performance share awards and restricted stock units	242	50	264	45
Weighted average common shares outstanding - diluted	203,877	203,401	203,894	203,396
Income from continuing operations	$ 0.72	$ 0.18	$ 1.14	$ 0.51
Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share	(0.08)	0.17	(0.31)	(0.01)
Earnings Per Share, Basic	0.64	0.35	0.83	0.50
Income (Loss) from Continuing Operations, Per Diluted Share	0.72	0.18	1.14	0.51
Discontinued operations, net of tax	(0.08)	0.17	(0.31)	(0.01)
Earnings Per Share, Diluted	$ 0.64	$ 0.35	$ 0.83	$ 0.50
Shares excluded from the calculation of diluted earnings per share	0	52	0	175
Dividends declared per common share	$ 0.2225	$ 0.2175	$ 0.4450	$ 0.4350

Earnings per share (Details 1)

Earnings per share (Details 1) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023
Earnings Per Share [Abstract]
Treasury Stock, Shares, Retired	538,921	538,921

Accumulated other comprehensi_3

Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated other comprehensive loss [Roll Forward]
Balance	$ 3,575,382	$ 3,587,129	$ 3,360,718	$ 3,382,874	$ 3,587,129	$ 3,382,874
Other comprehensive income (loss)	363	217	(2,796)	269	580	(2,527)
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset, net of tax	0		(3,265)		0	(3,265)
Balance	2,706,193	3,575,382	3,386,810	3,360,718	2,706,193	3,386,810
Net unrealized gain (loss) on derivative instruments qualifying as hedges
Accumulated other comprehensive loss [Roll Forward]
Balance	(91)	(125)	(426)	(538)	(125)	(538)
Other comprehensive loss before reclassifications	0	0	0	0
Other comprehensive income (loss)	47	34	111	112
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset, net of tax			0
Amounts reclassified from accumulated other comprehensive loss		34	111	112
Amounts reclassified related to the separation of Knife River	(44)
Balance	0	(91)	(315)	(426)	0	(315)
Postretirement liability adjustment
Accumulated other comprehensive loss [Roll Forward]
Balance	(29,800)	(29,900)	(40,016)	(40,461)	(29,900)	(40,461)
Other comprehensive loss before reclassifications	0	0	0	0
Other comprehensive income (loss)	387	100	(2,804)	445
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset, net of tax			(3,265)
Amounts reclassified from accumulated other comprehensive loss		100	461	445
Amounts reclassified related to the separation of Knife River	(12,262)
Balance	(17,151)	(29,800)	(42,820)	(40,016)	(17,151)	(42,820)
Net unrealized gain (loss) on available-for-sale investments
Accumulated other comprehensive loss [Roll Forward]
Balance	(475)	(558)	(293)	(5)	(558)	(5)
Other comprehensive loss before reclassifications		70	(128)	(320)
Other comprehensive income (loss)	(71)	83	(103)	(288)
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset, net of tax			0
Amounts reclassified from accumulated other comprehensive loss		13	25	32
Amounts reclassified related to the separation of Knife River	0
Balance	(546)	(475)	(396)	(293)	(546)	(396)
Total accumulated other comprehensive loss
Accumulated other comprehensive loss [Roll Forward]
Balance	(30,366)	(30,583)	(40,735)	(41,004)	(30,583)	(41,004)
Other comprehensive loss before reclassifications	(84)	70	(128)	(320)
Other comprehensive income (loss)	363	217	(2,796)	269
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset, net of tax			(3,265)
Amounts reclassified from accumulated other comprehensive loss	447	147	597	589
Amounts reclassified related to the separation of Knife River	(12,306)
Balance	$ (17,697)	$ (30,366)	$ (43,531)	$ (40,735)	$ (17,697)	$ (43,531)

Reclassification out of accumul

Reclassification out of accumulated other comprehensive loss (Details 2) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	$ (26,459)		$ (19,187)		$ (50,412)	$ (38,079)
Income taxes	(57,918)		(5,347)		(78,986)	(24,140)
Other income	9,959		(2,209)		20,333	(3,253)
Net income	130,692	$ 38,353	70,667	$ 31,763	169,044	102,430
Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Net income	(447)		(597)		(594)	(1,186)
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	(53)		(147)		(98)	(295)
Income taxes	6		36		17	72
Net income	(47)		(111)		(81)	(223)
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	131		148		165	312
Other income	(518)		(609)		(652)	(1,218)
Net income	(387)		(461)		(487)	(906)
Reclassification adjustment on available-for-sale investments included in net income | Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Income taxes	3		7		6	15
Other income	(16)		(32)		(32)	(72)
Net income	$ (13)		$ (25)		$ (26)	$ (57)

Disaggregation of revenue (Deta

Disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Operating revenues:	$ 1,091,126	$ 1,009,749	$ 2,521,224	$ 2,116,864
Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(11,165)	(10,875)	(39,105)	(39,183)
Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	46,065	43,423	94,553	87,378
Natural gas storage
Disaggregation of Revenue [Line Items]
Operating revenues:	3,758	2,896	7,620	6,615
Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	568,307	507,233	1,158,570	900,041
Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	167,485	166,174	319,507	314,640
Other
Disaggregation of Revenue [Line Items]
Operating revenues:	22,068	18,208	42,132	36,768
Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	1,079,031	1,001,352	2,501,913	2,100,961
Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	12,095	8,397	19,311	15,903
Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	151,792	146,112	517,267	442,232
Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	109,458	106,369	350,731	305,578
Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	19,553	19,932	47,154	43,262
Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	1,710	1,880	3,484	3,630
Electric
Disaggregation of Revenue [Line Items]
Operating revenues:	90,989	85,551	186,686	179,235
Electric | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(27)	(34)	(55)	(68)
Electric | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	11,531	10,216	23,410	22,969
Electric | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	92,671	86,363	191,231	184,042
Electric | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	(1,682)	(812)	(4,545)	(4,807)
Electric | Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	30,825	29,363	68,650	66,667
Electric | Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	38,262	34,015	74,609	69,615
Electric | Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	10,370	10,923	21,133	21,229
Electric | Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	1,710	1,880	3,484	3,630
Natural gas distribution
Disaggregation of Revenue [Line Items]
Operating revenues:	218,995	210,510	784,590	660,998
Natural gas distribution | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(69)	(71)	(139)	(137)
Natural gas distribution | Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	11,671	11,456	25,175	23,837
Natural gas distribution | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	3,272	3,751	7,993	6,360
Natural gas distribution | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	216,220	213,248	783,789	663,621
Natural gas distribution | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	2,775	(2,738)	801	(2,623)
Natural gas distribution | Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	120,967	116,749	448,617	375,565
Natural gas distribution | Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	71,196	72,354	276,122	235,963
Natural gas distribution | Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	9,183	9,009	26,021	22,033
Natural gas distribution | Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0	0	0
Pipeline
Disaggregation of Revenue [Line Items]
Operating revenues:	34,209	29,818	48,683	40,938
Pipeline | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(7,918)	(7,787)	(34,188)	(33,729)
Pipeline | Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	34,394	31,967	69,378	63,541
Pipeline | Natural gas storage
Disaggregation of Revenue [Line Items]
Operating revenues:	3,758	2,896	7,620	6,615
Pipeline | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	3,937	2,676	5,797	4,387
Pipeline | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	34,171	29,752	48,607	40,814
Pipeline | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	38	66	76	124
Construction services
Disaggregation of Revenue [Line Items]
Operating revenues:	746,933	683,870	1,501,265	1,235,693
Construction services | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	0	(1,527)	0	(2,353)
Construction services | Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	568,307	507,233	1,158,570	900,041
Construction services | Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	167,485	166,174	319,507	314,640
Construction services | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	177	109	209	156
Construction services | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	735,969	671,989	1,478,286	1,212,484
Construction services | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	10,964	11,881	22,979	23,209
Other
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0	0	0
Other | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(3,151)	(1,456)	(4,723)	(2,896)
Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	3,151	1,456	4,723	2,896
Other | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0	0	0
Other | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	$ 0	$ 0	$ 0	$ 0

Contract balances (Details 2)

Contract balances (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Contract assets	$ 179,282		$ 179,282		$ 154,144
Change in contract assets			25,138
Contract liabilities - current	(166,268)		(166,268)		(168,361)
Change in contract liabilities - current			2,093
Contract liabilities - noncurrent	(438)		(438)		(6)
Change in contract liabilities - noncurrent			(432)
Net contract assets (liabilities)	12,576		12,576		$ (14,223)
Change in net contract assets (liabilities)			26,799
Amounts included in contract liability at the beginning of the period	23,400	$ 8,600	157,900	$ 110,400
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 23,100	$ 24,300	$ 31,800	$ 33,200

Revenue from contracts with c_4

Revenue from contracts with customers Remaining performance obligations (Details 3) $ in Millions	Jun. 30, 2023 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2,500
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,600
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 384
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	13 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 544
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	25 months

Lessor accounting (Details)

Lessor accounting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Leases [Abstract]
Operating Lease, Lease Income	$ 11.1	$ 12	$ 23.3	$ 23.4
Lessor, Operating Lease, Payments to be Received, Next Twelve Months	$ 7.9		$ 7.9

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 488,960	$ 488,960	$ 488,960

Other intangible assets (Detail

Other intangible assets (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 3,049	$ 5,213	$ 3,049	$ 5,213	$ 4,102
Amortization of intangible assets	522	568	1,100	1,100
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	10,450	10,450	10,450	10,450	10,450
Intangible assets, less accumulated amortization	7,401	5,312	7,401	5,312	6,356
Intangible assets, net (excluding goodwill)	3,049	5,138	3,049	5,138	4,094
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	292	552	292	552	552
Intangible assets, less accumulated amortization	292	477	292	477	544
Intangible assets, net (excluding goodwill)	$ 0	$ 75	$ 0	$ 75	$ 8

Future amortization expense (De

Future amortization expense (Details 3) $ in Thousands	Jun. 30, 2023 USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2023	$ 1,045
2024	1,888
2025	116
2026	0
2027	0
Thereafter	$ 0

Regulatory assets (Details)

Regulatory assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Regulatory Assets
Regulatory Assets, Current	$ 193,162	$ 165,092	$ 102,535
Regulatory Assets, Noncurrent	345,185	329,659	347,061
Total regulatory assets	538,347	494,751	449,596
Regulatory assets not earning a rate of return	$ 226,400	242,500	262,900
Natural gas costs recoverable through rate adjustments
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Regulatory Assets, Current	$ 170,249	141,306	83,557
Conservation programs
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Regulatory Assets, Current	$ 10,897	8,544	7,883
Cost recovery mechanisms
Regulatory Assets
Regulatory Assets, Current	4,758	4,019	3,459
Regulatory Assets, Noncurrent	$ 63,890	67,171	64,096
Cost recovery mechanisms | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Cost recovery mechanisms | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Up to 10 years
Other regulatory assets
Regulatory Assets
Regulatory Assets, Current	$ 7,258	11,223	7,636
Regulatory Assets, Noncurrent	$ 10,766	11,010	12,543
Other regulatory assets | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Other regulatory assets | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Up to 16 years
Pension and postretirement benefits
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	**
Regulatory Assets, Noncurrent	$ 144,448	143,349	137,582
Plant costs/asset retirement obligations
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Over plant lives
Regulatory Assets, Noncurrent	$ 43,855	44,462	63,334
Manufactured gas plant site remediation
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	-
Regulatory Assets, Noncurrent	$ 25,764	26,624	26,031
Plant to be retired
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	-
Regulatory Assets, Noncurrent	$ 20,858	21,525	27,628
Environmental compliance programs
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	-
Regulatory Assets, Noncurrent	$ 20,611	0	0
Taxes recoverable from customers
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Over plant lives
Regulatory Assets, Noncurrent	$ 12,099	12,330	12,365
Long-term debt refinancing costs
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2023	Up to 37 years
Regulatory Assets, Noncurrent	$ 2,894	$ 3,188	$ 3,482

Regulatory liabilities (Details

Regulatory liabilities (Details 2) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	$ 48,057	$ 26,440	$ 17,884
Regulatory liabilities	455,877	448,454	433,019
Total regulatory liabilities	503,934	474,894	450,903
Net regulatory position	$ 34,413	19,857	(1,307)
Natural gas costs refundable through rate adjustments
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Regulatory liabilities due within one year	$ 17,820	955	738
Electric fuel and purchased power deferral
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Regulatory liabilities due within one year	$ 8,481	4,929	4,161
Cost Recovery Mechanisms
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	3,304	1,977	3,172
Regulatory liabilities	$ 18,226	14,025	10,898
Cost Recovery Mechanisms | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Cost Recovery Mechanisms | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 19 years
Conservation programs
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Regulatory liabilities due within one year	$ 2,851	4,126	352
Taxes refundable to customers
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	1,513	3,937	3,728
Regulatory liabilities	$ 197,757	203,222	209,022
Taxes refundable to customers | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Taxes refundable to customers | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Over plant lives
Refundable Fuel and Electric Costs
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Regulatory liabilities due within one year	$ 103	3,253	1,092
Other regulatory liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	13,985	7,263	4,641
Regulatory liabilities	$ 1,694	1,587	6,649
Other regulatory liabilities | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 1 year
Other regulatory liabilities | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 15 years
Plant removal and decommissioning costs
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Over plant lives
Regulatory liabilities	$ 216,682	208,650	172,755
Accumulated Deferred ITC
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	Up to 19 years
Regulatory liabilities	$ 14,398	13,594	14,009
Pension and postretirement benefits
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2023	**
Regulatory liabilities	$ 7,120	$ 7,376	$ 19,686

Environmental allowances and _2

Environmental allowances and obligations (Details) $ in Millions	Jun. 30, 2023 USD ($)
Accounting Policies [Abstract]
Environmental Compliance Obligations	$ 20.6

Fair value measurements Insuran

Fair value measurements Insurance contracts (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Investments used to satisfy nonqualified benefit plans obligations	$ 84.1	$ 77.5	$ 84.1	$ 77.5	$ 78
Net unrealized gain (loss) on investments used to satisfy obligations under nonqualified benefit plans	$ 1.9	$ (6.7)	$ 4.9	$ (11)

Available-for-sale securities (

Available-for-sale securities (Details 2) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Available-for-sale securities [Abstract]
Cost	$ 11,633	$ 11,536	$ 11,253
Gross Unrealized Gains	5	2	0
Gross Unrealized Losses	697	708	502
Fair Value	10,941	10,830	10,751
Mortgage-backed securities
Available-for-sale securities [Abstract]
Cost	8,542	8,928	8,128
Gross Unrealized Gains	0	2	0
Gross Unrealized Losses	651	636	419
Fair Value	7,891	8,294	7,709
U.S. Treasury securities
Available-for-sale securities [Abstract]
Cost	3,091	2,608	3,125
Gross Unrealized Gains	5	0	0
Gross Unrealized Losses	46	72	83
Fair Value	$ 3,050	$ 2,536	$ 3,042

Investment in Knife River (Deta

Investment in Knife River (Details 3) - USD ($) $ in Thousands, shares in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Jun. 30, 2022	May 31, 2023
Fair value, balance sheet grouping [Line Items]
Retained Shares Ownership Percentage				10%
Retained Shares				5.7
Unrealized Gain (Loss) on Investments	$ 140,000	$ 4,885	$ (10,579)
Investment in Knife River
Fair value, balance sheet grouping [Line Items]
Investments, Fair Value Disclosure	$ 246,100	246,100
Unrealized Gain (Loss) on Investments		$ 140,000

Fair value measurements Assets

Fair value measurements Assets (Details 4) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Concentration risks, percentage [Abstract]
Percentage in fixed-income and other investments	67%	63%	64%
Percentage investment in common stock of large-cap companies	14%	15%	15%
Percentage investment in common stock of mid-cap companies	7%	8%	7%
Percentage investment in common stock of small-cap companies	6%	6%	6%
Percentage investment in target date investments	4%	6%	6%
Percentage investment in cash and cash equivalents	2%	2%	2%
Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 346,840	$ 93,701	$ 94,256
Fair Value, Inputs, Level 1 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	246,063
Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	100,777	93,701	94,256
Investment in Knife River | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	246,063
Investment in Knife River | Fair Value, Inputs, Level 1 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	246,063
Money market funds | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	5,737	4,913	5,976
Money market funds | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	5,737	4,913	5,976
Insurance contracts* | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	84,099	77,958	77,529
Insurance contracts* | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	84,099	77,958	77,529
Mortgage-backed securities | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,891	8,294	7,709
Mortgage-backed securities | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,891	8,294	7,709
U.S. Treasury securities | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	3,050	2,536	3,042
U.S. Treasury securities | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 3,050	$ 2,536	$ 3,042

Fair value measurements Debt (D

Fair value measurements Debt (Details 5) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Fair value, balance sheet grouping [Line Items]
Long-term debt	$ 2,247,422	$ 2,365,667	$ 2,090,200
Carrying amount
Fair value, balance sheet grouping [Line Items]
Long-term debt	2,247,422	2,365,667	2,090,200
Fair value
Fair value, balance sheet grouping [Line Items]
Long-term debt, fair value	$ 1,949,905	$ 2,053,396	$ 1,940,092

Short-term Debt (Details 1)

Short-term Debt (Details 1) - USD ($) $ in Thousands				6 Months Ended
	May 31, 2023	Apr. 30, 2023	Mar. 31, 2023	Jun. 30, 2023	Jun. 30, 2022	May 01, 2023	Mar. 18, 2023	Jan. 20, 2023	Dec. 31, 2022	Dec. 19, 2022
Short-Term Debt [Line Items]
Short-term borrowings				$ 345,000	$ 0				$ 38,500
Repayment of short-term borrowings				$ 193,500	$ 0
Term Loan Agreement | Cascade Natural Gas [Member]
Short-Term Debt [Line Items]
Short-term borrowings								$ 150,000
Ratio of total debt to total capitalization as specified in debt covenants								65%
Term Loan Agreement | Intermountain Gas Company
Short-Term Debt [Line Items]
Short-term borrowings								$ 125,000
Ratio of total debt to total capitalization as specified in debt covenants								65%
Repayment of short-term borrowings	$ 30,000	$ 30,000	$ 20,000
Term Loan Agreement | Centennial Energy Holdings, Inc.
Short-Term Debt [Line Items]
Short-term borrowings							$ 100,000			$ 135,000
Ratio of total debt to total capitalization as specified in debt covenants							65%			65%
Repayment of short-term borrowings	135,000
Term Loan Agreement | Centennial Energy Holdings, Inc. | Debt
Short-Term Debt [Line Items]
Repayment of short-term borrowings	100,000
Term Loan Agreement | MDU Resources Group, Inc.
Short-Term Debt [Line Items]
Short-term borrowings						$ 75,000
Ratio of total debt to total capitalization as specified in debt covenants						65%
Repayment of short-term borrowings	75,000
Revolving Credit Facility | MDU Resources Group, Inc.
Short-Term Debt [Line Items]
Short-term borrowings	$ 150,000
Ratio of total debt to total capitalization as specified in debt covenants	65%

Long-term debt outstanding (Det

Long-term debt outstanding (Details 2) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Jun. 30, 2022	May 31, 2023	Dec. 31, 2022
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,247,422	$ 2,247,422	$ 2,090,200		$ 2,365,667
Long-term debt due within one year	1,319	1,319	86,319		47,819
Long-term debt	2,246,103	2,246,103	2,003,881		2,317,848
Repayments of Long-term Debt		506,191	147,397
Senior Notes
Long-term debt outstanding [Line Items]
Long-term debt	$ 1,757,000	$ 1,757,000	1,847,000		1,848,500
Weighted Average Interest Rate	4.33%	4.33%
Term Loan Agreements
Long-term debt outstanding [Line Items]
Long-term debt	$ 382,000	$ 382,000	7,700		7,000
Weighted Average Interest Rate	6.46%	6.46%
Commercial Paper
Long-term debt outstanding [Line Items]
Long-term debt	$ 58,900	$ 58,900	175,020		349,050
Weighted Average Interest Rate	5.70%	5.70%
Medium-term Notes
Long-term debt outstanding [Line Items]
Long-term debt	$ 35,000	$ 35,000	35,000		35,000
Weighted Average Interest Rate	7.32%	7.32%
Credit Agreements
Long-term debt outstanding [Line Items]
Long-term debt	$ 20,300	$ 20,300	29,860		130,000
Weighted Average Interest Rate	8.35%	8.35%
Other Notes
Long-term debt outstanding [Line Items]
Long-term debt	$ 987	$ 987	1,621		1,614
Weighted Average Interest Rate	2.24%	2.24%
Long-term Debt
Long-term debt outstanding [Line Items]
Unamortized Debt Issuance Costs	$ 6,765	$ 6,765	5,406		5,211
Discount	0	$ 0	$ 595		$ 286
Long-term Debt | Centennial Energy Holdings, Inc.
Long-term debt outstanding [Line Items]
Repayments of Long-term Debt	$ 455,000
Revolving Credit Facility | MDU Resources Group, Inc.
Long-term debt outstanding [Line Items]
Long-term debt				$ 200,000
Ratio of total debt to total capitalization as specified in debt covenants				65%
Term Loan Agreement | MDU Resources Group, Inc.
Long-term debt outstanding [Line Items]
Long-term debt				$ 375,000
Ratio of total debt to total capitalization as specified in debt covenants				65%

Schedule of debt maturities (De

Schedule of debt maturities (Details 3) $ in Thousands	Jun. 30, 2023 USD ($)
Long-term debt maturities [Line Items]
Remainder of 2023	$ 1,319
2024	119,600
2025	532,700
2026	140,700
2027	26,500
Thereafter	$ 1,433,368

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Tax Disclosure [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ 205,551	$ 41,109	$ 310,494	$ 128,668
Income taxes	$ 57,918	$ 5,347	$ 78,986	$ 24,140
Effective Income Tax Rate Reconciliation, Percent	28.20%	13%	25.40%	18.80%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			24.90%	25.30%

Cash flow information (Details)

Cash flow information (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Interest, net*	$ 54,616	$ 39,573
Income taxes paid, net**	17,542	50
AFUDC borrowed	4,900	1,300
Right-of-use assets obtained in exchange for new operating lease liabilities	24,201	14,148	$ 39,158
Property, plant and equipment additions in accounts payable	37,076	40,510	$ 35,637
Continuing and discontinued operations
Income taxes paid, net**	$ 18,300	$ 16,500

Business segment data (Details)

Business segment data (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Revenues	$ 1,091,126		$ 1,009,749		$ 2,521,224	$ 2,116,864
Operating income	82,031		62,505		200,553	170,000
Income from continuing operations	147,633		35,762		231,508	104,528
Discontinued operations, net of tax	(16,941)		34,905		(62,464)	(2,098)
Net income	130,692	$ 38,353	70,667	$ 31,763	169,044	102,430
Electric
Segment Reporting Information [Line Items]
Revenues	90,989		85,551		186,686	179,235
Operating income	21,561		8,325		42,654	23,369
Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	218,995		210,510		784,590	660,998
Operating income	2,428		(638)		60,932	55,617
Pipeline
Segment Reporting Information [Line Items]
Revenues	34,209		29,818		48,683	40,938
Operating income	13,886		12,602		26,926	24,484
Construction services
Segment Reporting Information [Line Items]
Revenues	746,933		683,870		1,501,265	1,235,693
Operating income	54,310		46,141		89,527	75,639
Other
Segment Reporting Information [Line Items]
Revenues	0		0		0	0
Operating income	(10,154)		(3,925)		(19,486)	(9,109)
Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	(11,165)		(10,875)		(39,105)	(39,183)
Intersegment eliminations | Electric
Segment Reporting Information [Line Items]
Revenues	(27)		(34)		(55)	(68)
Intersegment eliminations | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	(69)		(71)		(139)	(137)
Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	(7,918)		(7,787)		(34,188)	(33,729)
Intersegment eliminations | Construction services
Segment Reporting Information [Line Items]
Revenues	0		(1,527)		0	(2,353)
Intersegment eliminations | Other
Segment Reporting Information [Line Items]
Revenues	(3,151)		(1,456)		(4,723)	(2,896)
Total intersegment operating revenues
Segment Reporting Information [Line Items]
Revenues	11,165		10,875		39,105	39,183
Regulated operation
Segment Reporting Information [Line Items]
Revenues	340,492		323,616		1,014,423	877,233
Income from continuing operations	21,832		4,429		86,296	60,047
Regulated operation | Electric
Segment Reporting Information [Line Items]
Revenues	90,989		85,551		186,686	179,235
Income from continuing operations	16,338		4,601		32,945	15,880
Regulated operation | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	218,995		210,510		784,590	660,998
Income from continuing operations	(3,157)		(7,498)		35,771	28,817
Regulated operation | Pipeline
Segment Reporting Information [Line Items]
Revenues	30,508		27,555		43,147	37,000
Income from continuing operations	8,651		7,326		17,580	15,350
Regulated operation | Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	7,795		7,509		34,152	33,543
Regulated operation | Intersegment eliminations | Electric
Segment Reporting Information [Line Items]
Revenues	27		34		55	68
Regulated operation | Intersegment eliminations | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	69		71		139	137
Regulated operation | Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	7,699		7,404		33,958	33,338
Nonregulated operation
Segment Reporting Information [Line Items]
Revenues	750,634		686,133		1,506,801	1,239,631
Income from continuing operations	125,801		31,333		145,212	44,481
Nonregulated operation | Pipeline
Segment Reporting Information [Line Items]
Revenues	3,701		2,263		5,536	3,938
Income from continuing operations	286		(57)		(172)	(674)
Nonregulated operation | Construction services
Segment Reporting Information [Line Items]
Revenues	746,933		683,870		1,501,265	1,235,693
Income from continuing operations	41,167		35,324		69,976	57,349
Nonregulated operation | Other
Segment Reporting Information [Line Items]
Revenues	0		0		0	0
Income from continuing operations	84,348		(3,934)		75,408	(12,194)
Nonregulated operation | Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	3,370		3,366		4,953	5,640
Nonregulated operation | Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	219		336		230	391
Nonregulated operation | Intersegment eliminations | Construction services
Segment Reporting Information [Line Items]
Revenues	0		1,527		0	2,353
Nonregulated operation | Intersegment eliminations | Other
Segment Reporting Information [Line Items]
Revenues	$ 3,151		$ 1,503		$ 4,723	$ 2,896

Business segment data operating

Business segment data operating revenues reconciliation (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 1,091,126	$ 1,009,749	$ 2,521,224	$ 2,116,864
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,099,140	1,019,121	2,555,606	2,153,151
Corporate, Non-Segment
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	3,151	1,503	4,723	2,896
Intersegment Eliminations [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ (11,165)	$ (10,875)	$ (39,105)	$ (39,183)

Employee benefit plans (Details

Employee benefit plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Qualified plan | Underfunded plan | Pension benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Interest cost	$ 3,380	$ 2,349	$ 7,169	$ 4,698
Expected return on assets	(4,299)	(4,371)	(9,048)	(8,742)
Amortization of net actuarial (gain) loss	773	1,457	1,674	2,914
Net periodic benefit cost (credit)	(146)	(565)	(205)	(1,130)
Qualified plan | Overfunded Plan | Other postretirement benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Service cost	136	223	274	446
Interest cost	489	346	978	692
Expected return on assets	(1,334)	(1,319)	(2,668)	(2,638)
Amortization of prior service credit	(329)	(330)	(659)	(660)
Amortization of net actuarial (gain) loss	(70)	(142)	(126)	(284)
Net periodic benefit credit, including amount capitalized	(1,108)	(1,222)	(2,201)	(2,444)
Less amount capitalized	53	53	77	84
Net periodic benefit cost (credit)	(1,161)	(1,275)	(2,278)	(2,528)
Nonqualified plan | Unfunded plan | Supplemental employee retirement plans
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Net periodic benefit cost (credit)	$ 750	$ 648	$ 1,500	$ 1,300

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - Employee Stock	6 Months Ended
	Jun. 30, 2023 USD ($)
Share-Based Payment Arrangement [Abstract]
Share-Based Payment Arrangement, Plan Modification, Incremental Cost	$ 204,000
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-Based Payment Arrangement, Plan Modification, Incremental Cost	$ 204,000

IPUC (Details)

IPUC (Details) - Gas Distribution [Member] - IPUC - Intermountain Gas Company - USD ($) $ in Millions	Jun. 30, 2023	Mar. 09, 2023	Dec. 01, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 11.3
Public Utilities, Requested Rate Increase (Decrease), Percentage			3.20%
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 3.1	$ 6.8
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	0.70%	1.90%

MTPSC (Details 2)

MTPSC (Details 2) - MTPSC - Montana-Dakota Utilities Co. [Member] - Electric - USD ($) $ in Millions	Jun. 12, 2023	Mar. 15, 2023	Feb. 01, 2023	Nov. 04, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Interim Rate Increase (Decrease), Amount			$ 1.7
Public Utilities, Interim Rate Increase (Decrease), Percentage			2.70%
Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 10.5
Public Utilities, Requested Rate Increase (Decrease), Percentage				15.20%
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount	$ 6.1	$ 11.5
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage	9.10%	17%
Public Utilities, Requested Return on Equity, Percentage	9.65%

NDPSC (Details 3)

NDPSC (Details 3) - Electric - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - USD ($) $ in Millions	Jul. 14, 2023	Apr. 26, 2023	Jul. 14, 2022	May 16, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Interim Rate Increase (Decrease), Amount			$ 10.9
Public Utilities, Interim Rate Increase (Decrease), Percentage			5.30%
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount		$ 15.3
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage		7.40%
Public Utilities, Requested Return on Equity, Percentage		9.75%
Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount				$ 25.4
Public Utilities, Requested Rate Increase (Decrease), Percentage				12.30%
Pending Rate Case [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ (10.7)
Total Transmission Cost Adjustment Rider	2.2
Public Utilities, Requested Rate (Decrease), Net Benefit Amount	$ (7.6)

WUTC (Details 4)

WUTC (Details 4) - Pipeline Cost Recovery Mechanism - WUTC [Member] - Cascade Natural Gas [Member] - Pending Rate Case [Member] $ in Millions	Jun. 01, 2023 USD ($)
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 3.1
Public Utilities, Requested Rate Increase (Decrease), Percentage	0.90%

Litigation (Details)

Litigation (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Loss Contingencies [Line Items]
Potential liabilities related to litigation and environmental matters	$ 20,900	$ 31,900	$ 28,100
Insurance Receivable	338	10,000	5,900
Regulatory Assets	$ 20,500	$ 20,900	$ 20,900

Guarantees (Details 2)

Guarantees (Details 2)	Jun. 30, 2023 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 325,500,000
Fixed maximum amounts guaranteed by year 2023	21,600,000
Fixed maximum amounts guaranteed by year 2024	135,600,000
Fixed maximum amounts guaranteed by year 2025	165,500,000
Fixed maximum amounts guaranteed by year 2026	1,500,000
Fixed maximum amounts guaranteed by year 2027	1,000,000
Fixed maximum amounts guaranteed, thereafter	300,000
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit	21,000,000
Outstanding letters of credit	0
Amount of surety bonds outstanding	$ 707,800,000

Variable interest entities (Det

Variable interest entities (Details 3) $ in Millions	Jun. 30, 2023 USD ($)
Fuel contract
Variable Interest Entities [Line Items]
Variable interest entity, reporting entity involvement, maximum loss exposure, amount	$ 28.5