MDU Resources (MDU) 10-Q 5 Aug 22 2022 Q2 Quarterly report Financial data

Cover page

Cover page - shares	6 Months Ended
	Jun. 30, 2022	Jul. 28, 2022
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2022
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		203,350,740
Entity Central Index Key	0000067716
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Operating revenues:
Operating revenues:	$ 1,720,921	$ 1,423,657	$ 3,137,480	$ 2,651,595
Operating expenses:
Operation and maintenance:	1,316,801	1,077,796	2,224,698	1,889,454
Purchased natural gas sold	115,312	63,213	382,665	239,450
Depreciation, depletion and amortization	84,758	73,661	164,880	147,384
Taxes, other than income	61,551	53,189	129,035	115,724
Electric fuel and purchased power	21,929	18,109	48,290	36,730
Total operating expenses	1,600,351	1,285,968	2,949,568	2,428,742
Operating income	120,570	137,689	187,912	222,853
Other income (expense)	(4,246)	9,027	(6,646)	12,381
Interest expense	28,113	23,381	53,373	46,835
Income before income taxes	88,211	123,335	127,893	188,399
Income taxes	17,579	23,164	25,528	36,112
Income from continuing operations	70,632	100,171	102,365	152,287
Discontinued operations, net of tax	35	19	65	34
Net income	$ 70,667	$ 100,190	$ 102,430	$ 152,321
Earnings per share - basic:
Income from continuing operations	$ 0.35	$ 0.50	$ 0.50	$ 0.76
Discontinued operations, net of tax	0	0	0	0
Earnings per share - basic	0.35	0.50	0.50	0.76
Earnings per share - diluted:
Income from continuing operations	0.35	0.50	0.50	0.76
Discontinued operations, net of tax	0	0	0	0
Earnings per share - diluted	$ 0.35	$ 0.50	$ 0.50	$ 0.76
Weighted average common shares outstanding - basic	203,351	201,345	203,351	201,028
Weighted average common shares outstanding - diluted	203,401	201,693	203,396	201,328
Regulated operation
Operating revenues:
Operating revenues:	$ 323,457	$ 260,568	$ 876,913	$ 702,951
Operating expenses:
Operation and maintenance:	94,261	89,404	191,928	183,737
Income from continuing operations	4,294	17,686	59,844	73,808
Nonregulated operation
Operating revenues:
Operating revenues:	1,397,464	1,163,089	2,260,567	1,948,644
Operating expenses:
Operation and maintenance:	1,222,540	988,392	2,032,770	1,705,717
Income from continuing operations	$ 66,338	$ 82,485	$ 42,521	$ 78,479

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Net income	$ 70,667	$ 100,190	$ 102,430	$ 152,321
Other comprehensive income (loss):
Reclassification adjustment for loss on derivative instruments included in net income, tax	36	36	72	73
Reclassification adjustment for loss on derivative instruments included in net income, net of tax	111	112	223	223
Postretirement liability adjustment:
Amortization of postretirement liability losses included in net periodic benefit credit, tax	148	160	312	311
Amortization of postretirement liability losses included in net periodic benefit credit, net of tax	461	457	906	923
Reclassification of postretirement liability adjustment from regulatory asset, tax	(1,086)	0	(1,086)	0
Reclassification of postretirement liability adjustment from regulatory asset, net of tax	(3,265)	0	(3,265)	0
Postretirement liability adjustment	(2,804)	457	(2,359)	923
Net unrealized loss on available-for-sale investments:
Net unrealized loss on available-for-sale investments arising during the period, tax	(34)	(13)	(119)	(25)
Net unrealized loss on available-for-sale investments arising during the period, net of tax	(128)	(52)	(448)	(96)
Reclassification adjustment for loss on available-for-sale investments included in net income, tax	7	6	15	15
Reclassification adjustment for loss on available-for-sale investments included in net income, net of tax	25	25	57	60
Net unrealized loss on available-for-sale investments	(103)	(27)	(391)	(36)
Other comprehensive income (loss)	(2,796)	542	(2,527)	1,110
Comprehensive income attributable to common stockholders	$ 67,871	$ 100,732	$ 99,903	$ 153,431

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Current assets:
Cash and cash equivalents	$ 65,394	$ 54,161	$ 57,946
Receivables, net	1,184,116	946,741	903,831
Inventories	401,433	335,609	316,328
Current regulatory assets	102,535	118,691	109,581
Prepayments and other current assets	105,753	95,741	74,259
Total current assets	1,859,231	1,550,943	1,461,945
Noncurrent assets:
Property, plant and equipment	9,099,752	8,972,849	8,417,559
Less accumulated depreciation, depletion and amortization	3,210,940	3,216,461	3,129,717
Net property, plant and equipment	5,888,812	5,756,388	5,287,842
Goodwill	763,262	765,386	717,863
Other intangible assets, net	20,040	22,578	23,401
Regulatory assets	347,061	357,851	376,913
Investments	161,247	175,476	173,157
Operating lease right-of-use assets	115,802	124,138	112,437
Other	173,670	157,675	144,653
Total noncurrent assets	7,469,894	7,359,492	6,836,266
Total assets	9,329,125	8,910,435	8,298,211
Current liabilities:
Short-term borrowings	100,000	0	50,000
Long-term debt due within one year	214,453	148,053	1,549
Accounts payable	579,064	478,933	431,878
Taxes payable	84,970	80,372	78,805
Dividends payable	44,229	44,229	42,791
Accrued compensation	98,159	81,904	95,909
Operating lease liabilities due within one year	33,626	35,368	31,787
Regulatory liabilities due within one year	17,884	16,303	23,454
Other accrued liabilities	208,290	207,078	188,187
Total current liabilities	1,380,675	1,092,240	944,360
Noncurrent liabilities:
Long-term debt	2,713,514	2,593,847	2,335,500
Deferred income taxes	597,733	591,962	538,633
Asset retirement obligations	467,995	458,061	450,620
Regulatory liabilities	433,019	428,790	428,467
Operating lease liabilities	82,891	89,253	81,052
Other	266,488	273,408	320,777
Total noncurrent liabilities	4,561,640	4,435,321	4,155,049
Commitments and contingencies
Stockholders' equity:
Common stock	203,889	203,889	202,822
Other paid-in capital	1,454,131	1,461,205	1,422,169
Retained earnings	1,775,947	1,762,410	1,624,405
Accumulated other comprehensive loss	(43,531)	(41,004)	(46,968)
Treasury stock at cost - 538,921 shares	(3,626)	(3,626)	(3,626)
Total stockholders' equity	3,386,810	3,382,874	3,198,802
Total liabilities and stockholders' equity	$ 9,329,125	$ 8,910,435	$ 8,298,211
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	203,889,661	203,889,661	202,822,301
Treasury Stock, Common, Shares	538,921	538,921	538,921

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common stock	Other paid-in capital	Retained earnings	Accumulated other comprehensive loss	Treasury stock
Common stock balance (in shares) at Dec. 31, 2020		201,061,198
Treasury stock (in shares) at Dec. 31, 2020						(538,921)
Balance at Dec. 31, 2020	$ 3,079,105	$ 201,061	$ 1,371,385	$ 1,558,363	$ (48,078)	$ (3,626)
Net income	52,131			52,131
Other comprehensive income	568				568
Dividends declared on common stock	(42,943)			(42,943)
Stock-based compensation	2,574		2,574
Repurchase of common stock						(392,294)
Repurchase of common stock	(6,701)					$ (6,701)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(10,828)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						392,294
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						$ 6,701
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(4,127)
Issuance of common stock (shares)		672,260
Issuance of common stock	19,699	$ 672	19,027
Common stock balance (in shares) at Mar. 31, 2021		201,733,458
Treasury stock (in shares) at Mar. 31, 2021						(538,921)
Balance at Mar. 31, 2021	3,100,306	$ 201,733	1,382,158	1,567,551	(47,510)	$ (3,626)
Common stock balance (in shares) at Dec. 31, 2020		201,061,198
Treasury stock (in shares) at Dec. 31, 2020						(538,921)
Balance at Dec. 31, 2020	3,079,105	$ 201,061	1,371,385	1,558,363	(48,078)	$ (3,626)
Net income	152,321
Other comprehensive income	1,110
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	$ (4,127)
Common stock balance (in shares) at Jun. 30, 2021	202,822,301	202,822,301
Treasury stock (in shares) at Jun. 30, 2021						(538,921)
Balance at Jun. 30, 2021	$ 3,198,802	$ 202,822	1,422,169	1,624,405	(46,968)	$ (3,626)
Common stock balance (in shares) at Mar. 31, 2021		201,733,458
Treasury stock (in shares) at Mar. 31, 2021						(538,921)
Balance at Mar. 31, 2021	3,100,306	$ 201,733	1,382,158	1,567,551	(47,510)	$ (3,626)
Net income	100,190			100,190
Other comprehensive income	542				542
Dividends declared on common stock	(43,336)			(43,336)
Stock-based compensation	6,150		6,150
Issuance of common stock (shares)		1,088,843
Issuance of common stock	$ 34,950	$ 1,089	33,861
Common stock balance (in shares) at Jun. 30, 2021	202,822,301	202,822,301
Treasury stock (in shares) at Jun. 30, 2021						(538,921)
Balance at Jun. 30, 2021	$ 3,198,802	$ 202,822	1,422,169	1,624,405	(46,968)	$ (3,626)
Common stock balance (in shares) at Dec. 31, 2021	203,889,661	203,889,661
Treasury stock (in shares) at Dec. 31, 2021						(538,921)
Balance at Dec. 31, 2021	$ 3,382,874	$ 203,889	1,461,205	1,762,410	(41,004)	$ (3,626)
Net income	31,763			31,763
Other comprehensive income	269				269
Dividends declared on common stock	(44,447)			(44,447)
Stock-based compensation	2,689		2,689
Repurchase of common stock						(266,821)
Repurchase of common stock	(7,399)					$ (7,399)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			(12,303)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						266,821
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings						$ 7,399
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	(4,904)
Issuance of common stock	(127)		(127)
Common stock balance (in shares) at Mar. 31, 2022		203,889,661
Treasury stock (in shares) at Mar. 31, 2022						(538,921)
Balance at Mar. 31, 2022	$ 3,360,718	$ 203,889	1,451,464	1,749,726	(40,735)	$ (3,626)
Common stock balance (in shares) at Dec. 31, 2021	203,889,661	203,889,661
Treasury stock (in shares) at Dec. 31, 2021						(538,921)
Balance at Dec. 31, 2021	$ 3,382,874	$ 203,889	1,461,205	1,762,410	(41,004)	$ (3,626)
Net income	102,430
Other comprehensive income	(2,527)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings	$ (4,904)
Common stock balance (in shares) at Jun. 30, 2022	203,889,661	203,889,661
Treasury stock (in shares) at Jun. 30, 2022						(538,921)
Balance at Jun. 30, 2022	$ 3,386,810	$ 203,889	1,454,131	1,775,947	(43,531)	$ (3,626)
Common stock balance (in shares) at Mar. 31, 2022		203,889,661
Treasury stock (in shares) at Mar. 31, 2022						(538,921)
Balance at Mar. 31, 2022	3,360,718	$ 203,889	1,451,464	1,749,726	(40,735)	$ (3,626)
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
Treasury stock (in shares) at Jun. 30, 2022						(538,921)
Balance at Jun. 30, 2022	$ 3,386,810	$ 203,889	$ 1,454,131	$ 1,775,947	$ (43,531)	$ (3,626)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities:
Net income	$ 102,430	$ 152,321
Discontinued operations, net of tax	65	34
Income from continuing operations	102,365	152,287
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	164,880	147,384
Deferred income taxes	1,464	14,498
Provision for credit losses	2,244	(1,158)
Amortization of debt issuance costs	709	633
Employee stock-based compensation costs	5,378	8,724
Pension and postretirement benefit plan net periodic benefit credit	(3,004)	(2,457)
Unrealized (gains) losses on investments	13,210	(3,795)
Gains on sales of assets	(5,434)	(8,021)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(242,252)	(17,358)
Inventories	(63,840)	(25,330)
Other current assets	12,888	(52,768)
Accounts payable	104,451	(3,845)
Other current liabilities	29,178	(22,605)
Pension and postretirement benefit plan contributions	(262)	(225)
Other noncurrent changes	(4,509)	(3,095)
Net cash provided by continuing operations	117,466	182,869
Net cash used in discontinued operations	(16)	(58)
Net cash provided by operating activities	117,450	182,811
Investing activities:
Capital expenditures	(290,145)	(261,937)
Acquisitions, net of cash acquired	(524)	(13,721)
Net proceeds from sale or disposition of property and other	4,324	12,402
Investments	(4,680)	(3,244)
Net cash used in investing activities	(291,025)	(266,500)
Financing activities:
Issuance of short-term borrowings	100,000	50,000
Repayment of short-term borrowings	0	(50,000)
Issuance of long-term debt	334,329	171,774
Repayment of long-term debt	(147,544)	(48,151)
Debt issuance costs	(1,068)	(5)
Net proceeds from issuance of common stock	(149)	54,649
Dividends paid	(88,457)	(85,351)
Repurchase of common stock	(7,399)	(6,701)
Tax withholding on stock-based compensation	(4,904)	(4,127)
Net cash provided by financing activities	184,808	82,088
Increase (decrease) in cash and cash equivalents	11,233	(1,601)
Cash and cash equivalents -- beginning of year	54,161	59,547
Cash and cash equivalents -- end of period	$ 65,394	$ 57,946

Basis of presentation

Basis of presentation	6 Months Ended
	Jun. 30, 2022
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 2021 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. On August 4, 2022, the Company announced its Board of Directors unanimously approved a plan to pursue the separation of Knife River from the Company. The separation is planned as a tax-free spinoff transaction to the Company’s stockholders for U.S. federal income tax purposes. The assets and liabilities of the Company's discontinued operations have been classified as held for sale and are included in prepayments and other current assets, noncurrent assets - other and other accrued liabilities on the Consolidated Balance Sheets. The results and supporting activities are shown in income from discontinued operations on the Consolidated Statements of Income. Unless otherwise indicated, the amounts presented in the accompanying notes to the consolidated financial statements relate to the Company's continuing operations. In the fourth quarter of 2021, the Company made changes to the presentation of the Consolidated Statements of Cash Flows to provide further clarity on the sources and uses of net cash provided by operating activities and net cash provided by (used in) financing activities. Certain prior period amounts have been reclassified to conform to the current year presentation. These reclassifications did not impact total net cash provided by operating activities or net cash provided by financing activities for the six months ended June 30, 2021 .

New accounting standards

New accounting standards	6 Months Ended
	Jun. 30, 2022
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 ASU 2021-10 - Government Assistance In November 2021, the FASB issued guidance on modifying the disclosure requirements to increase the transparency of government assistance including disclosure of the types of assistance, an entity's accounting for the assistance and the effect of the assistance on an entity's financial statements. January 1, 2022 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2022. ASU 2020-04 - Reference Rate Reform In March 2020, the FASB issued optional guidance to ease the facilitation of the effects of reference rate reform on financial reporting. The guidance applies to certain contract modifications, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. Beginning January 1, 2022, LIBOR or other discontinued reference rates cannot be applied to new contracts. New contracts will incorporate a new reference rate, which includes SOFR. LIBOR or other discontinued reference rates cannot be applied to contract modifications or hedging relationships entered into or evaluated after December 31, 2022. Existing contracts referencing LIBOR or other reference rates expected to be discontinued must identify a replacement rate by June 30, 2023. Effective as of March 12, 2020 and will continue through December 31, 2022 The Company has updated its credit agreements to include language regarding the successor or alternate rate to LIBOR, and a review of other contracts and agreements is on-going. The Company does not expect the guidance to have a material impact on its results of operations, financial position, cash flows or disclosures.

Seasonality of operations

Seasonality of operations	6 Months Ended
	Jun. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Seasonality of operations	Seasonality of operations Some of the Company's operations are highly seasonal and revenues from, and certain expenses for, such operations may fluctuate significantly among quarterly periods. Accordingly, the interim results for particular businesses, and for the Company as a whole, may not be indicative of results for the full fiscal year.

Receivables and allowance for e

Receivables and allowance for expected credit losses	6 Months Ended
	Jun. 30, 2022
Credit Loss [Abstract]
Receivables and allowance for expected credit loss	Receivables and allowance for expected credit losses Receivables consists 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 $37.0 million, $34.2 million and $44.8 million at June 30, 2022 and 2021, and December 31, 2021, respectively. The Company's expected credit losses are determined through a review using historical credit loss experience; changes in asset specific characteristics; current conditions; and reasonable and supportable future forecasts, among other specific account data, and is performed at least quarterly. The Company develops and documents its methodology to determine its allowance for expected credit losses at each of its reportable business segments. Risk characteristics used by the business segments may include customer mix, knowledge of customers and general economic conditions of the various local economies, among others. Specific account balances are written off when management determines the amounts to be uncollectible. Management has reviewed the balance reserved through the allowance for expected credit losses and believes it is reasonable. Details of the Company's expected credit losses were as follows: Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 2021 $ 269 $ 1,506 $ 2 $ 5,406 $ 2,533 $ 9,716 Current expected credit loss provision 565 1,369 — (253) 54 1,735 Less write-offs charged against the allowance 597 932 — 27 71 1,627 Credit loss recoveries collected 124 180 — — 28 332 At March 31, 2022 $ 361 $ 2,123 $ 2 $ 5,126 $ 2,544 $ 10,156 Current expected credit loss provision 113 92 — 12 292 509 Less write-offs charged against the allowance 234 939 — 108 104 1,385 Credit loss recoveries collected 108 177 — — — 285 At June 30, 2022 $ 348 $ 1,453 $ 2 $ 5,030 $ 2,732 $ 9,565 Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 2020 $ 899 $ 2,571 $ 2 $ 6,164 $ 5,722 $ 15,358 Current expected credit loss provision 538 1,273 — (1,049) (1,079) (317) Less write-offs charged against the allowance 888 1,107 — 273 401 2,669 Credit loss recoveries collected 129 213 — — — 342 At March 31, 2021 $ 678 $ 2,950 $ 2 $ 4,842 $ 4,242 $ 12,714 Current expected credit loss provision (110) (103) — 11 (639) (841) Less write-offs charged against the allowance 341 787 — 232 64 1,424 Credit loss recoveries collected 100 199 — — — 299 At June 30, 2021 $ 327 $ 2,259 $ 2 $ 4,621 $ 3,539 $ 10,748

Inventories and natural gas in

Inventories and natural gas in storage	6 Months Ended
	Jun. 30, 2022
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, 2022 June 30, 2021 December 31, 2021 (In thousands) Aggregates held for resale $ 200,569 $ 183,977 $ 184,363 Asphalt oil 92,905 51,500 57,002 Materials and supplies 40,405 27,969 30,629 Merchandise for resale 38,293 26,871 28,501 Natural gas in storage (current) 15,014 10,824 18,867 Other 14,247 15,187 16,247 Total $ 401,433 $ 316,328 $ 335,609

Earnings per share

Earnings per share	6 Months Ended
	Jun. 30, 2022
Earnings Per Share [Abstract]
Earnings per share	Earnings per share Basic earnings per share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the applicable period. Diluted earnings per share is computed by dividing net income by the total of the weighted average number of shares of common stock outstanding during the applicable period, plus the effect of non-vested performance share awards and restricted stock units. Common stock outstanding includes issued shares less shares held in treasury. Net income was the same for both the basic and diluted earnings per share calculations. A reconciliation of the weighted average common shares outstanding used in the basic and diluted earnings per share calculations follows: Three Months Ended Six Months Ended June 30, June 30, 2022 2021 2022 2021 (In thousands, except per share amounts) Weighted average common shares outstanding - basic 203,351 201,345 203,351 201,028 Effect of dilutive performance share awards and restricted stock units 50 348 45 300 Weighted average common shares outstanding - diluted 203,401 201,693 203,396 201,328 Shares excluded from the calculation of diluted earnings per share 52 — 175 — Dividends declared per common share $ .2175 $ .2125 $ .4350 $ .4250

Equity

Equity	6 Months Ended
	Jun. 30, 2022
Equity [Abstract]
Equity	Equity The Company currently has a shelf registration statement on file with the SEC, under which the Company may issue and sell any combination of common stock and debt securities. The Company may sell such securities if warranted by market conditions and the Company's capital requirements. In August 2020, the Company amended the Distribution Agreement dated February 22, 2019, with J.P. Morgan Securities LLC and MUFG Securities Americas Inc., as sales agents. This agreement, as amended, allows the offering, issuance and sale of up to 6.4 million shares of the Company's common stock in connection with an "at-the-market" offering. The common stock may be offered for sale, from time to time, in accordance with the terms and conditions of this agreement. As of June 30, 2022, the Company had capacity to issue up to 3.6 million additional shares of common stock under the "at-the-market" offering program. Details of the Company's "at-the-market" offering activity was as follows: Three Months Ended Six Months Ended June 30, June 30, 2022 2021 2022 2021 (In millions) Shares issued — 1.1 — 1.8 Net proceeds * $ — $ 34.9 ** $ (.1) $ 54.6 ** * Net proceeds include issuance costs of $22,000 and $149,000 for the three and six months ended June 30, 2022, respectively, and $443,000 and $743,000 for the three and six months ended June 30, 2021, respectively. ** Net proceeds were used for capital expenditures.

Accumulated other comprehensive

Accumulated other comprehensive loss	6 Months Ended
	Jun. 30, 2022
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, 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) Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2020 $ (984) $ (47,207) $ 113 $ (48,078) Other comprehensive loss before reclassifications — — (44) (44) Amounts reclassified from accumulated other comprehensive loss 111 466 35 612 Net current-period other comprehensive income (loss) 111 466 (9) 568 At March 31, 2021 $ (873) $ (46,741) $ 104 $ (47,510) Other comprehensive loss before reclassifications — — (52) (52) Amounts reclassified from accumulated other comprehensive loss 112 457 25 594 Net current-period other comprehensive income (loss) 112 457 (27) 542 At June 30, 2021 $ (761) $ (46,284) $ 77 $ (46,968) 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, 2022 2021 2022 2021 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (147) $ (148) $ (295) $ (296) Interest expense 36 36 72 73 Income taxes (111) (112) (223) (223) Amortization of postretirement liability losses included in net periodic benefit credit (609) (617) (1,218) (1,234) Other income 148 160 312 311 Income taxes (461) (457) (906) (923) Reclassification adjustment on available-for-sale investments included in net income (32) (31) (72) (75) Other income 7 6 15 15 Income taxes (25) (25) (57) (60) Total reclassifications $ (597) $ (594) $ (1,186) $ (1,206)

Revenue from contracts with cus

Revenue from contracts with customers	6 Months Ended
	Jun. 30, 2022
Revenue from Contract with Customer [Abstract]
Revenue from contracts with customers	Revenue from contracts with customers Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes. Disaggregation In the following tables, revenue is disaggregated by the type of customer or service provided. The Company believes this level of disaggregation best depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. The table also includes a reconciliation of the disaggregated revenue by reportable segments. For more information on the Company's business segments, see Note 17. Three Months Ended June 30, 2022 Electric Natural gas Pipeline Construction 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 Contracting services — — — 330,682 — — 330,682 Construction materials — — — 550,363 — — 550,363 Intrasegment eliminations — — — (169,232) — — (169,232) Electrical & mechanical specialty contracting — — — — 507,233 — 507,233 Transmission & distribution specialty contracting — — — — 166,174 — 166,174 Other 10,216 3,751 2,676 — 109 4,389 21,141 Intersegment eliminations (124) (141) (7,792) (200) (1,803) (4,389) (14,449) Revenues from contracts with customers 86,273 213,178 29,747 711,613 671,713 — 1,712,524 Revenues out of scope (812) (2,738) 66 — 11,881 — 8,397 Total external operating revenues $ 85,461 $ 210,440 $ 29,813 $ 711,613 $ 683,594 $ — $ 1,720,921 Three Months Ended June 30, 2021 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 29,258 $ 83,480 $ — $ — $ — $ — $ 112,738 Commercial utility sales 33,834 47,612 — — — — 81,446 Industrial utility sales 10,354 6,180 — — — — 16,534 Other utility sales 1,825 — — — — — 1,825 Natural gas transportation — 11,451 27,685 — — — 39,136 Natural gas storage — — 3,094 — — — 3,094 Contracting services — — — 280,834 — — 280,834 Construction materials — — — 498,762 — — 498,762 Intrasegment eliminations — — — (145,780) — — (145,780) Electrical & mechanical specialty contracting — — — — 347,702 — 347,702 Transmission & distribution specialty contracting — — — — 165,123 — 165,123 Other 9,465 2,794 4,810 — 57 3,389 20,515 Intersegment eliminations (136) (142) (7,862) (142) (797) (3,361) (12,440) Revenues from contracts with customers 84,600 151,375 27,727 633,674 512,085 28 1,409,489 Revenues out of scope (950) 2,413 46 — 12,659 — 14,168 Total external operating revenues $ 83,650 $ 153,788 $ 27,773 $ 633,674 $ 524,744 $ 28 $ 1,423,657 Six Months Ended June 30, 2022 Electric Natural gas Pipeline Construction 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 Contracting services — — — 444,949 — — 444,949 Construction materials — — — 792,095 — — 792,095 Intrasegment eliminations — — — (215,266) — — (215,266) Electrical & mechanical specialty contracting — — — — 900,041 — 900,041 Transmission & distribution specialty contracting — — — — 314,640 — 314,640 Other 22,969 6,360 4,386 — 157 8,730 42,602 Intersegment eliminations (247) (277) (33,734) (330) (2,861) (8,730) (46,179) Revenues from contracts with customers 183,863 663,481 40,808 1,021,448 1,211,977 — 3,121,577 Revenues out of scope (4,807) (2,623) 124 — 23,209 — 15,903 Total external operating revenues $ 179,056 $ 660,858 $ 40,932 $ 1,021,448 $ 1,235,186 $ — $ 3,137,480 Six Months Ended June 30, 2021 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 62,694 $ 286,617 $ — $ — $ — $ — $ 349,311 Commercial utility sales 66,762 167,664 — — — — 234,426 Industrial utility sales 20,383 14,992 — — — — 35,375 Other utility sales 3,391 — — — — — 3,391 Natural gas transportation — 23,903 57,102 — — — 81,005 Natural gas storage — — 7,123 — — — 7,123 Contracting services — — — 376,859 — — 376,859 Construction materials — — — 715,174 — — 715,174 Intrasegment eliminations — — — (192,496) — — (192,496) Electrical & mechanical specialty contracting — — — — 702,892 — 702,892 Transmission & distribution specialty contracting — — — — 316,486 — 316,486 Other 19,238 5,803 7,470 — 93 6,730 39,334 Intersegment eliminations (271) (284) (34,092) (204) (1,839) (6,685) (43,375) Revenues from contracts with customers 172,197 498,695 37,603 899,333 1,017,632 45 2,625,505 Revenues out of scope (3,873) 5,299 82 — 24,582 — 26,090 Total external operating revenues $ 168,324 $ 503,994 $ 37,685 $ 899,333 $ 1,042,214 $ 45 $ 2,651,595 Presented in the previous tables are intrasegment revenues within the construction materials and contracting segment to highlight the focus on vertical integration as this segment sells materials to both third parties and internal customers. Due to consolidation requirements, these revenues must be eliminated against construction materials to arrive at the external operating revenue total for the segment. Contract balances The timing of revenue recognition may differ from the timing of invoicing to customers. The timing of invoicing to customers does not necessarily correlate with the timing of revenues being recognized under the cost-to-cost method of accounting. Contracts from contracting services are billed as work progresses in accordance with agreed upon contractual terms. Generally, billing to the customer occurs contemporaneous to revenue recognition. A variance in timing of the billings may result in a contract asset or a contract liability. A contract asset occurs when revenues are recognized under the cost-to-cost measure of progress, which exceeds amounts billed on uncompleted contracts. Such amounts will be billed as standard contract terms allow, usually based on various measures of performance or achievement. A contract liability occurs when there are billings in excess of revenues recognized under the cost-to-cost measure of progress on uncompleted contracts. Contract liabilities decrease as revenue is recognized from the satisfaction of the related performance obligation. The changes in contract assets and liabilities were as follows: June 30, 2022 December 31, 2021 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 236,951 $ 125,742 $ 111,209 Receivables, net Contract liabilities - current (167,507) (179,140) 11,633 Accounts payable Contract liabilities - noncurrent (19) (118) 99 Noncurrent liabilities - other Net contract assets (liabilities) $ 69,425 $ (53,516) $ 122,941 The Company recognized $14.8 million and $136.7 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 $21.9 million and $145.3 million in revenue for the three and six months ended June 30, 2021, respectively, which was previously included in contract liabilities at December 31, 2020. The Company recognized a net increase in revenues of $30.0 million and $42.4 million for the three and six months ended June 30, 2022, respectively, from performance obligations satisfied in prior periods. The company recognized a net increase in revenues of $27.3 million and $54.6 million for the three and six months ended June 30, 2021, respectively, from performance obligations satisfied in prior periods. Remaining performance obligations The remaining performance obligations, also referred to as backlog, at the construction materials and contracting and construction services segments include unrecognized revenues that the Company reasonably expects to be realized. These unrecognized revenues can include: projects that have a written award, a letter of intent, a notice to proceed, an agreed upon work order to perform work on mutually accepted terms and conditions and change orders or claims to the extent management believes additional contract revenues will be earned and are deemed probable of collection. Excluded from remaining performance obligations are potential orders under master service agreements. The majority of the Company's construction contracts have an original duration of less than two years. The remaining performance obligations at the pipeline segment include firm transportation contracts with fixed pricing and fixed volumes. The Company has applied the practical expedient, which does not require additional disclosures for contracts with an original duration of less than 12 months, to certain firm transportation and non-regulated contracts. The Company's firm transportation contracts included in the remaining performance obligations have weighted average remaining durations of less than five years. At June 30, 2022, the Company's remaining performance obligations were $3.5 billion. The Company expects to recognize the following revenue amounts in future periods related to these remaining performance obligations: $2.8 billion within the next 12 months or less; $389.0 million within the next 13 to 24 months; and $368.4 million in 25 months or more.

Business Combinations

Business Combinations	6 Months Ended
	Jun. 30, 2022
Business Combinations [Abstract]
Business Combinations	Business combinations The following acquisitions were accounted for as business combinations in accordance with ASC 805 - Business Combinations. The results of the acquired businesses have been included in the Consolidated Financial Statements beginning on the acquisition date. Pro forma financial amounts reflecting the effects of the business combinations are not presented, as none of these business combinations, individually or in the aggregate, were material to the Company's financial position or results of operations. The acquisitions are also subject to customary adjustments based on, among other things, the amount of cash, debt and working capital in the business as of the closing date. The amounts included in the Consolidated Balance Sheets for these adjustments are considered provisional until final settlement has occurred. The Company had no acquisitions in the first half of 2022. In 2021, the construction materials and contracting segment's acquisitions included: • Baker Rock Resources and Oregon Mainline Paving, two premier construction materials companies located around the Portland, Oregon metro area, acquired in November 2021. At June 30, 2022, the purchase price allocation was preliminary and will be finalized within 12 months of the acquisition date. • Mt. Hood Rock, a construction aggregates business in Oregon, acquired in April 2021. As of March 31, 2022, the purchase price allocation was settled with no material adjustments to the provisional accounting. In 2021, the total purchase price for acquisitions was $236.1 million, subject to certain adjustments, with cash acquired totaling $900,000. The purchase price includes consideration paid of $235.2 million. The amounts allocated to the aggregated assets acquired and liabilities assumed during 2021 were as follows: $17.0 million to current assets; $179.8 million to property, plant and equipment; $50.6 million to goodwill; $2.2 million to other intangible assets; $8.7 million to current liabilities; $2.5 million to noncurrent liabilities - other; and $3.2 million to deferred tax liabilities. During the first quarter of 2022, measurement period adjustments were made to previously reported provisional amounts, which decreased goodwill and increased property, plant and equipment by $2.1 million. The Company issued debt to finance these acquisitions. Costs incurred for acquisitions are included in operation and maintenance expense on the Consolidated Statements of Income. For the six months ended June 30, 2022, the Company had no acquisition costs. For the six months ended June 30, 2021, acquisition costs were not material.

Leases

Leases	6 Months Ended
	Jun. 30, 2022
Leases [Abstract]
Lessee, Operating Leases	Leases The Company's leases primarily include operating leases for equipment, buildings, easements and vehicles. The Company leases certain equipment to third parties through its utility and construction services segments, which are considered short-term operating leases with terms of less than 12 months. The Company recognized revenue from operating leases of $12.0 million and $23.4 million for the three and six months ended June 30, 2022, respectively. The Company recognized revenue from operating leases of $12.8 million and $24.8 million for the three and six months ended June 30, 2021, respectively. At June 30, 2022, the Company had $8.7 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, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and other intangible assets	Goodwill and other intangible assets The changes in the carrying amount of goodwill were as follows: Balance at January 1, 2022 Goodwill Measurement Balance at June 30, 2022 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 276,426 — (2,124) 274,302 Construction services 143,224 — — 143,224 Total $ 765,386 $ — $ (2,124) $ 763,262 Balance at January 1, 2021 Goodwill Measurement Balance at June 30, 2021 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 226,003 2,900 — 228,903 Construction services 143,224 — — 143,224 Total $ 714,963 $ 2,900 $ — $ 717,863 Balance at January 1, 2021 Goodwill Measurement Balance at December 31, 2021 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 226,003 50,640 (217) 276,426 Construction services 143,224 — — 143,224 Total $ 714,963 $ 50,640 $ (217) $ 765,386 Other amortizable intangible assets were as follows: June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Customer relationships $ 28,990 $ 29,423 $ 29,740 Less accumulated amortization 11,812 8,765 10,650 17,178 20,658 19,090 Noncompete agreements 4,591 3,991 4,591 Less accumulated amortization 3,206 2,576 2,856 1,385 1,415 1,735 Other 5,607 11,957 12,601 Less accumulated amortization 4,130 10,629 10,848 1,477 1,328 1,753 Total $ 20,040 $ 23,401 $ 22,578 The previous tables include goodwill and intangible assets associated with the business combinations completed during 2021. For more information related to these business combinations, see Note 10. Amortization expense for amortizable intangible assets for the three and six months ended June 30, 2022, was $1.3 million and $2.5 million, respectively. Amortization expense for amortizable intangible assets for the three and six months ended June 30, 2021, was $1.2 million and $2.7 million, respectively. Estimated amortization expense for identifiable intangible assets as of June 30, 2022, was: Remainder of 2022 2023 2024 2025 2026 Thereafter (In thousands) Amortization expense $ 2,285 $ 4,591 $ 4,305 $ 2,291 $ 1,781 $ 4,787

Regulatory assets and liabiliti

Regulatory assets and liabilities	6 Months Ended
	Jun. 30, 2022
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets and Liabilities	Regulatory assets and liabilities The following table summarizes the individual components of unamortized regulatory assets and liabilities: Estimated Recovery or Refund Period as of June 30, 2022 * June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 83,557 $ 85,045 $ 86,371 Conservation programs Up to 1 year 7,883 7,580 8,225 Decoupling Up to 1 year 4,615 6,750 9,131 Cost recovery mechanisms Up to 1 year 3,459 5,692 4,536 Other Up to 1 year 3,021 4,514 10,428 102,535 109,581 118,691 Noncurrent: Pension and postretirement benefits ** 137,582 155,906 142,681 Cost recovery mechanisms Up to 10 years 64,096 44,415 44,870 Plant costs/asset retirement obligations Over plant lives 63,334 72,853 63,116 Plant to be retired - 27,628 46,061 50,070 Manufactured gas plant site remediation - 26,031 26,155 26,053 Taxes recoverable from customers Over plant lives 12,365 10,929 12,339 Long-term debt refinancing costs Up to 38 years 3,482 4,110 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years 1,839 8,389 5,186 Other Up to 17 years 10,704 8,095 9,742 347,061 376,913 357,851 Total regulatory assets $ 449,596 $ 486,494 $ 476,542 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year $ 4,161 $ 5,431 $ — Taxes refundable to customers Up to 1 year 3,728 3,434 3,841 Cost recovery mechanisms Up to 1 year 3,172 1,388 214 Natural gas costs refundable through rate adjustments Up to 1 year 738 8,935 6,700 Other Up to 1 year 6,085 4,266 5,548 17,884 23,454 16,303 Noncurrent: Taxes refundable to customers Over plant lives 209,022 222,098 215,421 Plant removal and decommissioning costs Over plant lives 172,755 171,381 168,152 Pension and postretirement benefits ** 19,686 16,940 20,434 Accumulated deferred investment tax credit Up to 20 years 14,009 11,915 12,696 Cost recovery mechanisms Up to 20 years 10,898 2,499 7,727 Other Up to 16 years 6,649 3,634 4,360 433,019 428,467 428,790 Total regulatory liabilities $ 450,903 $ 451,921 $ 445,093 Net regulatory position $ (1,307) $ 34,573 $ 31,449 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made. At June 30, 2022 and 2021, and December 31, 2021, approximately $262.9 million, $317.0 million and $296.6 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, asset retirement obligations, accelerated depreciation on plant retirement and the estimated future cost of manufactured gas plant site remediation. In the last half of 2021 and the first half of 2022, the Company has experienced higher natural gas costs due to the increase in demand outpacing the supply along with the impact of global events. This increase in natural gas costs experienced in certain jurisdictions has been offset by the recovery of prior period natural gas costs being recovered over a period longer than the normal one-year period, as further discussed below. In February 2021, a prolonged period of unseasonably cold temperatures in the central United States significantly increased the demand for electric and natural gas services and contributed to increased market prices. Overall, Montana-Dakota and Great Plains incurred approximately $44.0 million in increased natural gas costs in order to maintain services for its customers. These extraordinary gas costs were recorded as regulatory assets as they are expected to be recovered from customers. Montana-Dakota and Great Plains have received approval for the recovery of purchased gas adjustments related to the cold-weather event in all jurisdictions impacted, including out-of-cycle purchased gas adjustment requests in most jurisdictions. For a discussion of the Company's most recent cases by jurisdiction, see Note 19. In 2019, the Company experienced increased natural gas costs in Washington from the rupture of the Enbridge pipeline in Canada in late 2018. As a result, the Company requested, and the WUTC approved, recovery through 2022 of the balance of natural gas costs recoverable related to this period of time, which was over three years rather than its normal one-year recovery period. In February 2019, the Company announced the retirement of three aging coal-fired electric generating units. The Company accelerated the depreciation related to these facilities in property, plant and equipment and recorded the difference between the accelerated depreciation, in accordance with GAAP, and the depreciation approved for rate-making purposes as regulatory assets. Requests were filed with the NDPSC and SDPUC, and subsequently approved, to offset the savings associated with the cessation of operations of these units with the amortization of the deferred regulatory assets. The Company ceased operations of Lewis & Clark Station in March 2021 and Units 1 and 2 at Heskett Station in February 2022. The Company subsequently reclassified the costs being recovered for these facilities from plant retirement to cost recovery mechanisms in the previous table and began amortizing the associated plant retirement and closure costs in the jurisdictions where requests were filed, as previously discussed. The Company expects to recover the regulatory assets related to the plant retirements in future rates. If, for any reason, the Company's regulated businesses cease to meet the criteria for application of regulatory accounting for all or part of their operations, the regulatory assets and liabilities relating to those portions ceasing to meet such criteria would be 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, 2022
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the measurement date. The fair value ASC establishes a hierarchy for grouping assets and liabilities, based on the significance of inputs. The estimated fair values of the Company's assets and liabilities measured on a recurring basis are determined using the market approach. The Company measures its investments in certain fixed-income and equity securities at fair value with changes in fair value recognized in income. The Company anticipates using these investments, which consist of insurance contracts, to satisfy its obligations under its unfunded, nonqualified defined benefit and defined contribution plans for 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 $97.4 million, $105.7 million and $109.6 million, at June 30, 2022 and 2021, and December 31, 2021, respectively, are classified as investments on the Consolidated Balance Sheets. The net unrealized loss on these investments was $8.4 million and $14.1 million for the three and six months ended June 30, 2022, respectively. The net unrealized gain on these investments was $3.8 million and $3.9 million for the three and six months ended June 30, 2021. 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, 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 June 30, 2021 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,278 $ 127 $ 9 $ 8,396 U.S. Treasury securities 2,893 — 21 2,872 Total $ 11,171 $ 127 $ 30 $ 11,268 December 31, 2021 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,702 $ 51 $ 47 $ 8,706 U.S. Treasury securities 2,407 — 11 2,396 Total $ 11,109 $ 51 $ 58 $ 11,102 The Company's assets measured at fair value on a recurring basis were as follows: Fair Value Measurements at June 30, 2022, Using Quoted Prices in Significant Significant Balance at June 30, 2022 (In thousands) Assets: Money market funds $ — $ 8,333 $ — $ 8,333 Insurance contracts* — 97,431 — 97,431 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 $ — $ 116,515 $ — $ 116,515 * 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 June 30, 2021, Using Quoted Prices in Significant Significant Balance at June 30, 2021 (In thousands) Assets: Money market funds $ — $ 12,234 $ — $ 12,234 Insurance contracts* — 105,684 — 105,684 Available-for-sale securities: Mortgage-backed securities — 8,396 — 8,396 U.S. Treasury securities — 2,872 — 2,872 Total assets measured at fair value $ — $ 129,186 $ — $ 129,186 * The insurance contracts invest approximately 53 percent in fixed-income investments, 20 percent in common stock of large-cap companies, 10 percent in common stock of mid-cap companies, 9 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at December 31, 2021, Using Quoted Prices in Significant Significant Balance at December 31, 2021 (In thousands) Assets: Money market funds $ — $ 10,190 $ — $ 10,190 Insurance contracts* — 109,603 — 109,603 Available-for-sale securities: Mortgage-backed securities — 8,706 — 8,706 U.S. Treasury securities — 2,396 — 2,396 Total assets measured at fair value $ — $ 130,895 $ — $ 130,895 * The insurance contracts invest approximately 61 percent in fixed-income investments, 17 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 7 percent in common stock of small-cap companies, 5 percent in target date investments and 2 percent in cash equivalents. The Company's money market funds are valued at the net asset value of shares held at the end of the period, based on published market quotations on active markets, or using other known sources including pricing from outside sources. The estimated fair value of the Company's mortgage-backed securities and U.S. Treasury securities are based on comparable market transactions, other observable inputs or other sources, including pricing from outside sources. The estimated fair value of the Company's insurance contracts are based on contractual cash surrender values that are determined primarily by investments in managed separate accounts of the insurer. These amounts approximate fair value. The managed separate accounts are valued based on other observable inputs or corroborated market data. Though the Company believes the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value. The Company applies the provisions of the fair value measurement standard to its nonrecurring, non-financial measurements, including long-lived asset impairments. These assets are not measured at fair value on an ongoing basis but are subject to fair value adjustments only in certain circumstances. The Company reviews the carrying value of its long-lived assets, excluding goodwill, whenever events or changes in circumstances indicate that such carrying amounts may not be recoverable. The Company performed fair value assessments of the assets acquired and liabilities assumed in the business combinations that occurred during 2021. The fair value of these assets and liabilities were determined based on Level 2 and Level 3 inputs. The Company's long-term debt is not measured at fair value on the Consolidated Balance Sheets and the fair value is being provided for disclosure purposes only. The fair value was categorized as Level 2 in the fair value hierarchy and was based on discounted future cash flows using current market interest rates. The estimated fair value of the Company's Level 2 long-term debt was as follows: June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Carrying amount $ 2,927,967 $ 2,337,049 $ 2,741,900 Fair value $ 2,753,684 $ 2,616,232 $ 2,984,866 The carrying amounts of the Company's remaining financial instruments included in current assets and current liabilities approximate their fair values .

Debt

Debt	6 Months Ended
	Jun. 30, 2022
Debt Disclosure [Abstract]
Debt	Debt Certain debt instruments of the Company's subsidiaries contain restrictive and financial covenants and cross-default provisions. In order to borrow under the debt agreements, the subsidiary companies must be in compliance with the applicable covenants and certain other conditions, all of which the subsidiaries, as applicable, were in compliance with at June 30, 2022. In the event the subsidiaries do not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued. Montana-Dakota's and Centennial's respective commercial paper programs are supported by revolving credit agreements. While the amount of commercial paper outstanding does not reduce available capacity under the respective revolving credit agreements, Montana-Dakota and Centennial do not issue commercial paper in an aggregate amount exceeding the available capacity under the credit agreements. The commercial paper borrowings may vary during the period, largely the result of fluctuations in working capital requirements due to the seasonality of certain operations of the Company's subsidiaries. Short-term debt Centennial On March 18, 2022, Centennial entered into a $100.0 million term loan agreement with a SOFR-based variable interest rate and a maturity date of March 17, 2023. The agreement contains customary covenants and provisions, including a covenant of Centennial not to permit, at any time, the ratio of total debt to total capitalization to be greater than 65 percent. The covenants also include certain restrictions on the sale of certain assets, loans and investments. Long-term debt Long-term Debt Outstanding Long-term debt outstanding was as follows: Weighted Average Interest Rate at June 30, 2022 June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Senior Notes due on dates ranging from October 22, 2022 to June 15, 2062 4.29 % $ 2,365,000 $ 1,950,000 $ 2,125,000 Commercial paper supported by revolving credit agreements 1.96 % 495,400 297,400 450,300 Credit agreements due on June 7, 2024 4.75 % 29,860 48,550 127,500 Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 7.32 % 35,000 35,000 35,000 Term Loan Agreement due on September 3, 2032 2.00 % 7,700 8,400 7,700 Other notes due on dates ranging from January 1, 2024 to January 1, 2061 .95 % 2,411 3,232 2,564 Less unamortized debt issuance costs 6,809 5,505 6,090 Less discount 595 28 74 Total long-term debt 2,927,967 2,337,049 2,741,900 Less current maturities 214,453 1,549 148,053 Net long-term debt $ 2,713,514 $ 2,335,500 $ 2,593,847 Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs and discount, at June 30, 2022, were as follows: Remainder of 2022 2023 2024 2025 2026 Thereafter (In thousands) Long-term debt maturities $ 147,953 $ 77,923 $ 586,064 $ 177,802 $ 140,802 $ 1,804,827

Cash flow information

Cash flow information	6 Months Ended
	Jun. 30, 2022
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, 2022 2021 (In thousands) Interest, net* $ 50,294 $ 45,870 Income taxes paid, net $ 16,520 $ 46,734 * AFUDC - borrowed was $1.3 million and $816,000 for the six months ended June 30, 2022 and 2021, respectively. Noncash investing and financing transactions were as follows: June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 18,907 $ 17,224 $ 55,987 Property, plant and equipment additions in accounts payable $ 46,295 $ 31,886 $ 57,605 Debt assumed in connection with a business combination $ — $ — $ 10

Business segment data

Business segment data	6 Months Ended
	Jun. 30, 2022
Segment Reporting [Abstract]
Business segment data	Business segment data The Company's reportable segments are those that are based on the Company's method of internal reporting, which generally segregates the strategic business units due to differences in products, services and regulation. The internal reporting of these operating segments is defined based on the reporting and review process used by the Company's chief executive officer. The Company's operations are located within the United States. The electric segment generates, transmits and distributes electricity in Montana, North Dakota, South Dakota and Wyoming. The natural gas distribution segment distributes natural gas in those states, as well as in Idaho, Minnesota, Oregon and Washington. These operations also supply related value-added services. The pipeline segment provides natural gas transportation and underground storage services through a regulated pipeline system primarily in the Rocky Mountain and northern Great Plains regions of the United States. This segment also provides non-regulated cathodic protection and other energy-related services. The construction materials and contracting segment mines, processes and sells construction aggregates (crushed stone, sand and gravel); produces and sells asphalt mix; and supplies ready-mix concrete. This segment focuses on vertical integration of its contracting services with its construction materials to support the aggregate-based product lines including aggregate placement, asphalt and concrete paving, and site development and grading. Although not common to all locations, other products include the sale of cement, asphalt oil for various commercial and roadway applications, various finished concrete products and other building materials and related contracting services. This segment operates in the central, southern and western United States, including Alaska and Hawaii. The construction services segment provides a full spectrum of construction services through its electrical and mechanical and transmission and distribution specialty contracting services across the United States. These specialty contracting services are provided to utilities and manufacturing, transportation, commercial, industrial, institutional, renewable and governmental customers. Its electrical and mechanical contracting services include construction and maintenance of electrical and communication wiring and infrastructure, fire suppression systems, and mechanical piping and services. Its transmission and distribution contracting services include construction and maintenance of overhead and underground electrical, gas and communication infrastructure, as well as manufacturing and distribution of transmission line construction equipment and tools. The Other category includes the activities of Centennial Capital, which, through its subsidiary InterSource Insurance Company, insures various types of risks as a captive insurer for certain of the Company's subsidiaries. The function of the captive insurer is to fund the self-insured layers of the insured Company's general liability, automobile liability, pollution liability and other coverages. Centennial Capital also owns certain real and personal property. In addition, the Other category includes certain assets, liabilities and tax adjustments of the holding company primarily associated with corporate functions and certain general and administrative costs (reflected in operation and maintenance expense) and interest expense, which were previously allocated to the refining business and Fidelity and do not meet the criteria for income (loss) from discontinued operations. Discontinued operations include the supporting activities of Fidelity other than certain general and administrative costs and interest expense as described above. The information below follows the same accounting policies as described in Note 2 of the Notes to Consolidated Financial Statements in the 2021 Annual Report. Information on the Company's segments was as follows: Three Months Ended Six Months Ended June 30, June 30, 2022 2021 2022 2021 (In thousands) External operating revenues: Regulated operations: Electric $ 85,461 $ 83,650 $ 179,056 $ 168,324 Natural gas distribution 210,440 153,788 660,858 503,994 Pipeline 27,556 23,130 36,999 30,633 323,457 260,568 876,913 702,951 Non-regulated operations: Pipeline 2,257 4,643 3,933 7,052 Construction materials and contracting 711,613 633,674 1,021,448 899,333 Construction services 683,594 524,744 1,235,186 1,042,214 Other — 28 — 45 1,397,464 1,163,089 2,260,567 1,948,644 Total external operating revenues $ 1,720,921 $ 1,423,657 $ 3,137,480 $ 2,651,595 Three Months Ended Six Months Ended June 30, June 30, 2022 2021 2022 2021 (In thousands) Intersegment operating revenues: Regulated operations: Electric $ 124 $ 136 $ 247 $ 271 Natural gas distribution 141 142 277 284 Pipeline 7,404 7,695 33,338 33,685 7,669 7,973 33,862 34,240 Non-regulated operations: Pipeline 388 167 396 407 Construction materials and contracting 200 142 330 204 Construction services 1,803 797 2,861 1,839 Other 4,389 3,361 8,730 6,685 6,780 4,467 12,317 9,135 Intersegment eliminations (14,449) (12,440) (46,179) (43,375) Total intersegment operating revenues $ — $ — $ — $ — Operating income (loss): Electric $ 8,325 $ 12,806 $ 23,369 $ 26,672 Natural gas distribution (638) 3,601 55,617 57,173 Pipeline 12,602 11,076 24,484 23,612 Construction materials and contracting 54,354 72,452 9,749 37,563 Construction services 46,141 37,774 75,639 78,051 Other (214) (20) (946) (218) Total operating income $ 120,570 $ 137,689 $ 187,912 $ 222,853 Net income (loss): Regulated operations: Electric $ 4,601 $ 10,304 $ 15,880 $ 21,054 Natural gas distribution (7,498) (707) 28,817 35,471 Pipeline 7,191 8,089 15,147 17,283 4,294 17,686 59,844 73,808 Non-regulated operations: Pipeline (60) 1,106 (679) 810 Construction materials and contracting 32,584 51,396 (7,427) 20,584 Construction services 34,454 28,885 55,778 58,709 Other (640) 1,098 (5,151) (1,624) 66,338 82,485 42,521 78,479 Income from continuing operations 70,632 100,171 102,365 152,287 Discontinued operations, net of tax 35 19 65 34 Net income $ 70,667 $ 100,190 $ 102,430 $ 152,321

Employee benefit plans

Employee benefit plans	6 Months Ended
	Jun. 30, 2022
Retirement Benefits [Abstract]
Employee benefit plans	Employee benefit plans Pension and other postretirement plans The Company has noncontributory qualified defined benefit pension plans and other postretirement benefit plans for certain eligible employees. Components of net periodic benefit credit for the Company's pension benefit plans were as follows: Three Months Ended Six Months Ended June 30, June 30, 2022 2021 2022 2021 (In thousands) Components of net periodic benefit credit: Interest cost $ 2,631 $ 2,455 $ 5,262 $ 4,910 Expected return on assets (4,864) (4,894) (9,728) (9,788) Amortization of net actuarial loss 1,671 2,004 3,342 4,008 Net periodic benefit credit $ (562) $ (435) $ (1,124) $ (870) 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, 2022 2021 2022 2021 (In thousands) Components of net periodic benefit credit: Service cost $ 354 $ 400 $ 708 $ 800 Interest cost 474 466 948 932 Expected return on assets (1,322) (1,275) (2,644) (2,550) Amortization of prior service credit (350) (349) (700) (698) Amortization of net actuarial (gain) loss (54) 6 (108) 12 Net periodic benefit credit, including amount capitalized (898) (752) (1,796) (1,504) Less amount capitalized 53 44 84 83 Net periodic benefit credit $ (951) $ (796) $ (1,880) $ (1,587) 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 $773,000 and $769,000 for the three months ended June 30, 2022 and 2021, respectively, and $1.5 million for both the six months ended June 30, 2022 and 2021. The components of net periodic benefit cost for these plans are included in other income on the Consolidated Statements of Income.

Regulatory matters

Regulatory matters	6 Months Ended
	Jun. 30, 2022
Regulated Operations [Abstract]
Regulatory Matters	Regulatory matters The Company regularly reviews the need for electric and natural gas rate changes in each of the jurisdictions in which service is provided. The Company files for rate adjustments to seek recovery of operating costs and capital investments, as well as reasonable returns as allowed by regulators. Certain regulatory proceedings and cases may also contain recurring mechanisms that can have an annual true-up. Examples of these recurring mechanisms include: infrastructure riders, transmission trackers, renewable resource cost adjustment riders, as well as weather normalization and decoupling mechanisms. The following paragraphs summarize the Company's significant open regulatory proceedings and cases by jurisdiction including updates to those reported in the 2021 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 defers the difference between the actual cost of gas spent to serve customers and the amount approved to be recovered from customers and annually prepares a true-up pursuant to the purchased gas adjustment tariff. On May 31, 2022, Intermountain filed an application with the IPUC for an out-of-cycle cost of gas adjustment requesting an increase in rates of approximately $67.0 million annually or approximately 25.2 percent above current rates. The primary reason for the requested increase was to mitigate the under collection balance due to the significant increase in the commodity price for natural gas. On July 29, 2022, the request was approved with rates effective August 1, 2022. The new rates will be in effect until October 1, 2022, when rates based on Intermountain's annual purchased gas adjustment tariff filing will take effect, which is expected to be filed in August 2022. MNPUC Great Plains defers the difference between the actual cost of gas spent to serve customers and that recovered from customers on a monthly basis. Annually, Great Plains prepares a true-up pursuant to the purchased gas adjustment tariff. On August 30, 2021, the MNPUC issued an order to allow Great Plains recovery of an out-of-cycle cost of gas adjustment of $8.8 million over a period of 27 months. The order was effective September 1, 2021, and is subject to a prudence review by the MNPUC. The requested increase was for the February 2021 extreme cold weather, primarily in the central United States, and market conditions surrounding the natural gas commodity market. The MNPUC prudence review is pending with an order to be issued on or before August 29, 2022. On June 1, 2022, Great Plains filed an application with the MNPUC for a decrease in its depreciation and amortization rates of approximately $1.2 million annually or a decrease from a combined rate of 4.5 percent to 2.8 percent. Great Plains has requested the rates be retroactive to January 1, 2022. This matter is pending before the MNPUC. 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 was 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. The NDPSC has 7 months to render a final decision on the rate case. 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. On July 15, 2022, Montana-Dakota filed an application with the NDPSC to request an update to its transmission cost adjustment rider requesting to recover revenues of $12.9 million, which includes a true-up of the prior period adjustment, resulting in a decrease of $1.6 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 proposes the rates be effective for service rendered on and after November 1, 2022. This matter is pending before the NDPSC. SDPUC Montana-Dakota has a transmission cost recovery rider that allows annual updates to rates for actual costs associated with transmission-related projects and services. On March 1, 2022, Montana-Dakota filed an annual update to its transmission cost recovery rider to recover a revenue requirement of approximately $2.5 million annually, which reflects a true-up of the prior period adjustment, resulting in an increase in current rates of approximately $1.5 million. On May 12, 2022, the SDPUC approved the rates as requested with an effective date of June 1, 2022. WUTC On September 30, 2021, Cascade filed an application with the WUTC for a natural gas rate increase of approximately $13.7 million annually or approximately 5.1 percent above current rates. The requested increase was primarily to recover investments made in infrastructure upgrades, as well as to recover 2021 wage increases. On March 22, 2022, Cascade filed a multi-party settlement and stipulation on behalf of Cascade and the staff of the WUTC that would result in a revenue requirement increase of approximately $10.7 million annually or approximately 4.0 percent above current rates. The WUTC has until September 1, 2022, to render a final decision on the rate case. This matter is pending before the WUTC. On March 24, 2022, Cascade filed a request for a tariff revision with the WUTC to rectify an inadvertent IRS normalization violation resulting from its tariff established in 2018 that passes back to customers the reversal of plant-related excess deferred income taxes through an annual rate adjustment. This request was made in response to the issuance of an IRS private letter ruling to another Washington utility with the same annual rate adjustment tariff, which addressed its normalization violation. The private letter ruling concluded the tariff to refund excess deferred income taxes without corresponding adjustments for other components of rate base or changes in depreciation or income tax expense, is an impermissible methodology under the IRS normalization and consistency rules. Cascade's request proposes a similar remedy through the tariff to recover the excess amounts refunded to customers while this tariff has been in place, and revises the method going forward to reflect excess deferred income taxes in rates in the same manner as other components of rate base from its most recent general rate case. Cascade has requested recovery of the excess refunded to customers of approximately $3.3 million and elimination of the currently deferred, but not yet refunded balance. This matter is pending before the WUTC, with an evidentiary hearing scheduled for November 17, 2022.

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2022
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, 2022 and 2021, and December 31, 2021, the Company accrued liabilities, which have not been discounted, of $28.2 million, $30.8 million and $37.0 million, respectively. At June 30, 2022 and 2021, and December 31, 2021, the Company also recorded corresponding insurance receivables of $5.9 million, $6.9 million and $14.1 million, respectively, and regulatory assets of $20.9 million, $21.2 million and $21.2 million, respectively, related to the accrued liabilities. The accruals are for contingencies resulting from litigation, production taxes, royalty claims and environmental matters. This includes amounts that have been accrued for matters discussed in Environmental matters within this note. The Company will continue to monitor each matter and adjust accruals as might be warranted based on new information and further developments. Management believes that the outcomes with respect to probable and reasonably possible losses in excess of the amounts accrued, net of insurance recoveries, while uncertain, either cannot be estimated or will not have a material effect upon the Company's financial position, results of operations or cash flows. Unless otherwise required by GAAP, legal costs are expensed as they are incurred. Environmental matters The Company is a party to claims for the cleanup of environmental contamination at certain manufactured gas plant sites, as well as a superfund site. There were no material changes to the Company's environmental matters that were previously reported in the 2021 Annual Report. Guarantees Certain subsidiaries of the Company have outstanding guarantees to third parties that guarantee the performance of other subsidiaries of the Company. These guarantees are related to construction contracts, insurance deductibles and loss limits, and certain other guarantees. At June 30, 2022, the fixed maximum amounts guaranteed under these agreements aggregate $276.0 million. Certain of the guarantees also have no fixed maximum amounts specified. At June 30, 2022, the amounts of scheduled expiration of the maximum amounts guaranteed under these agreements aggregate to $21.8 million in 2022; $82.0 million in 2023; $160.6 million in 2024; $900,000 in 2025; $900,000 in 2026; $800,000 thereafter; and $9.0 million, which has no scheduled maturity date. There were no amounts outstanding under the previously mentioned guarantees at June 30, 2022. In the event of default under these guarantee obligations, the subsidiary issuing the guarantee for that particular obligation would be required to make payments under its guarantee. Certain subsidiaries have outstanding letters of credit to third parties related to insurance policies and other agreements, some of which are guaranteed by other subsidiaries of the Company. At June 30, 2022, the fixed maximum amounts guaranteed under these letters of credit aggregated $28.2 million. At June 30, 2022, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $27.6 million in 2022 and $600,000 in 2023. There were no amounts outstanding under the previously mentioned letters of credit at June 30, 2022. In the event of default under these letter of credit obligations, the subsidiary guaranteeing the letter of credit would be obligated for reimbursement of payments made under the letter of credit. In addition, Centennial, Knife River and MDU Construction Services have issued guarantees to third parties related to the routine purchase of maintenance items, materials and lease obligations for which no fixed maximum amounts have been specified. These guarantees have no scheduled maturity date. In the event a subsidiary of the Company defaults under these obligations, Centennial, Knife River or MDU Construction Services would be required to make payments under these guarantees. Any amounts outstanding by subsidiaries of the Company were reflected on the Consolidated Balance Sheet at June 30, 2022. In the normal course of business, Centennial has surety bonds related to construction contracts and reclamation obligations of its subsidiaries. In the event a subsidiary of Centennial does not fulfill a bonded obligation, Centennial would be responsible to the surety bond company for completion of the bonded contract or obligation. A large portion of the surety bonds is expected to expire within the next 12 months; however, Centennial will likely continue to enter into surety bonds for its subsidiaries in the future. At June 30, 2022, approximately $1.2 billion of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet. Variable interest entities The Company evaluates its arrangements and contracts with other entities to determine if they are VIEs and if so, if the Company is the primary beneficiary. Fuel Contract Coyote Station entered into a coal supply agreement with Coyote Creek that provides for the purchase of coal necessary to supply the coal requirements of the Coyote Station for the period May 2016 through December 2040. Coal purchased under the coal supply agreement is reflected in inventories on the Consolidated Balance Sheets and is recovered from customers as a component of electric fuel and purchased power. The coal supply agreement creates a variable interest in Coyote Creek due to the transfer of all operating and economic risk to the Coyote Station owners, as the agreement is structured so that the price of the coal will cover all costs of operations, as well as future reclamation costs. The Coyote Station owners are also providing a guarantee of the value of the assets of Coyote Creek as they would be required to buy the assets at book value should they terminate the contract prior to the end of the contract term and are providing a guarantee of the value of the equity of Coyote Creek in that they are required to buy the entity at the end of the contract term at equity value. Although the Company has determined that Coyote Creek is a VIE, the Company has concluded that it is not the primary beneficiary of Coyote Creek because the authority to direct the activities of the entity is shared by the four unrelated owners of the Coyote Station, with no primary beneficiary existing. As a result, Coyote Creek is not required to be consolidated in the Company's financial statements. At June 30, 2022, the Company's exposure to loss as a result of the Company's involvement with the VIE, based on the Company's ownership percentage, was $30.5 million.

Basis of presentation (Policies

Basis of presentation (Policies)	6 Months Ended
	Jun. 30, 2022
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 2021 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.On August 4, 2022, the Company announced its Board of Directors unanimously approved a plan to pursue the separation of Knife River from the Company. The separation is planned as a tax-free spinoff transaction to the Company’s stockholders for U.S. federal income tax purposes.

New accounting standards (Polic

New accounting standards (Policies)	6 Months Ended
	Jun. 30, 2022
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 ASU 2021-10 - Government Assistance In November 2021, the FASB issued guidance on modifying the disclosure requirements to increase the transparency of government assistance including disclosure of the types of assistance, an entity's accounting for the assistance and the effect of the assistance on an entity's financial statements. January 1, 2022 The Company is currently evaluating the impact the guidance will have on its disclosures for the year ended December 31, 2022. ASU 2020-04 - Reference Rate Reform In March 2020, the FASB issued optional guidance to ease the facilitation of the effects of reference rate reform on financial reporting. The guidance applies to certain contract modifications, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. Beginning January 1, 2022, LIBOR or other discontinued reference rates cannot be applied to new contracts. New contracts will incorporate a new reference rate, which includes SOFR. LIBOR or other discontinued reference rates cannot be applied to contract modifications or hedging relationships entered into or evaluated after December 31, 2022. Existing contracts referencing LIBOR or other reference rates expected to be discontinued must identify a replacement rate by June 30, 2023. Effective as of March 12, 2020 and will continue through December 31, 2022 The Company has updated its credit agreements to include language regarding the successor or alternate rate to LIBOR, and a review of other contracts and agreements is on-going. The Company does not expect the guidance to have a material impact on its results of operations, financial position, cash flows or disclosures.

Receivables and allowance for_2

Receivables and allowance for expected credit losses (Policies)	6 Months Ended
	Jun. 30, 2022
Credit Loss [Abstract]
Accounts receivable and allowance for doubtful accounts	Receivables consists 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, 2022
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, 2022
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, 2022
Revenue from Contract with Customer [Abstract]
Revenue from contracts with customers	Revenue is recognized when a performance obligation is satisfied by transferring control over a product or service to a customer. Revenue is measured based on consideration specified in a contract with a customer and excludes any sales incentives and amounts collected on behalf of third parties. The Company is considered an agent for certain taxes collected from customers. As such, the Company presents revenues net of these taxes at the time of sale to be remitted to governmental authorities, including sales and use taxes.

Business Combinations (Policies

Business Combinations (Policies)	6 Months Ended
	Jun. 30, 2022
Business Combinations [Abstract]
Business Combinations Policy	The following acquisitions were accounted for as business combinations in accordance with ASC 805 - Business Combinations. The results of the acquired businesses have been included in the Consolidated Financial Statements beginning on the acquisition date. Pro forma financial amounts reflecting the effects of the business combinations are not presented, as none of these business combinations, individually or in the aggregate, were material to the Company's financial position or results of operations.

Fair value disclosures (Policie

Fair value disclosures (Policies)	6 Months Ended
	Jun. 30, 2022
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, 2022
Segment Reporting [Abstract]
Business segment data	The Company's reportable segments are those that are based on the Company's method of internal reporting, which generally segregates the strategic business units due to differences in products, services and regulation. The internal reporting of these operating segments is defined based on the reporting and review process used by the Company's chief executive officer.

Contingencies (Policies)

Contingencies (Policies)	6 Months Ended
	Jun. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Contingencies	The Company is party to claims and lawsuits arising out of its business and that of its consolidated subsidiaries, which may include, but are not limited to, matters involving property damage, personal injury, and environmental, contractual, statutory and regulatory obligations. The Company accrues a liability for those contingencies when the incurrence of a loss is probable and the amount can be reasonably estimated. If a range of amounts can be reasonably estimated and no amount within the range is a better estimate than any other amount, then the minimum of the range is accrued. The Company does not accrue liabilities when the likelihood that the liability has been incurred is probable but the amount cannot be reasonably estimated or when the liability is believed to be only reasonably possible or remote. For contingencies where an unfavorable outcome is probable or reasonably possible and which are material, the Company discloses the nature of the contingency and, in some circumstances, an estimate of the possible loss. Accruals are based on the best information available, but in certain situations management is unable to estimate an amount or range of a reasonably possible loss including, but not limited to when: (1) the damages are unsubstantiated or indeterminate, (2) the proceedings are in the early stages, (3) numerous parties are involved, or (4) the matter involves novel or unsettled legal theories.
Variable interest entity	The Company evaluates its arrangements and contracts with other entities to determine if they are VIEs and if so, if the Company is the primary beneficiary.

Receivables and allowance for_3

Receivables and allowance for expected credit losses (Tables)	6 Months Ended
	Jun. 30, 2022
Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss [Table Text Block]	Details of the Company's expected credit losses were as follows: Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 2021 $ 269 $ 1,506 $ 2 $ 5,406 $ 2,533 $ 9,716 Current expected credit loss provision 565 1,369 — (253) 54 1,735 Less write-offs charged against the allowance 597 932 — 27 71 1,627 Credit loss recoveries collected 124 180 — — 28 332 At March 31, 2022 $ 361 $ 2,123 $ 2 $ 5,126 $ 2,544 $ 10,156 Current expected credit loss provision 113 92 — 12 292 509 Less write-offs charged against the allowance 234 939 — 108 104 1,385 Credit loss recoveries collected 108 177 — — — 285 At June 30, 2022 $ 348 $ 1,453 $ 2 $ 5,030 $ 2,732 $ 9,565 Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 2020 $ 899 $ 2,571 $ 2 $ 6,164 $ 5,722 $ 15,358 Current expected credit loss provision 538 1,273 — (1,049) (1,079) (317) Less write-offs charged against the allowance 888 1,107 — 273 401 2,669 Credit loss recoveries collected 129 213 — — — 342 At March 31, 2021 $ 678 $ 2,950 $ 2 $ 4,842 $ 4,242 $ 12,714 Current expected credit loss provision (110) (103) — 11 (639) (841) Less write-offs charged against the allowance 341 787 — 232 64 1,424 Credit loss recoveries collected 100 199 — — — 299 At June 30, 2021 $ 327 $ 2,259 $ 2 $ 4,621 $ 3,539 $ 10,748

Inventories and natural gas i_3

Inventories and natural gas in storage (Tables)	6 Months Ended
	Jun. 30, 2022
Inventory Disclosure [Abstract]
Inventories	Inventories on the Consolidated Balance Sheets were as follows: June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Aggregates held for resale $ 200,569 $ 183,977 $ 184,363 Asphalt oil 92,905 51,500 57,002 Materials and supplies 40,405 27,969 30,629 Merchandise for resale 38,293 26,871 28,501 Natural gas in storage (current) 15,014 10,824 18,867 Other 14,247 15,187 16,247 Total $ 401,433 $ 316,328 $ 335,609

Earnings per share (Tables)

Earnings per share (Tables)	6 Months Ended
	Jun. 30, 2022
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, 2022 2021 2022 2021 (In thousands, except per share amounts) Weighted average common shares outstanding - basic 203,351 201,345 203,351 201,028 Effect of dilutive performance share awards and restricted stock units 50 348 45 300 Weighted average common shares outstanding - diluted 203,401 201,693 203,396 201,328 Shares excluded from the calculation of diluted earnings per share 52 — 175 — Dividends declared per common share $ .2175 $ .2125 $ .4350 $ .4250

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2022
Equity [Abstract]
Schedule of Stock by Class	Details of the Company's "at-the-market" offering activity was as follows: Three Months Ended Six Months Ended June 30, June 30, 2022 2021 2022 2021 (In millions) Shares issued — 1.1 — 1.8 Net proceeds * $ — $ 34.9 ** $ (.1) $ 54.6 ** * Net proceeds include issuance costs of $22,000 and $149,000 for the three and six months ended June 30, 2022, respectively, and $443,000 and $743,000 for the three and six months ended June 30, 2021, respectively. ** Net proceeds were used for capital expenditures.

Accumulated other comprehensi_2

Accumulated other comprehensive loss (Tables)	6 Months Ended
	Jun. 30, 2022
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, 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) Net Unrealized Postretirement Net Unrealized Total (In thousands) At December 31, 2020 $ (984) $ (47,207) $ 113 $ (48,078) Other comprehensive loss before reclassifications — — (44) (44) Amounts reclassified from accumulated other comprehensive loss 111 466 35 612 Net current-period other comprehensive income (loss) 111 466 (9) 568 At March 31, 2021 $ (873) $ (46,741) $ 104 $ (47,510) Other comprehensive loss before reclassifications — — (52) (52) Amounts reclassified from accumulated other comprehensive loss 112 457 25 594 Net current-period other comprehensive income (loss) 112 457 (27) 542 At June 30, 2021 $ (761) $ (46,284) $ 77 $ (46,968)
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, 2022 2021 2022 2021 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (147) $ (148) $ (295) $ (296) Interest expense 36 36 72 73 Income taxes (111) (112) (223) (223) Amortization of postretirement liability losses included in net periodic benefit credit (609) (617) (1,218) (1,234) Other income 148 160 312 311 Income taxes (461) (457) (906) (923) Reclassification adjustment on available-for-sale investments included in net income (32) (31) (72) (75) Other income 7 6 15 15 Income taxes (25) (25) (57) (60) Total reclassifications $ (597) $ (594) $ (1,186) $ (1,206)

Revenue from contracts with c_3

Revenue from contracts with customers (Tables)	6 Months Ended
	Jun. 30, 2022
Revenue from Contract with Customer [Abstract]
Disaggregation of revenue	In the following tables, revenue is disaggregated by the type of customer or service provided. The Company believes this level of disaggregation best depicts how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. The table also includes a reconciliation of the disaggregated revenue by reportable segments. For more information on the Company's business segments, see Note 17. Three Months Ended June 30, 2022 Electric Natural gas Pipeline Construction 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 Contracting services — — — 330,682 — — 330,682 Construction materials — — — 550,363 — — 550,363 Intrasegment eliminations — — — (169,232) — — (169,232) Electrical & mechanical specialty contracting — — — — 507,233 — 507,233 Transmission & distribution specialty contracting — — — — 166,174 — 166,174 Other 10,216 3,751 2,676 — 109 4,389 21,141 Intersegment eliminations (124) (141) (7,792) (200) (1,803) (4,389) (14,449) Revenues from contracts with customers 86,273 213,178 29,747 711,613 671,713 — 1,712,524 Revenues out of scope (812) (2,738) 66 — 11,881 — 8,397 Total external operating revenues $ 85,461 $ 210,440 $ 29,813 $ 711,613 $ 683,594 $ — $ 1,720,921 Three Months Ended June 30, 2021 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 29,258 $ 83,480 $ — $ — $ — $ — $ 112,738 Commercial utility sales 33,834 47,612 — — — — 81,446 Industrial utility sales 10,354 6,180 — — — — 16,534 Other utility sales 1,825 — — — — — 1,825 Natural gas transportation — 11,451 27,685 — — — 39,136 Natural gas storage — — 3,094 — — — 3,094 Contracting services — — — 280,834 — — 280,834 Construction materials — — — 498,762 — — 498,762 Intrasegment eliminations — — — (145,780) — — (145,780) Electrical & mechanical specialty contracting — — — — 347,702 — 347,702 Transmission & distribution specialty contracting — — — — 165,123 — 165,123 Other 9,465 2,794 4,810 — 57 3,389 20,515 Intersegment eliminations (136) (142) (7,862) (142) (797) (3,361) (12,440) Revenues from contracts with customers 84,600 151,375 27,727 633,674 512,085 28 1,409,489 Revenues out of scope (950) 2,413 46 — 12,659 — 14,168 Total external operating revenues $ 83,650 $ 153,788 $ 27,773 $ 633,674 $ 524,744 $ 28 $ 1,423,657 Six Months Ended June 30, 2022 Electric Natural gas Pipeline Construction 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 Contracting services — — — 444,949 — — 444,949 Construction materials — — — 792,095 — — 792,095 Intrasegment eliminations — — — (215,266) — — (215,266) Electrical & mechanical specialty contracting — — — — 900,041 — 900,041 Transmission & distribution specialty contracting — — — — 314,640 — 314,640 Other 22,969 6,360 4,386 — 157 8,730 42,602 Intersegment eliminations (247) (277) (33,734) (330) (2,861) (8,730) (46,179) Revenues from contracts with customers 183,863 663,481 40,808 1,021,448 1,211,977 — 3,121,577 Revenues out of scope (4,807) (2,623) 124 — 23,209 — 15,903 Total external operating revenues $ 179,056 $ 660,858 $ 40,932 $ 1,021,448 $ 1,235,186 $ — $ 3,137,480 Six Months Ended June 30, 2021 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 62,694 $ 286,617 $ — $ — $ — $ — $ 349,311 Commercial utility sales 66,762 167,664 — — — — 234,426 Industrial utility sales 20,383 14,992 — — — — 35,375 Other utility sales 3,391 — — — — — 3,391 Natural gas transportation — 23,903 57,102 — — — 81,005 Natural gas storage — — 7,123 — — — 7,123 Contracting services — — — 376,859 — — 376,859 Construction materials — — — 715,174 — — 715,174 Intrasegment eliminations — — — (192,496) — — (192,496) Electrical & mechanical specialty contracting — — — — 702,892 — 702,892 Transmission & distribution specialty contracting — — — — 316,486 — 316,486 Other 19,238 5,803 7,470 — 93 6,730 39,334 Intersegment eliminations (271) (284) (34,092) (204) (1,839) (6,685) (43,375) Revenues from contracts with customers 172,197 498,695 37,603 899,333 1,017,632 45 2,625,505 Revenues out of scope (3,873) 5,299 82 — 24,582 — 26,090 Total external operating revenues $ 168,324 $ 503,994 $ 37,685 $ 899,333 $ 1,042,214 $ 45 $ 2,651,595
Contract balances	The changes in contract assets and liabilities were as follows: June 30, 2022 December 31, 2021 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 236,951 $ 125,742 $ 111,209 Receivables, net Contract liabilities - current (167,507) (179,140) 11,633 Accounts payable Contract liabilities - noncurrent (19) (118) 99 Noncurrent liabilities - other Net contract assets (liabilities) $ 69,425 $ (53,516) $ 122,941

Goodwill and other intangible_2

Goodwill and other intangible assets (Tables)	6 Months Ended
	Jun. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the carrying amount of goodwill	The changes in the carrying amount of goodwill were as follows: Balance at January 1, 2022 Goodwill Measurement Balance at June 30, 2022 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 276,426 — (2,124) 274,302 Construction services 143,224 — — 143,224 Total $ 765,386 $ — $ (2,124) $ 763,262 Balance at January 1, 2021 Goodwill Measurement Balance at June 30, 2021 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 226,003 2,900 — 228,903 Construction services 143,224 — — 143,224 Total $ 714,963 $ 2,900 $ — $ 717,863 Balance at January 1, 2021 Goodwill Measurement Balance at December 31, 2021 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 226,003 50,640 (217) 276,426 Construction services 143,224 — — 143,224 Total $ 714,963 $ 50,640 $ (217) $ 765,386
Other amortizable intangible assets	Other amortizable intangible assets were as follows: June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Customer relationships $ 28,990 $ 29,423 $ 29,740 Less accumulated amortization 11,812 8,765 10,650 17,178 20,658 19,090 Noncompete agreements 4,591 3,991 4,591 Less accumulated amortization 3,206 2,576 2,856 1,385 1,415 1,735 Other 5,607 11,957 12,601 Less accumulated amortization 4,130 10,629 10,848 1,477 1,328 1,753 Total $ 20,040 $ 23,401 $ 22,578
Estimated amortization expense	Estimated amortization expense for identifiable intangible assets as of June 30, 2022, was: Remainder of 2022 2023 2024 2025 2026 Thereafter (In thousands) Amortization expense $ 2,285 $ 4,591 $ 4,305 $ 2,291 $ 1,781 $ 4,787

Regulatory assets and liabili_2

Regulatory assets and liabilities (Tables)	6 Months Ended
	Jun. 30, 2022
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, 2022 * June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 83,557 $ 85,045 $ 86,371 Conservation programs Up to 1 year 7,883 7,580 8,225 Decoupling Up to 1 year 4,615 6,750 9,131 Cost recovery mechanisms Up to 1 year 3,459 5,692 4,536 Other Up to 1 year 3,021 4,514 10,428 102,535 109,581 118,691 Noncurrent: Pension and postretirement benefits ** 137,582 155,906 142,681 Cost recovery mechanisms Up to 10 years 64,096 44,415 44,870 Plant costs/asset retirement obligations Over plant lives 63,334 72,853 63,116 Plant to be retired - 27,628 46,061 50,070 Manufactured gas plant site remediation - 26,031 26,155 26,053 Taxes recoverable from customers Over plant lives 12,365 10,929 12,339 Long-term debt refinancing costs Up to 38 years 3,482 4,110 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years 1,839 8,389 5,186 Other Up to 17 years 10,704 8,095 9,742 347,061 376,913 357,851 Total regulatory assets $ 449,596 $ 486,494 $ 476,542 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year $ 4,161 $ 5,431 $ — Taxes refundable to customers Up to 1 year 3,728 3,434 3,841 Cost recovery mechanisms Up to 1 year 3,172 1,388 214 Natural gas costs refundable through rate adjustments Up to 1 year 738 8,935 6,700 Other Up to 1 year 6,085 4,266 5,548 17,884 23,454 16,303 Noncurrent: Taxes refundable to customers Over plant lives 209,022 222,098 215,421 Plant removal and decommissioning costs Over plant lives 172,755 171,381 168,152 Pension and postretirement benefits ** 19,686 16,940 20,434 Accumulated deferred investment tax credit Up to 20 years 14,009 11,915 12,696 Cost recovery mechanisms Up to 20 years 10,898 2,499 7,727 Other Up to 16 years 6,649 3,634 4,360 433,019 428,467 428,790 Total regulatory liabilities $ 450,903 $ 451,921 $ 445,093 Net regulatory position $ (1,307) $ 34,573 $ 31,449 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made.
Regulatory Liabilities	The following table summarizes the individual components of unamortized regulatory assets and liabilities: Estimated Recovery or Refund Period as of June 30, 2022 * June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 83,557 $ 85,045 $ 86,371 Conservation programs Up to 1 year 7,883 7,580 8,225 Decoupling Up to 1 year 4,615 6,750 9,131 Cost recovery mechanisms Up to 1 year 3,459 5,692 4,536 Other Up to 1 year 3,021 4,514 10,428 102,535 109,581 118,691 Noncurrent: Pension and postretirement benefits ** 137,582 155,906 142,681 Cost recovery mechanisms Up to 10 years 64,096 44,415 44,870 Plant costs/asset retirement obligations Over plant lives 63,334 72,853 63,116 Plant to be retired - 27,628 46,061 50,070 Manufactured gas plant site remediation - 26,031 26,155 26,053 Taxes recoverable from customers Over plant lives 12,365 10,929 12,339 Long-term debt refinancing costs Up to 38 years 3,482 4,110 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years 1,839 8,389 5,186 Other Up to 17 years 10,704 8,095 9,742 347,061 376,913 357,851 Total regulatory assets $ 449,596 $ 486,494 $ 476,542 Regulatory liabilities: Current: Electric fuel and purchased power deferral Up to 1 year $ 4,161 $ 5,431 $ — Taxes refundable to customers Up to 1 year 3,728 3,434 3,841 Cost recovery mechanisms Up to 1 year 3,172 1,388 214 Natural gas costs refundable through rate adjustments Up to 1 year 738 8,935 6,700 Other Up to 1 year 6,085 4,266 5,548 17,884 23,454 16,303 Noncurrent: Taxes refundable to customers Over plant lives 209,022 222,098 215,421 Plant removal and decommissioning costs Over plant lives 172,755 171,381 168,152 Pension and postretirement benefits ** 19,686 16,940 20,434 Accumulated deferred investment tax credit Up to 20 years 14,009 11,915 12,696 Cost recovery mechanisms Up to 20 years 10,898 2,499 7,727 Other Up to 16 years 6,649 3,634 4,360 433,019 428,467 428,790 Total regulatory liabilities $ 450,903 $ 451,921 $ 445,093 Net regulatory position $ (1,307) $ 34,573 $ 31,449 * Estimated recovery or refund period for amounts currently being recovered or refunded in rates to customers. ** Recovered as expense is incurred or cash contributions are made.

Fair value measurements (Tables

Fair value measurements (Tables)	6 Months Ended
	Jun. 30, 2022
Fair Value Disclosures [Abstract]
Available-for-sale securities	Details of available-for-sale securities were as follows: 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 June 30, 2021 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,278 $ 127 $ 9 $ 8,396 U.S. Treasury securities 2,893 — 21 2,872 Total $ 11,171 $ 127 $ 30 $ 11,268 December 31, 2021 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,702 $ 51 $ 47 $ 8,706 U.S. Treasury securities 2,407 — 11 2,396 Total $ 11,109 $ 51 $ 58 $ 11,102
Assets and liabilities measured at fair value on a recurring basis	The Company's assets measured at fair value on a recurring basis were as follows: Fair Value Measurements at June 30, 2022, Using Quoted Prices in Significant Significant Balance at June 30, 2022 (In thousands) Assets: Money market funds $ — $ 8,333 $ — $ 8,333 Insurance contracts* — 97,431 — 97,431 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 $ — $ 116,515 $ — $ 116,515 * 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 June 30, 2021, Using Quoted Prices in Significant Significant Balance at June 30, 2021 (In thousands) Assets: Money market funds $ — $ 12,234 $ — $ 12,234 Insurance contracts* — 105,684 — 105,684 Available-for-sale securities: Mortgage-backed securities — 8,396 — 8,396 U.S. Treasury securities — 2,872 — 2,872 Total assets measured at fair value $ — $ 129,186 $ — $ 129,186 * The insurance contracts invest approximately 53 percent in fixed-income investments, 20 percent in common stock of large-cap companies, 10 percent in common stock of mid-cap companies, 9 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at December 31, 2021, Using Quoted Prices in Significant Significant Balance at December 31, 2021 (In thousands) Assets: Money market funds $ — $ 10,190 $ — $ 10,190 Insurance contracts* — 109,603 — 109,603 Available-for-sale securities: Mortgage-backed securities — 8,706 — 8,706 U.S. Treasury securities — 2,396 — 2,396 Total assets measured at fair value $ — $ 130,895 $ — $ 130,895 * The insurance contracts invest approximately 61 percent in fixed-income investments, 17 percent in common stock of large-cap companies, 8 percent in common stock of mid-cap companies, 7 percent in common stock of small-cap companies, 5 percent in target date investments and 2 percent in cash equivalents.
Fair value of long term debt outstanding	The estimated fair value of the Company's Level 2 long-term debt was as follows: June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Carrying amount $ 2,927,967 $ 2,337,049 $ 2,741,900 Fair value $ 2,753,684 $ 2,616,232 $ 2,984,866

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2022
Debt Disclosure [Abstract]
Long-term debt outstanding	Long-term debt outstanding was as follows: Weighted Average Interest Rate at June 30, 2022 June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Senior Notes due on dates ranging from October 22, 2022 to June 15, 2062 4.29 % $ 2,365,000 $ 1,950,000 $ 2,125,000 Commercial paper supported by revolving credit agreements 1.96 % 495,400 297,400 450,300 Credit agreements due on June 7, 2024 4.75 % 29,860 48,550 127,500 Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029 7.32 % 35,000 35,000 35,000 Term Loan Agreement due on September 3, 2032 2.00 % 7,700 8,400 7,700 Other notes due on dates ranging from January 1, 2024 to January 1, 2061 .95 % 2,411 3,232 2,564 Less unamortized debt issuance costs 6,809 5,505 6,090 Less discount 595 28 74 Total long-term debt 2,927,967 2,337,049 2,741,900 Less current maturities 214,453 1,549 148,053 Net long-term debt $ 2,713,514 $ 2,335,500 $ 2,593,847
Schedule of debt maturities	Long-term debt maturities, which excludes unamortized debt issuance costs and discount, at June 30, 2022, were as follows: Remainder of 2022 2023 2024 2025 2026 Thereafter (In thousands) Long-term debt maturities $ 147,953 $ 77,923 $ 586,064 $ 177,802 $ 140,802 $ 1,804,827

Cash flow information (Tables)

Cash flow information (Tables)	6 Months Ended
	Jun. 30, 2022
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, 2022 2021 (In thousands) Interest, net* $ 50,294 $ 45,870 Income taxes paid, net $ 16,520 $ 46,734 * AFUDC - borrowed was $1.3 million and $816,000 for the six months ended June 30, 2022 and 2021, respectively. Noncash investing and financing transactions were as follows: June 30, 2022 June 30, 2021 December 31, 2021 (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 18,907 $ 17,224 $ 55,987 Property, plant and equipment additions in accounts payable $ 46,295 $ 31,886 $ 57,605 Debt assumed in connection with a business combination $ — $ — $ 10

Business segment data (Tables)

Business segment data (Tables)	6 Months Ended
	Jun. 30, 2022
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, 2022 2021 2022 2021 (In thousands) External operating revenues: Regulated operations: Electric $ 85,461 $ 83,650 $ 179,056 $ 168,324 Natural gas distribution 210,440 153,788 660,858 503,994 Pipeline 27,556 23,130 36,999 30,633 323,457 260,568 876,913 702,951 Non-regulated operations: Pipeline 2,257 4,643 3,933 7,052 Construction materials and contracting 711,613 633,674 1,021,448 899,333 Construction services 683,594 524,744 1,235,186 1,042,214 Other — 28 — 45 1,397,464 1,163,089 2,260,567 1,948,644 Total external operating revenues $ 1,720,921 $ 1,423,657 $ 3,137,480 $ 2,651,595 Three Months Ended Six Months Ended June 30, June 30, 2022 2021 2022 2021 (In thousands) Intersegment operating revenues: Regulated operations: Electric $ 124 $ 136 $ 247 $ 271 Natural gas distribution 141 142 277 284 Pipeline 7,404 7,695 33,338 33,685 7,669 7,973 33,862 34,240 Non-regulated operations: Pipeline 388 167 396 407 Construction materials and contracting 200 142 330 204 Construction services 1,803 797 2,861 1,839 Other 4,389 3,361 8,730 6,685 6,780 4,467 12,317 9,135 Intersegment eliminations (14,449) (12,440) (46,179) (43,375) Total intersegment operating revenues $ — $ — $ — $ — Operating income (loss): Electric $ 8,325 $ 12,806 $ 23,369 $ 26,672 Natural gas distribution (638) 3,601 55,617 57,173 Pipeline 12,602 11,076 24,484 23,612 Construction materials and contracting 54,354 72,452 9,749 37,563 Construction services 46,141 37,774 75,639 78,051 Other (214) (20) (946) (218) Total operating income $ 120,570 $ 137,689 $ 187,912 $ 222,853 Net income (loss): Regulated operations: Electric $ 4,601 $ 10,304 $ 15,880 $ 21,054 Natural gas distribution (7,498) (707) 28,817 35,471 Pipeline 7,191 8,089 15,147 17,283 4,294 17,686 59,844 73,808 Non-regulated operations: Pipeline (60) 1,106 (679) 810 Construction materials and contracting 32,584 51,396 (7,427) 20,584 Construction services 34,454 28,885 55,778 58,709 Other (640) 1,098 (5,151) (1,624) 66,338 82,485 42,521 78,479 Income from continuing operations 70,632 100,171 102,365 152,287 Discontinued operations, net of tax 35 19 65 34 Net income $ 70,667 $ 100,190 $ 102,430 $ 152,321

Employee benefit plans (Tables)

Employee benefit plans (Tables)	6 Months Ended
	Jun. 30, 2022
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, 2022 2021 2022 2021 (In thousands) Components of net periodic benefit credit: Interest cost $ 2,631 $ 2,455 $ 5,262 $ 4,910 Expected return on assets (4,864) (4,894) (9,728) (9,788) Amortization of net actuarial loss 1,671 2,004 3,342 4,008 Net periodic benefit credit $ (562) $ (435) $ (1,124) $ (870) 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, 2022 2021 2022 2021 (In thousands) Components of net periodic benefit credit: Service cost $ 354 $ 400 $ 708 $ 800 Interest cost 474 466 948 932 Expected return on assets (1,322) (1,275) (2,644) (2,550) Amortization of prior service credit (350) (349) (700) (698) Amortization of net actuarial (gain) loss (54) 6 (108) 12 Net periodic benefit credit, including amount capitalized (898) (752) (1,796) (1,504) Less amount capitalized 53 44 84 83 Net periodic benefit credit $ (951) $ (796) $ (1,880) $ (1,587)

Receivables and allowance for_4

Receivables and allowance for expected credit losses (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Credit Loss [Abstract]
Accounts Receivable, Noncurrent, 90 Days or More Past Due, Still Accruing	$ 37	$ 44.8	$ 34.2

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, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses					$ 2,244	$ (1,158)
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	$ 10,156	$ 9,716	$ 12,714	$ 15,358	9,716	15,358
Provision for credit losses	509	1,735	(841)	(317)
Less write-offs charged against the allowance	1,385	1,627	1,424	2,669
Credit loss recoveries collected	285	332	299	342
Balance	9,565	10,156	10,748	12,714	9,565	10,748
Electric | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	361	269	678	899	269	899
Provision for credit losses	113	565	(110)	538
Less write-offs charged against the allowance	234	597	341	888
Credit loss recoveries collected	108	124	100	129
Balance	348	361	327	678	348	327
Natural gas distribution | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2,123	1,506	2,950	2,571	1,506	2,571
Provision for credit losses	92	1,369	(103)	1,273
Less write-offs charged against the allowance	939	932	787	1,107
Credit loss recoveries collected	177	180	199	213
Balance	1,453	2,123	2,259	2,950	1,453	2,259
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 materials and contracting | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	5,126	5,406	4,842	6,164	5,406	6,164
Provision for credit losses	12	(253)	11	(1,049)
Less write-offs charged against the allowance	108	27	232	273
Credit loss recoveries collected	0	0	0	0
Balance	5,030	5,126	4,621	4,842	5,030	4,621
Construction services | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2,544	2,533	4,242	5,722	2,533	5,722
Provision for credit losses	292	54	(639)	(1,079)
Less write-offs charged against the allowance	104	71	64	401
Credit loss recoveries collected	0	28	0	0
Balance	$ 2,732	$ 2,544	$ 3,539	$ 4,242	$ 2,732	$ 3,539

Inventories and natural gas i_4

Inventories and natural gas in storage (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Inventory Disclosure [Abstract]
Aggregates held for resale	$ 200,569	$ 184,363	$ 183,977
Asphalt oil	92,905	57,002	51,500
Materials and supplies	40,405	30,629	27,969
Merchandise for resale	38,293	28,501	26,871
Natural gas in storage (current)	15,014	18,867	10,824
Other	14,247	16,247	15,187
Total	401,433	335,609	316,328
Natural gas in storage noncurrent	$ 47,200	$ 47,500	$ 47,500

Earnings per share (Details)

Earnings per share (Details) - $ / shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings Per Share [Abstract]
Weighted average common shares outstanding - basic	203,351	201,345	203,351	201,028
Effect of dilutive performance share awards and restricted stock units	50	348	45	300
Weighted average common shares outstanding - diluted	203,401	201,693	203,396	201,328
Shares excluded from the calculation of diluted earnings per share	52	0	175	0
Dividends declared per common share	$ 0.2175	$ 0.2125	$ 0.4350	$ 0.4250

Equity (Details)

Equity (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Class of Stock [Line Items]
Common stock shares authorized under equity program	500,000,000	500,000,000	500,000,000	500,000,000	500,000,000
Net proceeds *			$ (149,000)	$ 54,649,000
At-the-market offering
Class of Stock [Line Items]
Common stock shares authorized under equity program	6,400,000		6,400,000
Common stock shares reserved for future issuance	3,600,000		3,600,000
Shares issued	0	1,100,000	0	1,800,000
Net proceeds *	$ 0	$ 34,900,000	$ (100,000)	$ 54,600,000
Issuance costs	$ 22,000	$ 443,000	$ 149,000	$ 743,000

Accumulated other comprehensi_3

Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated other comprehensive loss [Roll Forward]
Balance	$ 3,360,718	$ 3,382,874	$ 3,100,306	$ 3,079,105	$ 3,382,874	$ 3,079,105
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	(3,265)		0		(3,265)	0
Other comprehensive income (loss)	(2,796)	269	542	568	(2,527)	1,110
Balance	3,386,810	3,360,718	3,198,802	3,100,306	3,386,810	3,198,802
Net unrealized gain (loss) on derivative instruments qualifying as hedges
Accumulated other comprehensive loss [Roll Forward]
Balance	(426)	(538)	(873)	(984)	(538)	(984)
Other comprehensive loss before reclassifications	0	0	0	0
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	0
Amounts reclassified from accumulated other comprehensive loss	111	112	112	111
Other comprehensive income (loss)	111	112	112	111
Balance	(315)	(426)	(761)	(873)	(315)	(761)
Postretirement liability adjustment
Accumulated other comprehensive loss [Roll Forward]
Balance	(40,016)	(40,461)	(46,741)	(47,207)	(40,461)	(47,207)
Other comprehensive loss before reclassifications	0	0	0	0
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	(3,265)
Amounts reclassified from accumulated other comprehensive loss	461	445	457	466
Other comprehensive income (loss)	(2,804)	445	457	466
Balance	(42,820)	(40,016)	(46,284)	(46,741)	(42,820)	(46,284)
Net unrealized gain (loss) on available-for-sale investments
Accumulated other comprehensive loss [Roll Forward]
Balance	(293)	(5)	104	113	(5)	113
Other comprehensive loss before reclassifications	(128)	(320)	(52)	(44)
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	0
Amounts reclassified from accumulated other comprehensive loss	25	32	25	35
Other comprehensive income (loss)	(103)	(288)	(27)	(9)
Balance	(396)	(293)	77	104	(396)	77
Total accumulated other comprehensive loss
Accumulated other comprehensive loss [Roll Forward]
Balance	(40,735)	(41,004)	(47,510)	(48,078)	(41,004)	(48,078)
Other comprehensive loss before reclassifications	(128)	(320)	(52)	(44)
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	(3,265)
Amounts reclassified from accumulated other comprehensive loss	597	589	594	612
Other comprehensive income (loss)	(2,796)	269	542	568
Balance	$ (43,531)	$ (40,735)	$ (46,968)	$ (47,510)	$ (43,531)	$ (46,968)

Reclassification out of accumul

Reclassification out of accumulated other comprehensive loss (Details 2) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	$ (28,113)		$ (23,381)		$ (53,373)	$ (46,835)
Income taxes	(17,579)		(23,164)		(25,528)	(36,112)
Other income	(4,246)		9,027		(6,646)	12,381
Net income	70,667	$ 31,763	100,190	$ 52,131	102,430	152,321
Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Net income	(597)		(594)		(1,186)	(1,206)
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	(147)		(148)		(295)	(296)
Income taxes	36		36		72	73
Net income	(111)		(112)		(223)	(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	148		160		312	311
Other income	(609)		(617)		(1,218)	(1,234)
Net income	(461)		(457)		(906)	(923)
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	7		6		15	15
Other income	(32)		(31)		(72)	(75)
Net income	$ (25)		$ (25)		$ (57)	$ (60)

Disaggregation of revenue (Deta

Disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Operating revenues:	$ 1,720,921	$ 1,423,657	$ 3,137,480	$ 2,651,595
Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(14,449)	(12,440)	(46,179)	(43,375)
Intrasegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(169,232)	(145,780)	(215,266)	(192,496)
Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	43,423	39,136	87,378	81,005
Natural gas storage
Disaggregation of Revenue [Line Items]
Operating revenues:	2,896	3,094	6,615	7,123
Contracting services
Disaggregation of Revenue [Line Items]
Operating revenues:	330,682	280,834	444,949	376,859
Construction materials
Disaggregation of Revenue [Line Items]
Operating revenues:	550,363	498,762	792,095	715,174
Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	507,233	347,702	900,041	702,892
Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	166,174	165,123	314,640	316,486
Other
Disaggregation of Revenue [Line Items]
Operating revenues:	21,141	20,515	42,602	39,334
Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	1,712,524	1,409,489	3,121,577	2,625,505
Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	8,397	14,168	15,903	26,090
Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	146,112	112,738	442,232	349,311
Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	106,369	81,446	305,578	234,426
Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	19,932	16,534	43,262	35,375
Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	1,880	1,825	3,630	3,391
Electric
Disaggregation of Revenue [Line Items]
Operating revenues:	85,461	83,650	179,056	168,324
Electric | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(124)	(136)	(247)	(271)
Electric | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	10,216	9,465	22,969	19,238
Electric | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	86,273	84,600	183,863	172,197
Electric | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	(812)	(950)	(4,807)	(3,873)
Electric | Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	29,363	29,258	66,667	62,694
Electric | Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	34,015	33,834	69,615	66,762
Electric | Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	10,923	10,354	21,229	20,383
Electric | Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	1,880	1,825	3,630	3,391
Natural gas distribution
Disaggregation of Revenue [Line Items]
Operating revenues:	210,440	153,788	660,858	503,994
Natural gas distribution | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(141)	(142)	(277)	(284)
Natural gas distribution | Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	11,456	11,451	23,837	23,903
Natural gas distribution | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	3,751	2,794	6,360	5,803
Natural gas distribution | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	213,178	151,375	663,481	498,695
Natural gas distribution | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	(2,738)	2,413	(2,623)	5,299
Natural gas distribution | Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	116,749	83,480	375,565	286,617
Natural gas distribution | Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	72,354	47,612	235,963	167,664
Natural gas distribution | Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	9,009	6,180	22,033	14,992
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:	29,813	27,773	40,932	37,685
Pipeline | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(7,792)	(7,862)	(33,734)	(34,092)
Pipeline | Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	31,967	27,685	63,541	57,102
Pipeline | Natural gas storage
Disaggregation of Revenue [Line Items]
Operating revenues:	2,896	3,094	6,615	7,123
Pipeline | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	2,676	4,810	4,386	7,470
Pipeline | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	29,747	27,727	40,808	37,603
Pipeline | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	66	46	124	82
Construction materials and contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	711,613	633,674	1,021,448	899,333
Construction materials and contracting | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(200)	(142)	(330)	(204)
Construction materials and contracting | Intrasegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(169,232)	(145,780)	(215,266)	(192,496)
Construction materials and contracting | Contracting services
Disaggregation of Revenue [Line Items]
Operating revenues:	330,682	280,834	444,949	376,859
Construction materials and contracting | Construction materials
Disaggregation of Revenue [Line Items]
Operating revenues:	550,363	498,762	792,095	715,174
Construction materials and contracting | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0	0	0
Construction materials and contracting | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	711,613	633,674	1,021,448	899,333
Construction materials and contracting | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0	0	0
Construction services
Disaggregation of Revenue [Line Items]
Operating revenues:	683,594	524,744	1,235,186	1,042,214
Construction services | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(1,803)	(797)	(2,861)	(1,839)
Construction services | Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	507,233	347,702	900,041	702,892
Construction services | Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	166,174	165,123	314,640	316,486
Construction services | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	109	57	157	93
Construction services | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	671,713	512,085	1,211,977	1,017,632
Construction services | Revenues out of scope
Disaggregation of Revenue [Line Items]
Operating revenues:	11,881	12,659	23,209	24,582
Other
Disaggregation of Revenue [Line Items]
Operating revenues:	0	28	0	45
Other | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(4,389)	(3,361)	(8,730)	(6,685)
Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	4,389	3,389	8,730	6,730
Other | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	0	28	0	45
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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Contract assets	$ 236,951		$ 236,951		$ 125,742
Change in contract assets			111,209
Contract liabilities - current	(167,507)		(167,507)		(179,140)
Change in contract liabilities - current			11,633
Contract liabilities - noncurrent	(19)		(19)		(118)
Change in contract liabilities - noncurrent			99
Net contract assets (liabilities)	69,425		69,425		$ (53,516)
Change in net contract assets (liabilities)			122,941
Amounts included in contract liability at the beginning of the period	14,800	$ 21,900	136,700	$ 145,300
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 30,000	$ 27,300	$ 42,400	$ 54,600

Revenue from contracts with c_4

Revenue from contracts with customers Remaining performance obligations (Details 3) $ in Millions	Jun. 30, 2022 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 3,500
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2,800
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
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	$ 389
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	13 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	$ 368.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	25 months

Business Combinations (Details)

Business Combinations (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill		$ 765,386,000	$ 763,262,000	$ 717,863,000	$ 714,963,000
Business Acquisition, Transaction Costs			$ 0	$ 0
2021 Acquisition
Business Acquisition [Line Items]
Gross Aggregate Consideration		236,100,000
Cash Assumed		900,000
Business Combination, Consideration Transferred		235,200,000
Current Assets		17,000,000
Property, Plant, and Equipment		179,800,000
Goodwill		50,600,000
Other Intangibles		2,200,000
Current Liabilities		8,700,000
Noncurrent liabilities - Other		2,500,000
Deferred Tax Liabilities		$ 3,200,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets	$ 2,100,000

Lessor accounting (Details)

Lessor accounting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Leases [Abstract]
Operating Lease, Lease Income	$ 12	$ 12.8	$ 23.4	$ 24.8
Lessor, Operating Lease, Payments to be Received, Next Twelve Months	$ 8.7		$ 8.7

Goodwill rollforward (Details)

Goodwill rollforward (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Goodwill [Roll Forward]
Balance at beginning of period	$ 765,386	$ 714,963	$ 714,963
Goodwill acquired during the year	0	2,900	50,640
Measurement period adjustments	(2,124)	0	(217)
Balance at end of period	763,262	717,863	765,386
Natural gas distribution
Goodwill [Roll Forward]
Balance at beginning of period	345,736	345,736	345,736
Goodwill acquired during the year	0	0	0
Measurement period adjustments	0	0	0
Balance at end of period	345,736	345,736	345,736
Construction materials and contracting
Goodwill [Roll Forward]
Balance at beginning of period	276,426	226,003	226,003
Goodwill acquired during the year	0	2,900	50,640
Measurement period adjustments	(2,124)	0	(217)
Balance at end of period	274,302	228,903	276,426
Construction services
Goodwill [Roll Forward]
Balance at beginning of period	143,224	143,224	143,224
Goodwill acquired during the year	0	0	0
Measurement period adjustments	0	0	0
Balance at end of period	$ 143,224	$ 143,224	$ 143,224

Other intangible assets (Detail

Other intangible assets (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 20,040	$ 23,401	$ 20,040	$ 23,401	$ 22,578
Amortization of intangible assets	1,300	1,200	2,500	2,700
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	28,990	29,423	28,990	29,423	29,740
Intangible assets, less accumulated amortization	11,812	8,765	11,812	8,765	10,650
Intangible assets, net (excluding goodwill)	17,178	20,658	17,178	20,658	19,090
Noncompete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	4,591	3,991	4,591	3,991	4,591
Intangible assets, less accumulated amortization	3,206	2,576	3,206	2,576	2,856
Intangible assets, net (excluding goodwill)	1,385	1,415	1,385	1,415	1,735
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	5,607	11,957	5,607	11,957	12,601
Intangible assets, less accumulated amortization	4,130	10,629	4,130	10,629	10,848
Intangible assets, net (excluding goodwill)	$ 1,477	$ 1,328	$ 1,477	$ 1,328	$ 1,753

Future amortization expense (De

Future amortization expense (Details 3) $ in Thousands	Jun. 30, 2022 USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2022	$ 2,285
2023	4,591
2024	4,305
2025	2,291
2026	1,781
Thereafter	$ 4,787

Regulatory assets (Details)

Regulatory assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Feb. 28, 2021
Regulatory Assets
Regulatory Assets, Current	$ 102,535	$ 118,691	$ 109,581
Regulatory Assets, Noncurrent	347,061	357,851	376,913
Total regulatory assets	449,596	476,542	486,494
Regulatory assets not earning a rate of return	262,900	296,600	317,000
Natural gas costs recoverable through rate adjustments
Regulatory Assets
Regulatory Assets, Current	83,557	86,371	85,045
Regulatory Assets, Noncurrent	$ 1,839	5,186	8,389
Total regulatory assets				$ 44,000
Natural gas costs recoverable through rate adjustments | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Natural gas costs recoverable through rate adjustments | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 2 years
Conservation programs
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Regulatory Assets, Current	$ 7,883	8,225	7,580
Decoupling
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Regulatory Assets, Current	$ 4,615	9,131	6,750
Cost recovery mechanisms
Regulatory Assets
Regulatory Assets, Current	3,459	4,536	5,692
Regulatory Assets, Noncurrent	$ 64,096	44,870	44,415
Cost recovery mechanisms | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Cost recovery mechanisms | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 10 years
Other regulatory assets
Regulatory Assets
Regulatory Assets, Current	$ 3,021	10,428	4,514
Regulatory Assets, Noncurrent	$ 10,704	9,742	8,095
Other regulatory assets | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Other regulatory assets | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 17 years
Pension and postretirement benefits
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	**
Regulatory Assets, Noncurrent	$ 137,582	142,681	155,906
Plant costs/asset retirement obligations
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Over plant lives
Regulatory Assets, Noncurrent	$ 63,334	63,116	72,853
Plant retirement
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	-
Regulatory Assets, Noncurrent	$ 27,628	50,070	46,061
Manufactured gas plant site remediation
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	-
Regulatory Assets, Noncurrent	$ 26,031	26,053	26,155
Taxes recoverable from customers
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Over plant lives
Regulatory Assets, Noncurrent	$ 12,365	12,339	10,929
Long-term debt refinancing costs
Regulatory Assets
Estimated Recovery or Refund Period as of June 30, 2022	Up to 38 years
Regulatory Assets, Noncurrent	$ 3,482	$ 3,794	$ 4,110

Regulatory liabilities (Details

Regulatory liabilities (Details 2) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	$ 17,884	$ 16,303	$ 23,454
Regulatory liabilities	433,019	428,790	428,467
Total regulatory liabilities	450,903	445,093	451,921
Net regulatory position	$ (1,307)	31,449	34,573
Electric fuel and purchased power deferral
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Regulatory liabilities due within one year	$ 4,161	0	5,431
Taxes refundable to customers
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	3,728	3,841	3,434
Regulatory liabilities	$ 209,022	215,421	222,098
Taxes refundable to customers | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Taxes refundable to customers | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Over plant lives
Cost Recovery Mechanisms
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	$ 3,172	214	1,388
Regulatory liabilities	$ 10,898	7,727	2,499
Cost Recovery Mechanisms | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Cost Recovery Mechanisms | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Up to 20 years
Natural gas costs refundable through rate adjustments
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Regulatory liabilities due within one year	$ 738	6,700	8,935
Other regulatory liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	6,085	5,548	4,266
Regulatory liabilities	$ 6,649	4,360	3,634
Other regulatory liabilities | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Up to 1 year
Other regulatory liabilities | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Up to 16 years
Plant removal and decommissioning costs
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Over plant lives
Regulatory liabilities	$ 172,755	168,152	171,381
Pension and postretirement benefits
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	**
Regulatory liabilities	$ 19,686	20,434	16,940
Accumulated Deferred ITC
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of June 30, 2022	Up to 20 years
Regulatory liabilities	$ 14,009	$ 12,696	$ 11,915

Fair value measurements Insuran

Fair value measurements Insurance contracts (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Investments used to satisfy nonqualified benefit plans obligations	$ 97.4	$ 105.7	$ 97.4	$ 105.7	$ 109.6
Net unrealized gain (loss) on investments used to satisfy obligations under nonqualified benefit plans	$ 8.4	$ 3.8	$ 14.1	$ 3.9

Available-for-sale securities (

Available-for-sale securities (Details 2) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Available-for-sale securities [Abstract]
Cost	$ 11,253	$ 11,109	$ 11,171
Gross Unrealized Gains	0	51	127
Gross Unrealized Losses	502	58	30
Fair Value	10,751	11,102	11,268
Mortgage-backed securities
Available-for-sale securities [Abstract]
Cost	8,128	8,702	8,278
Gross Unrealized Gains	0	51	127
Gross Unrealized Losses	419	47	9
Fair Value	7,709	8,706	8,396
U.S. Treasury securities
Available-for-sale securities [Abstract]
Cost	3,125	2,407	2,893
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	83	11	21
Fair Value	$ 3,042	$ 2,396	$ 2,872

Fair value measurements (Detail

Fair value measurements (Details 3) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Concentration risks, percentage [Abstract]
Percentage in fixed-income and other investments	64%	61%	53%
Percentage investment in common stock of large-cap companies	15%	17%	20%
Percentage investment in common stock of mid-cap companies	7%	8%	10%
Percentage investment in common stock of small-cap companies	6%	7%	9%
Percentage investment in target date investments	6%	5%	6%
Percentage investment in cash and cash equivalents	2%	2%	2%
Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 116,515	$ 130,895	$ 129,186
Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	116,515	130,895	129,186
Money market funds | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	8,333	10,190	12,234
Money market funds | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	8,333	10,190	12,234
Insurance contracts* | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	97,431	109,603	105,684
Insurance contracts* | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	97,431	109,603	105,684
Mortgage-backed securities | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,709	8,706	8,396
Mortgage-backed securities | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,709	8,706	8,396
U.S. Treasury securities | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	3,042	2,396	2,872
U.S. Treasury securities | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 3,042	$ 2,396	$ 2,872

Fair value measurements (Deta_2

Fair value measurements (Details 4) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Fair value, balance sheet grouping [Line Items]
Long-term debt	$ 2,927,967	$ 2,741,900	$ 2,337,049
Carrying amount
Fair value, balance sheet grouping [Line Items]
Long-term debt	2,927,967	2,741,900	2,337,049
Fair value
Fair value, balance sheet grouping [Line Items]
Long-term debt, fair value	$ 2,753,684	$ 2,984,866	$ 2,616,232

Short-term Debt (Details 1)

Short-term Debt (Details 1) - USD ($) $ in Thousands	Jun. 30, 2022	Mar. 18, 2022	Dec. 31, 2021	Jun. 30, 2021
Short-term Debt [Line Items]
Short-term borrowings	$ 100,000		$ 0	$ 50,000
Term Loan Agreement | Centennial Energy Holdings, Inc.
Short-term Debt [Line Items]
Short-term borrowings		$ 100,000
Ratio of total debt to total capitalization as specified in debt covenants		65%

Long-term debt outstanding (Det

Long-term debt outstanding (Details 2) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,927,967	$ 2,741,900	$ 2,337,049
Long-term debt due within one year	214,453	148,053	1,549
Long-term debt	$ 2,713,514	2,593,847	2,335,500
Senior Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	4.29%
Long-term debt	$ 2,365,000	2,125,000	1,950,000
Commercial Paper
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	1.96%
Long-term debt	$ 495,400	450,300	297,400
Credit Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	4.75%
Long-term debt	$ 29,860	127,500	48,550
Medium-term Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	7.32%
Long-term debt	$ 35,000	35,000	35,000
Term Loan Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	2%
Long-term debt	$ 7,700	7,700	8,400
Other Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	0.95%
Long-term debt	$ 2,411	2,564	3,232
Long-term Debt
Long-term debt outstanding [Line Items]
Unamortized Debt Issuance Costs	6,809	6,090	5,505
Discount	$ 595	$ 74	$ 28

Schedule of debt maturities (De

Schedule of debt maturities (Details 3) $ in Thousands	Jun. 30, 2022 USD ($)
Long-term debt maturities [Line Items]
Remainder of 2022	$ 147,953
2023	77,923
2024	586,064
2025	177,802
2026	140,802
Thereafter	$ 1,804,827

Cash flow information (Details)

Cash flow information (Details) - USD ($)	6 Months Ended		12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Supplemental Cash Flow Information [Abstract]
Interest, net*	$ 50,294,000	$ 45,870,000
Income taxes paid, net	16,520,000	46,734,000
AFUDC borrowed	1,300,000	816,000
Right-of-use assets obtained in exchange for new operating lease liabilities	18,907,000	17,224,000	$ 55,987,000
Property, plant and equipment additions in accounts payable	46,295,000	31,886,000	57,605,000
Debt assumed in connection with a business combination	$ 0	$ 0	$ 10,000

Business segment data (Details)

Business segment data (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 1,720,921		$ 1,423,657		$ 3,137,480	$ 2,651,595
Operating income	120,570		137,689		187,912	222,853
Income from continuing operations	70,632		100,171		102,365	152,287
Discontinued operations, net of tax	35		19		65	34
Net income	70,667	$ 31,763	100,190	$ 52,131	102,430	152,321
Electric
Segment Reporting Information [Line Items]
Revenues	85,461		83,650		179,056	168,324
Operating income	8,325		12,806		23,369	26,672
Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	210,440		153,788		660,858	503,994
Operating income	(638)		3,601		55,617	57,173
Pipeline
Segment Reporting Information [Line Items]
Revenues	29,813		27,773		40,932	37,685
Operating income	12,602		11,076		24,484	23,612
Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	711,613		633,674		1,021,448	899,333
Operating income	54,354		72,452		9,749	37,563
Construction services
Segment Reporting Information [Line Items]
Revenues	683,594		524,744		1,235,186	1,042,214
Operating income	46,141		37,774		75,639	78,051
Other
Segment Reporting Information [Line Items]
Revenues	0		28		0	45
Operating income	(214)		(20)		(946)	(218)
Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	(14,449)		(12,440)		(46,179)	(43,375)
Intersegment eliminations | Electric
Segment Reporting Information [Line Items]
Revenues	(124)		(136)		(247)	(271)
Intersegment eliminations | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	(141)		(142)		(277)	(284)
Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	(7,792)		(7,862)		(33,734)	(34,092)
Intersegment eliminations | Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	(200)		(142)		(330)	(204)
Intersegment eliminations | Construction services
Segment Reporting Information [Line Items]
Revenues	(1,803)		(797)		(2,861)	(1,839)
Intersegment eliminations | Other
Segment Reporting Information [Line Items]
Revenues	(4,389)		(3,361)		(8,730)	(6,685)
Total intersegment operating revenues
Segment Reporting Information [Line Items]
Revenues	0		0		0	0
Regulated operation
Segment Reporting Information [Line Items]
Revenues	323,457		260,568		876,913	702,951
Income from continuing operations	4,294		17,686		59,844	73,808
Regulated operation | Electric
Segment Reporting Information [Line Items]
Revenues	85,461		83,650		179,056	168,324
Income from continuing operations	4,601		10,304		15,880	21,054
Regulated operation | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	210,440		153,788		660,858	503,994
Income from continuing operations	(7,498)		(707)		28,817	35,471
Regulated operation | Pipeline
Segment Reporting Information [Line Items]
Revenues	27,556		23,130		36,999	30,633
Income from continuing operations	7,191		8,089		15,147	17,283
Regulated operation | Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	7,669		7,973		33,862	34,240
Regulated operation | Intersegment eliminations | Electric
Segment Reporting Information [Line Items]
Revenues	124		136		247	271
Regulated operation | Intersegment eliminations | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	141		142		277	284
Regulated operation | Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	7,404		7,695		33,338	33,685
Nonregulated operation
Segment Reporting Information [Line Items]
Revenues	1,397,464		1,163,089		2,260,567	1,948,644
Income from continuing operations	66,338		82,485		42,521	78,479
Nonregulated operation | Pipeline
Segment Reporting Information [Line Items]
Revenues	2,257		4,643		3,933	7,052
Income from continuing operations	(60)		1,106		(679)	810
Nonregulated operation | Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	711,613		633,674		1,021,448	899,333
Income from continuing operations	32,584		51,396		(7,427)	20,584
Nonregulated operation | Construction services
Segment Reporting Information [Line Items]
Revenues	683,594		524,744		1,235,186	1,042,214
Income from continuing operations	34,454		28,885		55,778	58,709
Nonregulated operation | Other
Segment Reporting Information [Line Items]
Revenues	0		28		0	45
Income from continuing operations	(640)		1,098		(5,151)	(1,624)
Nonregulated operation | Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	6,780		4,467		12,317	9,135
Nonregulated operation | Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	388		167		396	407
Nonregulated operation | Intersegment eliminations | Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	200		142		330	204
Nonregulated operation | Intersegment eliminations | Construction services
Segment Reporting Information [Line Items]
Revenues	1,803		797		2,861	1,839
Nonregulated operation | Intersegment eliminations | Other
Segment Reporting Information [Line Items]
Revenues	$ 4,389		$ 3,361		$ 8,730	$ 6,685

Employee benefit plans (Details

Employee benefit plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Qualified plan | Underfunded plan | Pension benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Interest cost	$ 2,631	$ 2,455	$ 5,262	$ 4,910
Expected return on assets	(4,864)	(4,894)	(9,728)	(9,788)
Amortization of net actuarial (gain) loss	1,671	2,004	3,342	4,008
Net periodic benefit cost (credit)	(562)	(435)	(1,124)	(870)
Qualified plan | Overfunded Plan | Other postretirement benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Service cost	354	400	708	800
Interest cost	474	466	948	932
Expected return on assets	(1,322)	(1,275)	(2,644)	(2,550)
Amortization of prior service credit	(350)	(349)	(700)	(698)
Amortization of net actuarial (gain) loss	(54)	6	(108)	12
Net periodic benefit credit, including amount capitalized	(898)	(752)	(1,796)	(1,504)
Less amount capitalized	53	44	84	83
Net periodic benefit cost (credit)	(951)	(796)	(1,880)	(1,587)
Nonqualified plan | Unfunded plan | Supplemental employee retirement plans
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Net periodic benefit cost (credit)	$ 773	$ 769	$ 1,500	$ 1,500

IPUC (Details)

IPUC (Details) - Natural gas distribution - IPUC - Intermountain Gas Co. - Subsequent Event [Member] $ in Millions	Aug. 01, 2022 USD ($)
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 67
Public Utilities, Approved Rate Increase (Decrease), Percentage	25.20%

MNPUC (Details 2)

MNPUC (Details 2) - MNPUC [Member] - Gas Distribution [Member] - Great Plains Natural Gas Co. [Member] - Pending Rate Case [Member] - USD ($) $ in Millions	Jun. 01, 2022	Sep. 01, 2021
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 8.8
Depreciation and Amortization Requested Rate Increase (Decrease), Amount	$ (1.2)
Depreciation and Amortization, Rate, Percent	4.50%
Depreciation and Amortization, Requested Rate, Percent	2.80%

NDPSC (Details 3)

NDPSC (Details 3) - Electric - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - USD ($) $ in Millions	Jul. 15, 2022	Jul. 14, 2022	May 16, 2022
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%
Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Interim Rate Increase (Decrease), Amount		$ 10.9
Public Utilities, Interim Rate Increase (Decrease), Percentage		5.30%
Subsequent Event [Member] | Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Total Transmission Cost Adjustment Rider	$ 12.9
Public Utilities, Requested Rate Increase (Decrease), Amount	$ (1.6)

SDPUC (Details 4)

SDPUC (Details 4) - SDPUC - Electricity [Member] - Montana-Dakota Utilities Co. [Member] $ in Millions	Jun. 01, 2022 USD ($)
Public Utilities, General Disclosures [Line Items]
Total Transmission Cost Adjustment Rider	$ 2.5
Transmission Capital Projects Increase (Decrease)	$ 1.5

WUTC (Details 5)

WUTC (Details 5) - Pending Rate Case [Member] - WUTC [Member] - Cascade Natural Gas [Member] - USD ($) $ in Millions	Jun. 01, 2022	Mar. 24, 2022	Mar. 22, 2022	Sep. 30, 2021
Gas Distribution [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 3.3		$ 13.7
Public Utilities, Requested Rate Increase (Decrease), Percentage				5.10%
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount			$ 10.7
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage			4%
Pipeline Cost Recovery Mechanism
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	$ 2.6
Public Utilities, Requested Rate Increase (Decrease), Percentage	0.90%

Litigation (Details)

Litigation (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Loss Contingencies [Line Items]
Potential liabilities related to litigation and environmental matters	$ 28.2	$ 37	$ 30.8
Insurance Receivable	5.9	14.1	6.9
Regulatory Assets	$ 20.9	$ 21.2	$ 21.2

Guarantees (Details 2)

Guarantees (Details 2)	Jun. 30, 2022 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 276,000,000
Fixed maximum amounts guaranteed by year 2022	21,800,000
Fixed maximum amounts guaranteed by year 2023	82,000,000
Fixed maximum amounts guaranteed by year 2024	160,600,000
Fixed maximum amounts guaranteed by year 2025	900,000
Fixed maximum amounts guaranteed by year 2026	900,000
Fixed maximum amounts guaranteed, thereafter	800,000
No scheduled maturity date	9,000,000
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit	28,200,000
Letters of credit set to expire - 2022	27,600,000
Letters of credit set to expire - 2023	600,000
Outstanding letters of credit	0
Amount of surety bonds outstanding	$ 1,200,000,000

Variable interest entities (Det

Variable interest entities (Details 3) $ in Millions	Jun. 30, 2022 USD ($)
Fuel contract
Variable Interest Entities [Line Items]
Variable interest entity, reporting entity involvement, maximum loss exposure, amount	$ 30.5