MDU Resources (MDU) 10-Q 3 Nov 22 2022 Q3 Quarterly report Financial data

Cover page

Cover page - shares	9 Months Ended
	Sep. 30, 2022	Oct. 27, 2022
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 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	Q3
Amendment Flag	false

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Operating revenues:
Operating revenues:	$ 1,977,206	$ 1,586,013	$ 5,114,686	$ 4,237,608
Operating expenses:
Operation and maintenance:	1,546,852	1,212,898	3,771,550	3,102,353
Purchased natural gas sold	61,863	41,135	444,527	280,584
Depreciation, depletion and amortization	82,293	75,229	247,173	222,613
Taxes, other than income	56,267	48,096	185,303	163,819
Electric fuel and purchased power	20,080	19,486	68,370	56,216
Total operating expenses	1,767,355	1,396,844	4,716,923	3,825,585
Operating income	209,851	189,169	397,763	412,023
Other income (expense)	4,769	5,930	(1,877)	18,310
Interest expense	31,369	23,389	84,741	70,224
Income before income taxes	183,251	171,710	311,145	360,109
Income taxes	35,318	32,748	60,847	68,860
Income from continuing operations	147,933	138,962	250,298	291,249
Discontinued operations, net of tax	38	314	103	348
Net income	$ 147,971	$ 139,276	$ 250,401	$ 291,597
Earnings per share - basic:
Income from continuing operations	$ 0.73	$ 0.68	$ 1.23	$ 1.44
Discontinued operations, net of tax	0	0	0	0
Earnings per share - basic	0.73	0.68	1.23	1.44
Earnings per share - diluted:
Income from continuing operations	0.73	0.68	1.23	1.44
Discontinued operations, net of tax	0	0	0	0
Earnings per share - diluted	$ 0.73	$ 0.68	$ 1.23	$ 1.44
Weighted average common shares outstanding - basic	203,351	202,863	203,351	201,647
Weighted average common shares outstanding - diluted	203,644	203,190	203,407	201,955
Regulated operation
Operating revenues:
Operating revenues:	$ 263,614	$ 237,065	$ 1,140,528	$ 940,017
Operating expenses:
Operation and maintenance:	89,502	90,058	281,430	273,796
Income from continuing operations	12,917	15,399	72,761	89,207
Nonregulated operation
Operating revenues:
Operating revenues:	1,713,592	1,348,948	3,974,158	3,297,591
Operating expenses:
Operation and maintenance:	1,457,350	1,122,840	3,490,120	2,828,557
Income from continuing operations	$ 135,016	$ 123,563	$ 177,537	$ 202,042

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Net income	$ 147,971	$ 139,276	$ 250,401	$ 291,597
Other comprehensive income (loss):
Reclassification adjustment for loss on derivative instruments included in net income, tax	37	36	109	109
Reclassification adjustment for loss on derivative instruments included in net income, net of tax	111	111	334	334
Postretirement liability adjustment:
Amortization of postretirement liability losses included in net periodic benefit credit, tax	148	151	460	462
Amortization of postretirement liability losses included in net periodic benefit credit, net of tax	461	466	1,367	1,389
Reclassification of postretirement liability adjustment from regulatory asset, tax	0	0	(1,086)	0
Reclassification of postretirement liability adjustment from regulatory asset, net of tax	0	0	(3,265)	0
Postretirement liability adjustment	461	466	(1,898)	1,389
Net unrealized loss on available-for-sale investments:
Net unrealized loss on available-for-sale investments arising during the period, tax	(88)	(15)	(207)	(40)
Net unrealized loss on available-for-sale investments arising during the period, net of tax	(329)	(54)	(777)	(150)
Reclassification adjustment for loss on available-for-sale investments included in net income, tax	12	6	27	21
Reclassification adjustment for loss on available-for-sale investments included in net income, net of tax	42	20	99	80
Net unrealized loss on available-for-sale investments	(287)	(34)	(678)	(70)
Other comprehensive income (loss)	285	543	(2,242)	1,653
Comprehensive income attributable to common stockholders	$ 148,256	$ 139,819	$ 248,159	$ 293,250

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Current assets:
Cash and cash equivalents	$ 74,620	$ 54,161	$ 57,241
Receivables, net	1,298,019	946,741	979,862
Inventories	398,642	335,609	312,285
Current regulatory assets	148,160	118,691	133,135
Prepayments and other current assets	104,850	95,741	83,364
Total current assets	2,024,291	1,550,943	1,565,887
Noncurrent assets:
Property, plant and equipment	9,257,067	8,972,849	8,634,737
Less accumulated depreciation, depletion and amortization	3,263,217	3,216,461	3,175,756
Net property, plant and equipment	5,993,850	5,756,388	5,458,981
Goodwill	763,262	765,386	717,646
Other intangible assets, net	18,745	22,578	22,241
Regulatory assets	344,442	357,851	379,245
Investments	157,860	175,476	171,859
Operating lease right-of-use assets	119,586	124,138	109,439
Other	185,094	157,675	143,565
Total noncurrent assets	7,582,839	7,359,492	7,002,976
Total assets	9,607,130	8,910,435	8,568,863
Current liabilities:
Short-term borrowings	100,000	0	50,000
Long-term debt due within one year	214,453	148,053	1,548
Accounts payable	630,699	478,933	525,704
Taxes payable	93,565	80,372	87,455
Dividends payable	44,229	44,229	43,212
Accrued compensation	99,824	81,904	105,867
Operating lease liabilities due within one year	34,569	35,368	30,502
Regulatory liabilities due within one year	18,599	16,303	16,491
Other accrued liabilities	232,364	207,078	212,140
Total current liabilities	1,468,302	1,092,240	1,072,919
Noncurrent liabilities:
Long-term debt	2,773,999	2,593,847	2,326,718
Deferred income taxes	617,996	591,962	557,582
Asset retirement obligations	472,931	458,061	455,522
Regulatory liabilities	433,212	428,790	426,141
Operating lease liabilities	85,884	89,253	79,397
Other	262,948	273,408	318,306
Total noncurrent liabilities	4,646,970	4,435,321	4,163,666
Commitments and contingencies
Stockholders' equity:
Common stock	203,889	203,889	203,889
Other paid-in capital	1,455,241	1,461,205	1,458,208
Retained earnings	1,879,600	1,762,410	1,720,232
Accumulated other comprehensive loss	(43,246)	(41,004)	(46,425)
Treasury stock at cost - 538,921 shares	(3,626)	(3,626)	(3,626)
Total stockholders' equity	3,491,858	3,382,874	3,332,278
Total liabilities and stockholders' equity	$ 9,607,130	$ 8,910,435	$ 8,568,863
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	203,889,661
Treasury Stock, Common, Shares	538,921	538,921	538,921

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common stock	Other paid-in capital	Retained earnings	Accumulated other comprehensive loss	Treasury stock
Common 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	291,597
Other comprehensive income	1,653
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 Sep. 30, 2021	203,889,661	203,889,661
Treasury stock (in shares) at Sep. 30, 2021						(538,921)
Balance at Sep. 30, 2021	$ 3,332,278	$ 203,889	1,458,208	1,720,232	(46,425)	$ (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
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)
Net income	139,276			139,276
Other comprehensive income	543				543
Dividends declared on common stock	(43,449)			(43,449)
Stock-based compensation	2,925		2,925
Issuance of common stock (shares)		1,067,360
Issuance of common stock	$ 34,181	$ 1,067	33,114
Common stock balance (in shares) at Sep. 30, 2021	203,889,661	203,889,661
Treasury stock (in shares) at Sep. 30, 2021						(538,921)
Balance at Sep. 30, 2021	$ 3,332,278	$ 203,889	1,458,208	1,720,232	(46,425)	$ (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	250,401
Other comprehensive income	(2,242)
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 Sep. 30, 2022	203,889,661	203,889,661
Treasury stock (in shares) at Sep. 30, 2022						(538,921)
Balance at Sep. 30, 2022	$ 3,491,858	$ 203,889	1,455,241	1,879,600	(43,246)	$ (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
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)
Net income	147,971			147,971
Other comprehensive income	285				285
Dividends declared on common stock	(44,318)			(44,318)
Stock-based compensation	$ 1,110		1,110
Common stock balance (in shares) at Sep. 30, 2022	203,889,661	203,889,661
Treasury stock (in shares) at Sep. 30, 2022						(538,921)
Balance at Sep. 30, 2022	$ 3,491,858	$ 203,889	$ 1,455,241	$ 1,879,600	$ (43,246)	$ (3,626)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Operating activities:
Net income	$ 250,401	$ 291,597
Discontinued operations, net of tax	103	348
Income from continuing operations	250,298	291,249
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	247,173	222,613
Deferred income taxes	18,741	30,353
Provision for credit losses	3,258	(801)
Amortization of debt issuance costs	1,080	997
Employee stock-based compensation costs	6,488	11,649
Pension and postretirement benefit plan net periodic benefit credit	(4,515)	(3,690)
Unrealized (gains) losses on investments	15,529	(4,408)
Gains on sales of assets	(8,500)	(10,518)
Changes in current assets and liabilities, net of acquisitions:
Receivables	(346,879)	(103,637)
Inventories	(60,670)	(21,402)
Other current assets	(31,405)	(74,413)
Accounts payable	148,456	33,173
Other current liabilities	62,106	14,175
Pension and postretirement benefit plan contributions	(375)	(326)
Other noncurrent changes	(15,835)	(19,129)
Net cash provided by continuing operations	284,950	365,885
Net cash used in discontinued operations	(17)	(75)
Net cash provided by operating activities	284,933	365,810
Investing activities:
Capital expenditures	(463,002)	(428,114)
Acquisitions, net of cash acquired	450	(13,721)
Net proceeds from sale or disposition of property and other	1,615	12,954
Investments	(4,411)	(3,777)
Net cash used in investing activities	(465,348)	(432,658)
Financing activities:
Issuance of short-term borrowings	100,000	50,000
Repayment of short-term borrowings	0	(50,000)
Issuance of long-term debt	270,250	178,879
Repayment of long-term debt	(23,155)	(63,835)
Debt issuance costs	(1,082)	(362)
Net proceeds from issuance of common stock	(149)	88,830
Dividends paid	(132,687)	(128,142)
Repurchase of common stock	(7,399)	(6,701)
Tax withholding on stock-based compensation	(4,904)	(4,127)
Net cash provided by financing activities	200,874	64,542
Increase (decrease) in cash and cash equivalents	20,459	(2,306)
Cash and cash equivalents -- beginning of year	54,161	59,547
Cash and cash equivalents -- end of period	$ 74,620	$ 57,241

Basis of presentation

Basis of presentation	9 Months Ended
	Sep. 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. As the next step of the Company’s strategic planning, on November 2, 2022, the board of directors unanimously determined the best way to optimize value would be to create two pure-play companies: a leading construction materials company and a regulated energy delivery company. Accordingly, the board has authorized management to commence a strategic review process for MDU Construction Services with the objective of achieving the board’s goal of creating two pure-play public companies. Discontinued operations include the supporting activities of Fidelity and are shown in income from discontinued operations on the Consolidated Statements of Income. Unless otherwise indicated, the amounts presented in the accompanying notes to the consolidated financial statements relate to the Company's continuing operations. 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 nine months ended September 30, 2021 .

New accounting standards

New accounting standards	9 Months Ended
	Sep. 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	9 Months Ended
	Sep. 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	9 Months Ended
	Sep. 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 $41.5 million, $37.9 million and $44.8 million at September 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 Current expected credit loss provision 300 881 — (55) (111) 1,015 Less write-offs charged against the allowance 399 1,822 — 75 152 2,448 Credit loss recoveries collected 85 169 — — 40 294 At September 30, 2022 $ 334 $ 681 $ 2 $ 4,900 $ 2,509 $ 8,426 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 Current expected credit loss provision 388 411 — 233 (675) 357 Less write-offs charged against the allowance 525 1,178 — 184 265 2,152 Credit loss recoveries collected 92 168 — — 93 353 At September 30, 2021 $ 282 $ 1,660 $ 2 $ 4,670 $ 2,692 $ 9,306

Inventories and natural gas in

Inventories and natural gas in storage	9 Months Ended
	Sep. 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: September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Aggregates held for resale $ 198,711 $ 183,693 $ 184,363 Asphalt oil 56,609 32,964 57,002 Natural gas in storage (current) 48,532 28,683 18,867 Materials and supplies 42,359 27,253 30,629 Merchandise for resale 39,198 26,639 28,501 Other 13,233 13,053 16,247 Total $ 398,642 $ 312,285 $ 335,609

Earnings per share

Earnings per share	9 Months Ended
	Sep. 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 Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands, except per share amounts) Weighted average common shares outstanding - basic 203,351 202,863 203,351 201,647 Effect of dilutive performance share awards and restricted stock units 293 327 56 308 Weighted average common shares outstanding - diluted 203,644 203,190 203,407 201,955 Shares excluded from the calculation of diluted earnings per share — — 77 — Dividends declared per common share $ .2175 $ .2125 $ .6525 $ .6375

Equity

Equity	9 Months Ended
	Sep. 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 September 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 Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In millions) Shares issued — 1.0 — 2.8 Net proceeds * $ — $ 34.2 ** $ (.1) $ 88.8 ** * Net proceeds include issuance costs of $— and $149,000 for the three and nine months ended September 30, 2022, respectively, and $425,000 and $1.2 million for the three and nine months ended September 30, 2021, respectively. ** Net proceeds were used for capital expenditures.

Accumulated other comprehensive

Accumulated other comprehensive loss	9 Months Ended
	Sep. 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) Other comprehensive loss before reclassifications — — (329) (329) Amounts reclassified from accumulated other comprehensive loss 111 461 42 614 Net current-period other comprehensive income (loss) 111 461 (287) 285 At September 30, 2022 $ (204) $ (42,359) $ (683) $ (43,246) 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) Other comprehensive loss before reclassifications — — (54) (54) Amounts reclassified from accumulated other comprehensive loss 111 466 20 597 Net current-period other comprehensive income (loss) 111 466 (34) 543 At September 30, 2021 $ (650) $ (45,818) $ 43 $ (46,425) 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 Nine Months Ended Location on Consolidated September 30, September 30, 2022 2021 2022 2021 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (148) $ (147) $ (443) $ (443) Interest expense 37 36 109 109 Income taxes (111) (111) (334) (334) Amortization of postretirement liability losses included in net periodic benefit credit (609) (617) (1,827) (1,851) Other income 148 151 460 462 Income taxes (461) (466) (1,367) (1,389) Reclassification adjustment on available-for-sale investments included in net income (54) (26) (126) (101) Other income 12 6 27 21 Income taxes (42) (20) (99) (80) Total reclassifications $ (614) $ (597) $ (1,800) $ (1,803)

Revenue from contracts with cus

Revenue from contracts with customers	9 Months Ended
	Sep. 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 September 30, 2022 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 36,981 $ 64,074 $ — $ — $ — $ — $ 101,055 Commercial utility sales 38,785 43,734 — — — — 82,519 Industrial utility sales 10,838 7,209 — — — — 18,047 Other utility sales 2,002 — — — — — 2,002 Natural gas transportation — 11,910 32,144 — — — 44,054 Natural gas storage — — 3,595 — — — 3,595 Contracting services — — — 492,207 — — 492,207 Construction materials — — — 742,982 — — 742,982 Intrasegment eliminations — — — (259,761) — — (259,761) Electrical & mechanical specialty contracting — — — — 543,717 — 543,717 Transmission & distribution specialty contracting — — — — 181,550 — 181,550 Other 10,758 3,494 3,815 — 200 4,438 22,705 Intersegment eliminations (124) (139) (3,595) (343) (2,229) (4,438) (10,868) Revenues from contracts with customers 99,240 130,282 35,959 975,085 723,238 — 1,963,804 Other revenues (47) 1,792 86 — 11,571 — 13,402 Total external operating revenues $ 99,193 $ 132,074 $ 36,045 $ 975,085 $ 734,809 $ — $ 1,977,206 Three Months Ended September 30, 2021 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 36,412 $ 55,284 $ — $ — $ — $ — $ 91,696 Commercial utility sales 39,033 35,338 — — — — 74,371 Industrial utility sales 10,495 5,395 — — — — 15,890 Other utility sales 1,993 — — — — — 1,993 Natural gas transportation — 11,812 28,058 — — — 39,870 Natural gas storage — — 3,483 — — — 3,483 Contracting services — — — 415,106 — — 415,106 Construction materials — — — 617,823 — — 617,823 Intrasegment eliminations — — — (201,630) — — (201,630) Electrical & mechanical specialty contracting — — — — 317,238 — 317,238 Transmission & distribution specialty contracting — — — — 185,842 — 185,842 Other 12,589 2,110 3,290 — 75 3,423 21,487 Intersegment eliminations (136) (142) (3,908) (110) (289) (3,398) (7,983) Revenues from contracts with customers 100,386 109,797 30,923 831,189 502,866 25 1,575,186 Other revenues (1,456) 581 45 — 11,657 — 10,827 Total external operating revenues $ 98,930 $ 110,378 $ 30,968 $ 831,189 $ 514,523 $ 25 $ 1,586,013 Nine Months Ended September 30, 2022 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 103,648 $ 439,639 $ — $ — $ — $ — $ 543,287 Commercial utility sales 108,400 279,697 — — — — 388,097 Industrial utility sales 32,067 29,242 — — — — 61,309 Other utility sales 5,632 — — — — — 5,632 Natural gas transportation — 35,747 95,685 — — — 131,432 Natural gas storage — — 10,210 — — — 10,210 Contracting services — — — 937,156 — — 937,156 Construction materials — — — 1,535,077 — — 1,535,077 Intrasegment eliminations — — — (475,026) — — (475,026) Electrical & mechanical specialty contracting — — — — 1,443,758 — 1,443,758 Transmission & distribution specialty contracting — — — — 496,190 — 496,190 Other 33,727 9,854 8,200 — 357 13,168 65,306 Intersegment eliminations (371) (416) (37,328) (674) (5,090) (13,168) (57,047) Revenues from contracts with customers 283,103 793,763 76,767 1,996,533 1,935,215 — 5,085,381 Other revenues (4,854) (831) 210 — 34,780 — 29,305 Total external operating revenues $ 278,249 $ 792,932 $ 76,977 $ 1,996,533 $ 1,969,995 $ — $ 5,114,686 Nine Months Ended September 30, 2021 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 99,106 $ 341,901 $ — $ — $ — $ — $ 441,007 Commercial utility sales 105,795 203,002 — — — — 308,797 Industrial utility sales 30,878 20,387 — — — — 51,265 Other utility sales 5,384 — — — — — 5,384 Natural gas transportation — 35,715 85,160 — — — 120,875 Natural gas storage — — 10,606 — — — 10,606 Contracting services — — — 791,964 — — 791,964 Construction materials — — — 1,332,997 — — 1,332,997 Intrasegment eliminations — — — (394,126) — — (394,126) Electrical & mechanical specialty contracting — — — — 1,020,130 — 1,020,130 Transmission & distribution specialty contracting — — — — 502,328 — 502,328 Other 31,827 7,913 10,760 — 168 10,152 60,820 Intersegment eliminations (407) (425) (38,000) (314) (2,128) (10,082) (51,356) Revenues from contracts with customers 272,583 608,493 68,526 1,730,521 1,520,498 70 4,200,691 Other revenues (5,329) 5,880 127 — 36,239 — 36,917 Total external operating revenues $ 267,254 $ 614,373 $ 68,653 $ 1,730,521 $ 1,556,737 $ 70 $ 4,237,608 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 for construction work are billed as work progresses in accordance with agreed upon contractual terms. Generally, billing to the customer occurs contemporaneous to revenue recognition. A variance in timing of the billings may result in a contract asset or a contract liability. A contract asset occurs when revenues are recognized under the cost-to-cost measure of progress, which exceeds amounts billed on uncompleted contracts. Such amounts will be billed as standard contract terms allow, usually based on various measures of performance or achievement. A contract liability occurs when there are billings in excess of revenues recognized under the cost-to-cost measure of progress on uncompleted contracts. Contract liabilities decrease as revenue is recognized from the satisfaction of the related performance obligation. The changes in contract assets and liabilities were as follows: September 30, 2022 December 31, 2021 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 265,585 $ 125,742 $ 139,843 Receivables, net Contract liabilities - current (216,439) (179,140) (37,299) Accounts payable Contract liabilities - noncurrent (12) (118) 106 Noncurrent liabilities - other Net contract assets (liabilities) $ 49,134 $ (53,516) $ 102,650 The Company recognized $11.2 million and $147.9 million in revenue for the three and nine months ended September 30, 2022, respectively, which was previously included in contract liabilities at December 31, 2021. The Company recognized $7.1 million and $152.4 million in revenue for the three and nine months ended September 30, 2021, respectively, which was previously included in contract liabilities at December 31, 2020. The Company recognized a net increase in revenues of $14.5 million and $54.1 million for the three and nine months ended September 30, 2022, respectively, from performance obligations satisfied in prior periods. The company recognized a net increase in revenues of $19.2 million and $63.3 million for the three and nine months ended September 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 September 30, 2022, the Company's remaining performance obligations were $3.3 billion. The Company expects to recognize the following revenue amounts in future periods related to these remaining performance obligations: $2.6 billion within the next 12 months or less; $369.7 million within the next 13 to 24 months; and $418.1 million in 25 months or more.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 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 nine months ended September 30, 2022. In 2021, the construction materials and contracting segment's acquisitions included: • Baker Rock Resources and Oregon Mainline Paving, two construction materials companies located around the Portland, Oregon metro area, acquired in November 2021. As of September 30, 2022, the purchase price allocation was settled with no material adjustments to the provisional accounting. • Mt. Hood Rock, a construction aggregates business in Oregon, acquired in April 2021. As of March 31, 2022, the purchase price allocation was settled with no material adjustments to the provisional accounting. 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 nine months ended September 30, 2022, the Company had no acquisition costs. For the nine months ended September 30, 2021, acquisition costs were not material.

Leases

Leases	9 Months Ended
	Sep. 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 $11.7 million and $35.1 million for the three and nine months ended September 30, 2022, respectively. The Company recognized revenue from operating leases of $11.8 million and $36.6 million for the three and nine months ended September 30, 2021, respectively. At September 30, 2022, the Company had $9.1 million of lease receivables with a majority due within 12 months.

Goodwill and other intangible a

Goodwill and other intangible assets	9 Months Ended
	Sep. 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 September 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 September 30, 2021 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 226,003 2,900 (217) 228,686 Construction services 143,224 — — 143,224 Total $ 714,963 $ 2,900 $ (217) $ 717,646 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: September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Customer relationships $ 28,990 $ 29,423 $ 29,740 Less accumulated amortization 12,768 9,705 10,650 16,222 19,718 19,090 Noncompete agreements 4,591 3,991 4,591 Less accumulated amortization 3,377 2,710 2,856 1,214 1,281 1,735 Other 5,279 11,957 12,601 Less accumulated amortization 3,970 10,715 10,848 1,309 1,242 1,753 Total $ 18,745 $ 22,241 $ 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 nine months ended September 30, 2022, was $1.3 million and $3.8 million, respectively. Amortization expense for amortizable intangible assets for the three and nine months ended September 30, 2021, was $1.2 million and $3.9 million, respectively. Estimated amortization expense for identifiable intangible assets as of September 30, 2022, was: Remainder of 2022 2023 2024 2025 2026 Thereafter (In thousands) Amortization expense $ 1,159 $ 4,591 $ 4,249 $ 2,200 $ 1,781 $ 4,765

Regulatory assets and liabiliti

Regulatory assets and liabilities	9 Months Ended
	Sep. 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 September 30, 2022 * September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 112,079 $ 98,211 $ 86,371 Conservation programs Up to 1 year 9,363 8,495 8,225 Decoupling Up to 1 year 6,549 7,195 9,131 Cost recovery mechanisms Up to 1 year 3,354 4,693 4,536 Other Up to 1 year 16,815 14,541 10,428 148,160 133,135 118,691 Noncurrent: Pension and postretirement benefits ** 137,582 155,888 142,681 Cost recovery mechanisms Up to 10 years 67,094 43,955 44,870 Plant costs/asset retirement obligations Over plant lives 61,941 73,528 63,116 Plant to be retired - 24,740 48,544 50,070 Manufactured gas plant site remediation - 25,963 26,000 26,053 Taxes recoverable from customers Over plant lives 12,394 11,438 12,339 Long-term debt refinancing costs Up to 38 years 3,335 3,952 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years 462 6,084 5,186 Other Up to 17 years 10,931 9,856 9,742 344,442 379,245 357,851 Total regulatory assets $ 492,602 $ 512,380 $ 476,542 Regulatory liabilities: Current: Taxes refundable to customers Up to 1 year $ 4,264 $ 3,867 $ 3,841 Electric fuel and purchased power deferral Up to 1 year 3,763 3,205 — Cost recovery mechanisms Up to 1 year 2,674 2,797 214 Natural gas costs refundable through rate adjustments Up to 1 year 873 — 6,700 Other Up to 1 year 7,025 6,622 5,548 18,599 16,491 16,303 Noncurrent: Taxes refundable to customers Over plant lives 205,517 218,566 215,421 Plant removal and decommissioning costs Over plant lives 174,481 172,683 168,152 Pension and postretirement benefits ** 19,687 16,915 20,434 Accumulated deferred investment tax credit Up to 20 years 14,665 12,403 12,696 Cost recovery mechanisms Up to 20 years 12,535 — 7,727 Other Up to 16 years 6,327 5,574 4,360 433,212 426,141 428,790 Total regulatory liabilities $ 451,811 $ 442,632 $ 445,093 Net regulatory position $ 40,791 $ 69,748 $ 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 September 30, 2022 and 2021, and December 31, 2021, approximately $264.4 million, $318.2 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 in 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 partially 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. With the exception of $845,000 in Minnesota, 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	9 Months Ended
	Sep. 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 $95.2 million, $106.4 million and $109.6 million, at September 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 $2.6 million and $16.8 million for the three and nine months ended September 30, 2022, respectively. The net unrealized gain on these investments was $373,000 and $4.2 million for the three and nine months ended September 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: September 30, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,486 $ — $ 783 $ 7,703 U.S. Treasury securities 2,468 — 82 2,386 Total $ 10,954 $ — $ 865 $ 10,089 September 30, 2021 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,597 $ 93 $ 11 $ 8,679 U.S. Treasury securities 2,681 — 28 2,653 Total $ 11,278 $ 93 $ 39 $ 11,332 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 September 30, 2022, Using Quoted Prices in Significant Significant Balance at September 30, 2022 (In thousands) Assets: Money market funds $ — $ 7,309 $ — $ 7,309 Insurance contracts* — 95,170 — 95,170 Available-for-sale securities: Mortgage-backed securities — 7,703 — 7,703 U.S. Treasury securities — 2,386 — 2,386 Total assets measured at fair value $ — $ 112,568 $ — $ 112,568 * The insurance contracts invest approximately 65 percent in fixed-income investments, 14 percent in common stock of large-cap companies, 7 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at September 30, 2021, Using Quoted Prices in Significant Significant Balance at September 30, 2021 (In thousands) Assets: Money market funds $ — $ 9,907 $ — $ 9,907 Insurance contracts* — 106,371 — 106,371 Available-for-sale securities: Mortgage-backed securities — 8,679 — 8,679 U.S. Treasury securities — 2,653 — 2,653 Total assets measured at fair value $ — $ 127,610 $ — $ 127,610 * The insurance contracts invest approximately 63 percent in fixed-income investments, 16 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 1 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: September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Carrying amount $ 2,988,452 $ 2,328,266 $ 2,741,900 Fair value $ 2,647,387 $ 2,599,907 $ 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	9 Months Ended
	Sep. 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 September 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 September 30, 2022 September 30, 2022 September 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 $ 2,025,000 $ 2,125,000 Commercial paper supported by revolving credit agreements 3.66 % 460,600 168,800 450,300 Credit agreements due on June 7, 2024 4.55 % 125,580 94,300 127,500 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 3.64 % 7,000 7,700 7,700 Other notes due on dates ranging from January 1, 2024 to January 1, 2061 .97 % 2,349 3,198 2,564 Less unamortized debt issuance costs 6,633 5,709 6,090 Less discount 444 23 74 Total long-term debt 2,988,452 2,328,266 2,741,900 Less current maturities 214,453 1,548 148,053 Net long-term debt $ 2,773,999 $ 2,326,718 $ 2,593,847 Schedule of Debt Maturities Long-term debt maturities, which excludes unamortized debt issuance costs and discount, at September 30, 2022, were as follows: Remainder of 2022 2023 2024 2025 2026 Thereafter (In thousands) Long-term debt maturities $ 147,253 $ 77,923 $ 646,983 $ 177,802 $ 140,802 $ 1,804,766

Cash flow information

Cash flow information	9 Months Ended
	Sep. 30, 2022
Supplemental Cash Flow Information [Abstract]
Cash flow information	Cash flow information Cash expenditures for interest and income taxes were as follows: Nine Months Ended September 30, 2022 2021 (In thousands) Interest, net* $ 75,425 $ 59,876 Income taxes paid, net $ 17,664 $ 61,250 * AFUDC - borrowed was $2.4 million and $1.6 million for the nine months ended September 30, 2022 and 2021, respectively. Noncash investing and financing transactions were as follows: September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 36,492 $ 26,120 $ 55,987 Property, plant and equipment additions in accounts payable $ 44,277 $ 88,355 $ 57,605 Debt assumed in connection with a business combination $ — $ — $ 10

Business segment data

Business segment data	9 Months Ended
	Sep. 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, as well as transaction costs associated with the anticipated separation of Knife River. 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 Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands) External operating revenues: Regulated operations: Electric $ 99,193 $ 98,930 $ 278,249 $ 267,254 Natural gas distribution 132,074 110,378 792,932 614,373 Pipeline 32,347 27,757 69,347 58,390 263,614 237,065 1,140,528 940,017 Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands) Non-regulated operations: Pipeline 3,698 3,211 7,630 10,263 Construction materials and contracting 975,085 831,189 1,996,533 1,730,521 Construction services 734,809 514,523 1,969,995 1,556,737 Other — 25 — 70 1,713,592 1,348,948 3,974,158 3,297,591 Total external operating revenues $ 1,977,206 $ 1,586,013 $ 5,114,686 $ 4,237,608 Intersegment operating revenues: Regulated operations: Electric $ 124 $ 136 $ 371 $ 407 Natural gas distribution 139 142 416 425 Pipeline 3,508 3,845 36,845 37,530 3,771 4,123 37,632 38,362 Non-regulated operations: Pipeline 87 63 483 470 Construction materials and contracting 343 110 674 314 Construction services 2,229 289 5,090 2,128 Other 4,438 3,398 13,168 10,082 7,097 3,860 19,415 12,994 Intersegment eliminations (10,868) (7,983) (57,047) (51,356) Total intersegment operating revenues $ — $ — $ — $ — Operating income (loss): Electric $ 30,395 $ 27,310 $ 53,764 $ 53,982 Natural gas distribution (16,688) (14,249) 38,929 42,925 Pipeline 14,963 12,284 39,447 35,896 Construction materials and contracting 147,367 133,712 157,116 171,274 Construction services 34,949 30,120 110,588 108,172 Other (1,135) (8) (2,081) (226) Total operating income $ 209,851 $ 189,169 $ 397,763 $ 412,023 Net income (loss): Regulated operations: Electric $ 21,596 $ 20,564 $ 37,476 $ 41,618 Natural gas distribution (18,058) (15,390) 10,758 20,081 Pipeline 9,379 10,225 24,527 27,508 12,917 15,399 72,761 89,207 Non-regulated operations: Pipeline 492 356 (187) 1,166 Construction materials and contracting 102,764 96,282 95,337 116,865 Construction services 27,977 23,130 83,755 81,839 Other 3,783 3,795 (1,368) 2,172 135,016 123,563 177,537 202,042 Income from continuing operations 147,933 138,962 250,298 291,249 Discontinued operations, net of tax 38 314 103 348 Net income $ 147,971 $ 139,276 $ 250,401 $ 291,597

Employee benefit plans

Employee benefit plans	9 Months Ended
	Sep. 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 Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands) Components of net periodic benefit credit: Interest cost $ 2,630 $ 2,455 $ 7,892 $ 7,365 Expected return on assets (4,864) (4,894) (14,592) (14,682) Amortization of net actuarial loss 1,670 2,004 5,012 6,012 Net periodic benefit credit $ (564) $ (435) $ (1,688) $ (1,305) Components of net periodic benefit credit for the Company's other postretirement benefit plans were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands) Components of net periodic benefit credit: Service cost $ 354 $ 400 $ 1,062 $ 1,200 Interest cost 474 466 1,422 1,398 Expected return on assets (1,322) (1,275) (3,966) (3,825) Amortization of prior service credit (350) (349) (1,050) (1,047) Amortization of net actuarial (gain) loss (55) 6 (163) 18 Net periodic benefit credit, including amount capitalized (899) (752) (2,695) (2,256) Less amount capitalized 48 46 132 129 Net periodic benefit credit $ (947) $ (798) $ (2,827) $ (2,385) 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 September 30, 2022 and 2021, respectively, and $2.3 million for both the nine months ended September 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	9 Months Ended
	Sep. 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. MNPUC Great Plains defers the difference between the actual cost of gas spent to serve customers and that recovered from customers on a monthly basis. Annually, Great Plains prepares a true-up pursuant to the purchased gas adjustment tariff. On August 30, 2021, the MNPUC issued an order to allow Great Plains recovery of an out-of-cycle cost of gas adjustment of $8.8 million over a period of 27 months. The order was effective September 1, 2021, and was subject to a prudence review by the MNPUC. The requested increase was for the February 2021 extreme cold weather, primarily in the central United States, and market conditions surrounding the natural gas commodity market. On October 19, 2022, the MNPUC issued a final order disallowing $845,000 of the gas costs. These costs, which were deferred as a regulatory asset in natural gas costs recoverable through rate adjustments, were then recorded to expense as they were no longer recoverable from customers. On 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 is primarily to recover investments in production, transmission and distribution facilities and the associated depreciation, operation and maintenance expenses and taxes associated with the increased investment. 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. The lower interim rate increase is largely due to excluding the recovery of Heskett Unit 4, which is expected to be in service in the first half of 2023. 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. On October 5, 2022, the NDPSC approved the decrease with rates effective November 1, 2022. Montana-Dakota has a renewable resource cost adjustment rate tariff that allows for annual adjustments for recent projected capital costs and related expenses for projects determined to be recoverable under the tariff. On November 1, 2022, Montana-Dakota filed an annual update to its renewable resource cost adjustment requesting to recover a revenue requirement of approximately $17.9 million annually. The update reflects a decrease of approximately $127,000 from the revenues currently included in rates. 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 issued a final order on August 23, 2022, adjusting the settlement primarily for 2020 actual depreciation expense. The final order approved an increase of $7.2 million annually with an effective date of September 1, 2022. 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. A multi-party settlement was filed with the WUTC on October 21, 2022. This matter is pending before the WUTC. On October 14, 2022, Cascade filed an update to its annual pipeline cost recovery mechanism requesting an increase in annual revenue of approximately $1.2 million or approximately 0.4 percent. The filing was effective November 1, 2022. FERC On September 1, 2022, Montana-Dakota filed an update to its transmission formula rate under the MISO tariff for its multi-value project and network upgrade charges for $15.4 million, which is effective January 1, 2023.

Contingencies

Contingencies	9 Months Ended
	Sep. 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 September 30, 2022 and 2021, and December 31, 2021, the Company accrued contingent liabilities, which have not been discounted, of $33.6 million, $34.7 million and $37.0 million, respectively. At September 30, 2022 and 2021, and December 31, 2021, the Company also recorded corresponding insurance receivables of $11.9 million, $11.7 million and $14.1 million, respectively, and regulatory assets of $20.5 million, $21.1 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 September 30, 2022, the fixed maximum amounts guaranteed under these agreements aggregate $333.7 million. Certain of the guarantees also have no fixed maximum amounts specified. At September 30, 2022, the amounts of scheduled expiration of the maximum amounts guaranteed under these agreements aggregate to $10.8 million in 2022; $68.6 million in 2023; $110.6 million in 2024; $130.5 million in 2025; $1.3 million in 2026; $700,000 thereafter; and $11.2 million, which has no scheduled maturity date. There were no amounts outstanding under the previously mentioned guarantees at September 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 September 30, 2022, the fixed maximum amounts guaranteed under these letters of credit aggregated $25.0 million. At September 30, 2022, the amounts of scheduled expiration of the maximum amounts guaranteed under these letters of credit aggregate to $21.8 million in 2022, $2.7 million in 2023 and $500,000 in 2024. There were no amounts outstanding under the previously mentioned letters of credit at September 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 September 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 September 30, 2022, approximately $932.4 million of surety bonds were outstanding, which were not reflected on the Consolidated Balance Sheet. Variable interest entities The Company evaluates its arrangements and contracts with other entities to determine if they are VIEs and if so, if the Company is the primary beneficiary. Fuel Contract Coyote Station entered into a coal supply agreement with Coyote Creek that provides for the purchase of coal necessary to supply the coal requirements of the Coyote Station for the period May 2016 through December 2040. Coal purchased under the coal supply agreement is reflected in inventories on the Consolidated Balance Sheets and is recovered from customers as a component of electric fuel and purchased power. The coal supply agreement creates a variable interest in Coyote Creek due to the transfer of all operating and economic risk to the Coyote Station owners, as the agreement is structured so that the price of the coal will cover all costs of operations, as well as future reclamation costs. The Coyote Station owners are also providing a guarantee of the value of the assets of Coyote Creek as they would be required to buy the assets at book value should they terminate the contract prior to the end of the contract term and are providing a guarantee of the value of the equity of Coyote Creek in that they are required to buy the entity at the end of the contract term at equity value. Although the Company has determined that Coyote Creek is a VIE, the Company has concluded that it is not the primary beneficiary of Coyote Creek because the authority to direct the activities of the entity is shared by the four unrelated owners of the Coyote Station, with no primary beneficiary existing. As a result, Coyote Creek is not required to be consolidated in the Company's financial statements. At September 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 $30.0 million.

Basis of presentation (Policies

Basis of presentation (Policies)	9 Months Ended
	Sep. 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.

New accounting standards (Polic

New accounting standards (Policies)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 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)	9 Months Ended
	Sep. 30, 2022
Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss	Details of the Company's expected credit losses were as follows: Electric Natural gas Pipeline Construction Construction Total (In thousands) At December 31, 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 Current expected credit loss provision 300 881 — (55) (111) 1,015 Less write-offs charged against the allowance 399 1,822 — 75 152 2,448 Credit loss recoveries collected 85 169 — — 40 294 At September 30, 2022 $ 334 $ 681 $ 2 $ 4,900 $ 2,509 $ 8,426 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 Current expected credit loss provision 388 411 — 233 (675) 357 Less write-offs charged against the allowance 525 1,178 — 184 265 2,152 Credit loss recoveries collected 92 168 — — 93 353 At September 30, 2021 $ 282 $ 1,660 $ 2 $ 4,670 $ 2,692 $ 9,306

Inventories and natural gas i_3

Inventories and natural gas in storage (Tables)	9 Months Ended
	Sep. 30, 2022
Inventory Disclosure [Abstract]
Inventories	Inventories on the Consolidated Balance Sheets were as follows: September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Aggregates held for resale $ 198,711 $ 183,693 $ 184,363 Asphalt oil 56,609 32,964 57,002 Natural gas in storage (current) 48,532 28,683 18,867 Materials and supplies 42,359 27,253 30,629 Merchandise for resale 39,198 26,639 28,501 Other 13,233 13,053 16,247 Total $ 398,642 $ 312,285 $ 335,609

Earnings per share (Tables)

Earnings per share (Tables)	9 Months Ended
	Sep. 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 Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands, except per share amounts) Weighted average common shares outstanding - basic 203,351 202,863 203,351 201,647 Effect of dilutive performance share awards and restricted stock units 293 327 56 308 Weighted average common shares outstanding - diluted 203,644 203,190 203,407 201,955 Shares excluded from the calculation of diluted earnings per share — — 77 — Dividends declared per common share $ .2175 $ .2125 $ .6525 $ .6375

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 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 Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In millions) Shares issued — 1.0 — 2.8 Net proceeds * $ — $ 34.2 ** $ (.1) $ 88.8 ** * Net proceeds include issuance costs of $— and $149,000 for the three and nine months ended September 30, 2022, respectively, and $425,000 and $1.2 million for the three and nine months ended September 30, 2021, respectively. ** Net proceeds were used for capital expenditures.

Accumulated other comprehensi_2

Accumulated other comprehensive loss (Tables)	9 Months Ended
	Sep. 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) Other comprehensive loss before reclassifications — — (329) (329) Amounts reclassified from accumulated other comprehensive loss 111 461 42 614 Net current-period other comprehensive income (loss) 111 461 (287) 285 At September 30, 2022 $ (204) $ (42,359) $ (683) $ (43,246) 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) Other comprehensive loss before reclassifications — — (54) (54) Amounts reclassified from accumulated other comprehensive loss 111 466 20 597 Net current-period other comprehensive income (loss) 111 466 (34) 543 At September 30, 2021 $ (650) $ (45,818) $ 43 $ (46,425)
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 Nine Months Ended Location on Consolidated September 30, September 30, 2022 2021 2022 2021 (In thousands) Reclassification adjustment for loss on derivative instruments included in net income $ (148) $ (147) $ (443) $ (443) Interest expense 37 36 109 109 Income taxes (111) (111) (334) (334) Amortization of postretirement liability losses included in net periodic benefit credit (609) (617) (1,827) (1,851) Other income 148 151 460 462 Income taxes (461) (466) (1,367) (1,389) Reclassification adjustment on available-for-sale investments included in net income (54) (26) (126) (101) Other income 12 6 27 21 Income taxes (42) (20) (99) (80) Total reclassifications $ (614) $ (597) $ (1,800) $ (1,803)

Revenue from contracts with c_3

Revenue from contracts with customers (Tables)	9 Months Ended
	Sep. 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 September 30, 2022 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 36,981 $ 64,074 $ — $ — $ — $ — $ 101,055 Commercial utility sales 38,785 43,734 — — — — 82,519 Industrial utility sales 10,838 7,209 — — — — 18,047 Other utility sales 2,002 — — — — — 2,002 Natural gas transportation — 11,910 32,144 — — — 44,054 Natural gas storage — — 3,595 — — — 3,595 Contracting services — — — 492,207 — — 492,207 Construction materials — — — 742,982 — — 742,982 Intrasegment eliminations — — — (259,761) — — (259,761) Electrical & mechanical specialty contracting — — — — 543,717 — 543,717 Transmission & distribution specialty contracting — — — — 181,550 — 181,550 Other 10,758 3,494 3,815 — 200 4,438 22,705 Intersegment eliminations (124) (139) (3,595) (343) (2,229) (4,438) (10,868) Revenues from contracts with customers 99,240 130,282 35,959 975,085 723,238 — 1,963,804 Other revenues (47) 1,792 86 — 11,571 — 13,402 Total external operating revenues $ 99,193 $ 132,074 $ 36,045 $ 975,085 $ 734,809 $ — $ 1,977,206 Three Months Ended September 30, 2021 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 36,412 $ 55,284 $ — $ — $ — $ — $ 91,696 Commercial utility sales 39,033 35,338 — — — — 74,371 Industrial utility sales 10,495 5,395 — — — — 15,890 Other utility sales 1,993 — — — — — 1,993 Natural gas transportation — 11,812 28,058 — — — 39,870 Natural gas storage — — 3,483 — — — 3,483 Contracting services — — — 415,106 — — 415,106 Construction materials — — — 617,823 — — 617,823 Intrasegment eliminations — — — (201,630) — — (201,630) Electrical & mechanical specialty contracting — — — — 317,238 — 317,238 Transmission & distribution specialty contracting — — — — 185,842 — 185,842 Other 12,589 2,110 3,290 — 75 3,423 21,487 Intersegment eliminations (136) (142) (3,908) (110) (289) (3,398) (7,983) Revenues from contracts with customers 100,386 109,797 30,923 831,189 502,866 25 1,575,186 Other revenues (1,456) 581 45 — 11,657 — 10,827 Total external operating revenues $ 98,930 $ 110,378 $ 30,968 $ 831,189 $ 514,523 $ 25 $ 1,586,013 Nine Months Ended September 30, 2022 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 103,648 $ 439,639 $ — $ — $ — $ — $ 543,287 Commercial utility sales 108,400 279,697 — — — — 388,097 Industrial utility sales 32,067 29,242 — — — — 61,309 Other utility sales 5,632 — — — — — 5,632 Natural gas transportation — 35,747 95,685 — — — 131,432 Natural gas storage — — 10,210 — — — 10,210 Contracting services — — — 937,156 — — 937,156 Construction materials — — — 1,535,077 — — 1,535,077 Intrasegment eliminations — — — (475,026) — — (475,026) Electrical & mechanical specialty contracting — — — — 1,443,758 — 1,443,758 Transmission & distribution specialty contracting — — — — 496,190 — 496,190 Other 33,727 9,854 8,200 — 357 13,168 65,306 Intersegment eliminations (371) (416) (37,328) (674) (5,090) (13,168) (57,047) Revenues from contracts with customers 283,103 793,763 76,767 1,996,533 1,935,215 — 5,085,381 Other revenues (4,854) (831) 210 — 34,780 — 29,305 Total external operating revenues $ 278,249 $ 792,932 $ 76,977 $ 1,996,533 $ 1,969,995 $ — $ 5,114,686 Nine Months Ended September 30, 2021 Electric Natural gas Pipeline Construction Construction Other Total (In thousands) Residential utility sales $ 99,106 $ 341,901 $ — $ — $ — $ — $ 441,007 Commercial utility sales 105,795 203,002 — — — — 308,797 Industrial utility sales 30,878 20,387 — — — — 51,265 Other utility sales 5,384 — — — — — 5,384 Natural gas transportation — 35,715 85,160 — — — 120,875 Natural gas storage — — 10,606 — — — 10,606 Contracting services — — — 791,964 — — 791,964 Construction materials — — — 1,332,997 — — 1,332,997 Intrasegment eliminations — — — (394,126) — — (394,126) Electrical & mechanical specialty contracting — — — — 1,020,130 — 1,020,130 Transmission & distribution specialty contracting — — — — 502,328 — 502,328 Other 31,827 7,913 10,760 — 168 10,152 60,820 Intersegment eliminations (407) (425) (38,000) (314) (2,128) (10,082) (51,356) Revenues from contracts with customers 272,583 608,493 68,526 1,730,521 1,520,498 70 4,200,691 Other revenues (5,329) 5,880 127 — 36,239 — 36,917 Total external operating revenues $ 267,254 $ 614,373 $ 68,653 $ 1,730,521 $ 1,556,737 $ 70 $ 4,237,608
Contract balances	The changes in contract assets and liabilities were as follows: September 30, 2022 December 31, 2021 Change Location on Consolidated Balance Sheets (In thousands) Contract assets $ 265,585 $ 125,742 $ 139,843 Receivables, net Contract liabilities - current (216,439) (179,140) (37,299) Accounts payable Contract liabilities - noncurrent (12) (118) 106 Noncurrent liabilities - other Net contract assets (liabilities) $ 49,134 $ (53,516) $ 102,650

Goodwill and other intangible_2

Goodwill and other intangible assets (Tables)	9 Months Ended
	Sep. 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 September 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 September 30, 2021 (In thousands) Natural gas distribution $ 345,736 $ — $ — $ 345,736 Construction materials and contracting 226,003 2,900 (217) 228,686 Construction services 143,224 — — 143,224 Total $ 714,963 $ 2,900 $ (217) $ 717,646 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: September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Customer relationships $ 28,990 $ 29,423 $ 29,740 Less accumulated amortization 12,768 9,705 10,650 16,222 19,718 19,090 Noncompete agreements 4,591 3,991 4,591 Less accumulated amortization 3,377 2,710 2,856 1,214 1,281 1,735 Other 5,279 11,957 12,601 Less accumulated amortization 3,970 10,715 10,848 1,309 1,242 1,753 Total $ 18,745 $ 22,241 $ 22,578
Estimated amortization expense	Estimated amortization expense for identifiable intangible assets as of September 30, 2022, was: Remainder of 2022 2023 2024 2025 2026 Thereafter (In thousands) Amortization expense $ 1,159 $ 4,591 $ 4,249 $ 2,200 $ 1,781 $ 4,765

Regulatory assets and liabili_2

Regulatory assets and liabilities (Tables)	9 Months Ended
	Sep. 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 September 30, 2022 * September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 112,079 $ 98,211 $ 86,371 Conservation programs Up to 1 year 9,363 8,495 8,225 Decoupling Up to 1 year 6,549 7,195 9,131 Cost recovery mechanisms Up to 1 year 3,354 4,693 4,536 Other Up to 1 year 16,815 14,541 10,428 148,160 133,135 118,691 Noncurrent: Pension and postretirement benefits ** 137,582 155,888 142,681 Cost recovery mechanisms Up to 10 years 67,094 43,955 44,870 Plant costs/asset retirement obligations Over plant lives 61,941 73,528 63,116 Plant to be retired - 24,740 48,544 50,070 Manufactured gas plant site remediation - 25,963 26,000 26,053 Taxes recoverable from customers Over plant lives 12,394 11,438 12,339 Long-term debt refinancing costs Up to 38 years 3,335 3,952 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years 462 6,084 5,186 Other Up to 17 years 10,931 9,856 9,742 344,442 379,245 357,851 Total regulatory assets $ 492,602 $ 512,380 $ 476,542 Regulatory liabilities: Current: Taxes refundable to customers Up to 1 year $ 4,264 $ 3,867 $ 3,841 Electric fuel and purchased power deferral Up to 1 year 3,763 3,205 — Cost recovery mechanisms Up to 1 year 2,674 2,797 214 Natural gas costs refundable through rate adjustments Up to 1 year 873 — 6,700 Other Up to 1 year 7,025 6,622 5,548 18,599 16,491 16,303 Noncurrent: Taxes refundable to customers Over plant lives 205,517 218,566 215,421 Plant removal and decommissioning costs Over plant lives 174,481 172,683 168,152 Pension and postretirement benefits ** 19,687 16,915 20,434 Accumulated deferred investment tax credit Up to 20 years 14,665 12,403 12,696 Cost recovery mechanisms Up to 20 years 12,535 — 7,727 Other Up to 16 years 6,327 5,574 4,360 433,212 426,141 428,790 Total regulatory liabilities $ 451,811 $ 442,632 $ 445,093 Net regulatory position $ 40,791 $ 69,748 $ 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 September 30, 2022 * September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Regulatory assets: Current: Natural gas costs recoverable through rate adjustments Up to 1 year $ 112,079 $ 98,211 $ 86,371 Conservation programs Up to 1 year 9,363 8,495 8,225 Decoupling Up to 1 year 6,549 7,195 9,131 Cost recovery mechanisms Up to 1 year 3,354 4,693 4,536 Other Up to 1 year 16,815 14,541 10,428 148,160 133,135 118,691 Noncurrent: Pension and postretirement benefits ** 137,582 155,888 142,681 Cost recovery mechanisms Up to 10 years 67,094 43,955 44,870 Plant costs/asset retirement obligations Over plant lives 61,941 73,528 63,116 Plant to be retired - 24,740 48,544 50,070 Manufactured gas plant site remediation - 25,963 26,000 26,053 Taxes recoverable from customers Over plant lives 12,394 11,438 12,339 Long-term debt refinancing costs Up to 38 years 3,335 3,952 3,794 Natural gas costs recoverable through rate adjustments Up to 2 years 462 6,084 5,186 Other Up to 17 years 10,931 9,856 9,742 344,442 379,245 357,851 Total regulatory assets $ 492,602 $ 512,380 $ 476,542 Regulatory liabilities: Current: Taxes refundable to customers Up to 1 year $ 4,264 $ 3,867 $ 3,841 Electric fuel and purchased power deferral Up to 1 year 3,763 3,205 — Cost recovery mechanisms Up to 1 year 2,674 2,797 214 Natural gas costs refundable through rate adjustments Up to 1 year 873 — 6,700 Other Up to 1 year 7,025 6,622 5,548 18,599 16,491 16,303 Noncurrent: Taxes refundable to customers Over plant lives 205,517 218,566 215,421 Plant removal and decommissioning costs Over plant lives 174,481 172,683 168,152 Pension and postretirement benefits ** 19,687 16,915 20,434 Accumulated deferred investment tax credit Up to 20 years 14,665 12,403 12,696 Cost recovery mechanisms Up to 20 years 12,535 — 7,727 Other Up to 16 years 6,327 5,574 4,360 433,212 426,141 428,790 Total regulatory liabilities $ 451,811 $ 442,632 $ 445,093 Net regulatory position $ 40,791 $ 69,748 $ 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)	9 Months Ended
	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Available-for-sale securities	Details of available-for-sale securities were as follows: September 30, 2022 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,486 $ — $ 783 $ 7,703 U.S. Treasury securities 2,468 — 82 2,386 Total $ 10,954 $ — $ 865 $ 10,089 September 30, 2021 Cost Gross Gross Fair Value (In thousands) Mortgage-backed securities $ 8,597 $ 93 $ 11 $ 8,679 U.S. Treasury securities 2,681 — 28 2,653 Total $ 11,278 $ 93 $ 39 $ 11,332 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 September 30, 2022, Using Quoted Prices in Significant Significant Balance at September 30, 2022 (In thousands) Assets: Money market funds $ — $ 7,309 $ — $ 7,309 Insurance contracts* — 95,170 — 95,170 Available-for-sale securities: Mortgage-backed securities — 7,703 — 7,703 U.S. Treasury securities — 2,386 — 2,386 Total assets measured at fair value $ — $ 112,568 $ — $ 112,568 * The insurance contracts invest approximately 65 percent in fixed-income investments, 14 percent in common stock of large-cap companies, 7 percent in common stock of mid-cap companies, 6 percent in common stock of small-cap companies, 6 percent in target date investments and 2 percent in cash equivalents. Fair Value Measurements at September 30, 2021, Using Quoted Prices in Significant Significant Balance at September 30, 2021 (In thousands) Assets: Money market funds $ — $ 9,907 $ — $ 9,907 Insurance contracts* — 106,371 — 106,371 Available-for-sale securities: Mortgage-backed securities — 8,679 — 8,679 U.S. Treasury securities — 2,653 — 2,653 Total assets measured at fair value $ — $ 127,610 $ — $ 127,610 * The insurance contracts invest approximately 63 percent in fixed-income investments, 16 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 1 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: September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Carrying amount $ 2,988,452 $ 2,328,266 $ 2,741,900 Fair value $ 2,647,387 $ 2,599,907 $ 2,984,866

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Long-term debt outstanding	Long-term debt outstanding was as follows: Weighted Average Interest Rate at September 30, 2022 September 30, 2022 September 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 $ 2,025,000 $ 2,125,000 Commercial paper supported by revolving credit agreements 3.66 % 460,600 168,800 450,300 Credit agreements due on June 7, 2024 4.55 % 125,580 94,300 127,500 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 3.64 % 7,000 7,700 7,700 Other notes due on dates ranging from January 1, 2024 to January 1, 2061 .97 % 2,349 3,198 2,564 Less unamortized debt issuance costs 6,633 5,709 6,090 Less discount 444 23 74 Total long-term debt 2,988,452 2,328,266 2,741,900 Less current maturities 214,453 1,548 148,053 Net long-term debt $ 2,773,999 $ 2,326,718 $ 2,593,847
Schedule of debt maturities	Long-term debt maturities, which excludes unamortized debt issuance costs and discount, at September 30, 2022, were as follows: Remainder of 2022 2023 2024 2025 2026 Thereafter (In thousands) Long-term debt maturities $ 147,253 $ 77,923 $ 646,983 $ 177,802 $ 140,802 $ 1,804,766

Cash flow information (Tables)

Cash flow information (Tables)	9 Months Ended
	Sep. 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: Nine Months Ended September 30, 2022 2021 (In thousands) Interest, net* $ 75,425 $ 59,876 Income taxes paid, net $ 17,664 $ 61,250 * AFUDC - borrowed was $2.4 million and $1.6 million for the nine months ended September 30, 2022 and 2021, respectively. Noncash investing and financing transactions were as follows: September 30, 2022 September 30, 2021 December 31, 2021 (In thousands) Right-of-use assets obtained in exchange for new operating lease liabilities $ 36,492 $ 26,120 $ 55,987 Property, plant and equipment additions in accounts payable $ 44,277 $ 88,355 $ 57,605 Debt assumed in connection with a business combination $ — $ — $ 10

Business segment data (Tables)

Business segment data (Tables)	9 Months Ended
	Sep. 30, 2022
Segment Reporting [Abstract]
Information on the Company's businesses	Information on the Company's segments was as follows: Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands) External operating revenues: Regulated operations: Electric $ 99,193 $ 98,930 $ 278,249 $ 267,254 Natural gas distribution 132,074 110,378 792,932 614,373 Pipeline 32,347 27,757 69,347 58,390 263,614 237,065 1,140,528 940,017 Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands) Non-regulated operations: Pipeline 3,698 3,211 7,630 10,263 Construction materials and contracting 975,085 831,189 1,996,533 1,730,521 Construction services 734,809 514,523 1,969,995 1,556,737 Other — 25 — 70 1,713,592 1,348,948 3,974,158 3,297,591 Total external operating revenues $ 1,977,206 $ 1,586,013 $ 5,114,686 $ 4,237,608 Intersegment operating revenues: Regulated operations: Electric $ 124 $ 136 $ 371 $ 407 Natural gas distribution 139 142 416 425 Pipeline 3,508 3,845 36,845 37,530 3,771 4,123 37,632 38,362 Non-regulated operations: Pipeline 87 63 483 470 Construction materials and contracting 343 110 674 314 Construction services 2,229 289 5,090 2,128 Other 4,438 3,398 13,168 10,082 7,097 3,860 19,415 12,994 Intersegment eliminations (10,868) (7,983) (57,047) (51,356) Total intersegment operating revenues $ — $ — $ — $ — Operating income (loss): Electric $ 30,395 $ 27,310 $ 53,764 $ 53,982 Natural gas distribution (16,688) (14,249) 38,929 42,925 Pipeline 14,963 12,284 39,447 35,896 Construction materials and contracting 147,367 133,712 157,116 171,274 Construction services 34,949 30,120 110,588 108,172 Other (1,135) (8) (2,081) (226) Total operating income $ 209,851 $ 189,169 $ 397,763 $ 412,023 Net income (loss): Regulated operations: Electric $ 21,596 $ 20,564 $ 37,476 $ 41,618 Natural gas distribution (18,058) (15,390) 10,758 20,081 Pipeline 9,379 10,225 24,527 27,508 12,917 15,399 72,761 89,207 Non-regulated operations: Pipeline 492 356 (187) 1,166 Construction materials and contracting 102,764 96,282 95,337 116,865 Construction services 27,977 23,130 83,755 81,839 Other 3,783 3,795 (1,368) 2,172 135,016 123,563 177,537 202,042 Income from continuing operations 147,933 138,962 250,298 291,249 Discontinued operations, net of tax 38 314 103 348 Net income $ 147,971 $ 139,276 $ 250,401 $ 291,597

Employee benefit plans (Tables)

Employee benefit plans (Tables)	9 Months Ended
	Sep. 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 Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands) Components of net periodic benefit credit: Interest cost $ 2,630 $ 2,455 $ 7,892 $ 7,365 Expected return on assets (4,864) (4,894) (14,592) (14,682) Amortization of net actuarial loss 1,670 2,004 5,012 6,012 Net periodic benefit credit $ (564) $ (435) $ (1,688) $ (1,305) Components of net periodic benefit credit for the Company's other postretirement benefit plans were as follows: Three Months Ended Nine Months Ended September 30, September 30, 2022 2021 2022 2021 (In thousands) Components of net periodic benefit credit: Service cost $ 354 $ 400 $ 1,062 $ 1,200 Interest cost 474 466 1,422 1,398 Expected return on assets (1,322) (1,275) (3,966) (3,825) Amortization of prior service credit (350) (349) (1,050) (1,047) Amortization of net actuarial (gain) loss (55) 6 (163) 18 Net periodic benefit credit, including amount capitalized (899) (752) (2,695) (2,256) Less amount capitalized 48 46 132 129 Net periodic benefit credit $ (947) $ (798) $ (2,827) $ (2,385)

Receivables and allowance for_4

Receivables and allowance for expected credit losses (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Credit Loss [Abstract]
Accounts Receivable, Noncurrent, 90 Days or More Past Due, Still Accruing	$ 41.5	$ 44.8	$ 37.9

Receivables and allowance for_5

Receivables and allowance for expected credit losses (Details 2) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision for credit losses							$ 3,258	$ (801)
Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	$ 9,565	$ 10,156	$ 9,716	$ 10,748	$ 12,714	$ 15,358	9,716	15,358
Provision for credit losses	1,015	509	1,735	357	(841)	(317)
Less write-offs charged against the allowance	2,448	1,385	1,627	2,152	1,424	2,669
Credit loss recoveries collected	294	285	332	353	299	342
Balance	8,426	9,565	10,156	9,306	10,748	12,714	8,426	9,306
Electric | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	348	361	269	327	678	899	269	899
Provision for credit losses	300	113	565	388	(110)	538
Less write-offs charged against the allowance	399	234	597	525	341	888
Credit loss recoveries collected	85	108	124	92	100	129
Balance	334	348	361	282	327	678	334	282
Natural gas distribution | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	1,453	2,123	1,506	2,259	2,950	2,571	1,506	2,571
Provision for credit losses	881	92	1,369	411	(103)	1,273
Less write-offs charged against the allowance	1,822	939	932	1,178	787	1,107
Credit loss recoveries collected	169	177	180	168	199	213
Balance	681	1,453	2,123	1,660	2,259	2,950	681	1,660
Pipeline | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2	2	2	2	2	2	2	2
Provision for credit losses	0	0	0	0	0	0
Less write-offs charged against the allowance	0	0	0	0	0	0
Credit loss recoveries collected	0	0	0	0	0	0
Balance	2	2	2	2	2	2	2	2
Construction materials and contracting | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	5,030	5,126	5,406	4,621	4,842	6,164	5,406	6,164
Provision for credit losses	(55)	12	(253)	233	11	(1,049)
Less write-offs charged against the allowance	75	108	27	184	232	273
Credit loss recoveries collected	0	0	0	0	0	0
Balance	4,900	5,030	5,126	4,670	4,621	4,842	4,900	4,670
Construction services | Trade Accounts Receivable
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	2,732	2,544	2,533	3,539	4,242	5,722	2,533	5,722
Provision for credit losses	(111)	292	54	(675)	(639)	(1,079)
Less write-offs charged against the allowance	152	104	71	265	64	401
Credit loss recoveries collected	40	0	28	93	0	0
Balance	$ 2,509	$ 2,732	$ 2,544	$ 2,692	$ 3,539	$ 4,242	$ 2,509	$ 2,692

Inventories and natural gas i_4

Inventories and natural gas in storage (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Inventory Disclosure [Abstract]
Aggregates held for resale	$ 198,711	$ 184,363	$ 183,693
Asphalt oil	56,609	57,002	32,964
Natural gas in storage (current)	48,532	18,867	28,683
Materials and supplies	42,359	30,629	27,253
Merchandise for resale	39,198	28,501	26,639
Other	13,233	16,247	13,053
Total	398,642	335,609	312,285
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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Weighted average common shares outstanding - basic	203,351	202,863	203,351	201,647
Effect of dilutive performance share awards and restricted stock units	293	327	56	308
Weighted average common shares outstanding - diluted	203,644	203,190	203,407	201,955
Shares excluded from the calculation of diluted earnings per share	0	0	77	0
Dividends declared per common share	$ 0.2175	$ 0.2125	$ 0.6525	$ 0.6375

Equity (Details)

Equity (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 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)	$ 88,830,000
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	1,000,000	0	2,800,000
Net proceeds *	$ 0	$ 34,200,000	$ (100,000)	$ 88,800,000
Issuance costs	$ 0	$ 425,000	$ 149,000	$ 1,200,000

Accumulated other comprehensi_3

Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Accumulated other comprehensive loss [Roll Forward]
Balance	$ 3,386,810	$ 3,360,718	$ 3,382,874	$ 3,198,802	$ 3,100,306	$ 3,079,105	$ 3,382,874	$ 3,079,105
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset	0			0			(3,265)	0
Other comprehensive income (loss)	285	(2,796)	269	543	542	568	(2,242)	1,653
Balance	3,491,858	3,386,810	3,360,718	3,332,278	3,198,802	3,100,306	3,491,858	3,332,278
Net unrealized gain (loss) on derivative instruments qualifying as hedges
Accumulated other comprehensive loss [Roll Forward]
Balance	(315)	(426)	(538)	(761)	(873)	(984)	(538)	(984)
Other comprehensive loss before reclassifications	0	0	0	0	0	0
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset		0
Amounts reclassified from accumulated other comprehensive loss	111	111	112	111	112	111
Other comprehensive income (loss)	111	111	112	111	112	111
Balance	(204)	(315)	(426)	(650)	(761)	(873)	(204)	(650)
Postretirement liability adjustment
Accumulated other comprehensive loss [Roll Forward]
Balance	(42,820)	(40,016)	(40,461)	(46,284)	(46,741)	(47,207)	(40,461)	(47,207)
Other comprehensive loss before reclassifications	0	0	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	461	445	466	457	466
Other comprehensive income (loss)	461	(2,804)	445	466	457	466
Balance	(42,359)	(42,820)	(40,016)	(45,818)	(46,284)	(46,741)	(42,359)	(45,818)
Net unrealized gain (loss) on available-for-sale investments
Accumulated other comprehensive loss [Roll Forward]
Balance	(396)	(293)	(5)	77	104	113	(5)	113
Other comprehensive loss before reclassifications	(329)	(128)	(320)	(54)	(52)	(44)
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset		0
Amounts reclassified from accumulated other comprehensive loss	42	25	32	20	25	35
Other comprehensive income (loss)	(287)	(103)	(288)	(34)	(27)	(9)
Balance	(683)	(396)	(293)	43	77	104	(683)	43
Total accumulated other comprehensive loss
Accumulated other comprehensive loss [Roll Forward]
Balance	(43,531)	(40,735)	(41,004)	(46,968)	(47,510)	(48,078)	(41,004)	(48,078)
Other comprehensive loss before reclassifications	(329)	(128)	(320)	(54)	(52)	(44)
Amounts reclassified to accumulated other comprehensive loss from a regulatory asset		(3,265)
Amounts reclassified from accumulated other comprehensive loss	614	597	589	597	594	612
Other comprehensive income (loss)	285	(2,796)	269	543	542	568
Balance	$ (43,246)	$ (43,531)	$ (40,735)	$ (46,425)	$ (46,968)	$ (47,510)	$ (43,246)	$ (46,425)

Reclassification out of accumul

Reclassification out of accumulated other comprehensive loss (Details 2) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Interest expense	$ (31,369)			$ (23,389)			$ (84,741)	$ (70,224)
Income taxes	(35,318)			(32,748)			(60,847)	(68,860)
Other income	4,769			5,930			(1,877)	18,310
Net income	147,971	$ 70,667	$ 31,763	139,276	$ 100,190	$ 52,131	250,401	291,597
Reclassification out of accumulated other comprehensive loss
Reclassification adjustment out of accumulated other comprehensive loss [Line Items]
Net income	(614)			(597)			(1,800)	(1,803)
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	(148)			(147)			(443)	(443)
Income taxes	37			36			109	109
Net income	(111)			(111)			(334)	(334)
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			151			460	462
Other income	(609)			(617)			(1,827)	(1,851)
Net income	(461)			(466)			(1,367)	(1,389)
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	12			6			27	21
Other income	(54)			(26)			(126)	(101)
Net income	$ (42)			$ (20)			$ (99)	$ (80)

Disaggregation of revenue (Deta

Disaggregation of revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Operating revenues:	$ 1,977,206	$ 1,586,013	$ 5,114,686	$ 4,237,608
Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(10,868)	(7,983)	(57,047)	(51,356)
Intrasegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(259,761)	(201,630)	(475,026)	(394,126)
Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	44,054	39,870	131,432	120,875
Natural gas storage
Disaggregation of Revenue [Line Items]
Operating revenues:	3,595	3,483	10,210	10,606
Contracting services
Disaggregation of Revenue [Line Items]
Operating revenues:	492,207	415,106	937,156	791,964
Construction materials
Disaggregation of Revenue [Line Items]
Operating revenues:	742,982	617,823	1,535,077	1,332,997
Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	543,717	317,238	1,443,758	1,020,130
Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	181,550	185,842	496,190	502,328
Other
Disaggregation of Revenue [Line Items]
Operating revenues:	22,705	21,487	65,306	60,820
Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	1,963,804	1,575,186	5,085,381	4,200,691
Other revenues
Disaggregation of Revenue [Line Items]
Operating revenues:	13,402	10,827	29,305	36,917
Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	101,055	91,696	543,287	441,007
Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	82,519	74,371	388,097	308,797
Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	18,047	15,890	61,309	51,265
Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	2,002	1,993	5,632	5,384
Electric
Disaggregation of Revenue [Line Items]
Operating revenues:	99,193	98,930	278,249	267,254
Electric | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(124)	(136)	(371)	(407)
Electric | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	10,758	12,589	33,727	31,827
Electric | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	99,240	100,386	283,103	272,583
Electric | Other revenues
Disaggregation of Revenue [Line Items]
Operating revenues:	(47)	(1,456)	(4,854)	(5,329)
Electric | Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	36,981	36,412	103,648	99,106
Electric | Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	38,785	39,033	108,400	105,795
Electric | Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	10,838	10,495	32,067	30,878
Electric | Other utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	2,002	1,993	5,632	5,384
Natural gas distribution
Disaggregation of Revenue [Line Items]
Operating revenues:	132,074	110,378	792,932	614,373
Natural gas distribution | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(139)	(142)	(416)	(425)
Natural gas distribution | Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	11,910	11,812	35,747	35,715
Natural gas distribution | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	3,494	2,110	9,854	7,913
Natural gas distribution | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	130,282	109,797	793,763	608,493
Natural gas distribution | Other revenues
Disaggregation of Revenue [Line Items]
Operating revenues:	1,792	581	(831)	5,880
Natural gas distribution | Residential utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	64,074	55,284	439,639	341,901
Natural gas distribution | Commercial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	43,734	35,338	279,697	203,002
Natural gas distribution | Industrial utility sales
Disaggregation of Revenue [Line Items]
Operating revenues:	7,209	5,395	29,242	20,387
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:	36,045	30,968	76,977	68,653
Pipeline | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(3,595)	(3,908)	(37,328)	(38,000)
Pipeline | Natural gas transportation
Disaggregation of Revenue [Line Items]
Operating revenues:	32,144	28,058	95,685	85,160
Pipeline | Natural gas storage
Disaggregation of Revenue [Line Items]
Operating revenues:	3,595	3,483	10,210	10,606
Pipeline | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	3,815	3,290	8,200	10,760
Pipeline | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	35,959	30,923	76,767	68,526
Pipeline | Other revenues
Disaggregation of Revenue [Line Items]
Operating revenues:	86	45	210	127
Construction materials and contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	975,085	831,189	1,996,533	1,730,521
Construction materials and contracting | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(343)	(110)	(674)	(314)
Construction materials and contracting | Intrasegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(259,761)	(201,630)	(475,026)	(394,126)
Construction materials and contracting | Contracting services
Disaggregation of Revenue [Line Items]
Operating revenues:	492,207	415,106	937,156	791,964
Construction materials and contracting | Construction materials
Disaggregation of Revenue [Line Items]
Operating revenues:	742,982	617,823	1,535,077	1,332,997
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:	975,085	831,189	1,996,533	1,730,521
Construction materials and contracting | Other revenues
Disaggregation of Revenue [Line Items]
Operating revenues:	0	0	0	0
Construction services
Disaggregation of Revenue [Line Items]
Operating revenues:	734,809	514,523	1,969,995	1,556,737
Construction services | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(2,229)	(289)	(5,090)	(2,128)
Construction services | Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	543,717	317,238	1,443,758	1,020,130
Construction services | Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Operating revenues:	181,550	185,842	496,190	502,328
Construction services | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	200	75	357	168
Construction services | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	723,238	502,866	1,935,215	1,520,498
Construction services | Other revenues
Disaggregation of Revenue [Line Items]
Operating revenues:	11,571	11,657	34,780	36,239
Other
Disaggregation of Revenue [Line Items]
Operating revenues:	0	25	0	70
Other | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Operating revenues:	(4,438)	(3,398)	(13,168)	(10,082)
Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues:	4,438	3,423	13,168	10,152
Other | Revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Operating revenues:	0	25	0	70
Other | Other revenues
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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Contract assets	$ 265,585		$ 265,585		$ 125,742
Change in contract assets			139,843
Contract liabilities - current	(216,439)		(216,439)		(179,140)
Change in contract liabilities - current			(37,299)
Contract liabilities - noncurrent	(12)		(12)		(118)
Change in contract liabilities - noncurrent			106
Net contract assets (liabilities)	49,134		49,134		$ (53,516)
Change in net contract assets (liabilities)			102,650
Amounts included in contract liability at the beginning of the period	11,200	$ 7,100	147,900	$ 152,400
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 14,500	$ 19,200	$ 54,100	$ 63,300

Revenue from contracts with c_4

Revenue from contracts with customers Remaining performance obligations (Details 3) $ in Millions	Sep. 30, 2022 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 3,300
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2,600
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 369.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	13 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 418.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	25 months

Business Combinations (Details)

Business Combinations (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill	$ 763,262,000	$ 765,386,000	$ 717,646,000	$ 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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Leases [Abstract]
Operating Lease, Lease Income	$ 11.7	$ 11.8	$ 35.1	$ 36.6
Lessor, Operating Lease, Payments to be Received, Next Twelve Months	$ 9.1		$ 9.1

Goodwill rollforward (Details)

Goodwill rollforward (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 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)	(217)	(217)
Balance at end of period	763,262	717,646	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)	(217)	(217)
Balance at end of period	274,302	228,686	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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net (excluding goodwill)	$ 18,745	$ 22,241	$ 18,745	$ 22,241	$ 22,578
Amortization of intangible assets	1,300	1,200	3,800	3,900
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	12,768	9,705	12,768	9,705	10,650
Intangible assets, net (excluding goodwill)	16,222	19,718	16,222	19,718	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	3,377	2,710	3,377	2,710	2,856
Intangible assets, net (excluding goodwill)	1,214	1,281	1,214	1,281	1,735
Other intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	5,279	11,957	5,279	11,957	12,601
Intangible assets, less accumulated amortization	3,970	10,715	3,970	10,715	10,848
Intangible assets, net (excluding goodwill)	$ 1,309	$ 1,242	$ 1,309	$ 1,242	$ 1,753

Future amortization expense (De

Future amortization expense (Details 3) $ in Thousands	Sep. 30, 2022 USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2022	$ 1,159
2023	4,591
2024	4,249
2025	2,200
2026	1,781
Thereafter	$ 4,765

Regulatory assets (Details)

Regulatory assets (Details) - USD ($)		9 Months Ended
	Oct. 19, 2022	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Feb. 28, 2021
Regulatory Assets
Regulatory Assets, Current		$ 148,160,000	$ 118,691,000	$ 133,135,000
Regulatory Assets, Noncurrent		344,442,000	357,851,000	379,245,000
Total regulatory assets		492,602,000	476,542,000	512,380,000
Regulatory assets not earning a rate of return		264,400,000	296,600,000	318,200,000
Gas Distribution [Member] | MNPUC [Member] | Subsequent Event [Member] | Great Plains Natural Gas Co. [Member]
Regulatory Assets
Disallowed Gas Costs	$ (845,000)
Natural gas costs recoverable through rate adjustments
Regulatory Assets
Regulatory Assets, Current		112,079,000	86,371,000	98,211,000
Regulatory Assets, Noncurrent		$ 462,000	5,186,000	6,084,000
Total regulatory assets					$ 44,000,000
Natural gas costs recoverable through rate adjustments | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Natural gas costs recoverable through rate adjustments | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 2 years
Conservation programs
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Regulatory Assets, Current		$ 9,363,000	8,225,000	8,495,000
Decoupling
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Regulatory Assets, Current		$ 6,549,000	9,131,000	7,195,000
Cost recovery mechanisms
Regulatory Assets
Regulatory Assets, Current		3,354,000	4,536,000	4,693,000
Regulatory Assets, Noncurrent		$ 67,094,000	44,870,000	43,955,000
Cost recovery mechanisms | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Cost recovery mechanisms | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 10 years
Other regulatory assets
Regulatory Assets
Regulatory Assets, Current		$ 16,815,000	10,428,000	14,541,000
Regulatory Assets, Noncurrent		$ 10,931,000	9,742,000	9,856,000
Other regulatory assets | Minimum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 1 year
Other regulatory assets | Maximum [Member]
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 17 years
Pension and postretirement benefits
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		**
Regulatory Assets, Noncurrent		$ 137,582,000	142,681,000	155,888,000
Plant costs/asset retirement obligations
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Over plant lives
Regulatory Assets, Noncurrent		$ 61,941,000	63,116,000	73,528,000
Plant to be retired
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		-
Regulatory Assets, Noncurrent		$ 24,740,000	50,070,000	48,544,000
Manufactured gas plant site remediation
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		-
Regulatory Assets, Noncurrent		$ 25,963,000	26,053,000	26,000,000
Taxes recoverable from customers
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Over plant lives
Regulatory Assets, Noncurrent		$ 12,394,000	12,339,000	11,438,000
Long-term debt refinancing costs
Regulatory Assets
Estimated Recovery or Refund Period as of September 30, 2022		Up to 38 years
Regulatory Assets, Noncurrent		$ 3,335,000	$ 3,794,000	$ 3,952,000

Regulatory liabilities (Details

Regulatory liabilities (Details 2) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	$ 18,599	$ 16,303	$ 16,491
Regulatory liabilities	433,212	428,790	426,141
Total regulatory liabilities	451,811	445,093	442,632
Net regulatory position	40,791	31,449	69,748
Taxes refundable to customers
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	4,264	3,841	3,867
Regulatory liabilities	$ 205,517	215,421	218,566
Taxes refundable to customers | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Up to 1 year
Taxes refundable to customers | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Over plant lives
Electric fuel and purchased power deferral
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Up to 1 year
Regulatory liabilities due within one year	$ 3,763	0	3,205
Cost Recovery Mechanisms
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	2,674	214	2,797
Regulatory liabilities	$ 12,535	7,727	0
Cost Recovery Mechanisms | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Up to 1 year
Cost Recovery Mechanisms | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Up to 20 years
Natural gas costs refundable through rate adjustments
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Up to 1 year
Regulatory liabilities due within one year	$ 873	6,700	0
Other regulatory liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities due within one year	7,025	5,548	6,622
Regulatory liabilities	$ 6,327	4,360	5,574
Other regulatory liabilities | Minimum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Up to 1 year
Other regulatory liabilities | Maximum [Member]
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Up to 16 years
Plant removal and decommissioning costs
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Over plant lives
Regulatory liabilities	$ 174,481	168,152	172,683
Pension and postretirement benefits
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	**
Regulatory liabilities	$ 19,687	20,434	16,915
Accumulated Deferred ITC
Regulatory Liabilities [Line Items]
Estimated Recovery or Refund Period as of September 30, 2022	Up to 20 years
Regulatory liabilities	$ 14,665	$ 12,696	$ 12,403

Fair value measurements Insuran

Fair value measurements Insurance contracts (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Investments used to satisfy nonqualified benefit plans obligations	$ 95,200,000	$ 106,400,000	$ 95,200,000	$ 106,400,000	$ 109,600,000
Net unrealized gain (loss) on investments used to satisfy obligations under nonqualified benefit plans	$ 2,600,000	$ 373,000	$ 16,800,000	$ 4,200,000

Available-for-sale securities (

Available-for-sale securities (Details 2) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Available-for-sale securities [Abstract]
Cost	$ 10,954	$ 11,109	$ 11,278
Gross Unrealized Gains	0	51	93
Gross Unrealized Losses	865	58	39
Fair Value	10,089	11,102	11,332
Mortgage-backed securities
Available-for-sale securities [Abstract]
Cost	8,486	8,702	8,597
Gross Unrealized Gains	0	51	93
Gross Unrealized Losses	783	47	11
Fair Value	7,703	8,706	8,679
U.S. Treasury securities
Available-for-sale securities [Abstract]
Cost	2,468	2,407	2,681
Gross Unrealized Gains	0	0	0
Gross Unrealized Losses	82	11	28
Fair Value	$ 2,386	$ 2,396	$ 2,653

Fair value measurements (Detail

Fair value measurements (Details 3) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Concentration risks, percentage [Abstract]
Percentage in fixed-income and other investments	65%	61%	63%
Percentage investment in common stock of large-cap companies	14%	17%	16%
Percentage investment in common stock of mid-cap companies	7%	8%	8%
Percentage investment in common stock of small-cap companies	6%	7%	7%
Percentage investment in target date investments	6%	5%	5%
Percentage investment in cash and cash equivalents	2%	2%	1%
Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 112,568	$ 130,895	$ 127,610
Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	112,568	130,895	127,610
Money market funds | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,309	10,190	9,907
Money market funds | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,309	10,190	9,907
Insurance contracts* | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	95,170	109,603	106,371
Insurance contracts* | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	95,170	109,603	106,371
Mortgage-backed securities | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,703	8,706	8,679
Mortgage-backed securities | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	7,703	8,706	8,679
U.S. Treasury securities | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	2,386	2,396	2,653
U.S. Treasury securities | Fair value, inputs, level 2 | Fair value, measurements, recurring
Fair value measurements [Line Items]
Assets, fair value disclosure	$ 2,386	$ 2,396	$ 2,653

Fair value measurements (Deta_2

Fair value measurements (Details 4) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Fair value, balance sheet grouping [Line Items]
Long-term debt	$ 2,988,452	$ 2,741,900	$ 2,328,266
Carrying amount
Fair value, balance sheet grouping [Line Items]
Long-term debt	2,988,452	2,741,900	2,328,266
Fair value
Fair value, balance sheet grouping [Line Items]
Long-term debt, fair value	$ 2,647,387	$ 2,984,866	$ 2,599,907

Short-term Debt (Details 1)

Short-term Debt (Details 1) - USD ($) $ in Thousands	Sep. 30, 2022	Mar. 18, 2022	Dec. 31, 2021	Sep. 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	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Long-term debt outstanding [Line Items]
Long-term debt	$ 2,988,452	$ 2,741,900	$ 2,328,266
Long-term debt due within one year	214,453	148,053	1,548
Long-term debt	$ 2,773,999	2,593,847	2,326,718
Senior Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	4.29%
Long-term debt	$ 2,365,000	2,125,000	2,025,000
Commercial Paper
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	3.66%
Long-term debt	$ 460,600	450,300	168,800
Credit Agreements
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	4.55%
Long-term debt	$ 125,580	127,500	94,300
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	3.64%
Long-term debt	$ 7,000	7,700	7,700
Other Notes
Long-term debt outstanding [Line Items]
Weighted Average Interest Rate	0.97%
Long-term debt	$ 2,349	2,564	3,198
Long-term Debt
Long-term debt outstanding [Line Items]
Unamortized Debt Issuance Costs	6,633	6,090	5,709
Discount	$ 444	$ 74	$ 23

Schedule of debt maturities (De

Schedule of debt maturities (Details 3) $ in Thousands	Sep. 30, 2022 USD ($)
Long-term debt maturities [Line Items]
Remainder of 2022	$ 147,253
2023	77,923
2024	646,983
2025	177,802
2026	140,802
Thereafter	$ 1,804,766

Cash flow information (Details)

Cash flow information (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Supplemental Cash Flow Information [Abstract]
Interest, net*	$ 75,425	$ 59,876
Income taxes paid, net	17,664	61,250
AFUDC borrowed	2,400	1,600
Right-of-use assets obtained in exchange for new operating lease liabilities	36,492	26,120	$ 55,987
Property, plant and equipment additions in accounts payable	44,277	88,355	57,605
Debt assumed in connection with a business combination	$ 0	$ 0	$ 10

Business segment data (Details)

Business segment data (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 1,977,206			$ 1,586,013			$ 5,114,686	$ 4,237,608
Operating income	209,851			189,169			397,763	412,023
Income from continuing operations	147,933			138,962			250,298	291,249
Discontinued operations, net of tax	38			314			103	348
Net income	147,971	$ 70,667	$ 31,763	139,276	$ 100,190	$ 52,131	250,401	291,597
Electric
Segment Reporting Information [Line Items]
Revenues	99,193			98,930			278,249	267,254
Operating income	30,395			27,310			53,764	53,982
Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	132,074			110,378			792,932	614,373
Operating income	(16,688)			(14,249)			38,929	42,925
Pipeline
Segment Reporting Information [Line Items]
Revenues	36,045			30,968			76,977	68,653
Operating income	14,963			12,284			39,447	35,896
Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	975,085			831,189			1,996,533	1,730,521
Operating income	147,367			133,712			157,116	171,274
Construction services
Segment Reporting Information [Line Items]
Revenues	734,809			514,523			1,969,995	1,556,737
Operating income	34,949			30,120			110,588	108,172
Other
Segment Reporting Information [Line Items]
Revenues	0			25			0	70
Operating income	(1,135)			(8)			(2,081)	(226)
Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	(10,868)			(7,983)			(57,047)	(51,356)
Intersegment eliminations | Electric
Segment Reporting Information [Line Items]
Revenues	(124)			(136)			(371)	(407)
Intersegment eliminations | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	(139)			(142)			(416)	(425)
Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	(3,595)			(3,908)			(37,328)	(38,000)
Intersegment eliminations | Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	(343)			(110)			(674)	(314)
Intersegment eliminations | Construction services
Segment Reporting Information [Line Items]
Revenues	(2,229)			(289)			(5,090)	(2,128)
Intersegment eliminations | Other
Segment Reporting Information [Line Items]
Revenues	(4,438)			(3,398)			(13,168)	(10,082)
Total intersegment operating revenues
Segment Reporting Information [Line Items]
Revenues	0			0			0	0
Regulated operation
Segment Reporting Information [Line Items]
Revenues	263,614			237,065			1,140,528	940,017
Income from continuing operations	12,917			15,399			72,761	89,207
Regulated operation | Electric
Segment Reporting Information [Line Items]
Revenues	99,193			98,930			278,249	267,254
Income from continuing operations	21,596			20,564			37,476	41,618
Regulated operation | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	132,074			110,378			792,932	614,373
Income from continuing operations	(18,058)			(15,390)			10,758	20,081
Regulated operation | Pipeline
Segment Reporting Information [Line Items]
Revenues	32,347			27,757			69,347	58,390
Income from continuing operations	9,379			10,225			24,527	27,508
Regulated operation | Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	3,771			4,123			37,632	38,362
Regulated operation | Intersegment eliminations | Electric
Segment Reporting Information [Line Items]
Revenues	124			136			371	407
Regulated operation | Intersegment eliminations | Natural gas distribution
Segment Reporting Information [Line Items]
Revenues	139			142			416	425
Regulated operation | Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	3,508			3,845			36,845	37,530
Nonregulated operation
Segment Reporting Information [Line Items]
Revenues	1,713,592			1,348,948			3,974,158	3,297,591
Income from continuing operations	135,016			123,563			177,537	202,042
Nonregulated operation | Pipeline
Segment Reporting Information [Line Items]
Revenues	3,698			3,211			7,630	10,263
Income from continuing operations	492			356			(187)	1,166
Nonregulated operation | Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	975,085			831,189			1,996,533	1,730,521
Income from continuing operations	102,764			96,282			95,337	116,865
Nonregulated operation | Construction services
Segment Reporting Information [Line Items]
Revenues	734,809			514,523			1,969,995	1,556,737
Income from continuing operations	27,977			23,130			83,755	81,839
Nonregulated operation | Other
Segment Reporting Information [Line Items]
Revenues	0			25			0	70
Income from continuing operations	3,783			3,795			(1,368)	2,172
Nonregulated operation | Intersegment eliminations
Segment Reporting Information [Line Items]
Revenues	7,097			3,860			19,415	12,994
Nonregulated operation | Intersegment eliminations | Pipeline
Segment Reporting Information [Line Items]
Revenues	87			63			483	470
Nonregulated operation | Intersegment eliminations | Construction materials and contracting
Segment Reporting Information [Line Items]
Revenues	343			110			674	314
Nonregulated operation | Intersegment eliminations | Construction services
Segment Reporting Information [Line Items]
Revenues	2,229			289			5,090	2,128
Nonregulated operation | Intersegment eliminations | Other
Segment Reporting Information [Line Items]
Revenues	$ 4,438			$ 3,398			$ 13,168	$ 10,082

Employee benefit plans (Details

Employee benefit plans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Qualified plan | Underfunded plan | Pension benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Interest cost	$ 2,630,000	$ 2,455,000	$ 7,892,000	$ 7,365,000
Expected return on assets	(4,864,000)	(4,894,000)	(14,592,000)	(14,682,000)
Amortization of net actuarial (gain) loss	1,670,000	2,004,000	5,012,000	6,012,000
Net periodic benefit cost (credit)	(564,000)	(435,000)	(1,688,000)	(1,305,000)
Qualified plan | Overfunded Plan | Other postretirement benefits
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Service cost	354,000	400,000	1,062,000	1,200,000
Interest cost	474,000	466,000	1,422,000	1,398,000
Expected return on assets	(1,322,000)	(1,275,000)	(3,966,000)	(3,825,000)
Amortization of prior service credit	(350,000)	(349,000)	(1,050,000)	(1,047,000)
Amortization of net actuarial (gain) loss	(55,000)	6,000	(163,000)	18,000
Net periodic benefit credit, including amount capitalized	(899,000)	(752,000)	(2,695,000)	(2,256,000)
Less amount capitalized	48,000	46,000	132,000	129,000
Net periodic benefit cost (credit)	(947,000)	(798,000)	(2,827,000)	(2,385,000)
Nonqualified plan | Unfunded plan | Supplemental employee retirement plans
Defined benefit plan disclosure, net periodic benefit cost [Line Items]
Net periodic benefit cost (credit)	$ 773,000	$ 769,000	$ 2,300,000	$ 2,300,000

MNPUC (Details)

MNPUC (Details) - MNPUC [Member] - Gas Distribution [Member] - Great Plains Natural Gas Co. [Member] - USD ($)	Oct. 19, 2022	Jun. 01, 2022	Sep. 01, 2021
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount			$ 8,800,000
Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Depreciation and Amortization Requested Rate Increase (Decrease), Amount		$ (1,200,000)
Depreciation and Amortization, Rate, Percent		4.50%
Depreciation and Amortization, Requested Rate, Percent		2.80%
Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Disallowed Gas Costs	$ (845,000)

NDPSC (Details 2)

NDPSC (Details 2) - Electric - NDPSC [Member] - Montana-Dakota Utilities Co. [Member] - USD ($)	Nov. 01, 2022	Jul. 14, 2022	May 16, 2022
Public Utilities, General Disclosures [Line Items]
Public Utilities, Interim Rate Increase (Decrease), Amount		$ 10,900,000
Public Utilities, Interim Rate Increase (Decrease), Percentage		5.30%
Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Total Transmission Cost Adjustment Rider	$ 12,900,000
Public Utilities, Approved Rate Increase (Decrease), Amount	(1,600,000)
Pending Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 25,400,000
Public Utilities, Requested Rate Increase (Decrease), Percentage			12.30%
Pending Rate Case [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount	(127,000)
Renewable Resource Cost Adjustment Rate Tariff	$ 17,900,000

WUTC (Details 3)

WUTC (Details 3) - WUTC [Member] - Cascade Natural Gas [Member] - USD ($) $ in Millions	Nov. 01, 2022	Sep. 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					$ 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%
Public Utilities, Approved Rate Increase (Decrease), Amount		$ 7.2
Pipeline Cost Recovery Mechanism | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 1.2
Public Utilities, Approved Rate Increase (Decrease), Percentage	0.40%
Pending Rate Case [Member] | Gas Distribution [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount			$ 3.3

FERC (Details 4)

FERC (Details 4) $ in Millions	Jan. 01, 2023 USD ($)
Electric | FERC [Member] | Montana-Dakota Utilities Co. [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Transmission Formula Revenue Requirement	$ 15.4

Litigation (Details)

Litigation (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Loss Contingencies [Line Items]
Potential liabilities related to litigation and environmental matters	$ 33.6	$ 37	$ 34.7
Insurance Receivable	11.9	14.1	11.7
Regulatory Assets	$ 20.5	$ 21.2	$ 21.1

Guarantees (Details 2)

Guarantees (Details 2)	Sep. 30, 2022 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 333,700,000
Fixed maximum amounts guaranteed by year 2022	10,800,000
Fixed maximum amounts guaranteed by year 2023	68,600,000
Fixed maximum amounts guaranteed by year 2024	110,600,000
Fixed maximum amounts guaranteed by year 2025	130,500,000
Fixed maximum amounts guaranteed by year 2026	1,300,000
Fixed maximum amounts guaranteed, thereafter	700,000
No scheduled maturity date	11,200,000
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit	25,000,000
Letters of credit set to expire - 2022	21,800,000
Letters of credit set to expire - 2023	2,700,000
Letters of credit set to expire - 2024	500,000
Outstanding letters of credit	0
Amount of surety bonds outstanding	$ 932,400,000

Variable interest entities (Det

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