Otter Tail (OTTR) 10-Q 2 Nov 22 2022 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2022	Oct. 25, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity File Number	0-53713
Entity Registrant Name	OTTER TAIL CORPORATION
Entity Incorporation, State or Country Code	MN
Entity Tax Identification Number	27-0383995
Entity Address, Address Line One	215 South Cascade Street
Entity Address, Address Line Two	Box 496
Entity Address, City or Town	Fergus Falls
Entity Address, State or Province	MN
Entity Address, Postal Zip Code	56538-0496
City Area Code	866
Local Phone Number	410-8780
Title of 12(b) Security	Common Shares, par value $5.00 per share
Trading Symbol	OTTR
Security Exchange Name	NASDAQ
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		41,630,952
Entity Central Index Key	0001466593
Amendment Flag	false
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2022
Current Fiscal Year End Date	--12-31

CONSOLIDATED BALANCE SHEETS (un

CONSOLIDATED BALANCE SHEETS (unaudited) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current Assets
Cash and Cash Equivalents	$ 72,987	$ 1,537
Receivables, net of allowance for credit losses	193,797	174,953
Inventories	146,376	148,490
Regulatory Assets	29,921	27,342
Other Current Assets	17,412	17,032
Total Current Assets	460,493	369,354
Noncurrent Assets
Investments	52,966	56,690
Property, Plant and Equipment, net of accumulated depreciation	2,186,643	2,124,605
Regulatory Assets	116,593	125,508
Intangible Assets, net of accumulated amortization	8,218	9,044
Goodwill	37,572	37,572
Other Noncurrent Assets	35,419	32,057
Total Noncurrent Assets	2,437,411	2,385,476
Total Assets	2,897,904	2,754,830
Current Liabilities
Short-Term Debt	0	91,163
Current Maturities of Long-Term Debt	0	29,983
Accounts Payable	121,995	135,089
Accrued Salaries and Wages	27,454	31,704
Accrued Taxes	25,635	19,245
Regulatory Liabilities	21,114	24,844
Other Current Liabilities	45,655	55,671
Total Current Liabilities	241,853	387,699
Noncurrent Liabilities
Pension Benefit Liability	50,489	73,973
Other Postretirement Benefits Liability	67,352	66,481
Regulatory Liabilities	240,545	234,430
Deferred Income Taxes	212,838	188,268
Deferred Tax Credits	16,102	16,661
Other Noncurrent Liabilities	60,942	62,527
Total Noncurrent Liabilities	648,268	642,340
Commitments and Contingencies (Note 9)
Capitalization
Long-Term Debt, net of current maturities	823,760	734,014
Shareholders' Equity
Common Shares: 50,000,000 shares authorized, $5 par value; 41,630,952 and 41,551,524 outstanding at September 30, 2022 and December 31, 2021	208,155	207,758
Additional Paid-In Capital	422,448	419,760
Retained Earnings	560,398	369,783
Accumulated Other Comprehensive Loss	(6,978)	(6,524)
Total Shareholders' Equity	1,184,023	990,777
Total Capitalization	2,007,783	1,724,791
Total Liabilities and Shareholders' Equity	$ 2,897,904	$ 2,754,830

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (unaudited) (Parentheticals) - $ / shares	Sep. 30, 2022	Dec. 31, 2021
Shareholders' Equity
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, shares outstanding (in shares)	41,630,952	41,551,524

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (unaudited) - 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
Total Operating Revenues	$ 383,856	$ 316,294	$ 1,158,800	$ 863,612
Operating Expenses
Electric Production Fuel	24,972	17,698	54,538	44,576
Electric Purchased Power	19,913	9,878	64,604	40,273
Electric Operating and Maintenance Expenses	39,799	36,465	126,460	114,615
Cost of Products Sold (excluding depreciation)	139,361	134,212	443,586	358,767
Other Nonelectric Expenses	16,524	16,224	50,981	45,587
Depreciation and Amortization	22,716	22,815	69,829	68,109
Electric Property Taxes	4,438	4,474	13,304	13,136
Total Operating Expenses	267,723	241,766	823,302	685,063
Operating Income	116,133	74,528	335,498	178,549
Other Income and Expense
Interest Charges	9,259	9,648	27,198	28,601
Nonservice Cost Components of Postretirement Benefits	(52)	505	(824)	1,511
Other Income (Expense), net	(174)	203	(802)	2,095
Income Before Income Taxes	106,752	64,578	308,322	150,532
Income Tax Expense	22,513	11,824	66,143	25,380
Net Income	$ 84,239	$ 52,754	$ 242,179	$ 125,152
Weighted-Average Common Shares Outstanding:
Basic (in shares)	41,600	41,504	41,582	41,487
Diluted (in shares)	41,974	41,869	41,930	41,795
Earnings Per Share:
Basic (in dollars per share)	$ 2.02	$ 1.27	$ 5.82	$ 3.02
Diluted (in dollars per share)	$ 2.01	$ 1.26	$ 5.78	$ 2.99
Electric
Operating Revenues
Total Operating Revenues	$ 142,747	$ 118,775	$ 404,112	$ 348,629
Product Sales
Operating Revenues
Total Operating Revenues	$ 241,109	$ 197,519	$ 754,688	$ 514,983

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net Income	$ 84,239	$ 52,754	$ 242,179	$ 125,152
Other Comprehensive Income (Loss):
Unrealized Loss on Available-for-Sale Securities, net of tax benefit of $46, $7, $127, and $27	(171)	(26)	(476)	(101)
Pension and Other Postretirement Benefits, net of tax expense of $(37), $(51), $(8), and $(154)	106	146	22	437
Total Other Comprehensive Income (Loss)	(65)	120	(454)	336
Total Comprehensive Income	$ 84,174	$ 52,874	$ 241,725	$ 125,488

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Unrealized Gain (Loss) on Available-for-Sale Securities, tax benefit	$ 46	$ 7	$ 127	$ 27
Pension and Other Postretirement Benefit Plan, tax benefit (expense)	$ (37)	$ (51)	$ (8)	$ (154)

CONSOLIDATED STATEMENTS OF SHAR

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Common Shares	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance, shares (in shares) at Dec. 31, 2020		41,469,879
Beginning balance at Dec. 31, 2020	$ 870,966	$ 207,349	$ 414,246	$ 257,878	$ (8,507)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes (in shares)		70,105
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	(1,614)	$ 351	(1,965)
Stock Issued Under Dividend Reinvestment and Stock Purchase Plans, net of expenses and repurchased shares	(67)		(67)
Net Income	125,152			125,152
Other Comprehensive Income (Loss)	336				336
Stock Compensation Expense	6,354		6,354
Common Dividends	(48,645)			(48,645)
Ending balance, shares (in shares) at Sep. 30, 2021		41,539,984
Ending balance at Sep. 30, 2021	952,482	$ 207,700	418,568	334,385	(8,171)
Beginning balance, shares (in shares) at Jun. 30, 2021		41,538,709
Beginning balance at Jun. 30, 2021	915,123	$ 207,694	417,870	297,850	(8,291)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes (in shares)		1,275
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	(126)	$ 6	(132)
Net Income	52,754			52,754
Other Comprehensive Income (Loss)	120				120
Stock Compensation Expense	830		830
Common Dividends	(16,219)			(16,219)
Ending balance, shares (in shares) at Sep. 30, 2021		41,539,984
Ending balance at Sep. 30, 2021	$ 952,482	$ 207,700	418,568	334,385	(8,171)
Beginning balance, shares (in shares) at Dec. 31, 2021	41,551,524	41,551,524
Beginning balance at Dec. 31, 2021	$ 990,777	$ 207,758	419,760	369,783	(6,524)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes (in shares)		79,428
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	(2,924)	$ 397	(3,321)
Stock Issued Under Dividend Reinvestment and Stock Purchase Plans, net of expenses and repurchased shares	(132)		(132)
Net Income	242,179			242,179
Other Comprehensive Income (Loss)	(454)				(454)
Stock Compensation Expense	6,141		6,141
Common Dividends	$ (51,564)			(51,564)
Ending balance, shares (in shares) at Sep. 30, 2022	41,630,952	41,630,952
Ending balance at Sep. 30, 2022	$ 1,184,023	$ 208,155	422,448	560,398	(6,978)
Beginning balance, shares (in shares) at Jun. 30, 2022		41,630,799
Beginning balance at Jun. 30, 2022	1,116,543	$ 208,154	421,951	493,351	(6,913)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes (in shares)		153
Stock Issued Under Share-Based Compensation Plans, net of shares withheld for employee taxes	0	$ 1	(1)
Stock Issued Under Dividend Reinvestment and Stock Purchase Plans, net of expenses and repurchased shares	(132)		(132)
Net Income	84,239			84,239
Other Comprehensive Income (Loss)	(65)				(65)
Stock Compensation Expense	630		630
Common Dividends	$ (17,192)			(17,192)
Ending balance, shares (in shares) at Sep. 30, 2022	41,630,952	41,630,952
Ending balance at Sep. 30, 2022	$ 1,184,023	$ 208,155	$ 422,448	$ 560,398	$ (6,978)

CONSOLIDATED STATEMENTS OF SH_2

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (unaudited) (Parentheticals) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Stockholders' Equity [Abstract]
Common Dividends (in dollars per share)	$ 0.4125	$ 0.39	$ 1.2375	$ 1.17

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Operating Activities
Net Income	$ 242,179	$ 125,152
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Depreciation and Amortization	69,829	68,109
Deferred Tax Credits	(558)	(558)
Deferred Income Taxes	23,648	18,835
Discretionary Contribution to Pension Plan	(20,000)	(10,000)
Allowance for Equity Funds Used During Construction	(938)	(427)
Stock Compensation Expense	6,141	6,354
Other, Net	5,477	(2,747)
Changes in Operating Assets and Liabilities:
Receivables	(18,845)	(64,800)
Inventories	3,632	(22,450)
Regulatory Assets	170	5,301
Other Assets	1,789	(18,708)
Accounts Payable	(10,681)	30,921
Accrued and Other Liabilities	(13,970)	12,027
Regulatory Liabilities	(1,208)	2,350
Pension and Other Postretirement Benefits	1,308	5,393
Net Cash Provided by Operating Activities	287,973	154,752
Investing Activities
Capital Expenditures	(123,227)	(117,312)
Proceeds from Disposal of Noncurrent Assets	3,803	5,819
Cash Used for Investments and Other Assets	(8,132)	(5,591)
Net Cash Used in Investing Activities	(127,556)	(117,084)
Financing Activities
Net Borrowings (Repayments) on Short-Term Debt	(91,163)	16,860
Proceeds from Issuance of Long-Term Debt	90,000	0
Payments for Retirement of Long-Term Debt	(30,000)	(169)
Dividends Paid	(51,564)	(48,645)
Payments for Shares Withheld for Employee Tax Obligations	(2,942)	(1,633)
Other, net	(3,298)	(3,972)
Net Cash Used in Financing Activities	(88,967)	(37,559)
Net Change in Cash and Cash Equivalents	71,450	109
Cash and Cash Equivalents at Beginning of Period	1,537	1,163
Cash and Cash Equivalents at End of Period	$ 72,987	$ 1,272

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Overview Otter Tail Corporation (OTC) and its subsidiaries (collectively, the "Company", "us", "our" or "we") form a diverse, multi-platform business consisting of a vertically integrated, regulated utility with generation, transmission and distribution facilities complemented by manufacturing businesses providing metal fabrication for custom machine parts and metal components, manufacturing of extruded and thermoformed plastic products, and manufacturing of polyvinyl chloride (PVC) pipe products. We classify our business into three segments: Electric, Manufacturing and Plastics. Basis of Presentation The unaudited consolidated financial statements included herein have been prepared pursuant to the rules and regulations of the SEC for interim reporting. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles. In the opinion of management, we have included all adjustments, including normal recurring accruals, necessary for a fair presentation of the consolidated financial statements for the periods presented. The consolidated financial statements and condensed notes thereto should be read in conjunction with the consolidated financial statements and notes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021. Because of the seasonality of our businesses and other factors, the earnings for the three and nine months ended September 30, 2022 should not be taken as an indication of earnings for all or any part of the balance of the current year or as an indication of earnings for future years. Use of Estimates We use estimates based on the best information available in recording transactions and balances resulting from business operations. As better information becomes available or actual amounts are known, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates. Reclassifications Certain reclassifications of amounts previously reported have been made to the accompanying consolidated statements of shareholders' equity and consolidated statements of cash flows to maintain consistency and comparability between periods presented. The reclassifications had no impact on previously reported shareholders' equity, net cash provided by operating activities, net cash used in investing activities, net cash used in financing activities, or cash and cash equivalents.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2022
Segment Reporting [Abstract]
Segment Information	Segment Information We classify our business into three segments, Electric, Manufacturing and Plastics, consistent with our business strategy, organizational structure and our internal reporting and review processes used by our chief operating decision maker to make decisions regarding allocation of resources, to assess operating performance and to make strategic decisions. Certain assets and costs are not allocated to our operating segments. Corporate operating costs include items such as corporate staff and overhead costs, the results of our captive insurance company and other items excluded from the measurement of operating segment performance. Corporate assets consist primarily of cash and cash equivalents, prepaid expenses, investments and fixed assets. Corporate is not an operating segment, rather it is added to operating segment totals to reconcile to consolidated amounts. Information for each segment and our unallocated corporate costs for the three and nine months ended September 30, 2022 and 2021 are as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2022 2021 2022 2021 Operating Revenue Electric $ 142,747 $ 118,775 $ 404,112 $ 348,629 Manufacturing 98,767 89,977 306,921 250,085 Plastics 142,342 107,542 447,767 264,898 Total $ 383,856 $ 316,294 $ 1,158,800 $ 863,612 Net Income (Loss) Electric $ 24,847 $ 22,528 $ 62,938 $ 55,547 Manufacturing 6,219 4,200 17,858 15,290 Plastics 55,982 28,410 170,788 60,102 Corporate (2,809) (2,384) (9,405) (5,787) Total $ 84,239 $ 52,754 $ 242,179 $ 125,152 The following provides the identifiable assets by segment and corporate assets as of September 30, 2022 and December 31, 2021: (in thousands) September 30, December 31, Identifiable Assets Electric $ 2,347,461 $ 2,283,776 Manufacturing 253,819 251,044 Plastics 179,925 162,565 Corporate 116,699 57,445 Total $ 2,897,904 $ 2,754,830

Revenue

Revenue	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Presented below are our operating revenues to external customers, in total and by amounts arising from contracts with customers and alternative revenue program (ARP) arrangements, disaggregated by revenue source and segment for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2022 2021 2022 2021 Operating Revenues Electric Segment Retail: Residential $ 35,122 $ 33,902 $ 108,883 $ 100,067 Retail: Commercial and Industrial 83,022 60,557 232,532 185,376 Retail: Other 2,033 1,979 6,004 5,687 Total Retail 120,177 96,438 347,419 291,130 Transmission 13,156 13,300 37,409 37,085 Wholesale 7,196 6,944 13,196 14,711 Other 2,218 2,093 6,088 5,703 Total Electric Segment 142,747 118,775 404,112 348,629 Manufacturing Segment Metal Parts and Tooling 84,054 76,455 261,923 210,141 Plastic Products and Tooling 12,723 10,198 36,584 30,624 Scrap Metal Sales 1,990 3,324 8,414 9,320 Total Manufacturing Segment 98,767 89,977 306,921 250,085 Plastics Segment PVC Pipe 142,342 107,542 447,767 264,898 Total Operating Revenue 383,856 316,294 1,158,800 863,612 Less: Non-contract Revenues Included Above Electric Segment - ARP Revenues (548) (33) (7,937) (2,790) Total Operating Revenues from Contracts with Customers $ 384,404 $ 316,327 $ 1,166,737 $ 866,402

Select Balance Sheet Informatio

Select Balance Sheet Information	9 Months Ended
	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Select Balance Sheet Information	Select Balance Sheet Information Receivables and Allowance for Credit Losses Receivables as of September 30, 2022 and December 31, 2021 are as follows: (in thousands) September 30, December 31, Receivables Trade $ 167,480 $ 142,297 Other 9,052 10,591 Unbilled Receivables 18,813 23,901 Total Receivables 195,345 176,789 Less: Allowance for Credit Losses (1,548) (1,836) Receivables, net of allowance for credit losses $ 193,797 $ 174,953 The following is a summary of activity in the allowance for credit losses for the nine months ended September 30, 2022 and 2021: (in thousands) 2022 2021 Beginning Balance, January 1 $ 1,836 $ 3,215 Additions Charged to Expense 518 177 Reductions for Amounts Written Off, Net of Recoveries (806) (1,060) Ending Balance, September 30 $ 1,548 $ 2,332 Inventories Inventories consist of the following as of September 30, 2022 and December 31, 2021: (in thousands) September 30, December 31, Raw Material, Fuel and Supplies $ 74,249 $ 72,882 Work in Process 33,765 35,705 Finished Goods 38,362 39,903 Total Inventories $ 146,376 $ 148,490 Investments The following is a summary of our investments as of September 30, 2022 and December 31, 2021: (in thousands) September 30, December 31, Corporate-Owned Life Insurance Policies $ 37,288 $ 41,078 Debt Securities 8,710 9,202 Money Market Funds 1,854 949 Mutual Funds 5,084 5,432 Other Investments 30 29 Total Investments $ 52,966 $ 56,690 The amount of unrealized gains and losses on debt securities as of September 30, 2022 and December 31, 2021 was not material and no unrealized losses were deemed to be other-than-temporary. In addition, the amount of unrealized gains and losses on marketable equity securities still held as of September 30, 2022 and December 31, 2021 was not material. Property, Plant and Equipment Major classes of property, plant and equipment as of September 30, 2022 and December 31, 2021 include: (in thousands) September 30, December 31, Electric Plant Electric Plant in Service $ 2,795,649 $ 2,758,445 Construction Work in Progress 130,486 74,926 Total Gross Electric Plant 2,926,135 2,833,371 Less Accumulated Depreciation and Amortization 850,741 817,302 Net Electric Plant 2,075,394 2,016,069 Nonelectric Property, Plant and Equipment Nonelectric Property, Plant and Equipment in Service 281,584 273,950 Construction Work in Progress 20,746 16,611 Total Gross Nonelectric Property, Plant and Equipment 302,330 290,561 Less Accumulated Depreciation and Amortization 191,081 182,025 Net Nonelectric Property, Plant and Equipment 111,249 108,536 Net Property, Plant and Equipment $ 2,186,643 $ 2,124,605

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2022
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Regulatory Assets and Liabilities The following presents our current and long-term regulatory assets and liabilities as of September 30, 2022 and December 31, 2021 and the period we expect to recover or refund such amounts: Period of September 30, 2022 December 31, 2021 (in thousands) Recovery/Refund Current Long-Term Current Long Term Regulatory Assets Pension and Other Postretirement Benefit Plans 1 Various $ 7,791 $ 110,183 $ 7,791 $ 114,961 Alternative Revenue Program Riders 2 Up to 2 years 7,528 1,988 11,889 5,564 Asset Retirement Obligations 1 Asset lives — 1,323 — 742 ISO Cost Recovery Trackers 1 Up to 2 years 660 740 — 1,342 Unrecovered Project Costs 1 Up to 5 years 320 1,063 2,136 1,455 Deferred Rate Case Expenses 1 Various 412 848 607 1,131 Debt Reacquisition Premiums 1 10 years 25 222 100 240 Fuel Clause Adjustments 1 Up to 1 year 13,185 — 4,819 — Other 1 Various — 226 — 73 Total Regulatory Assets $ 29,921 $ 116,593 $ 27,342 $ 125,508 Regulatory Liabilities Deferred Income Taxes Asset lives $ — $ 128,397 $ — $ 129,437 Plant Removal Obligations Asset lives 8,526 106,008 8,306 101,595 Fuel Clause Adjustments Up to 1 year — — 1,554 — Alternative Revenue Program Riders Various 4,178 6,048 5,772 3,336 Pension and Other Postretirement Benefit Plans Up to 1 year 2,603 — 2,603 — Derivative Instruments Various 5,532 — 6,214 — Other Various 275 92 395 62 Total Regulatory Liabilities $ 21,114 $ 240,545 $ 24,844 $ 234,430 1 Costs subject to recovery without a rate of return. 2 Amount eligible for recovery includes an incentive or rate of return. Minnesota Rate Case On November 2, 2020, Otter Tail Power Company (OTP) filed an initial request with the Minnesota Public Utilities Commission (MPUC) for an increase in revenue recoverable through base rates in Minnesota, and on December 3, 2020, the MPUC approved an interim annual rate increase of $6.9 million, or 3.2%, effective January 1, 2021. On February 1, 2022, the MPUC issued its written order on final rates. The key provisions of the order included a revenue requirement of $209.0 million, based on a return on rate base of 7.18% and an allowed return on equity of 9.48% on an equity ratio of 52.5%. The order also authorized recovery of our remaining Hoot Lake Plant net asset over a five-year period and approved the requested decoupling mechanism for most residential and commercial customer rate groups with a cap of 4% of annual base revenues. On May 12, 2022, OTP's final rate case compliance filing was approved by the MPUC. The filing included final revenue calculations, rate design and resulting tariff revisions, along with a determination of the interim rate refund, which resulted in an increase in revenues during the second quarter of 2022 of $4.1 million. Final rates took effect on July 1, 2022, and interim rate refunds of $15.3 million were applied to customer accounts in the third quarter of 2022.

Short-Term and Long-Term Borrow

Short-Term and Long-Term Borrowings	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Short-Term and Long-Term Borrowings	Short-Term and Long-Term BorrowingsThe following is a summary of our outstanding short- and long-term borrowings by borrower, OTC or OTP, as of September 30, 2022 and December 31, 2021: Short-Term Debt The following is a summary of our lines of credit as of September 30, 2022 and December 31, 2021: September 30, 2022 December 31, (in thousands) Borrowing Limit Amount Outstanding Letters Amount Available Amount Available OTC Credit Agreement $ 170,000 $ — $ — $ 170,000 $ 147,363 OTP Credit Agreement 170,000 — 9,919 160,081 88,315 Total $ 340,000 $ — $ 9,919 $ 330,081 $ 235,678 On October 31, 2022, OTC entered into a Fifth Amended and Restated Credit Agreement and OTP entered into a Fourth Amended and Restated Credit Agreement, in each case amending and restating the previously existing credit agreements to extend the maturity date of each credit facility from September 30, 2026 to October 29, 2027, and to replace LIBOR as a benchmark interest rate with the Secured Overnight Finance Rate (SOFR). The adoption of SOFR as a benchmark interest rate is in advance of the scheduled elimination of LIBOR as a benchmark interest rate on June 30, 2023. No other significant terms or conditions, including borrowing capacity, credit spreads or financial covenants, were modified under these amendments and restatements. Long-Term Debt The following is a summary of outstanding long-term debt by borrower as of September 30, 2022 and December 31, 2021: (in thousands) Borrower Debt Instrument Rate Maturity September 30, December 31, OTC Guaranteed Senior Notes 3.55% 12/15/26 $ 80,000 $ 80,000 OTP Series 2007B Senior Unsecured Notes 6.15% 08/20/22 — 30,000 OTP Series 2007C Senior Unsecured Notes 6.37% 08/02/27 42,000 42,000 OTP Series 2013A Senior Unsecured Notes 4.68% 02/27/29 60,000 60,000 OTP Series 2019A Senior Unsecured Notes 3.07% 10/10/29 10,000 10,000 OTP Series 2020A Senior Unsecured Notes 3.22% 02/25/30 10,000 10,000 OTP Series 2020B Senior Unsecured Notes 3.22% 08/20/30 40,000 40,000 OTP Series 2021A Senior Unsecured Notes 2.74% 11/29/31 40,000 40,000 OTP Series 2007D Senior Unsecured Notes 6.47% 08/20/37 50,000 50,000 OTP Series 2019B Senior Unsecured Notes 3.52% 10/10/39 26,000 26,000 OTP Series 2020C Senior Unsecured Notes 3.62% 02/25/40 10,000 10,000 OTP Series 2013B Senior Unsecured Notes 5.47% 02/27/44 90,000 90,000 OTP Series 2018A Senior Unsecured Notes 4.07% 02/07/48 100,000 100,000 OTP Series 2019C Senior Unsecured Notes 3.82% 10/10/49 64,000 64,000 OTP Series 2020D Senior Unsecured Notes 3.92% 02/25/50 15,000 15,000 OTP Series 2021B Senior Unsecured Notes 3.69% 11/29/51 100,000 100,000 OTP Series 2022A Senior Unsecured Notes 3.77% 05/20/52 90,000 — Total $ 827,000 $ 767,000 Less: Current Maturities, Net of Unamortized Debt Issuance Costs — 29,983 Unamortized Long-Term Debt Issuance Costs 3,240 3,003 Total Long-Term Debt, Net of Unamortized Debt Issuance Costs $ 823,760 $ 734,014 On June 10, 2021, OTP entered into a Note Purchase Agreement pursuant to which OTP agreed to issue, in a private placement transaction, $230.0 million of senior unsecured notes consisting of (a) $40.0 million of 2.74% Series 2021A Senior Unsecured Notes due November 29, 2031, (b) $100.0 million of 3.69% Series 2021B Senior Unsecured Notes due November 29, 2051 and (c) $90.0 million of 3.77% Series 2022A Senior Unsecured Notes due May 20, 2052. In November 2021, OTP issued its Series 2021A and Series 2021B Notes for aggregate proceeds of $140.0 million, which were used to repay the Series 2011A Notes in full. In May 2022, OTP issued its Series 2022A Notes for proceeds of $90.0 million, which were used to repay the Series 2007B Senior Unsecured Notes at their maturity in August 2022, to repay short-term borrowings, to fund capital expenditures, and for other general corporate purposes. Financial Covenants Certain of OTC's and OTP's short- and long-term debt agreements require the borrower, whether OTC or OTP, to maintain certain financial covenants, including a maximum debt to total capitalization ratio of 0.60 to 1.00, a minimum interest and dividend coverage ratio of 1.50 to 1.00, and a maximum level of priority indebtedness. As of September 30, 2022, OTC and OTP were in compliance with these financial covenants.

Employee Postretirement Benefit

Employee Postretirement Benefits	9 Months Ended
	Sep. 30, 2022
Retirement Benefits [Abstract]
Employee Postretirement Benefits	Employee Postretirement Benefits Pension Plan and Other Postretirement Benefits The Company sponsors a noncontributory funded pension plan (the "Pension Plan"), an unfunded, nonqualified Executive Survivor and Supplemental Retirement Plan (the "ESSRP"), both accounted for as defined benefit pension plans, and a postretirement healthcare plan accounted for as an other postretirement benefit plan. The following tables include the components of net periodic benefit cost of our defined benefit pension plans and other postretirement benefits for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, Pension Benefits (Pension Plan) Pension Benefits (ESSRP) Postretirement Benefits (in thousands) 2022 2021 2022 2021 2022 2021 Service Cost $ 1,644 $ 1,866 $ 48 $ 47 $ 335 $ 430 Interest Cost 3,086 2,915 335 307 510 472 Expected Return on Assets (5,921) (5,590) — — — — Amortization of Prior Service Cost — — — — (1,433) (1,432) Amortization of Net Actuarial Loss 1,966 2,728 141 154 765 943 Net Periodic Benefit Cost $ 775 $ 1,919 $ 524 $ 508 $ 177 $ 413 Nine Months Ended September 30, Pension Benefits (Pension Plan) Pension Benefits (ESSRP) Postretirement Benefits (in thousands) 2022 2021 2022 2021 2022 2021 Service Cost $ 4,932 $ 5,597 $ 146 $ 140 $ 1,004 $ 1,291 Interest Cost 9,258 8,745 1,006 921 1,531 1,418 Expected Return on Assets (17,763) (16,769) — — — — Amortization of Prior Service Cost — — — — (4,300) (4,299) Amortization of Net Actuarial Loss 5,899 8,185 425 465 2,297 2,830 Net Periodic Benefit Cost $ 2,326 $ 5,758 $ 1,577 $ 1,526 $ 532 $ 1,240 The following table includes the impact of regulation on the recognition of periodic benefit cost arising from pension and other postretirement benefits for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2022 2021 2022 2021 Net Periodic Benefit Cost $ 1,476 $ 2,840 $ 4,435 $ 8,524 Net Amount Amortized (Deferred) Due to the Effect of Regulation 499 8 823 15 Net Periodic Benefit Cost Recognized $ 1,975 $ 2,848 $ 5,258 $ 8,539 We had no minimum funding requirements for our Pension Plan or any other postretirement benefit plans as of December 31, 2021, but made a discretionary contribution of $20.0 million to our Pension Plan in February 2022.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The reconciliation of the statutory federal income tax rate to our effective tax rate for each of the three and nine months ended September 30, 2022 and 2021 is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Federal Statutory Rate 21.0 % 21.0 % 21.0 % 21.0 % Increases (Decreases) in Tax from: State Taxes on Income, Net of Federal Tax 5.0 5.0 5.0 5.0 Production Tax Credits (PTCs) (3.6) (5.0) (4.1) (6.0) Amortization of Excess Deferred Income Taxes (0.9) (1.6) (0.7) (2.0) North Dakota Wind Tax Credit Amortization, Net of Federal Tax (0.1) (0.2) (0.2) (0.3) Corporate-Owned Life Insurance 0.2 (0.3) 0.4 (0.6) Other, Net (0.5) (0.6) 0.1 (0.2) Effective Tax Rate 21.1 % 18.3 % 21.5 % 16.9 %

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments Ashtabula III Purchase. On June 23, 2022, OTP exercised its option to acquire the Ashtabula III wind farm, a 62.4 megawatt wind farm located in eastern North Dakota, for $49.7 million, subject to certain closing adjustments. Since 2013, OTP has purchased the wind-generated electricity from the Ashtabula III wind farm pursuant to a purchase power agreement, and that agreement granted OTP the option to purchase the wind farm. The purchase has received regulatory approval. We anticipate the transaction will close, subject to certain customary closing conditions, in January 2023. Contingencies FERC ROE. In November 2013 and February 2015, customers filed complaints with the Federal Energy Regulatory Commission (FERC) seeking to reduce the return on equity (ROE) component of the transmission rates that Midcontinent Independent System Operator, Inc. (MISO) transmission owners, including OTP, may collect under the MISO tariff rate. FERC's most recent order, issued on November 19, 2020, adopted a revised ROE methodology and set the base ROE at 10.02% (10.52% with an adder) effective for the fifteen-month period from November 2013 to February 2015 and on a prospective basis beginning in September 2016. The order also dismissed any complaints covering the period from February 2015 to May 2016. On August 9, 2022, the U.S. Court of Appeals for the District of Columbia Circuit vacated the FERC order citing a lack of reasoned explanation by FERC in its adoption of its revised ROE methodology as outlined in its November 2020 order. The U.S. Court of Appeals remanded the matter to FERC to reopen the proceedings. Significant uncertainty exists as to how FERC will proceed upon remand and there is no prescribed timeline under which FERC must act. We have deferred recognition and recorded a refund liability of $2.5 million as of September 30, 2022. This refund liability reflects our best estimate of amounts previously collected from customers under the MISO tariff rate that may be required to be refunded to customers once all regulatory and judicial proceedings are complete and a final ROE is established for the periods outlined above. Regional Haze Rule (RHR). The RHR was adopted in an effort to improve visibility in national parks and wilderness areas. The RHR requires states, in coordination with the Environmental Protection Agency (EPA) and other governmental agencies, to develop and implement plans to achieve natural visibility conditions. The second RHR implementation period covers the years 2018-2028. States are required to submit a state implementation plan to assess reasonable progress with the RHR and determine what additional emission reductions are appropriate, if any. Coyote Station, OTP's jointly owned coal-fired power plant in North Dakota, is subject to assessment in the second implementation period under the North Dakota state implementation plan. The North Dakota Department of Environmental Quality (NDDEQ) submitted its state implementation plan to the EPA for approval in August 2022. In its plan, the NDDEQ concluded it is not reasonable to require additional emission controls during this planning period. The EPA has previously expressed disagreement with the NDDEQ's recommendation to forgo additional emission controls and has indicated that such a plan is not likely to be accepted. We cannot predict with certainty the impact the state implementation plan may have on our business until the state implementation plan has been approved or otherwise acted on by the EPA. However, significant emission control investments could be required and the recovery of such costs from customers would require regulatory approval. Alternatively, investments in emission control equipment may prove to be uneconomic and result in the early retirement of or the sale of our interest in Coyote Station, subject to regulatory approval. We cannot estimate the ultimate financial effects such a retirement or sale may have on our consolidated operating results, financial position or cash flows, but such amounts could be material and the recovery of such costs in rates would be subject to regulatory approval. Other Contingencies. We are party to litigation and regulatory matters arising in the normal course of business. We regularly analyze relevant information and, as necessary, estimate and record accrued liabilities for legal, regulatory enforcement and other matters in which a loss is probable of occurring and can be reasonably estimated. We believe the effect on our consolidated operating results, financial position and cash flows, if any, for the disposition of all matters pending as of September 30, 2022, other than those discussed above, will not be material.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2022
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity Registration Statements On May 3, 2021, we filed a shelf registration statement with the SEC under which we may offer for sale, from time to time, either separately or together in any combination, equity, debt or other securities described in the shelf registration statement. No new debt or equity has been issued pursuant to the registration statement. The registration statement expires in May 2024. On May 3, 2021, we filed a second registration statement with the SEC for the issuance of up to 1,500,000 common shares under an Automatic Dividend Reinvestment and a Share Purchase Plan, which provides shareholders, retail customers of OTP and other interested investors methods of purchasing our common shares, by reinvesting their dividends or making optional cash investments. Shares purchased under the plan may be newly issued common shares or common shares purchased on the open market. During the nine months ended September 30, 2022, we issued 97,046 shares under this plan. We repurchased a sufficient number of shares on the open market to satisfy issuance under the plan; accordingly no proceeds from the issuance were received. As of September 30, 2022, there were 1,287,774 shares available for purchase or issuance under the plan. The registration statement expires in May 2024. Dividend Restrictions OTC is a holding company with no significant operations of its own. The primary source of funds for payments of dividends to OTC's shareholders is from dividends paid or distributions made by OTC's subsidiaries. As a result of certain statutory limitations or regulatory or financing agreements, the amount of distributions allowed to be made by OTC's subsidiaries or the amount of dividends paid by OTC could be restricted. Both the OTC Credit Agreement and OTP Credit Agreement contain restrictions on the payment of cash dividends upon a default or event of default, including failure to maintain certain financial covenants. As of September 30, 2022, we were in compliance with these financial covenants. Under the Federal Power Act, a public utility may not pay dividends from any funds properly included in a capital account. What constitutes “funds properly included in a capital account” is undefined in the Federal Power Act or the related regulations; however, the FERC has consistently interpreted the provision to allow dividends to be paid as long as i) the source of the dividends is clearly disclosed, ii) the dividend is not excessive and iii) there is no self-dealing on the part of corporate officials.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2022
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following shows the changes in accumulated other comprehensive loss for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, 2022 2021 (in thousands) Pension and Other Postretirement Benefits Net Unrealized Gains (Losses) on Available-for-Sale Securities Total Pension and Other Postretirement Benefits Net Unrealized Gains (Losses) on Available-for-Sale Securities Total Balance, Beginning of Period $ (6,621) $ (292) $ (6,913) $ (8,425) $ 134 $ (8,291) Other Comprehensive Loss Before Reclassifications, net of tax — (172) (172) — (26) (26) Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) 106 (1) 1 (2) 107 146 (1) — (2) 146 Total Other Comprehensive Income (Loss) 106 (171) (65) 146 (26) 120 Balance, End of Period $ (6,515) $ (463) $ (6,978) $ (8,279) $ 108 $ (8,171) Nine Months Ended September 30, 2022 2021 (in thousands) Pension and Other Postretirement Benefits Net Unrealized Gains (Losses) on Available-for-Sale Securities Total Pension and Other Postretirement Benefits Net Unrealized Gains (Losses) on Available-for-Sale Securities Total Balance, Beginning of Period $ (6,537) $ 13 $ (6,524) $ (8,716) $ 209 $ (8,507) Other Comprehensive Loss Before Reclassifications, net of tax — (477) (477) — (58) (58) Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) 22 (1) 1 (2) 23 437 (1) (43) (2) 394 Total Other Comprehensive Income (Loss) 22 (476) (454) 437 (101) 336 Balance, End of Period $ (6,515) $ (463) $ (6,978) $ (8,279) $ 108 $ (8,171) (1) Included in the computation of net periodic pension and other postretirement benefit costs. See Note 7. (2) Included in other income (expense), net on the accompanying consolidated statements of income.

Share-Based Payments

Share-Based Payments	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Share-Based Payments	Share-Based Payments Stock Compensation Expense Stock-based compensation expense arising from our employee stock purchase plan and share-based compensation plans, recognized within operating expenses in the consolidated statements of income, amounted to $0.6 million and $0.8 million for the three months ended September 30, 2022 and 2021, respectively, and $6.1 million and $6.4 million for the nine months ended September 30, 2022 and 2021, respectively. Restricted Stock Awards. We grant restricted stock awards to members of our Board of Directors and restricted stock units to certain key employees. The awards vest, depending on award type and recipient, either ratably over periods of three The following is a summary of stock award activity for the nine months ended September 30, 2022: Shares Weighted Average Nonvested, January 1, 2022 138,093 $ 44.48 Granted 51,439 59.96 Vested (47,981) 45.30 Forfeited — — Nonvested, September 30, 2022 141,551 $ 49.83 The fair value of vested awards was $3.0 million and $2.1 million during the nine months ended September 30, 2022 and 2021, respectively. Stock Performance Awards. Stock performance awards are granted to executive officers and certain other key employees. The awards vest at the end of a three-year performance period. The number of common shares awarded, if any, at the end of the performance period ranges from zero to 150% of the target amount based on two performance measures: i) total shareholder return relative to a peer group and ii) return on equity. Vesting of the awards is accelerated in certain circumstances, including on retirement. The amount of common shares awarded on an accelerated vesting is based either on actual performance at the end of the performance period or the amount of common shares earned at target. The grant date fair value of stock performance awards granted during the nine months ended September 30, 2022 and 2021 was determined using a Monte Carlo fair value simulation model incorporating the following assumptions: 2022 2021 Risk-free interest rate 1.52 % 0.18 % Expected term (in years) 3.00 3.00 Expected volatility 32.00 % 32.00 % Dividend yield 2.90 % 3.60 % The risk-free interest rate was derived from yields on U.S. government bonds of a similar term. The expected term of the award is equal to the three-year performance period. Expected volatility was estimated based on actual historical volatility of our common stock. Dividend yield was estimated based on historic and future yield estimates. The following is a summary of stock performance award activity for the nine months ended September 30, 2022 (share amounts reflect awards at target): Shares Weighted Average Nonvested, January 1, 2022 189,600 $ 42.54 Granted 55,800 54.91 Vested (55,600) 43.30 Forfeited — — Nonvested, September 30, 2022 189,800 $ 45.95

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2022
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The numerator used in the calculation of both basic and diluted earnings per common share is net income. The denominator used in the calculation of basic earnings per common share is the weighted average number of common shares outstanding during the period. The denominator used in the calculation of diluted earnings per common share is derived by adjusting basic shares outstanding for the dilutive effect of potential common shares outstanding, which consist of time and performance based stock awards and employee stock purchase plan shares. The following includes the computation of the denominator for basic and diluted weighted-average shares outstanding for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2022 2021 2022 2021 Weighted Average Common Shares Outstanding – Basic 41,600 41,504 41,582 41,487 Effect of Dilutive Securities: Stock Performance Awards 276 262 251 209 Restricted Stock Awards 97 88 96 82 Employee Stock Purchase Plan Shares and Other 1 15 1 17 Dilutive Effect of Potential Common Shares 374 365 348 308 Weighted Average Common Shares Outstanding – Diluted 41,974 41,869 41,930 41,795 The amount of shares excluded from diluted weighted-average common shares outstanding because such shares were anti-dilutive was not material for the three and nine months ended September 30, 2022 and 2021.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative InstrumentsOTP enters into derivative instruments to manage its exposure to future price variability and reduce volatility in prices for our retail customers. These derivative instruments are not designated as qualifying hedging transactions but provide for an economic hedge against future price variability. The instruments are recorded at fair value on the consolidated balance sheets. In accordance with rate-making and cost recovery processes, we recognize a regulatory asset or liability to defer losses or gains from derivative activity until settlement of the associated derivative instrument. As of September 30, 2022, OTP had outstanding pay-fixed, receive-variable swap agreements with an aggregate notional amount of 156,800 megawatt-hours of electricity, which will be settled periodically throughout 2022 and 2023. As of September 30, 2022, the fair value of these derivative instruments was $5.4 million, of which $5.5 million is included in other current assets and $0.1 million, which is included in other noncurrent liabilities, on the consolidated balance sheets. As of December 31, 2021, the fair value of these types of derivative contracts was $6.2 million, which is included in other current assets. No contracts settled during the three months ended September 30, 2022. During the nine months ended September 30, 2022, contracts matured and were settled in an aggregate amount of $2.8 million. There were no contracts settled during the three or nine months ended September 30, 2021

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following tables present our assets and liabilities measured at fair value on a recurring basis as of September 30, 2022 and December 31, 2021 classified by the input method used to measure fair value: (in thousands) Level 1 Level 2 Level 3 September 30, 2022 Assets: Investments: Money Market Funds $ 1,854 $ — $ — Mutual Funds 5,084 — — Corporate Debt Securities — 1,424 — Government-Backed and Government-Sponsored Enterprises’ Debt Securities — 7,286 — Derivative Instruments — 5,532 — Total Assets $ 6,938 $ 14,242 $ — Liabilities: Derivative Instruments $ — $ 169 $ — Total Liabilities $ — $ 169 $ — December 31, 2021 Assets: Investments: Money Market Funds $ 949 $ — $ — Mutual Funds 5,432 — — Corporate Debt Securities — 1,333 — Government-Backed and Government-Sponsored Enterprises’ Debt Securities — 7,869 — Derivative Instruments — 6,214 — Total Assets $ 6,381 $ 15,416 $ — Level 1 fair value measurements are based on quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access at the measurement date. The level 2 fair value measurements for government-backed and government-sponsored enterprises and corporate debt securities are determined on the basis of valuations provided by a third-party pricing service which utilizes industry accepted valuation models and observable market inputs to determine valuation. Some valuations or model inputs used by the pricing service may be based on broker quotes. The level 2 fair value measurements for derivative instruments are determined by using inputs such as forward electric commodity prices, adjusted for location differences. These inputs are observable in the marketplace throughout the full term of the instrument, can be derived from observable data, or are supported by observable levels at which transactions are executed in the marketplace. In addition to assets recorded at fair value on a recurring basis, we also hold financial instruments that are not recorded at fair value in the consolidated balance sheets but for which disclosure of the fair value of these financial instruments is provided. The following reflects the carrying value and estimated fair value of these assets and liabilities as of September 30, 2022 and December 31, 2021: September 30, 2022 December 31, 2021 (in thousands) Carrying Fair Value Carrying Fair Value Assets: Cash and Cash Equivalents $ 72,987 $ 72,987 $ 1,537 $ 1,537 Total 72,987 72,987 1,537 1,537 Liabilities: Short-Term Debt — — 91,163 91,163 Long-Term Debt 823,760 679,360 763,997 878,272 Total $ 823,760 $ 679,360 $ 855,160 $ 969,435 The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value: Cash Equivalents: The carrying amount approximates fair value because of the short-term maturity of those instruments. Short-Term Debt: The carrying amount approximates fair value because the debt obligations are short-term and the balances outstanding are subject to variable rates of interest which reset frequently, a Level 2 fair value input. Long-Term Debt: The fair value of long-term debt is estimated based on current market indications for borrowings of similar maturities, a Level 2 fair value input.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited consolidated financial statements included herein have been prepared pursuant to the rules and regulations of the SEC for interim reporting. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles. In the opinion of management, we have included all adjustments, including normal recurring accruals, necessary for a fair presentation of the consolidated financial statements for the periods presented. The consolidated financial statements and condensed notes thereto should be read in conjunction with the consolidated financial statements and notes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021. Because of the seasonality of our businesses and other factors, the earnings for the three and nine months ended September 30, 2022 should not be taken as an indication of earnings for all or any part of the balance of the current year or as an indication of earnings for future years.
Use of Estimates	Use of Estimates We use estimates based on the best information available in recording transactions and balances resulting from business operations. As better information becomes available or actual amounts are known, the recorded estimates are revised. Consequently, operating results can be affected by revisions to prior accounting estimates.
Reclassifications	Reclassifications Certain reclassifications of amounts previously reported have been made to the accompanying consolidated statements of shareholders' equity and consolidated statements of cash flows to maintain consistency and comparability between periods presented. The reclassifications had no impact on previously reported shareholders' equity, net cash provided by operating activities, net cash used in investing activities, net cash used in financing activities, or cash and cash equivalents.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2022
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Information for each segment and our unallocated corporate costs for the three and nine months ended September 30, 2022 and 2021 are as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2022 2021 2022 2021 Operating Revenue Electric $ 142,747 $ 118,775 $ 404,112 $ 348,629 Manufacturing 98,767 89,977 306,921 250,085 Plastics 142,342 107,542 447,767 264,898 Total $ 383,856 $ 316,294 $ 1,158,800 $ 863,612 Net Income (Loss) Electric $ 24,847 $ 22,528 $ 62,938 $ 55,547 Manufacturing 6,219 4,200 17,858 15,290 Plastics 55,982 28,410 170,788 60,102 Corporate (2,809) (2,384) (9,405) (5,787) Total $ 84,239 $ 52,754 $ 242,179 $ 125,152 The following provides the identifiable assets by segment and corporate assets as of September 30, 2022 and December 31, 2021: (in thousands) September 30, December 31, Identifiable Assets Electric $ 2,347,461 $ 2,283,776 Manufacturing 253,819 251,044 Plastics 179,925 162,565 Corporate 116,699 57,445 Total $ 2,897,904 $ 2,754,830

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	Presented below are our operating revenues to external customers, in total and by amounts arising from contracts with customers and alternative revenue program (ARP) arrangements, disaggregated by revenue source and segment for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2022 2021 2022 2021 Operating Revenues Electric Segment Retail: Residential $ 35,122 $ 33,902 $ 108,883 $ 100,067 Retail: Commercial and Industrial 83,022 60,557 232,532 185,376 Retail: Other 2,033 1,979 6,004 5,687 Total Retail 120,177 96,438 347,419 291,130 Transmission 13,156 13,300 37,409 37,085 Wholesale 7,196 6,944 13,196 14,711 Other 2,218 2,093 6,088 5,703 Total Electric Segment 142,747 118,775 404,112 348,629 Manufacturing Segment Metal Parts and Tooling 84,054 76,455 261,923 210,141 Plastic Products and Tooling 12,723 10,198 36,584 30,624 Scrap Metal Sales 1,990 3,324 8,414 9,320 Total Manufacturing Segment 98,767 89,977 306,921 250,085 Plastics Segment PVC Pipe 142,342 107,542 447,767 264,898 Total Operating Revenue 383,856 316,294 1,158,800 863,612 Less: Non-contract Revenues Included Above Electric Segment - ARP Revenues (548) (33) (7,937) (2,790) Total Operating Revenues from Contracts with Customers $ 384,404 $ 316,327 $ 1,166,737 $ 866,402

Select Balance Sheet Informat_2

Select Balance Sheet Information (Tables)	9 Months Ended
	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Receivables	Receivables as of September 30, 2022 and December 31, 2021 are as follows: (in thousands) September 30, December 31, Receivables Trade $ 167,480 $ 142,297 Other 9,052 10,591 Unbilled Receivables 18,813 23,901 Total Receivables 195,345 176,789 Less: Allowance for Credit Losses (1,548) (1,836) Receivables, net of allowance for credit losses $ 193,797 $ 174,953
Schedule of Activity in Allowance for Credit Losses	The following is a summary of activity in the allowance for credit losses for the nine months ended September 30, 2022 and 2021: (in thousands) 2022 2021 Beginning Balance, January 1 $ 1,836 $ 3,215 Additions Charged to Expense 518 177 Reductions for Amounts Written Off, Net of Recoveries (806) (1,060) Ending Balance, September 30 $ 1,548 $ 2,332
Schedule of Inventories	Inventories consist of the following as of September 30, 2022 and December 31, 2021: (in thousands) September 30, December 31, Raw Material, Fuel and Supplies $ 74,249 $ 72,882 Work in Process 33,765 35,705 Finished Goods 38,362 39,903 Total Inventories $ 146,376 $ 148,490
Schedule of Investments	The following is a summary of our investments as of September 30, 2022 and December 31, 2021: (in thousands) September 30, December 31, Corporate-Owned Life Insurance Policies $ 37,288 $ 41,078 Debt Securities 8,710 9,202 Money Market Funds 1,854 949 Mutual Funds 5,084 5,432 Other Investments 30 29 Total Investments $ 52,966 $ 56,690
Schedule of Property, Plant and Equipment	Major classes of property, plant and equipment as of September 30, 2022 and December 31, 2021 include: (in thousands) September 30, December 31, Electric Plant Electric Plant in Service $ 2,795,649 $ 2,758,445 Construction Work in Progress 130,486 74,926 Total Gross Electric Plant 2,926,135 2,833,371 Less Accumulated Depreciation and Amortization 850,741 817,302 Net Electric Plant 2,075,394 2,016,069 Nonelectric Property, Plant and Equipment Nonelectric Property, Plant and Equipment in Service 281,584 273,950 Construction Work in Progress 20,746 16,611 Total Gross Nonelectric Property, Plant and Equipment 302,330 290,561 Less Accumulated Depreciation and Amortization 191,081 182,025 Net Nonelectric Property, Plant and Equipment 111,249 108,536 Net Property, Plant and Equipment $ 2,186,643 $ 2,124,605

Regulatory Matters (Tables)

Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 2022
Regulatory Assets and Liabilities Disclosure [Abstract]
Schedule of Regulatory Assets and Liabilities	The following presents our current and long-term regulatory assets and liabilities as of September 30, 2022 and December 31, 2021 and the period we expect to recover or refund such amounts: Period of September 30, 2022 December 31, 2021 (in thousands) Recovery/Refund Current Long-Term Current Long Term Regulatory Assets Pension and Other Postretirement Benefit Plans 1 Various $ 7,791 $ 110,183 $ 7,791 $ 114,961 Alternative Revenue Program Riders 2 Up to 2 years 7,528 1,988 11,889 5,564 Asset Retirement Obligations 1 Asset lives — 1,323 — 742 ISO Cost Recovery Trackers 1 Up to 2 years 660 740 — 1,342 Unrecovered Project Costs 1 Up to 5 years 320 1,063 2,136 1,455 Deferred Rate Case Expenses 1 Various 412 848 607 1,131 Debt Reacquisition Premiums 1 10 years 25 222 100 240 Fuel Clause Adjustments 1 Up to 1 year 13,185 — 4,819 — Other 1 Various — 226 — 73 Total Regulatory Assets $ 29,921 $ 116,593 $ 27,342 $ 125,508 Regulatory Liabilities Deferred Income Taxes Asset lives $ — $ 128,397 $ — $ 129,437 Plant Removal Obligations Asset lives 8,526 106,008 8,306 101,595 Fuel Clause Adjustments Up to 1 year — — 1,554 — Alternative Revenue Program Riders Various 4,178 6,048 5,772 3,336 Pension and Other Postretirement Benefit Plans Up to 1 year 2,603 — 2,603 — Derivative Instruments Various 5,532 — 6,214 — Other Various 275 92 395 62 Total Regulatory Liabilities $ 21,114 $ 240,545 $ 24,844 $ 234,430 1 Costs subject to recovery without a rate of return. 2 Amount eligible for recovery includes an incentive or rate of return.

Short-Term and Long-Term Borr_2

Short-Term and Long-Term Borrowings (Tables)	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Schedule of Line of Credit Facilities	The following is a summary of our lines of credit as of September 30, 2022 and December 31, 2021: September 30, 2022 December 31, (in thousands) Borrowing Limit Amount Outstanding Letters Amount Available Amount Available OTC Credit Agreement $ 170,000 $ — $ — $ 170,000 $ 147,363 OTP Credit Agreement 170,000 — 9,919 160,081 88,315 Total $ 340,000 $ — $ 9,919 $ 330,081 $ 235,678
Schedule of Debt	The following is a summary of outstanding long-term debt by borrower as of September 30, 2022 and December 31, 2021: (in thousands) Borrower Debt Instrument Rate Maturity September 30, December 31, OTC Guaranteed Senior Notes 3.55% 12/15/26 $ 80,000 $ 80,000 OTP Series 2007B Senior Unsecured Notes 6.15% 08/20/22 — 30,000 OTP Series 2007C Senior Unsecured Notes 6.37% 08/02/27 42,000 42,000 OTP Series 2013A Senior Unsecured Notes 4.68% 02/27/29 60,000 60,000 OTP Series 2019A Senior Unsecured Notes 3.07% 10/10/29 10,000 10,000 OTP Series 2020A Senior Unsecured Notes 3.22% 02/25/30 10,000 10,000 OTP Series 2020B Senior Unsecured Notes 3.22% 08/20/30 40,000 40,000 OTP Series 2021A Senior Unsecured Notes 2.74% 11/29/31 40,000 40,000 OTP Series 2007D Senior Unsecured Notes 6.47% 08/20/37 50,000 50,000 OTP Series 2019B Senior Unsecured Notes 3.52% 10/10/39 26,000 26,000 OTP Series 2020C Senior Unsecured Notes 3.62% 02/25/40 10,000 10,000 OTP Series 2013B Senior Unsecured Notes 5.47% 02/27/44 90,000 90,000 OTP Series 2018A Senior Unsecured Notes 4.07% 02/07/48 100,000 100,000 OTP Series 2019C Senior Unsecured Notes 3.82% 10/10/49 64,000 64,000 OTP Series 2020D Senior Unsecured Notes 3.92% 02/25/50 15,000 15,000 OTP Series 2021B Senior Unsecured Notes 3.69% 11/29/51 100,000 100,000 OTP Series 2022A Senior Unsecured Notes 3.77% 05/20/52 90,000 — Total $ 827,000 $ 767,000 Less: Current Maturities, Net of Unamortized Debt Issuance Costs — 29,983 Unamortized Long-Term Debt Issuance Costs 3,240 3,003 Total Long-Term Debt, Net of Unamortized Debt Issuance Costs $ 823,760 $ 734,014

Employee Postretirement Benef_2

Employee Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2022
Retirement Benefits [Abstract]
Schedule of Net Periodic Benefit Costs	The following tables include the components of net periodic benefit cost of our defined benefit pension plans and other postretirement benefits for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, Pension Benefits (Pension Plan) Pension Benefits (ESSRP) Postretirement Benefits (in thousands) 2022 2021 2022 2021 2022 2021 Service Cost $ 1,644 $ 1,866 $ 48 $ 47 $ 335 $ 430 Interest Cost 3,086 2,915 335 307 510 472 Expected Return on Assets (5,921) (5,590) — — — — Amortization of Prior Service Cost — — — — (1,433) (1,432) Amortization of Net Actuarial Loss 1,966 2,728 141 154 765 943 Net Periodic Benefit Cost $ 775 $ 1,919 $ 524 $ 508 $ 177 $ 413 Nine Months Ended September 30, Pension Benefits (Pension Plan) Pension Benefits (ESSRP) Postretirement Benefits (in thousands) 2022 2021 2022 2021 2022 2021 Service Cost $ 4,932 $ 5,597 $ 146 $ 140 $ 1,004 $ 1,291 Interest Cost 9,258 8,745 1,006 921 1,531 1,418 Expected Return on Assets (17,763) (16,769) — — — — Amortization of Prior Service Cost — — — — (4,300) (4,299) Amortization of Net Actuarial Loss 5,899 8,185 425 465 2,297 2,830 Net Periodic Benefit Cost $ 2,326 $ 5,758 $ 1,577 $ 1,526 $ 532 $ 1,240 The following table includes the impact of regulation on the recognition of periodic benefit cost arising from pension and other postretirement benefits for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2022 2021 2022 2021 Net Periodic Benefit Cost $ 1,476 $ 2,840 $ 4,435 $ 8,524 Net Amount Amortized (Deferred) Due to the Effect of Regulation 499 8 823 15 Net Periodic Benefit Cost Recognized $ 1,975 $ 2,848 $ 5,258 $ 8,539

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of the statutory federal income tax rate to our effective tax rate for each of the three and nine months ended September 30, 2022 and 2021 is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Federal Statutory Rate 21.0 % 21.0 % 21.0 % 21.0 % Increases (Decreases) in Tax from: State Taxes on Income, Net of Federal Tax 5.0 5.0 5.0 5.0 Production Tax Credits (PTCs) (3.6) (5.0) (4.1) (6.0) Amortization of Excess Deferred Income Taxes (0.9) (1.6) (0.7) (2.0) North Dakota Wind Tax Credit Amortization, Net of Federal Tax (0.1) (0.2) (0.2) (0.3) Corporate-Owned Life Insurance 0.2 (0.3) 0.4 (0.6) Other, Net (0.5) (0.6) 0.1 (0.2) Effective Tax Rate 21.1 % 18.3 % 21.5 % 16.9 %

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2022
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Loss	The following shows the changes in accumulated other comprehensive loss for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, 2022 2021 (in thousands) Pension and Other Postretirement Benefits Net Unrealized Gains (Losses) on Available-for-Sale Securities Total Pension and Other Postretirement Benefits Net Unrealized Gains (Losses) on Available-for-Sale Securities Total Balance, Beginning of Period $ (6,621) $ (292) $ (6,913) $ (8,425) $ 134 $ (8,291) Other Comprehensive Loss Before Reclassifications, net of tax — (172) (172) — (26) (26) Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) 106 (1) 1 (2) 107 146 (1) — (2) 146 Total Other Comprehensive Income (Loss) 106 (171) (65) 146 (26) 120 Balance, End of Period $ (6,515) $ (463) $ (6,978) $ (8,279) $ 108 $ (8,171) Nine Months Ended September 30, 2022 2021 (in thousands) Pension and Other Postretirement Benefits Net Unrealized Gains (Losses) on Available-for-Sale Securities Total Pension and Other Postretirement Benefits Net Unrealized Gains (Losses) on Available-for-Sale Securities Total Balance, Beginning of Period $ (6,537) $ 13 $ (6,524) $ (8,716) $ 209 $ (8,507) Other Comprehensive Loss Before Reclassifications, net of tax — (477) (477) — (58) (58) Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) 22 (1) 1 (2) 23 437 (1) (43) (2) 394 Total Other Comprehensive Income (Loss) 22 (476) (454) 437 (101) 336 Balance, End of Period $ (6,515) $ (463) $ (6,978) $ (8,279) $ 108 $ (8,171) (1) Included in the computation of net periodic pension and other postretirement benefit costs. See Note 7. (2) Included in other income (expense), net on the accompanying consolidated statements of income.

Share-Based Payments (Tables)

Share-Based Payments (Tables)	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Schedule of Share-based Compensation Arrangements by Share-based Payment Award	The following is a summary of stock award activity for the nine months ended September 30, 2022: Shares Weighted Average Nonvested, January 1, 2022 138,093 $ 44.48 Granted 51,439 59.96 Vested (47,981) 45.30 Forfeited — — Nonvested, September 30, 2022 141,551 $ 49.83 The grant date fair value of stock performance awards granted during the nine months ended September 30, 2022 and 2021 was determined using a Monte Carlo fair value simulation model incorporating the following assumptions: 2022 2021 Risk-free interest rate 1.52 % 0.18 % Expected term (in years) 3.00 3.00 Expected volatility 32.00 % 32.00 % Dividend yield 2.90 % 3.60 % The following is a summary of stock performance award activity for the nine months ended September 30, 2022 (share amounts reflect awards at target): Shares Weighted Average Nonvested, January 1, 2022 189,600 $ 42.54 Granted 55,800 54.91 Vested (55,600) 43.30 Forfeited — — Nonvested, September 30, 2022 189,800 $ 45.95

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2022
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following includes the computation of the denominator for basic and diluted weighted-average shares outstanding for the three and nine months ended September 30, 2022 and 2021: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2022 2021 2022 2021 Weighted Average Common Shares Outstanding – Basic 41,600 41,504 41,582 41,487 Effect of Dilutive Securities: Stock Performance Awards 276 262 251 209 Restricted Stock Awards 97 88 96 82 Employee Stock Purchase Plan Shares and Other 1 15 1 17 Dilutive Effect of Potential Common Shares 374 365 348 308 Weighted Average Common Shares Outstanding – Diluted 41,974 41,869 41,930 41,795

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Schedule of Fair Value Measurements, Recurring and Nonrecurring	The following tables present our assets and liabilities measured at fair value on a recurring basis as of September 30, 2022 and December 31, 2021 classified by the input method used to measure fair value: (in thousands) Level 1 Level 2 Level 3 September 30, 2022 Assets: Investments: Money Market Funds $ 1,854 $ — $ — Mutual Funds 5,084 — — Corporate Debt Securities — 1,424 — Government-Backed and Government-Sponsored Enterprises’ Debt Securities — 7,286 — Derivative Instruments — 5,532 — Total Assets $ 6,938 $ 14,242 $ — Liabilities: Derivative Instruments $ — $ 169 $ — Total Liabilities $ — $ 169 $ — December 31, 2021 Assets: Investments: Money Market Funds $ 949 $ — $ — Mutual Funds 5,432 — — Corporate Debt Securities — 1,333 — Government-Backed and Government-Sponsored Enterprises’ Debt Securities — 7,869 — Derivative Instruments — 6,214 — Total Assets $ 6,381 $ 15,416 $ —
Schedule of Fair Value of Assets and Liabilities	The following reflects the carrying value and estimated fair value of these assets and liabilities as of September 30, 2022 and December 31, 2021: September 30, 2022 December 31, 2021 (in thousands) Carrying Fair Value Carrying Fair Value Assets: Cash and Cash Equivalents $ 72,987 $ 72,987 $ 1,537 $ 1,537 Total 72,987 72,987 1,537 1,537 Liabilities: Short-Term Debt — — 91,163 91,163 Long-Term Debt 823,760 679,360 763,997 878,272 Total $ 823,760 $ 679,360 $ 855,160 $ 969,435

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details)	9 Months Ended
	Sep. 30, 2022 segment
Accounting Policies [Abstract]
Number of operating segments	3

Segment Information - Narrative

Segment Information - Narrative (Details)	9 Months Ended
	Sep. 30, 2022 segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information - Schedule

Segment Information - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total Operating Revenues	$ 383,856	$ 316,294	$ 1,158,800	$ 863,612
Net Income (Loss)	84,239	52,754	242,179	125,152
Identifiable Assets	2,897,904		2,897,904		$ 2,754,830
Corporate
Segment Reporting Information [Line Items]
Net Income (Loss)	(2,809)	(2,384)	(9,405)	(5,787)
Identifiable Assets	116,699		116,699		57,445
Electric | Operating Segments
Segment Reporting Information [Line Items]
Total Operating Revenues	142,747	118,775	404,112	348,629
Net Income (Loss)	24,847	22,528	62,938	55,547
Identifiable Assets	2,347,461		2,347,461		2,283,776
Manufacturing | Operating Segments
Segment Reporting Information [Line Items]
Total Operating Revenues	98,767	89,977	306,921	250,085
Net Income (Loss)	6,219	4,200	17,858	15,290
Identifiable Assets	253,819		253,819		251,044
Plastics | Operating Segments
Segment Reporting Information [Line Items]
Total Operating Revenues	142,342	107,542	447,767	264,898
Net Income (Loss)	55,982	$ 28,410	170,788	$ 60,102
Identifiable Assets	$ 179,925		$ 179,925		$ 162,565

Revenue (Details)

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]
Total Operating Revenues	$ 383,856	$ 316,294	$ 1,158,800	$ 863,612
Operating Segments
Disaggregation of Revenue [Line Items]
Total Operating Revenues from Contracts with Customers	384,404	316,327	1,166,737	866,402
Operating Segments | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	142,747	118,775	404,112	348,629
Electric Segment - ARP Revenues	(548)	(33)	(7,937)	(2,790)
Operating Segments | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	98,767	89,977	306,921	250,085
Operating Segments | Plastics
Disaggregation of Revenue [Line Items]
Total Operating Revenues	142,342	107,542	447,767	264,898
Operating Segments | Total Retail | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	120,177	96,438	347,419	291,130
Operating Segments | Retail: Residential | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	35,122	33,902	108,883	100,067
Operating Segments | Retail: Commercial and Industrial | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	83,022	60,557	232,532	185,376
Operating Segments | Retail: Other | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	2,033	1,979	6,004	5,687
Operating Segments | Transmission | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	13,156	13,300	37,409	37,085
Operating Segments | Wholesale | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	7,196	6,944	13,196	14,711
Operating Segments | Other | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	2,218	2,093	6,088	5,703
Operating Segments | Metal Parts and Tooling | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	84,054	76,455	261,923	210,141
Operating Segments | Plastic Products and Tooling | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	12,723	10,198	36,584	30,624
Operating Segments | Scrap Metal Sales | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 1,990	$ 3,324	$ 8,414	$ 9,320

Select Balance Sheet Informat_3

Select Balance Sheet Information - Schedule of Receivables (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Trade	$ 167,480	$ 142,297
Other	9,052	10,591
Unbilled Receivables	18,813	23,901
Total Receivables	195,345	176,789
Less: Allowance for Credit Losses	(1,548)	(1,836)	$ (2,332)	$ (3,215)
Receivables, net of allowance for credit losses	$ 193,797	$ 174,953

Select Balance Sheet Informat_4

Select Balance Sheet Information - Summary of Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance, January 1	$ 1,836	$ 3,215
Additions Charged to Expense	518	177
Reductions for Amounts Written Off, Net of Recoveries	(806)	(1,060)
Ending Balance, September 30	$ 1,548	$ 2,332

Select Balance Sheet Informat_5

Select Balance Sheet Information - Schedule of Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw Material, Fuel and Supplies	$ 74,249	$ 72,882
Work in Process	33,765	35,705
Finished Goods	38,362	39,903
Inventories	$ 146,376	$ 148,490

Select Balance Sheet Informat_6

Select Balance Sheet Information - Schedule of Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Corporate-Owned Life Insurance Policies	$ 37,288	$ 41,078
Debt Securities	8,710	9,202
Money Market Funds	1,854	949
Mutual Funds	5,084	5,432
Other Investments	30	29
Total Investments	$ 52,966	$ 56,690

Select Balance Sheet Informat_7

Select Balance Sheet Information - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, net of accumulated depreciation	$ 2,186,643	$ 2,124,605
Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,926,135	2,833,371
Less Accumulated Depreciation and Amortization	850,741	817,302
Property, Plant and Equipment, net of accumulated depreciation	2,075,394	2,016,069
Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	302,330	290,561
Less Accumulated Depreciation and Amortization	191,081	182,025
Property, Plant and Equipment, net of accumulated depreciation	111,249	108,536
Electric Plant in Service | Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,795,649	2,758,445
Construction Work in Progress | Electric Plant
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	130,486	74,926
Construction Work in Progress | Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	20,746	16,611
Nonelectric Property, Plant and Equipment in Service | Nonelectric Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 281,584	$ 273,950

Regulatory Matters - Schedule o

Regulatory Matters - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 29,921	$ 27,342
Regulatory assets, long-term	116,593	125,508
Regulatory liabilities, current	21,114	24,844
Regulatory liabilities, long -term	240,545	234,430
Deferred Income Taxes
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	0	0
Regulatory liabilities, long -term	128,397	129,437
Plant Removal Obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	8,526	8,306
Regulatory liabilities, long -term	106,008	101,595
Fuel Clause Adjustments
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	0	1,554
Regulatory liabilities, long -term	$ 0	0
Regulatory Liabilities - Remaining Recovery/Refund Period	1 year
Alternative Revenue Program Riders
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	$ 4,178	5,772
Regulatory liabilities, long -term	6,048	3,336
Pension and Other Postretirement Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	2,603	2,603
Regulatory liabilities, long -term	$ 0	0
Regulatory Liabilities - Remaining Recovery/Refund Period	1 year
Derivative Instruments
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	$ 5,532	6,214
Regulatory liabilities, long -term	0	0
Other
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory liabilities, current	275	395
Regulatory liabilities, long -term	92	62
Pension and Other Postretirement Benefit Plans
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	7,791	7,791
Regulatory assets, long-term	110,183	114,961
Alternative Revenue Program Riders
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	7,528	11,889
Regulatory assets, long-term	$ 1,988	5,564
Regulatory Assets - Remaining Recovery/Refund Period	2 years
Asset Retirement Obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 0	0
Regulatory assets, long-term	1,323	742
ISO Cost Recovery Trackers
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	660	0
Regulatory assets, long-term	$ 740	1,342
Regulatory Assets - Remaining Recovery/Refund Period	2 years
Unrecovered Project Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 320	2,136
Regulatory assets, long-term	$ 1,063	1,455
Regulatory Assets - Remaining Recovery/Refund Period	5 years
Deferred Rate Case Expenses
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 412	607
Regulatory assets, long-term	848	1,131
Debt Reacquisition Premiums
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	25	100
Regulatory assets, long-term	$ 222	240
Regulatory Assets - Remaining Recovery/Refund Period	10 years
Fuel Clause Adjustments
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 13,185	4,819
Regulatory assets, long-term	$ 0	0
Regulatory Assets - Remaining Recovery/Refund Period	1 year
Other
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory assets - current	$ 0	0
Regulatory assets, long-term	$ 226	$ 73

Regulatory Matters - Narrative

Regulatory Matters - Narrative (Details) - Minnesota Rate Case - MPUC - USD ($) $ in Millions			3 Months Ended
	Feb. 01, 2022	Dec. 03, 2020	Sep. 30, 2022	Jun. 30, 2022
Schedule of Regulatory Assets and Liabilities [Line Items]
Revenue, approved rate increase, amount		$ 6.9	$ 15.3	$ 4.1
Revenue, approved rate increase, percent		3.20%
Revenue requirement amount	$ 209
Approved return on base rate, percent	7.18%
Approved return on equity, percent	9.48%
Approved equity ratio, percent	52.50%
Recovery period	5 years
Approved cap of annual base revenues, percent	4%

Short-Term and Long-Term Borr_3

Short-Term and Long-Term Borrowings - Lines of Credit (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Line of Credit Facility [Line Items]
Borrowing Limit	$ 340,000,000
Amount Outstanding	0	$ 91,163,000
Letters of Credit	9,919,000
Amount Available	330,081,000	235,678,000
OTC Credit Agreement
Line of Credit Facility [Line Items]
Borrowing Limit	170,000,000
Amount Outstanding	0
Letters of Credit	0
Amount Available	170,000,000	147,363,000
OTP Credit Agreement
Line of Credit Facility [Line Items]
Borrowing Limit	170,000,000
Amount Outstanding	0
Letters of Credit	9,919,000
Amount Available	$ 160,081,000	$ 88,315,000

Short-Term and Long-Term Borr_4

Short-Term and Long-Term Borrowings - Breakdown of Outstanding Long-term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term debt	$ 827,000	$ 767,000
Current Maturities, Net of Unamortized Debt Issuance Costs	0	29,983
Unamortized Long-Term Debt Issuance Costs	3,240	3,003
Total Long-Term Debt, Net of Unamortized Debt Issuance Costs	$ 823,760	734,014
Guaranteed Senior Notes
Debt Instrument [Line Items]
Rate	3.55%
Long-term debt	$ 80,000	80,000
Series 2007B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	6.15%
Long-term debt	$ 0	30,000
Series 2007C Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	6.37%
Long-term debt	$ 42,000	42,000
Series 2013A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	4.68%
Long-term debt	$ 60,000	60,000
Series 2019A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.07%
Long-term debt	$ 10,000	10,000
Series 2020A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.22%
Long-term debt	$ 10,000	10,000
Series 2020B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.22%
Long-term debt	$ 40,000	40,000
Series 2021A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	2.74%
Long-term debt	$ 40,000	40,000
Series 2007D Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	6.47%
Long-term debt	$ 50,000	50,000
Series 2019B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.52%
Long-term debt	$ 26,000	26,000
Series 2020C Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.62%
Long-term debt	$ 10,000	10,000
Series 2013B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	5.47%
Long-term debt	$ 90,000	90,000
Series 2018A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	4.07%
Long-term debt	$ 100,000	100,000
Series 2019C Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.82%
Long-term debt	$ 64,000	64,000
Series 2020D Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.92%
Long-term debt	$ 15,000	15,000
Series 2021B Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.69%
Long-term debt	$ 100,000	100,000
Series 2022A Senior Unsecured Notes
Debt Instrument [Line Items]
Rate	3.77%
Long-term debt	$ 90,000	$ 0

Short-Term and Long-Term Borr_5

Short-Term and Long-Term Borrowings - Narrative (Details) - USD ($)	1 Months Ended
	May 31, 2022	Nov. 30, 2021	Sep. 30, 2022	Jun. 10, 2021
Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount				$ 230,000,000
Proceeds from issuance of debt	$ 90,000,000	$ 140,000,000
Series 2021A Senior Unsecured Notes
Debt Instrument [Line Items]
Interest rate (as a percent)			2.74%
Series 2021A Senior Unsecured Notes | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount				$ 40,000,000
Interest rate (as a percent)				2.74%
Series 2021B Senior Unsecured Notes
Debt Instrument [Line Items]
Interest rate (as a percent)			3.69%
Series 2021B Senior Unsecured Notes | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount				$ 100,000,000
Interest rate (as a percent)				3.69%
Series 2022A Senior Unsecured Notes
Debt Instrument [Line Items]
Interest rate (as a percent)			3.77%
Series 2022A Senior Unsecured Notes | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount				$ 90,000,000
Interest rate (as a percent)				3.77%
Minimum
Debt Instrument [Line Items]
Interest and dividend coverage ratio			1.50
Maximum
Debt Instrument [Line Items]
Debt to total capitalization ratio			60%

Employee Postretirement Benef_3

Employee Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Benefit Cost	$ 1,476	$ 2,840	$ 4,435	$ 8,524
Pension Benefits (Pension Plan)
Defined Benefit Plan Disclosure [Line Items]
Service Cost	1,644	1,866	4,932	5,597
Interest Cost	3,086	2,915	9,258	8,745
Expected Return on Assets	(5,921)	(5,590)	(17,763)	(16,769)
Amortization of Prior Service Cost	0	0	0	0
Amortization of Net Actuarial Loss	1,966	2,728	5,899	8,185
Net Periodic Benefit Cost	775	1,919	2,326	5,758
Pension Benefits (ESSRP)
Defined Benefit Plan Disclosure [Line Items]
Service Cost	48	47	146	140
Interest Cost	335	307	1,006	921
Expected Return on Assets	0	0	0	0
Amortization of Prior Service Cost	0	0	0	0
Amortization of Net Actuarial Loss	141	154	425	465
Net Periodic Benefit Cost	524	508	1,577	1,526
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service Cost	335	430	1,004	1,291
Interest Cost	510	472	1,531	1,418
Expected Return on Assets	0	0	0	0
Amortization of Prior Service Cost	(1,433)	(1,432)	(4,300)	(4,299)
Amortization of Net Actuarial Loss	765	943	2,297	2,830
Net Periodic Benefit Cost	$ 177	$ 413	$ 532	$ 1,240

Employee Postretirement Benef_4

Employee Postretirement Benefits - Composition of Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Retirement Benefits [Abstract]
Net Periodic Benefit Cost	$ 1,476	$ 2,840	$ 4,435	$ 8,524
Net Amount Amortized (Deferred) Due to the Effect of Regulation	499	8	823	15
Net Periodic Benefit Cost Recognized	$ 1,975	$ 2,848	$ 5,258	$ 8,539

Employee Postretirement Benef_5

Employee Postretirement Benefits - Narrative (Details) $ in Millions	1 Months Ended
	Feb. 28, 2022 USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer	$ 20

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Federal Statutory Rate	21%	21%	21%	21%
Increases (Decreases) in Tax from:
State Taxes on Income, Net of Federal Tax	5%	5%	5%	5%
Production Tax Credits (PTCs)	(3.60%)	(5.00%)	(4.10%)	(6.00%)
Amortization of Excess Deferred Income Taxes	(0.90%)	(1.60%)	(0.70%)	(2.00%)
North Dakota Wind Tax Credit Amortization, Net of Federal Tax	(0.10%)	(0.20%)	(0.20%)	(0.30%)
Corporate-Owned Life Insurance	0.20%	(0.30%)	0.40%	(0.60%)
Other, Net	(0.50%)	(0.60%)	0.10%	(0.20%)
Effective Tax Rate	21.10%	18.30%	21.50%	16.90%

Commitments and Contingencies (

Commitments and Contingencies (Details) - Otter Tail Power Company $ in Millions	Jun. 23, 2022 USD ($) MWh	Sep. 30, 2022 USD ($)
Other Commitments [Line Items]
Option exercised | MWh	62.4
Payments to acquire wind farm	$ 49.7
Federal Energy Regulatory Commission
Other Commitments [Line Items]
Estimated liability of refund obligation		$ 2.5

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ in Thousands			9 Months Ended
	Jan. 26, 2022	May 03, 2021	Sep. 30, 2022	Dec. 31, 2021
Class of Stock [Line Items]
Total capitalization			$ 2,007,783	$ 1,724,791
Otter Tail Power Company
Class of Stock [Line Items]
Equity to total capitalization ratio			54.90%
Net assets restricted from distribution			$ 686,600
Minimum | Otter Tail Power Company | Minnesota Public Utilities Commission
Class of Stock [Line Items]
Public utilities, requested equity capital structure, percentage	48%
Maximum | Otter Tail Power Company
Class of Stock [Line Items]
Total capitalization			$ 1,700,000
Maximum | Otter Tail Power Company | Minnesota Public Utilities Commission
Class of Stock [Line Items]
Public utilities, requested equity capital structure, percentage	58.70%
Second Shelf Registration
Class of Stock [Line Items]
Shelf registration (in shares)		1,500,000
Number of shares issued (in shares)			97,046
Number of shares available for grant (in shares)			1,287,774

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,116,543	$ 915,123	$ 990,777	$ 870,966
Other Comprehensive Loss Before Reclassifications, net of tax	(172)	(26)	(477)	(58)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	107	146	23	394
Total Other Comprehensive Income (Loss)	(65)	120	(454)	336
Ending balance	1,184,023	952,482	1,184,023	952,482
Pension and Other Postretirement Benefits
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(6,621)	(8,425)	(6,537)	(8,716)
Other Comprehensive Loss Before Reclassifications, net of tax	0	0	0	0
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	106	146	22	437
Total Other Comprehensive Income (Loss)	106	146	22	437
Ending balance	(6,515)	(8,279)	(6,515)	(8,279)
Net Unrealized Gains (Losses) on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(292)	134	13	209
Other Comprehensive Loss Before Reclassifications, net of tax	(172)	(26)	(477)	(58)
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	1	0	1	(43)
Total Other Comprehensive Income (Loss)	(171)	(26)	(476)	(101)
Ending balance	(463)	108	(463)	108
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(6,913)	(8,291)	(6,524)	(8,507)
Total Other Comprehensive Income (Loss)	(65)	120	(454)	336
Ending balance	$ (6,978)	$ (8,171)	$ (6,978)	$ (8,171)

Share-Based Payments - Narrativ

Share-Based Payments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment arrangement, expense	$ 0.6	$ 0.8	$ 6.1	$ 6.4
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vesting period			4 years
Fair value of awards vested			$ 3	2.1
Restricted Stock Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Restricted Stock Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years
Stock Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Fair value of awards vested			$ 5.1	$ 2.5
Stock Performance Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target amount as actual payment			0%
Stock Performance Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target amount as actual payment			150%

Share-Based Payments - Summary

Share-Based Payments - Summary of Restricted Stock Awards and Stock Performance Awards (Details)	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Restricted Stock Awards
Shares
Beginning of year (in shares) | shares	138,093
Granted (in shares) | shares	51,439
Vested (in shares) | shares	(47,981)
Forfeited (in shares) | shares	0
End of year (in shares) | shares	141,551
Weighted Average Grant-Date Fair Value
Beginning of year (in dollars per share) | $ / shares	$ 44.48
Granted (in dollars per share) | $ / shares	59.96
Vested (in dollars per share) | $ / shares	45.30
Forfeited (in dollars per share) | $ / shares	0
End of year (in dollars per share) | $ / shares	$ 49.83
Stock Performance Awards
Shares
Beginning of year (in shares) | shares	189,600
Granted (in shares) | shares	55,800
Vested (in shares) | shares	(55,600)
Forfeited (in shares) | shares	0
End of year (in shares) | shares	189,800
Weighted Average Grant-Date Fair Value
Beginning of year (in dollars per share) | $ / shares	$ 42.54
Granted (in dollars per share) | $ / shares	54.91
Vested (in dollars per share) | $ / shares	43.30
Forfeited (in dollars per share) | $ / shares	0
End of year (in dollars per share) | $ / shares	$ 45.95

Share-Based Payments - Weighted

Share-Based Payments - Weighted-Average Assumptions (Details) - Stock Performance Awards	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.52%	0.18%
Expected term (in years)	3 years	3 years
Expected volatility	32%	32%
Dividend yield	2.90%	3.60%

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, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted Average Common Shares Outstanding - Basic (in shares)	41,600	41,504	41,582	41,487
Effect of Dilutive Securities:
Total Dilutive Shares (in shares)	374	365	348	308
Weighted Average Common Shares Outstanding – Diluted (in shares)	41,974	41,869	41,930	41,795
Stock Performance Awards
Effect of Dilutive Securities:
Effect of Dilutive Securities (in shares)	276	262	251	209
Restricted Stock Awards
Effect of Dilutive Securities:
Effect of Dilutive Securities (in shares)	97	88	96	82
Employee Stock Purchase Plan Shares and Other
Effect of Dilutive Securities:
Effect of Dilutive Securities (in shares)	1	15	1	17

Derivative Instruments (Details

Derivative Instruments (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) MWh	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments	$ 5,400,000		$ 5,400,000
Current derivative asset	5,500,000		5,500,000		$ 6,200,000
Noncurrent derivative liability	100,000		$ 100,000
Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of outstanding swap agreements | MWh			156,800
Settlement of derivative contract	$ 0	$ 0	$ 2,800,000	$ 0

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Measurements, Recurring and Nonrecurring (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Investments:
Debt Securities	$ 8,710	$ 9,202
Derivative Instruments	5,400
Level 1 | Fair Value, Recurring
Investments:
Money Market Funds	1,854	949
Mutual Funds	5,084	5,432
Total Assets	6,938	6,381
Level 2 | Fair Value, Recurring
Investments:
Derivative Instruments	5,532	6,214
Total Assets	14,242	15,416
Liabilities:
Derivative Instruments	169
Total Liabilities	169
Level 2 | Fair Value, Recurring | Corporate Debt Securities
Investments:
Debt Securities	1,424	1,333
Level 2 | Fair Value, Recurring | Government-Backed and Government-Sponsored Enterprises’ Debt Securities
Investments:
Debt Securities	$ 7,286	$ 7,869

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Carrying Amount
Assets:
Cash and Cash Equivalents	$ 72,987	$ 1,537
Total Assets	72,987	1,537
Liabilities:
Short-Term Debt	0	91,163
Long-Term Debt	823,760	763,997
Total	823,760	855,160
Fair Value
Assets:
Cash and Cash Equivalents	72,987	1,537
Total Assets	72,987	1,537
Liabilities:
Short-Term Debt	0	91,163
Long-Term Debt	679,360	878,272
Total	$ 679,360	$ 969,435

Uncategorized Items - ottr-2022

Label	Element	Value
Capital Expenditures Incurred but Not yet Paid	us-gaap_CapitalExpendituresIncurredButNotYetPaid	$ 14,358,000
Capital Expenditures Incurred but Not yet Paid	us-gaap_CapitalExpendituresIncurredButNotYetPaid	$ 12,438,000