Segment Information - Schedule of Reconciliation to Consolidated Amounts (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Depreciation and Amortization	$ 29,554	$ 27,051	$ 88,376	$ 79,579
Interest Expense	11,790	11,173	35,063	31,225
Income Tax Expense (Benefit)	12,817	18,677	36,553	57,077
Net Income	78,292	85,479	224,119	246,812
Operating Segments
Segment Reporting Information [Line Items]
Interest Expense	11,670	11,084	34,791	30,843
Income Tax Expense (Benefit)	15,757	19,960	42,487	61,224
Net Income	74,719	85,183	220,179	245,586
Operating Segments \| Electric
Segment Reporting Information [Line Items]
Depreciation and Amortization	22,433	20,741	67,087	61,014
Interest Expense	10,891	10,274	32,370	28,534
Income Tax Expense (Benefit)	(701)	948	(9,178)	723
Net Income	27,308	28,530	71,211	69,486
Operating Segments \| Manufacturing
Segment Reporting Information [Line Items]
Depreciation and Amortization	5,411	5,199	16,357	15,199
Interest Expense	633	664	1,882	1,865
Income Tax Expense (Benefit)	1,141	(154)	2,371	3,563
Net Income	3,916	2,174	8,930	14,271
Operating Segments \| Plastics
Segment Reporting Information [Line Items]
Depreciation and Amortization	1,636	1,086	4,771	3,293
Interest Expense	146	146	539	444
Income Tax Expense (Benefit)	15,317	19,166	49,294	56,938
Net Income	43,495	54,479	140,038	161,829
Corporate
Segment Reporting Information [Line Items]
Depreciation and Amortization	74	25	161	73
Interest Expense	120	89	272	382
Income Tax Expense (Benefit)	(2,940)	(1,283)	(5,934)	(4,147)
Net Income	$ 3,573	$ 296	$ 3,940	$ 1,226

Otter Tail Corp 10-Q