v3.26.1
Segment Information - Schedule of Segment Profit or Loss (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting [Line Items]        
Operating Revenue $ 334,383 $ 333,043 $ 681,409 $ 670,396
Operating and Maintenance Expenses 54,692 46,804 104,948 95,685
Depreciation and Amortization 30,811 29,447 60,789 58,822
Property Taxes 5,121 4,227 9,583 8,455
Interest Expense 12,890 11,720 25,526 23,273
Selling, General, and Administrative Expenses 22,169 17,352 43,940 38,644
Legal Settlement Expenses (103,500) 0 (103,500) 0
Income Tax Expense (Benefit) (21,157) 13,652 (16,280) 23,737
Net Income (Loss) (7,607) 77,728 65,003 145,827
Electric        
Segment Reporting [Line Items]        
Operating Revenue 121,320 128,731 287,188 278,451
Manufacturing        
Segment Reporting [Line Items]        
Operating Revenue 88,461 78,726 178,021 160,412
Plastics        
Segment Reporting [Line Items]        
Operating Revenue 124,602 125,586 216,200 231,533
Operating Segments        
Segment Reporting [Line Items]        
Interest Expense 12,906 11,695 25,388 23,120
Income Tax Expense (Benefit) (21,446) 15,173 (13,760) 26,730
Net Income (Loss) (6,812) 75,780 65,661 145,459
Operating Segments | Electric        
Segment Reporting [Line Items]        
Operating Revenue 121,320 128,731 287,188 278,451
Production Fuel and Purchased Power 23,883 31,789 71,667 76,980
Operating and Maintenance Expenses 54,692 46,804 104,948 95,685
Depreciation and Amortization 24,223 22,278 47,669 44,655
Property Taxes 5,121 4,227 9,583 8,455
Interest Expense 11,990 10,822 23,726 21,479
Income Tax Expense (Benefit) (13,104) (4,469) (18,286) (8,477)
Other Segment Items (4,183) (1,915) (6,067) (4,229)
Net Income (Loss) 18,698 19,195 53,948 43,903
Operating Segments | Manufacturing        
Segment Reporting [Line Items]        
Operating Revenue 88,461 78,726 178,021 160,412
Depreciation and Amortization 4,762 5,523 9,549 10,946
Interest Expense 591 627 1,190 1,249
Cost of Goods Sold 69,419 63,311 140,621 131,827
Selling, General, and Administrative Expenses 12,544 10,350 24,772 21,093
Income Tax Expense (Benefit) 1,336 958 2,585 1,230
Other Segment Items 0 (1) (1) 0
Net Income (Loss) 4,571 3,481 8,854 5,013
Operating Segments | Plastics        
Segment Reporting [Line Items]        
Operating Revenue 124,602 125,586 216,200 231,533
Depreciation and Amortization 1,750 1,588 3,422 3,135
Interest Expense 325 246 472 392
Cost of Goods Sold 52,661 46,929 92,678 87,016
Selling, General, and Administrative Expenses 7,874 6,623 14,752 13,608
Legal Settlement Expenses 103,500 0 103,500 0
Income Tax Expense (Benefit) (9,678) 18,684 1,941 33,977
Other Segment Items 1 0 (2) (3)
Net Income (Loss) $ (30,081) $ 53,104 $ 2,859 $ 96,543