v3.26.1
Segment Reporting (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Segment Reporting [Line Items]      
Total operating revenues $ 841,203 $ 778,612  
Electric operations and maintenance 181,712 177,243  
Good and services provided 131,746 123,734  
Nonelectric selling, general and administrative 24,835 24,635  
Depreciation, depletion and amortization 65,043 66,123  
Other (income) expense (53,724) (46,199)  
Interest and other charges, net 73,625 63,579  
Income tax expense 1,100 4,821  
Net margin and earnings attributable to noncontrolling interest 6,200 6,316  
Net margin and earnings attributable to Basin Electric 75,367 47,702  
Segment capital expenditure 227,798 106,172  
Assets 9,482,652   $ 9,397,657
Operating Segments      
Segment Reporting [Line Items]      
Total operating revenues 872,169 807,216  
Net margin and earnings attributable to Basin Electric 72,929 45,312  
Segment capital expenditure 227,798 105,823  
Assets 10,705,508   10,636,104
Operating Segments | External      
Segment Reporting [Line Items]      
Total operating revenues 841,203 778,612  
Operating Segments | Intersegment      
Segment Reporting [Line Items]      
Total operating revenues 30,966 28,604  
Operating Segments | Electric Utility      
Segment Reporting [Line Items]      
Total operating revenues 671,589 618,433  
Electric fuel and purchased power 335,299 310,658  
Electric operations and maintenance 181,712 177,243  
Nonelectric selling, general and administrative 0 0  
Depreciation, depletion and amortization 49,697 51,505  
Other (income) expense (17,105) (16,781)  
Income tax expense (1,112) (275)  
Net margin and earnings attributable to noncontrolling interest 0 0  
Net margin and earnings attributable to Basin Electric 60,363 42,172  
Segment capital expenditure 221,105 99,693  
Assets 9,027,074   9,014,439
Operating Segments | Electric Utility | External      
Segment Reporting [Line Items]      
Total operating revenues 671,589 618,433  
Interest and other charges, net 66,527 51,535  
Operating Segments | Electric Utility | Intersegment      
Segment Reporting [Line Items]      
Total operating revenues 0 0  
Interest and other charges, net (3,792) 2,376  
Operating Segments | Gasification      
Segment Reporting [Line Items]      
Total operating revenues 114,453 110,956  
Nonelectric selling, general and administrative 23,740 22,240  
Depreciation, depletion and amortization 10,346 10,019  
Other (income) expense (39,684) (31,111)  
Income tax expense 3,822 2,706  
Net margin and earnings attributable to noncontrolling interest 0 0  
Net margin and earnings attributable to Basin Electric 2,738 (2,376)  
Segment capital expenditure 1,858 4,479  
Assets 1,106,862   1,053,066
Operating Segments | Gasification | External      
Segment Reporting [Line Items]      
Total operating revenues 114,453 110,956  
Good and services provided 78,525 72,186  
Interest and other charges, net 4,000 8,688  
Operating Segments | Gasification | Intersegment      
Segment Reporting [Line Items]      
Total operating revenues 0 0  
Good and services provided 30,966 28,604  
Interest and other charges, net 0 0  
Operating Segments | Coal and Limestone Operations      
Segment Reporting [Line Items]      
Total operating revenues 86,127 77,827  
Nonelectric selling, general and administrative 2,150 2,395  
Depreciation, depletion and amortization 5,000 4,599  
Other (income) expense 3,065 1,693  
Income tax expense 3,565 2,404  
Net margin and earnings attributable to noncontrolling interest 6,200 6,316  
Net margin and earnings attributable to Basin Electric 9,828 5,516  
Segment capital expenditure 4,835 1,651  
Assets 571,572   568,599
Operating Segments | Coal and Limestone Operations | External      
Segment Reporting [Line Items]      
Total operating revenues 55,161 49,223  
Good and services provided 53,221 51,548  
Interest and other charges, net 3,098 3,356  
Operating Segments | Coal and Limestone Operations | Intersegment      
Segment Reporting [Line Items]      
Total operating revenues 30,966 28,604  
Good and services provided 0 0  
Interest and other charges, net 0 0  
Intersegment Eliminations      
Segment Reporting [Line Items]      
Total operating revenues (30,966) (28,604)  
Net margin and earnings attributable to Basin Electric (3,792) 2,376  
Assets (1,258,027)   (1,273,951)
Other      
Segment Reporting [Line Items]      
Net margin and earnings attributable to Basin Electric 6,230 14  
Segment capital expenditure 0 $ 349  
Assets $ 35,171   $ 35,504