Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 374,904	$ 261,710
Operating Segments
Disaggregation of Revenue [Line Items]
Total Operating Revenues from Contracts with Customers	377,364	262,685
Operating Segments | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	130,416	123,699
Electric Segment - ARP Revenues	(2,460)	(975)
Operating Segments | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	104,957	75,825
Operating Segments | Plastics
Disaggregation of Revenue [Line Items]
Total Operating Revenues	139,531	62,186
Operating Segments | Retail: Residential | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	40,561	37,485
Operating Segments | Retail: Commercial and Industrial | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	71,171	66,403
Operating Segments | Retail: Other | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	1,907	1,818
Operating Segments | Total Retail | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	113,639	105,706
Operating Segments | Transmission | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	12,556	11,944
Operating Segments | Wholesale | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	2,463	4,507
Operating Segments | Other | Electric
Disaggregation of Revenue [Line Items]
Total Operating Revenues	1,758	1,542
Operating Segments | Metal Parts and Tooling | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	89,573	62,673
Operating Segments | Plastic Products and Tooling | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	12,445	10,295
Operating Segments | Scrap Metal Sales | Manufacturing
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 2,939	$ 2,857