v3.25.4
Revenues from Contracts with Customers - Summary of Company's Revenue by Major Source (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers $ 176,382 $ 175,736 $ 174,904
RNG [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 158,590 157,502 156,081
REG [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 17,792 18,234 18,823
Natural Gas Commodity [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 48,530 35,039 30,207
Natural Gas Environmental Attributes [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 110,060 122,463 125,874
Electric Commodity [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 10,326 10,648 11,301
Electric Environmental Attributes [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 7,466 7,586 7,522
Goods transferred at a point in time [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 117,526 130,049 133,396
Goods transferred at a point in time [Member] | RNG [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 110,060 122,463 125,874
Goods transferred at a point in time [Member] | REG [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 7,466 7,586 7,522
Goods transferred at a point in time [Member] | Natural Gas Commodity [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 0 0 0
Goods transferred at a point in time [Member] | Natural Gas Environmental Attributes [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 110,060 122,463 125,874
Goods transferred at a point in time [Member] | Electric Environmental Attributes [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 7,466 7,586 7,522
Goods transferred over time [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 58,856 45,687 41,508
Goods transferred over time [Member] | RNG [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 48,530 35,039 30,207
Goods transferred over time [Member] | REG [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 10,326 10,648 11,301
Goods transferred over time [Member] | Natural Gas Commodity [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers 48,530 35,039 30,207
Goods transferred over time [Member] | Electric Commodity [Member]      
Disaggregation of Revenue [Line Items]      
Revenues from Contracts with Customers $ 10,326 $ 10,648 $ 11,301