Derivatives - Net derivatives as reflected on the balance sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 1,077	$ 3,901
Heating oil and coal | Other current assets
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	3,540	4,214
Coal Contract | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ (2,463)	$ (313)