Derivatives (Net Derivatives As Reflected On The Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ (8,840)	$ 846
Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ (8,840)	(7)
Heating oil and coal | Other current assets
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet		$ 853