Derivatives (Net Derivatives As Reflected On The Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 2,612	$ 5,746
Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	(53)	(111)
Heating oil and coal | Other current assets
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 2,665	$ 5,857