Derivatives (Net Derivatives As Reflected On The Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 9,354	$ (12,210)
Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	(629)	(13,288)
Heating oil and coal | Other current assets
Derivatives, Fair Value [Line Items]
Net derivatives as classified in the balance sheet	$ 9,983	$ 1,078