Derivatives. (Details) - Schedule of derivatives not designated as hedging instruments - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Commodity contracts [Member]
Derivatives. (Details) - Schedule of derivatives not designated as hedging instruments [Line Items]
Assets, fair value	$ 22,355	$ 17,149
Liabilities, fair value	$ 4,741
Cash collateral balance [Member]
Derivatives. (Details) - Schedule of derivatives not designated as hedging instruments [Line Items]
Assets, fair value		$ 520