Derivatives. (Details) - Schedule of derivatives not designated as hedging instruments - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash collateral balance [Member]
Derivatives. (Details) - Schedule of derivatives not designated as hedging instruments [Line Items]
Assets, fair value	$ 520	$ 615
Commodity contracts [Member]
Derivatives. (Details) - Schedule of derivatives not designated as hedging instruments [Line Items]
Assets, fair value	17,149	2,438
Liabilities, fair value		$ 1,860