Derivatives. (Tables)

9 Months Ended

Sep. 30, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of derivatives not designated as hedging instruments

	As of September 30, 2020
	Assets			Liabilities
	Balance Sheet	Fair		Balance Sheet	Fair
Type of Instrument	Location	Value		Location	Value
Cash collateral balance	Other current assets	$	15
Commodity contracts	Derivative instruments	$	5,792	Derivative instruments	$	—

	As of December 31, 2019
	Assets			Liabilities
	Balance Sheet	Fair		Balance Sheet	Fair
Type of Instrument	Location	Value		Location	Value
Cash collateral balance	Other current assets	$	615
Commodity contracts	Derivative instruments	$	2,438	Derivative instruments	$	1,860

Schedule of recognized gains (losses) for derivatives

		Realized Gains (Losses)
		Three Months Ended September 30,
Type of Instrument	Statements of Operations Location	2020			2019
Commodity contracts	Cost of goods sold	$	(531	)	$	2,262

		Unrealized Gains (Losses)
		Three Months Ended September 30,
Type of Instrument	Statements of Operations Location	2020		2019
Commodity contracts	Cost of goods sold	$	2,113	$	(5,582	)

		Realized Gains (Losses)
		Nine Months Ended September 30,
Type of Instrument	Statements of Operations Location	2020		2019
Commodity contracts	Cost of goods sold	$	47	$	(2,150	)

		Unrealized Gains (Losses)
		Nine Months Ended September 30,
Type of Instrument	Statements of Operations Location	2020		2019
Commodity contracts	Cost of goods sold	$	1,535	$	3,715