Inventories (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Inventory [Line Items]
Lower of LIFO cost or market inventory reserve	$ (468,100)		$ (468,100)		$ (240,400)
Inventory Valuation Reserves	468,074		468,074		$ 240,363
Lower of cost or market inventory valuation adjustment	(62,849)	$ 34,062	227,711	$ (150,483)
Inventories [Member]
Inventory [Line Items]
Restructuring Reserve	$ 9,000		$ 9,000