Investments in Privately-Held Raw Material Companies - Minority Investment Entities (Details) - Five Minority Investments - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Summarized income information of all the minority investment entities that are not consolidated and accounted for under the equity method [Abstract]
Net revenue	$ 3,953,000	$ 6,441,000
Gross profit (loss)	2,020,000	(51,000)
Operating (loss)	197,000	(2,039,000)
Net income (loss)	2,000	(2,446,000)
Minority investment entities
Entity portion of loss from unconsolidated equity method investments, including impairment charges	$ (120,000)	$ 1,600,000