CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Costs and Expenses [Abstract]
Depreciation and amortization included in the cost of specialty petrochemicals, product sales, and processing	$ 15,361	$ 13,618	$ 10,089