Summary of Significant Accounting Policies - Accounts Receivable, net and Inventories (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Inventory, Net [Abstract]
Finished goods	$ 17,612	$ 25,136
Raw materials	243	439
Parts, supplies and other	36,075	37,979
Total Inventories	53,930	63,554
Inventory depreciation	$ 4,500	$ 5,700
Accounts receivable | Customer concentration
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of concentration risk	18.00%	25.00%