Related Party Transactions (General) (Details) - Affiliated Entity [Member] - Westlake [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Operating Lease, Expense	$ 407	$ 597	$ 1,803	$ 1,673
Interest earned related to the IMA	69	$ 716	876	$ 2,688
Accrued Liabilities [Member]
Related Party Transaction [Line Items]
Accrued interest included in receivable under IMA	$ 69		$ 69		$ 601