Related Party Transactions (General) (Details) - Affiliated Entity [Member] - Westlake [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Operating Lease, Expense	$ 726	$ 562	$ 1,396	$ 1,076
Interest earned related to the IMA	219	$ 1,155	807	$ 1,973
Accrued Liabilities [Member]
Related Party Transaction [Line Items]
Accrued interest included in receivable under IMA	$ 219		$ 219		$ 601