Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019
Allowance for Affiliate Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 6,692		$ 6,692
Charged to Costs and Expenses	0		0
Charged to Other Accounts	0		0
Deductions from Allowance	(6,552)	[1]	0
Balance at End of Period	140		6,692
Deferred Tax Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	128,483		128,365
Charged to Costs and Expenses	(69)		118
Charged to Other Accounts	0		0
Deductions from Allowance	0		0
Balance at End of Period	128,414		$ 128,483
XTAR, LLC [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Increase (decrease) in due from affiliates	(5,854)
Accounts Receivable, Allowance for Credit Loss, Writeoff	$ 698

[1] Deductions from allowance for affiliate receivables reflects $5,854 receivable collected and $698 receivable write-off during the year