Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Affiliate Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 6,692	$ 6,692	$ 6,692
Charged to Costs and Expenses
Balance at End of Period		6,692	6,692	6,692
Deferred Tax Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		8,212	7,905	7,228
Charged to Costs and Expenses		(4,565)	307	624
Charged to Other Accounts	[1]			53
Balance at End of Period		$ 3,647	$ 8,212	$ 7,905

[1] Changes in the deferred tax valuation allowance which have been charged to other accounts have been recorded in other comprehensive loss.