Schedule II Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Valuation and Qualifying Accounts Disclosure [Line Items]
Charged to Costs and Expenses	$ 624
Charged to Other Accounts	53
Allowance for Affiliate Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	6,692		5,246	4,037
Charged to Costs and Expenses			1,446	1,209
Balance at End of Period	6,692		6,692	5,246
Deferred Tax Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	7,228		7,108	10,887
Charged to Costs and Expenses	624		120	(3,779)
Charged to Other Accounts	53	[1]
Balance at End of Period	$ 7,905		$ 7,228	$ 7,108

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