Investments in Non-Consolidated Subsidiaries Investments in Non-Consolidated Subsidiaries - Summarized financial information - Glass Mountain (Details) (Glass Mountain Pipeline LLC [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Glass Mountain Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Revenue	$ 3,853
Equity Method Investment, Summarized Financial Information, Operating, General and Administrative Expenses	850
Equity Method Investment, Summarized Financial Information, Depreciation and Amortization Expense	2,348
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	$ 653