Equity Investments - Distributions from Equity Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	$ 7,000	$ 8,790	$ 12,260
Deepwater Gateway, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	5,200	6,150	7,600
Independence Hub, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	$ 1,800	$ 2,640	$ 4,660