Equity Investments - Distributions from Equity Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	$ 0	$ 2,140	$ 1,200	$ 3,540
Deepwater Gateway, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	0	1,700	1,200	2,700
Independence Hub, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	$ 0	$ 440	$ 0	$ 840