Equity Investments - Distributions from Equity Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	$ 0	$ 1,760	$ 1,200	$ 5,300
Deepwater Gateway, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	0	1,200	1,200	3,900
Independence Hub, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments	$ 0	$ 560	$ 0	$ 1,400