Equity Investments (Details) $ in Thousands	1 Months Ended	9 Months Ended
	Jul. 31, 2015 USD ($)	Sep. 30, 2015 USD ($) equity_investment ft	Dec. 31, 2014 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of equity investments | equity_investment		2
Equity investments in unconsolidated affiliates		$ 143,481	$ 149,623
Business combination, consideration transferred	$ 1,500,000
Deepwater Gateway, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%
Equity investments in unconsolidated affiliates		$ 77,500	80,900
Capitalized interest		$ 1,200	1,200
Independence Hub, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		20.00%
Equity investments in unconsolidated affiliates		$ 66,000	68,800
Capitalized interest		$ 3,700	$ 3,900
Water depth | ft		8,000