Equity Investments (Details) (USD $)	9 Months Ended
	Sep. 30, 2014 entity	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Number of equity investments	2
Equity investments in unconsolidated affiliates	$ 152,588,000	$ 157,919,000
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	82,400,000	85,800,000
Capitalized interest	1,200,000	1,300,000
Independence Hub, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	20.00%
Equity investments in unconsolidated affiliates	70,200,000	72,100,000
Capitalized interest	$ 4,000,000	$ 4,300,000
Water depth	8,000