Equity Investments (Distributions From Equity Investments) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Schedule of Equity Method Investments [Line Items]
Distributions from equity investments	$ 26,180	$ 30,008	$ 32,750
Deepwater Gateway [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity investments	7,600	8,125	6,750
Independence Hub [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity investments	18,580	21,615	26,000
Other [Member]
Schedule of Equity Method Investments [Line Items]
Distributions from equity investments		$ 268