Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Fair Value, Inputs, Level 1 [Member]		Jun. 30, 2012 Fair Value, Inputs, Level 2 [Member]		Jun. 30, 2012 Fair Value, Inputs, Level 3 [Member]	Apr. 02, 2012 Trailer Bridge Inc [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities					$ 32,759,000	[1]	$ 62,000	[1]	$ 0
Derivative instruments (included in other receivables)					1,510,000		5,408,000		0
Construction reserve funds and Title XI reserve funds					192,420,000		0		0
Short sales of marketable securities					13,507,000		138,000		0
Derivative instruments (included in other current liabilities)					8,029,000		8,064,000		0
Marketable security gains (losses), net include losses	$ 200,000	$ (1,800,000)	$ 2,600,000	$ (4,100,000)
Debt Instrument, Interest Rate, Stated Percentage										9.25%
Equity Method Investment, Ownership Percentage										47.30%

[1] Marketable security gains (losses), net include unrealized gains of $0.2 million and losses of $1.8 million for the three months ended June 30, 2012 and 2011, respectively, related to marketable security positions held by the Company as of June 30, 2012. Marketable security gains (losses), net include unrealized gains of $2.6 million and losses of $4.1 million for the six months ended June 30, 2012 and 2011, respectively, related to marketable security positions held by the Company as of June 30, 2012.