Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Fair Value, Inputs, Level 1 [Member]		Sep. 30, 2012 Fair Value, Inputs, Level 2 [Member]		Sep. 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					$ 22,068,000	[1]	$ 66,000	[1]	$ 0
Derivative instruments (included in other receivables)					4,514,000		5,873,000		0
Construction reserve funds and Title XI reserve funds					179,932,000		0		0
Short sales of marketable securities					8,860,000		0		0
Derivative instruments (included in other current liabilities)					3,939,000		7,104,000		0
Marketable security gains (losses), net include losses	$ (2,000,000)	$ (3,700,000)	$ (600,000)	$ (3,200,000)
Debt Instrument, Interest Rate, Stated Percentage										9.25%
Equity Method Investment, Ownership Percentage										47.30%

[1] Marketable security gains (losses), net include unrealized losses of $2.0 million and $3.7 million for the three months ended September 30, 2012 and 2011, respectively, related to marketable security positions held by the Company as of September 30, 2012. Marketable security gains (losses), net include unrealized losses of $0.6 million and $3.2 million for the nine months ended September 30, 2012 and 2011, respectively, related to marketable security positions held by the Company as of September 30, 2012.