Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010	Sep. 30, 2011		Sep. 30, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable security gains (losses), net include losses	$ 5,200,000		$ 1,000,000	$ 12,900,000		$ 100,000
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	45,471,000	[1]		45,471,000	[1]
Derivative instruments (included in other receivables)	2,415,000			2,415,000
Construction reserve funds and Title XI reserve funds	298,345,000			298,345,000
Short sale of marketable securities (included in other current liabilities)	32,176,000			32,176,000
Derivative instruments (included in other current liabilities)	11,550,000			11,550,000
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	37,507,000	[1]		37,507,000	[1]
Derivative instruments (included in other receivables)	4,235,000			4,235,000
Construction reserve funds and Title XI reserve funds
Short sale of marketable securities (included in other current liabilities)
Derivative instruments (included in other current liabilities)	12,617,000			12,617,000
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		[1]			[1]
Derivative instruments (included in other receivables)
Construction reserve funds and Title XI reserve funds
Short sale of marketable securities (included in other current liabilities)
Derivative instruments (included in other current liabilities)

[1] Marketable security gains (losses), net include losses of $5.2 million and gains of $1.0 million for the three months ended September 30, 2011 and 2010, respectively, related to marketable security positions held by the Company as of September 30, 2011. Marketable security losses, net include losses of $12.9 million and $0.1 million for the nine months ended September 30, 2011 and 2010, respectively, related to marketable security positions held by the Company as of September 30, 2011.