Fair Value Measurements (Financial Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Construction Reserve Funds & Title XI Reserve Funds	$ 321,278,000		$ 321,278,000		$ 261,739,000
Marketable security gains (losses), net include losses	9,700,000	(1,200,000)	15,300,000	9,400,000
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	43,286,000		43,286,000
Derivative instruments (included in other receivables)	1,419,000		1,419,000
Construction Reserve Funds & Title XI Reserve Funds	321,278,000		321,278,000
Short sales of marketable securities	10,351,000		10,351,000
Derivative instruments (included in other current liabilities)	3,268,000		3,268,000
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Derivative instruments (included in other receivables)	5,958,000		5,958,000
Construction Reserve Funds & Title XI Reserve Funds	0		0
Short sales of marketable securities	0		0
Derivative instruments (included in other current liabilities)	864,000		864,000
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0		0
Derivative instruments (included in other receivables)	0		0
Construction Reserve Funds & Title XI Reserve Funds	0		0
Short sales of marketable securities	0		0
Derivative instruments (included in other current liabilities)	$ 0		$ 0