Leases (Schedule Of Rent Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property Subject To Or Available for Operating Lease [Line Items]
Rental expense	$ 131,215	$ 116,348	$ 93,425
Other Buildings and Equipment [Member]
Property Subject To Or Available for Operating Lease [Line Items]
Rental expense	9,952	8,156	5,334
Tank Barges [Member] | Marine Equipment [Member]
Property Subject To Or Available for Operating Lease [Line Items]
Rental expense	23,835	16,396	9,075
Towing Vessels [Member] | Marine Equipment [Member]
Property Subject To Or Available for Operating Lease [Line Items]
Rental expense	$ 97,428	$ 91,796	$ 79,016