Leases (Schedule Of Rent Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property Subject To Or Available for Operating Lease [Line Items]
Rental expense	$ 165,257	$ 156,016	$ 131,215
Other Buildings and Equipment [Member]
Property Subject To Or Available for Operating Lease [Line Items]
Rental expense	9,146	10,298	9,952
Tank Barges [Member] | Marine Equipment [Member]
Property Subject To Or Available for Operating Lease [Line Items]
Rental expense	19,780	20,841	23,835
Towing Vessels [Member] | Marine Equipment [Member]
Property Subject To Or Available for Operating Lease [Line Items]
Rental expense	$ 136,331	$ 124,877	$ 97,428