Impairment Of Long Lived Assets (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2014 item	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Number of vessels held for sale	5
Impairment charges		$ 38,213,000
Tanker [Member]
Property, Plant and Equipment [Line Items]
Number of vessels held for sale	1
Tanker [Member] | Specialty Contracts [Member]
Property, Plant and Equipment [Line Items]
Impairment charges	3,300,000
Fair value less cost to sell	1,500,000	1,500,000
Total original carrying value prior to impairment	4,800,000	4,800,000
Handysize Bulk Carriers [Member]
Property, Plant and Equipment [Line Items]
Number of vessels held for sale	3	3
Fair value less cost to sell	48,700,000	48,700,000
Handysize Bulk Carriers [Member] | Dry Bulk Carriers [Member]
Property, Plant and Equipment [Line Items]
Impairment charges	28,300,000
Fair value less cost to sell	49,200,000	49,200,000
Total original carrying value prior to impairment	77,500,000	77,500,000
Tug-Barge Unit [Member]
Property, Plant and Equipment [Line Items]
Number of vessels held for sale	1
Fair value less cost to sell	6,400,000	6,400,000
Tug-Barge Unit [Member] | Jones Act [Member]
Property, Plant and Equipment [Line Items]
Impairment charges	6,600,000
Fair value less cost to sell	6,400,000	6,400,000
Total original carrying value prior to impairment	13,000,000	$ 13,000,000