Self-Retention Insurance (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Minimum self insurance coverage per incident	$ 150,000
Minimum number of days for loss of hire claims	14 days
Liabilities for self insurance exposure and for claims	4,400,000	5,400,000
Minimum [Member]
Property, Plant and Equipment [Line Items]
Third party insurance coverage per incident	100,000
Maximum [Member]
Property, Plant and Equipment [Line Items]
Third party insurance coverage per incident	250,000
Hull [Member]
Property, Plant and Equipment [Line Items]
Stop loss insurance policy amount	750,000
Machinery [Member]
Property, Plant and Equipment [Line Items]
Stop loss insurance policy amount	$ 750,000