Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Accumulated depreciation, vessels (in Dollars)	$ 351,835,709	$ 314,700,681
Accumulated amortization, other fixed assets (in Dollars)	$ 606,606	$ 515,896
Preferred stock par value (in Dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in Shares)	25,000,000	25,000,000
Preferred stock, shares issued (in Shares)	0	0
Common stock par value (in Dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in Shares)	100,000,000	100,000,000
Common stock, shares issued (in Shares)	16,658,417	16,638,092
Common stock, shares outstanding (in Shares)	16,658,417	16,638,092