Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Accumulated depreciation, vessels	$ 86,324,808	$ 76,463,743
Accumulated amortization, other fixed assets	$ 382,736	$ 307,880
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)	700,000,000	700,000,000
Common stock, issued (in shares)	70,329,050	48,106,827
Common stock, outstanding (in shares)	70,329,050	48,106,827