Note 6 - Derivative Instruments and Fair Value Measurements - Effect of Non-designated Derivative Instruments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Derivative Instruments Not Designated as Hedging Instruments, (Gain) Loss	$ (1,092,222)	$ 300,785	$ (785,663)	$ 300,785
Derivative Instruments Not Designated as Hedging Instruments, Asset, Fair value	736,609		736,609
Forward Freight Agreements [Member] | Other Current Assets [Member]
Derivative Instruments Not Designated as Hedging Instruments, Asset, Fair value	725,850		725,850
Forward Freight Agreements [Member] | Other Expense [Member]
Derivative Instruments Not Designated as Hedging Instruments, (Gain) Loss	(1,049,363)	300,785	(788,715)	300,785
Bunker Swaps [Member] | Other Current Assets [Member]
Derivative Instruments Not Designated as Hedging Instruments, Asset, Fair value	10,759		10,759
Bunker Swaps [Member] | Other Expense [Member]
Derivative Instruments Not Designated as Hedging Instruments, (Gain) Loss	$ (42,859)		$ 3,052