Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues, net	$ 74,110,376	$ 69,092,740	$ 220,891,288	$ 223,402,049
Voyage expenses	19,446,294	15,126,287	66,259,590	54,845,843
Vessel expenses	19,953,680	19,568,961	60,005,794	61,224,734
Charter hire expenses	11,345,615	7,459,921	34,017,002	27,836,243
Depreciation and amortization	10,055,938	9,460,192	29,224,368	28,009,067
General and administrative expenses	8,450,831	8,882,790	24,901,561	27,692,259
Gain on sale of vessels	(971,129)	(235,695)	(6,044,479)	(340,768)
Total operating expenses	68,281,229	60,262,456	208,363,836	199,267,378
Operating income	5,829,147	8,830,284	12,527,452	24,134,671
Interest expense	8,117,293	6,574,826	21,612,451	19,222,906
Interest income	(640,220)	(130,020)	(1,467,702)	(337,248)
Loss on debt extinguishment	0	0	2,268,452	0
Other expense/(income)	2,915,063	(199,344)	639,913	(839,321)
Total other expense, net	10,392,136	6,245,462	23,053,114	18,046,337
Net (loss)/income	$ (4,562,989)	$ 2,584,822	$ (10,525,662)	$ 6,088,334
Weighted average shares outstanding:
Basic (in shares)	71,349,895	70,649,556	71,327,454	70,539,951
Diluted (in shares)	71,349,895	72,356,655	71,327,454	71,855,683
Per share amounts:
Basic net (loss)/income (in usd per share)	$ (0.06)	$ 0.04	$ (0.15)	$ 0.09
Diluted net (loss)/income (in usd per share)	$ (0.06)	$ 0.04	$ (0.15)	$ 0.08