Revenues (Details) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Revenues.
Net pool revenues—related party	$ 31,610,427	$ 22,301,512	$ 80,554,166	$ 80,798,208
Time charter revenues	12,498,849	11,921,875	37,570,898	36,919,910
Voyage charter revenues	335,244	1,296,952	2,068,491	1,296,952
Other revenues, net	101,069	214,649	106,527	846,927
Total revenues	$ 44,545,589	$ 35,734,988	$ 120,300,082	$ 119,861,997