Vessels, Net (Details)	12 Months Ended
	Mar. 31, 2019 USD ($) item	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)
Accumulated depreciation
Vessels, net	$ 1,478,520,314	$ 1,539,111,833
The number of vessels with contracts to purchase exhaust gas cleaning systems | item	10
Vessels
Cost
Balance at the beginning of the period	$ 1,728,987,980	1,728,769,295
Other additions	4,005,830	218,685
Balance at the end of the period	1,732,993,810	1,728,987,980
Accumulated depreciation
Balance at the beginning of the period	(189,876,147)	(125,300,048)
Impairment	0	0
Depreciation	(64,597,349)	(64,576,099)
Balance at the end of the period	(254,473,496)	(189,876,147)
Vessels, net	$ 1,478,520,314	1,539,111,833	$ 1,603,469,247
Number of vessels with capital improvements | item	10
Mortgaged VLGC vessels, carrying value	$ 1,478,500,000	$ 1,539,100,000