Leases (assets and liabilities) (Details)	3 Months Ended		9 Months Ended
	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)
Leases
Number of option period for time charter | item	0		0
Operating lease liabilities - Time Charter in VLGCs	$ 19,300,000		$ 19,300,000
Weighted average discount rate (as a percent)	3.88%		3.88%
Weighted average remaining lease term	24 months 27 days		24 months 27 days
Operating lease right-of-use assets - Office Leases	$ 750,828		$ 750,828
Operating lease right-of-use assets - Time Charter in VLGCs	19,281,064		19,281,064
Operating lease liabilities current - Office Leases	442,793		442,793
Operating lease liabilities current - Time Charter in VLGCs	9,067,078		9,067,078
Operating lease liabilities non-current - Office Leases	311,188		311,188
Operating lease liabilities non-current - Time Charter in VLGCs	10,213,986		10,213,986
Charter hire expense
Leases
Operating lease income	$ 8,700,000	$ 4,500,000	$ 20,200,000	$ 11,300,000
Minimum
Leases
Weighted average discount rate (as a percent)	3.82%		3.82%
Maximum
Leases
Weighted average discount rate (as a percent)	5.53%		5.53%