Leases (assets and liabilities) (Details)	3 Months Ended		6 Months Ended
	Sep. 30, 2021 USD ($) item	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) item	Sep. 30, 2020 USD ($)	Mar. 31, 2021 USD ($)
Leases
Number of option period for time charter | item	0		0
Operating lease liabilities - Time Charter in VLGCs	$ 12,500,000		$ 12,500,000
Operating Lease, Expense	$ 164,334	$ 143,608	$ 316,010	$ 261,867
Weighted average discount rate (as a percent)	3.88%		3.88%
Weighted average remaining lease term	15 months 27 days		15 months 27 days
Operating lease right-of-use assets - Office Leases	$ 415,802		$ 415,802
Operating lease right-of-use assets - Time Charter in VLGCs	12,512,980		12,512,980
Operating lease liabilities current - Office Leases	341,055		341,055
Operating lease liabilities current - Time Charter in VLGCs	9,325,942		9,325,942
Operating lease liabilities non-current - Office Leases	65,819		65,819
Operating lease liabilities non-current - Time Charter in VLGCs	3,187,038		3,187,038
Operating lease right-of-use assets	12,928,782		12,928,782		$ 17,672,227
Operating lease liability	12,919,854		12,919,854
Charter hire expense
Leases
Operating lease income	$ 2,700,000	$ 4,600,000	$ 6,900,000	$ 11,500,000
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%