Leases (assets and liabilities) (Details)	3 Months Ended
	Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)
Leases
Number of option period for time charter | item	0
Operating lease liabilities - Time Charter in VLGCs	$ 23,700,000
Weighted average discount rate (as a percent)	3.88%
Weighted average remaining lease term	30 months 27 days
Operating lease right-of-use assets - Office Leases	$ 915,257
Operating lease right-of-use assets - Time Charter in VLGCs	23,687,426
Operating lease liabilities current - Office Leases	409,507
Operating lease liabilities current - Time Charter in VLGCs	8,898,201
Operating lease liabilities non-current - Office Leases	508,524
Operating lease liabilities non-current - Time Charter in VLGCs	14,789,225
Charter hire expense
Leases
Operating lease income	$ 6,900,000	$ 1,300,000
Minimum
Leases
Weighted average discount rate (as a percent)	3.82%
Maximum
Leases
Weighted average discount rate (as a percent)	5.53%