Financial Instruments and Fair Value Disclosures (Carry and FV) (Details) - USD ($)	Sep. 30, 2018	Mar. 31, 2018
Fair value
Carry Value	$ 726,536,136	$ 759,103,152
Corsair Japanese Financing
Fair value
Carry Value	49,020,833	50,645,833
Corsair Japanese Financing | Level 2
Fair value
Fair Value	45,410,069	50,645,833
Concorde Japanese Financing
Fair value
Carry Value	53,576,923	55,192,308
Concorde Japanese Financing | Level 2
Fair value
Fair Value	49,330,698	55,192,308
Corvette Japanese Financing
Fair value
Carry Value	54,115,385	55,730,769
Corvette Japanese Financing | Level 2
Fair value
Fair Value	49,792,999	$ 55,730,769
CJNP Japanese Financing
Fair value
Carry Value	21,230,000
CJNP Japanese Financing | Level 2
Fair value
Fair Value	20,993,639
CMNL Japanese Financing
Fair value
Carry Value	20,130,942
CMNL Japanese Financing | Level 2
Fair value
Fair Value	19,894,012
CNML Japanese Financing
Fair value
Carry Value	22,369,038
CNML Japanese Financing | Level 2
Fair value
Fair Value	$ 22,098,229