Recent Accounting Pronouncements - Additional Information (Details)					1 Months Ended	3 Months Ended		6 Months Ended
	Dec. 09, 2018 t $ / d	May 04, 2018 t $ / d	Apr. 28, 2017 t $ / d	Oct. 15, 2015 USD ($)	Nov. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) t	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) contract t	Jun. 30, 2018 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of contracts | contract								5
Dead weight tonnage of operating fleet | t						2,615,519		2,615,519
Fair value below contract value of time charters acquired											$ 1,800,000
Operating lease right-of-use assets						$ 22,462,057		$ 22,462,057		$ 28,705,002
Operating lease, liability						23,944,324		23,944,324
Cash paid on operating leases						$ 3,700,000		$ 7,400,000
Weighted average remaining lease term						25 years 4 months 6 days		25 years 4 months 6 days
Rent expense							$ 188,048		$ 340,470
Revenue recognized relating to performance obligations satisfied in prior periods						$ 5,200,000		$ 6,900,000
Performance obligation, timing of expectation								The voyage contract generally has standard payment terms of 95% freight paid within three days after completion of loading.
Deferred costs						200,000		$ 200,000
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets										28,700,000
Operating lease, liability										30,500,000
Letter of Credit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash, cash equivalents				$ 74,917
Chartered-in contracts greater than 12 months
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of contracts | contract								3
Operating lease right-of-use assets						20,194,474		$ 20,194,474		26,144,409
Operating lease, liability						$ 21,676,741		$ 21,676,741
2013 Built Japanese Vessel
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Dead weight tonnage of operating fleet | t			61,400
Charters agreement term			4 years
Charters agreement term, extension option			2 years
2013 Built Japanese Vessel | First Four Years
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vessel hiring rate (in dollars per day) | $ / d			12,800
2013 Built Japanese Vessel | First Optional Year
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vessel hiring rate (in dollars per day) | $ / d			13,800
2013 Built Japanese Vessel | Second Optional Year
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vessel hiring rate (in dollars per day) | $ / d			14,300
2013 Built Ultramax Vessel
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Dead weight tonnage of operating fleet | t		61,425				61,400		61,400
Charters agreement term		3 years						2 years
Charters agreement term, extension option		2 years
2013 Built Ultramax Vessel | First Optional Year
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vessel hiring rate (in dollars per day) | $ / d		13,750
2013 Built Ultramax Vessel | Second Optional Year
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vessel hiring rate (in dollars per day) | $ / d		14,750
2013 Built Ultramax Vessel | First Three Years
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vessel hiring rate (in dollars per day) | $ / d		12,700
2016 Built Ultramax Vessel
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Dead weight tonnage of operating fleet | t	62,487
Charters agreement term	2 years
2016 Built Ultramax Vessel | First Two Years
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vessel hiring rate (in dollars per day) | $ / d	14,250
2016 Built Ultramax Vessel | Third Year Option
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vessel hiring rate (in dollars per day) | $ / d	15,250
Office leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of contracts | contract								2
Operating lease right-of-use assets						$ 2,267,583		$ 2,267,583		$ 2,560,593
Operating lease, liability						$ 2,267,583		$ 2,267,583
Office leases | Lease Agreement for Office Space in Stamford
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Average annual rent expense				$ 400,000
Office leases | Singapore Lease Arrangement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Average annual rent expense					$ 300,000
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, term of contract						30 days		30 days
Incremental borrowing rate						5.05%		5.05%
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, term of contract						2 years		2 years
Incremental borrowing rate						6.08%		6.08%