Derivative Instruments and Fair Value Measurements - Derivative Instruments Not Designated As Hedging Instruments (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, location of (gain)/loss recognized	$ (199,344)	$ 647,457	$ (839,321)	$ (138,206)
FFAs | Other current assets
Derivative Instruments, Gain (Loss) [Line Items]
Collateral related to derivative instruments under collateral security arrangements	737,201		737,201		$ 178,836
FFAs | Derivatives not designated as hedging instruments | Fair value of derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, balance sheet location, fair value of derivatives	585,795		585,795		73,170
FFAs | Derivatives not designated as hedging instruments | Other current assets
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, balance sheet location, total	10,530		10,530		0
FFAs | Other expense/(income) | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, location of (gain)/loss recognized	163,848	862,224	246,280	73,509
Bunker Swaps | Derivatives not designated as hedging instruments | Other current assets
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, balance sheet location, total	683,446		683,446		$ 128,845
Bunker Swaps | Other expense/(income) | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, location of (gain)/loss recognized	$ (363,192)	$ (214,767)	$ (1,085,601)	$ (211,715)