Derivative Instruments and Fair Value Measurements - Derivative Instruments Not Designated As Hedging Instruments (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 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	$ 100,379	$ 306,559
FFAs | Other current assets
Derivative Instruments, Gain (Loss) [Line Items]
Collateral related to derivative instruments under collateral security arrangements	254,618		$ 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	141,000		73,170
FFAs | Other expense | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, location of (gain)/loss recognized	54,934	306,559
Bunker Swaps | 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, other current assets	11,560		0
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	0		$ 128,845
Bunker Swaps | Other expense | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, location of (gain)/loss recognized	$ 45,445	$ 0