Condensed Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income/(loss)	$ 3,503,512	$ (16,956,914)
Adjustments to reconcile net income/(loss) to net cash provided by/(used in) operating activities:
Depreciation	16,049,334	13,538,266
Amortization of deferred drydocking costs	2,499,541	1,975,139
Amortization of debt issuance costs	970,352	2,901,948
Amortization of fair value below contract value of time charter acquired	(340,950)	(375,833)
Payment-in-kind interest on debt	0	4,977,219
Net unrealized gain on fair value of derivative instruments	(234,988)	(736,609)
Stock-based compensation expense	5,920,510	4,648,751
Drydocking expenditures	(4,632,000)	(341,350)
Gain on sale of vessels	(105,073)	(1,897,899)
Fees paid on time charter termination	0	(1,500,000)
Changes in operating assets and liabilities:
Accounts receivable	4,173,849	(6,172,147)
Other current and non-current assets	(333,715)	(1,125,809)
Prepaid expenses	213,117	28,848
Inventories	2,201,681	(1,693,827)
Accounts payable	652,934	705,907
Accrued interest	(57,037)	(15,217)
Other accrued and other non-current liabilities	(3,332,732)	(3,593,657)
Unearned revenue	(2,360,838)	369,955
Net cash provided by/(used in) operating activities	24,787,497	(5,263,229)
Cash flows from investing activities:
Purchase of vessels and vessel improvements	(20,301,806)	(121,331,815)
Advance paid for purchase of vessel	0	(20,863,466)
Proceeds from redemption of Short-term investment	4,500,000	0
Proceeds from sale of vessels	9,719,013	10,586,500
Purchase of other fixed assets	(50,933)	(204,348)
Net cash used in investing activities	(6,133,726)	(131,813,129)
Cash flows from financing activities:
Proceeds from the common stock private placement, net of issuance costs	0	96,030,003
Cash received from exercise of stock options	4,865	0
Cash used to settle net share equity awards	(255,114)	0
Financing costs paid to the lender - Ultraco Debt Facility	0	(918,000)
Other financing costs	(1,373,449)	(575,000)
Net cash provided by financing activities	1,976,302	129,243,753
Net increase/(decrease) in cash and cash equivalents and restricted cash	20,630,073	(7,832,605)
Cash and cash equivalents and restricted cash at beginning of period	56,325,961	76,591,027
Cash and cash equivalents and restricted cash at end of period	76,956,034	68,758,422
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid during the year for interest	11,734,765	5,338,742
Ultraco Debt Facility
Cash flows from financing activities:
Proceeds from Ultraco Debt Facility	8,600,000	40,000,000
Term Loan
Cash flows from financing activities:
Repayments of lines of credit	0	(5,293,250)
Revolver Loan
Cash flows from financing activities:
Repayments of lines of credit	$ (5,000,000)	$ 0