Stockholders' Equity and Dilutive Equity Instruments - Summary of Common Shares and Creditor Warrants and Sum of Common Shares and Creditor Warrants Outstanding (Details) - shares	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Stockholders Equity Note [Line Items]
Common stock, shares outstanding	37,845,158	36,978,280	26,085,274
Total	41,562,540		30,009,715
New Creditor Warrants (Strike Price $0.001 Per Common Share)
Stockholders Equity Note [Line Items]
Creditor Warrants	2,034,235		3,924,441
GulfMark Creditor Warrants (Strike Price $0.01 Per Common Share)
Stockholders Equity Note [Line Items]
Creditor Warrants	1,683,147