Other Debt - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Trade payable, interest bearing interest rate	12.00%	12.00%
Trade payable in accounts payable	$ 600,000	$ 600,000
Collateral asset carrying value	0	0
Proceeds from sale of marine equipment		1,003,662	$ 50,000
Magellan Offshore Services Ltd [Member] \| Marine Equipment [Member]
Debt Instrument [Line Items]
Proceeds from sale of marine equipment	1,000,000
Gain recognized from sale of marine equipment	900,000
Contingent liability	$ 500,000	$ 500,000
Collateral Agreement [Member]
Debt Instrument [Line Items]
Debt instrument maturity date		Aug. 31, 2018

Collateral asset carrying value.

No definition available.

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- Definition

Contingent Liability

+ References

No definition available.

+ Details

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- Definition

Reflects the effective interest rate as of the balance sheet date on interest-bearing trade payables.

+ References

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-Publisher FASB
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- Definition

Carrying value as of the balance sheet date of obligations incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

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