Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Property, Plant and Equipment [Line Items]
Operating expenses	$ 5,199,915	$ 12,534,766	$ 15,429,728	$ 21,205,021
Ratio of remaining net proceed			0.25
Percentage Of Cash Proceeds From Monetization Of Recovered Cargo			80.00%
Percentage of subsequent cash proceeds after reimbursement			45.00%
Short-term investment maturity period			Three months or less
Securities owned	0		0
Weighted average number of common shares outstanding	84,898,133	79,345,030	84,420,661	78,350,236
Gairsoppa [Member]
Property, Plant and Equipment [Line Items]
Operating expenses			$ 0
Receiver [Member]
Property, Plant and Equipment [Line Items]
Percentage Of Cash Proceeds From Monetization Of Recovered Cargo			20.00%
Percentage of subsequent cash proceeds after reimbursement			55.00%
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, estimated useful life			3 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, estimated useful life			10 years