XML 49 R35.htm IDEA: XBRL DOCUMENT v3.7.0.1
Investments in Unconsolidated Entities - Additional Information (Detail) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2017
Dec. 31, 2012
Dec. 31, 2016
Chatham Rock Phosphate, Ltd. [Member]      
Schedule of Equity Method Investments [Line Items]      
Investment carrying value   $ 0  
Deep sea mining exploratory services   $ 1,680,000  
Shares received from CRP 141,884 9,320,348  
Outstanding equity stake in CRP 1.00%    
Neptune Minerals, Inc. [Member]      
Schedule of Equity Method Investments [Line Items]      
Ownership percentage 14.00%    
Investment carrying value $ 0   $ 0
Neptune Minerals, Inc. [Member] | Common Class A [Member]      
Schedule of Equity Method Investments [Line Items]      
Shares owned 0    
Neptune Minerals, Inc. [Member] | Common Class B Non Voting Shares [Member]      
Schedule of Equity Method Investments [Line Items]      
Current investment position in NMI 3,092,488    
Aggregate number of shares converted 261,200    
Neptune Minerals, Inc. [Member] | Series A Preferred Non Voting Shares [Member]      
Schedule of Equity Method Investments [Line Items]      
Current investment position in NMI 2,612    
Dorado Ocean Resources, Ltd. [Member]      
Schedule of Equity Method Investments [Line Items]      
Loss from unconsolidated entity     $ 21,300,000