XML 75 R63.htm IDEA: XBRL DOCUMENT v3.8.0.1
Commitments and Contingencies (Sonatide Joint Venture) - Additional Information (Detail)
$ in Thousands
 2 Months Ended 4 Months Ended 6 Months Ended 12 Months Ended
Jul. 31, 2017
USD ($)
Vessel
Sep. 30, 2017
USD ($)
Vessel
Jul. 31, 2017
USD ($)
Vessel
Sep. 30, 2016
USD ($)
Vessel
Mar. 31, 2017
USD ($)
Vessel
Commitments and Contingencies Disclosure [Line Items]          
Due from affiliate   $ 245,056      
Due to affiliate   112,642      
Commissions payable [1]   2,139      
Vessel revenues   70,571      
Investments in, at equity, and advances to unconsolidated companies   25,729      
Sonatide joint venture          
Commitments and Contingencies Disclosure [Line Items]          
Due from affiliate   245,000     $ 263,000
Unpaid vessel revenue   39,000      
Due to affiliate   113,000     133,000
Commissions payable   34,400      
Due from affiliate and due to affiliate   $ 12,000 $ 21,000    
Number of vessels operating | Vessel   7      
Number of vessels stacked | Vessel   4      
Ownership Interest In Joint Venture   49.00%      
Investments in, at equity, and advances to unconsolidated companies   $ 24,000     $ 45,000
Investment balance in difference between carrying value and net assets of the joint venture $ 27,900   27,900    
Amortization period of basis difference equity method investments 10 years        
Sonatide joint venture | ANGOLA          
Commitments and Contingencies Disclosure [Line Items]          
Proceeds from related party   9,000 22,000    
Vessel revenues   $ 14,000 $ 34,000 $ 71,400  
Percentage of Angolan operation revenue   20.00% 23.00% 24.00%  
Number of vessels operating | Vessel 50 44 50 59  
Number of vessels stacked | Vessel 21 16 21 17  
Number of vessels transferred out of Angola | Vessel   1 4   22
Sonatide joint venture | U.S. dollars initially received by Sonatide on behalf of the company or dollars collected from other customers          
Commitments and Contingencies Disclosure [Line Items]          
Proceeds from related party   $ 8,000 $ 19,000    
Sonatide joint venture | Sonatide's converting kwanzas into dollars and subsequent payment to company          
Commitments and Contingencies Disclosure [Line Items]          
Proceeds from related party   1,000 $ 3,000    
Sonatide joint venture | Angolan kwanza-denominated          
Commitments and Contingencies Disclosure [Line Items]          
Bank deposits maintained   $ 91,000      
[1] Excludes $34.4 million and $34.7 million of commissions due to Sonatide at September 30, 2017 and March 31, 2017, respectively. These amounts are included in amounts due to affiliate.