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Commitments and Contingencies (Brazilian Customs) - Additional Information (Detail)
R$ in Millions, $ in Millions
 1 Months Ended 9 Months Ended
May 31, 2016
BRL (R$)
Apr. 30, 2011
BRL (R$)
Vessel
Dec. 31, 2017
USD ($)
Dec. 31, 2017
BRL (R$)
Commitments And Contingencies Disclosure [Abstract]        
Fines assessed   R$ 155 $ 46.8  
Number of Tidewater vessels that the subsidiaries failed to obtain import licenses from | Vessel   17    
Fines assessed R$ 3   0.9  
Deposit Amount     1.8 R$ 6
Amount of fines contested     9.1 30
Remaining amount of fine resolved in entity favor     $ 36.8 122
Original fine amount | R$       R$ 155