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Commitments and Contingencies - Additional Information (Detail)
$ in Millions
 1 Months Ended
Jul. 23, 2015
USD ($)
Jan. 31, 2015
Drilling_Units
Jun. 30, 2018
USD ($)
Rigs
Contract
Dec. 31, 2017
USD ($)
Long-term Purchase Commitment [Line Items]        
Number of new building contracts | Contract     8  
Purchase commitments     $ 1,683 $ 1,700
Number of new building contracts for jack up rigs | Rigs     8  
Rosneft Transaction [Member]        
Long-term Purchase Commitment [Line Items]        
Loss contingency, estimated backlog of transaction $ 4,100      
Patent Infringement [Member]        
Long-term Purchase Commitment [Line Items]        
Number of drilling rigs | Drilling_Units   1