Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v2.4.0.6
Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
3 Months Ended 12 Months Ended
Dec. 31, 2012
Rigs
Country
Sep. 30, 2012
Jun. 30, 2012
Mar. 31, 2012
Dec. 31, 2011
Sep. 30, 2011
Jun. 30, 2011
Mar. 31, 2011
Dec. 31, 2012
Customer
Rigs
Country
Dec. 31, 2011
Dec. 31, 2010
Revenue, Major Customer [Line Items]                      
Number of countries with operations 12               12    
Number of countries in which Entity has operated since inception 50               50    
Barge drilling rigs 14               14    
Land rings 24               24    
Percentage accounted for under the equity method 50.00%               50.00%    
Reimbursement cost                 $ 44,900,000 $ 64,200,000 $ 40,100,000
Foreign currency translation impact over net income and retained earnings                     6,400,000
Collection period                 90 days    
Capitalized interest costs of construction of rigs                 10,200,000 19,300,000 13,500,000
Net assets held for sale including current asset 11,550,000       5,315,000       11,550,000 5,315,000  
Consumed and replenished period                 1 year    
Rate of recognized income tax position being realized                 50.00%    
Deposits in domestic bank 12,200,000       10,200,000       12,200,000 10,200,000  
Deposits in foreign banks 34,500,000       38,400,000       34,500,000 38,400,000  
Number of major customer                 2    
Construction revenue                   335,500,000 325,900,000
Contract margin 16,405,000 34,038,000 46,440,000 54,018,000 44,399,000 49,966,000 40,797,000 21,204,000 150,901,000 156,366,000 73,167,000
Share-based awards vesting period                 3 years    
Liberty Rig Construction Contract [Member]
                     
Revenue, Major Customer [Line Items]                      
Contract margin                   $ 11,700,000  
Exxon Neftegas Limited (ENL) [Member]
                     
Revenue, Major Customer [Line Items]                      
Percentage of revenue from major customer                 11.80%    
Dowell Schlumberger [Member]
                     
Revenue, Major Customer [Line Items]                      
Percentage of revenue from major customer                 10.40%