Quarterly report pursuant to Section 13 or 15(d)

General - Additional Information (Detail)

v2.4.0.6
General - Additional Information (Detail) (USD $)
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2012
Rigs
Sep. 30, 2011
Sep. 30, 2012
Rigs
Sep. 30, 2011
Dec. 31, 2011
Region
Segment
Revenue, Major Customer [Line Items]          
Barge drilling rigs 15   15    
Land rings 24   24    
Number of operating segments         6
Number of drilling units representing segment         2
Number geographic regions before consolidation         3
Number geographic regions after consolidation         2
Percentage accounted for under the equity method 50.00%   50.00%    
Reimbursement cost $ 12,100,000 $ 11,900,000 $ 29,800,000 $ 46,900,000  
Deposits in domestic banks in excess of federally insured limits 10,800,000   10,800,000   10,200,000
Deposits in foreign banks uninsured 31,900,000   31,900,000   38,400,000
Construction revenue         335,500,000
Contract margin 34,038,000 49,966,000 134,496,000 111,969,000 11,700,000
Number of AADU rigs     2    
Interest costs capitalized $ 2,500,000 $ 5,000,000 $ 7,900,000 $ 14,100,000  
Customer One
          
Revenue, Major Customer [Line Items]          
Percentage of two customer contribution     10.60%    
Customer Two
          
Revenue, Major Customer [Line Items]          
Percentage of two customer contribution     10.20%