Quarterly report pursuant to Section 13 or 15(d)

General (Details Textual)

v2.4.0.6
General (Details Textual) (USD $)
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2012
Rigs
Jun. 30, 2011
Jun. 30, 2012
Rigs
Jun. 30, 2011
Dec. 31, 2011
Segment
Region
General (Textual) [Abstract]          
Barge drilling rigs 15   15    
Land rings 25   25    
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 $ 10,100,000 $ 20,800,000 $ 17,700,000 $ 35,000,000  
Deposits in domestic banks in excess of federally insured limits 15,300,000   15,300,000   10,200,000
Deposits in foreign banks uninsured 38,600,000   38,600,000   38,400,000
Construction revenue         335,500,000
Contract margin 46,440,000 40,797,000 100,458,000 62,001,000 11,700,000
Number of AADU rigs     2    
Interest costs capitalized $ 3,000,000 $ 4,700,000 $ 5,400,000 $ 9,200,000  
Customer One [Member]
          
Revenue from customers          
Percentage of two customer contribution     9.90%    
Customer Two [Member]
          
Revenue from customers          
Percentage of two customer contribution     9.50%