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Property and Equipment - Additional Information (Detail) (USD $)
 12 Months Ended
Dec. 31, 2012
Rigs
Dec. 31, 2011
Rigs
Dec. 31, 2010
Rigs
Property, Plant and Equipment [Line Items]      
Impairment charges related to oil and natural gas properties $ 1,900,000 $ 3,000,000 $ 792,000
Number of drilling rigs that would no longer be marketed as rigs 36 53 4
Number of horsepower of pressure pumping equipment that would no longer be marketed 37,000    
Impairment charges on drilling rigs 12,500,000 15,700,000 4,200,000
Proceeds from sale of oil and natural gas properties 42,500,000   22,300,000
Gain on sale of oil and natural gas properties 22,600,000   20,100,000
Contract Drilling Equipments
      
Property, Plant and Equipment [Line Items]      
Proceeds from sale of oil and natural gas properties 10,600,000    
Gain on sale of oil and natural gas properties $ 4,500,000