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Goodwill by Operating Segment (Detail) (USD $)
In Thousands, unless otherwise specified
12 Months Ended 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2011
Contract Drilling
Dec. 31, 2009
Contract Drilling
Dec. 31, 2011
Pressure Pumping
Dec. 31, 2010
Pressure Pumping
Goodwill [Line Items]            
Beginning Balance $ 153,809 $ 86,234 $ 86,234 $ 86,234 $ 67,575  
Changes to goodwill               
Acquisition   67,575       67,575
Ending Balance $ 153,809 $ 153,809 $ 86,234 $ 86,234 $ 67,575 $ 67,575