Annual report pursuant to Section 13 and 15(d)

Schedule II - Valuation and Qualifying Accounts (Detail)

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Schedule II - Valuation and Qualifying Accounts (Detail) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Allowance for doubtful accounts and notes [Member]
      
Valuation and Qualifying Accounts Disclosure [Line Items]      
Balance at beginning of year $ 1,544 $ 7,020 $ 4,095
Charged to cost and expenses 4,264 2,258 3,244
Charged to other accounts 3,195 (2,034) (211)
Deductions (886) (5,700) (108)
Balance at end of year 8,117 1,544 7,020
Allowance for obsolete rig materials and supplies [Member]
      
Valuation and Qualifying Accounts Disclosure [Line Items]      
Balance at beginning of year 316 309  
Charged to cost and expenses   26 309
Deductions (4) (19)  
Balance at end of year 312 316 309
Deferred tax valuation allowance [Member]
      
Valuation and Qualifying Accounts Disclosure [Line Items]      
Balance at beginning of year 6,467 5,532 5,194
Charged to cost and expenses (1,662) 2,542 338
Charged to other accounts   (1,607)  
Balance at end of year $ 4,805 $ 6,467 $ 5,532