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Depreciation, Depletion, Amortization and Impairment Expense Related to Property and Equipment and Intangible Assets (Detail) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Depreciation and Other Amortization Expenses [Line Items]      
Depreciation and impairment expense $ 573,106 $ 502,953 $ 419,183
Amortization expense 3,993 4,110 4,110
Depletion expense 20,370 19,551 13,986
Total $ 597,469 $ 526,614 $ 437,279