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Restricted Cash - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2012
Dec. 31, 2011
Restricted Cash and Cash Equivalents Items [Line Items]    
Surety, payment and performance bonds $ 35.1  
Collateral payment for performance bonds 10.5  
Collateral related to workers compensation policy $ 2.3 $ 2.3