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Long-Term Debt - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
9 Months Ended
Sep. 30, 2012
Note payable to affiliate [Member]
 
Debt Instrument [Line Items]  
Repayment of aggregate amount on promissory note payable to affiliate $ 1.8
Repayment of long-term debt $ 1.0
Period end rate of long-term debt 1.50%
Average interest rate on long-term debt 1.50%
Revolving bank credit facility [Member]
 
Debt Instrument [Line Items]  
Period end rate of long-term debt 3.30%
Average interest rate on long-term debt 3.60%