Annual report pursuant to Section 13 and 15(d)

Business And Credit Concentrations - Company's Top Five Manufacturers Produced (Detail)

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Business And Credit Concentrations - Company's Top Five Manufacturers Produced (Detail)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Concentration Risk [Line Items]      
Total manufacturers produced 61.60% 62.50% 70.60%
Company's Top Five Manufacturers Produced [Member]
     
Concentration Risk [Line Items]      
Manufacturer #1 33.50% 30.80% 34.70%
Manufacturer #2 9.20% 11.50% 13.00%
Manufacturer #3 6.70% 7.70% 9.40%
Manufacturer #4 6.60% 6.60% 8.70%
Manufacturer #5 5.60% 5.90% 4.80%