Annual report pursuant to Section 13 and 15(d)

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

v3.10.0.1
Business and Credit Concentrations - Company's Top Five Manufacturers Produced (Detail) - Cost of Goods, Total [Member] - Supplier Concentration Risk [Member]
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Concentration Risk [Line Items]      
Percentage of total production 41.90% 47.50% 51.00%
Manufacturer One [Member]      
Concentration Risk [Line Items]      
Percentage of total production 12.80% 17.90% 22.90%
Manufacturer Two [Member]      
Concentration Risk [Line Items]      
Percentage of total production 10.10% 11.10% 10.10%
Manufacturer Three [Member]      
Concentration Risk [Line Items]      
Percentage of total production 8.60% 8.80% 8.80%
Manufacturer Four [Member]      
Concentration Risk [Line Items]      
Percentage of total production 5.40% 5.40% 4.90%
Manufacturer Five [Member]      
Concentration Risk [Line Items]      
Percentage of total production 5.00% 4.30% 4.30%