Quarterly report pursuant to Section 13 or 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]
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Concentration Risk [Line Items]        
Percentage of total production 39.90% 51.60% 43.20% 51.70%
Manufacturer One [Member]        
Concentration Risk [Line Items]        
Percentage of total production 11.20% 20.00% 12.10% 21.10%
Manufacturer Two [Member]        
Concentration Risk [Line Items]        
Percentage of total production 9.00% 11.00% 11.50% 11.00%
Manufacturer Three [Member]        
Concentration Risk [Line Items]        
Percentage of total production 8.80% 8.10% 8.70% 8.60%
Manufacturer Four [Member]        
Concentration Risk [Line Items]        
Percentage of total production 5.80% 6.30% 5.90% 6.00%
Manufacturer Five [Member]        
Concentration Risk [Line Items]        
Percentage of total production 5.10% 6.20% 5.00% 5.00%