Industry Segment and Geographic Data, Customer Concentration (Details) - Customer Concentration Risk [Member] - Customer	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Customer Concentration [Abstract]
Number of largest individual customers	5
Net Sales [Member]
Customer Concentration [Abstract]
Concentration risk, percentage	70.00%	70.00%	70.00%
Net Sales [Member] | Five Largest Individual Customers [Member]
Customer Concentration [Abstract]
Concentration risk, percentage	70.00%	70.00%	70.00%
Net Sales [Member] | O' Reilly [Member]
Customer Concentration [Abstract]
Concentration risk, percentage	22.00%
Net Sales [Member] | NAPA [Member]
Customer Concentration [Abstract]
Concentration risk, percentage	17.00%
Net Sales [Member] | Advance [Member]
Customer Concentration [Abstract]
Concentration risk, percentage	16.00%
Net Sales [Member] | AutoZone [Member]
Customer Concentration [Abstract]
Concentration risk, percentage	11.00%