Revenues (Schedule of Revenues Disaggregated by Product Category) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenue	100.00%	100.00%	100.00%	100.00%
Man-Made Tiles [Member]
Disaggregation of Revenue [Line Items]
Total revenue	47.00%	47.00%	46.00%	47.00%
Natural Stone Tiles [Member]
Disaggregation of Revenue [Line Items]
Total revenue	28.00%	29.00%	29.00%	29.00%
Setting And Maintenance Materials [Member]
Disaggregation of Revenue [Line Items]
Total revenue	14.00%	13.00%	14.00%	13.00%
Accessories [Member]
Disaggregation of Revenue [Line Items]
Total revenue	9.00%	10.00%	9.00%	10.00%
Delivery Service [Member]
Disaggregation of Revenue [Line Items]
Total revenue	2.00%	1.00%	2.00%	1.00%