Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue
Sales	$ 2,828,773	$ 3,207,638	$ 3,091,595	$ 2,476,487	$ 2,482,975	$ 2,666,528	$ 2,589,874	$ 2,410,608	$ 11,604,493	$ 10,149,985	$ 9,536,428
DIY customer [Member]
Disaggregation of Revenue
Sales									6,684,183	5,612,390	5,351,035
Professional service provider customer [Member]
Disaggregation of Revenue
Sales									4,647,189	4,369,541	4,035,898
Other sales and sales adjustments [Member]
Disaggregation of Revenue
Sales									$ 273,121	$ 168,054	$ 149,495