Revenue (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Net sales	$ 1,090,343	$ 964,249	$ 2,991,118	$ 2,736,029
Contract assets change			4,297
Contract liabilities change			13,886
Revenue recognized previously included in contract liabilities	1,400		29,200
Building Products [Member]
Disaggregation of Revenue [Line Items]
Net sales	850,900	728,500	2,276,900	2,061,800
Construction Services [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 239,500	$ 235,800	$ 714,200	$ 674,300