Revenue (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Net sales	$ 979,896	$ 946,375	$ 1,900,775	$ 1,771,780
Contract assets change			1,746
Contract liabilities change			11,516
Revenue recognized previously included in contract liabilities	3,400		27,800
Building Products [Member]
Disaggregation of Revenue [Line Items]
Net sales	739,400	712,400	1,426,000	1,333,300
Construction Services [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 240,500	$ 234,000	$ 474,700	$ 438,500