Revenue Revenue (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales	$ 890,564	$ 964,249	$ 946,375	$ 825,405	$ 859,521	$ 990,264	$ 998,461	$ 834,202	$ 3,626,593	$ 3,682,448	$ 3,365,968
Contract With Customer Asset, Period Change									223
Contract With Customer Liability, Period Change									(3,794)
Contract with Customer, Liability, Revenue Recognized									32,300
Building products [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales									2,727,700	2,856,700	2,561,500
Construction services [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales									$ 898,900	$ 825,800	$ 804,500