Segments Segments (External Customer Sales By Product) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenue from External Customer [Line Items]
Total net sales	$ 747,574	$ 821,204	$ 797,547	$ 727,418	$ 510,162	$ 416,471	$ 357,287	$ 292,826	$ 3,093,743	$ 1,576,746	$ 1,311,498
Structural components [Member]
Revenue from External Customer [Line Items]
Total net sales									471,619	249,371	205,036
Lumber & lumber sheet goods [Member]
Revenue from External Customer [Line Items]
Total net sales									921,304	459,446	428,084
Millwork, Doors And Windows [Member]
Revenue from External Customer [Line Items]
Total net sales									898,769	442,675	328,063
Other building products & services [Member]
Revenue from External Customer [Line Items]
Total net sales									$ 802,051	$ 425,254	$ 350,315