Acquisitions and Disposition (Narrative) (Details) - USD ($) $ in Thousands					10 Months Ended	12 Months Ended
	Nov. 01, 2018	Mar. 01, 2018	Apr. 03, 2017	Mar. 27, 2017	Dec. 31, 2018	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Business Acquisition [Line Items]
Proceeds from sale of business						$ 7,773		$ 0		$ 0
Goodwill					$ 262,997	262,997		261,792		254,832
Acquisition costs						1,829	[1]	424	[1]	0
Initial holdback						1,403		375		0
Cost of sales						2,773,232		2,570,453		2,351,778
Income from continuing operations before income taxes						156,914		81,827		45,146
WE Shone Co [Member]
Business Acquisition [Line Items]
Date of acquisition		Mar. 01, 2018
Purchase price		$ 22,400
Goodwill		2,500
Accounts receivable		6,400
Inventories		8,800
Property and equipment		2,900
Current liabilities		5,300
Net sales before acquisition								70,700
Revenue since acquisition date					60,900
Pre-tax earnings since acquisition date					$ 3,200
Initial holdback		1,400
WE Shone Co [Member] | Selling, general and administrative expenses [Member]
Business Acquisition [Line Items]
Acquisition costs						200
WE Shone Co [Member] | Customer relationships [Member]
Business Acquisition [Line Items]
Intangible assets		$ 7,000
Useful life		9 years
TexPly [Member]
Business Acquisition [Line Items]
Date of acquisition			Apr. 03, 2017
Purchase price			$ 31,700
Goodwill			3,600
Accounts receivable			5,200
Inventories			3,900
Property and equipment			5,400
TexPly [Member] | Customer relationships [Member]
Business Acquisition [Line Items]
Intangible assets			$ 13,600
Useful life			13 years
Code Plus [Member]
Business Acquisition [Line Items]
Date of acquisition				Mar. 27, 2017
Purchase price				$ 7,100
Goodwill				3,400
Earnout				800
Code Plus [Member] | Customer relationships [Member]
Business Acquisition [Line Items]
Intangible assets				$ 2,300
Useful life				12 years
Code Plus [Member] | Non-compete Agreements [Member]
Business Acquisition [Line Items]
Intangible assets				$ 500
Useful life				5 years
Code Plus And TexPly [Member]
Business Acquisition [Line Items]
Revenue since acquisition date								54,300
Pre-tax earnings since acquisition date								3,200
Building products [Member]
Business Acquisition [Line Items]
Cost of sales						2,095,093		$ 1,906,583		$ 1,725,843
Coleman Floor [Member]
Business Acquisition [Line Items]
Date of sale	Nov. 01, 2018
Proceeds from sale of business						$ 7,773
Percent of total net sales						1.00%
Coleman Floor [Member] | Other Income [Member]
Business Acquisition [Line Items]
Loss on sale of business						$ 300

[1] For the years ended December 31, 2018 and 2017, the amounts represent expenses incurred related to the acquisitions of Barefoot and Company (“Barefoot”), Locust Lumber, Shone Lumber, TexPly and Code Plus. For the year ended December 31, 2018, the amount also includes costs incurred related to the conversion of the enterprise resource planning system utilized by Shone Lumber.