Segments (Reconciliation of adjusted EBITDA to consolidated financial statements) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019		Sep. 30, 2020	Sep. 30, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Income before income taxes		$ 58,701	$ 46,787		$ 144,980	$ 119,326
Interest expense		5,744	5,773		17,880	17,385
Interest income		(224)	(1,047)		(1,146)	(2,832)
Depreciation and amortization		20,453	18,535		60,747	52,959
Merger related costs		8,488	0		9,150	0
Acquisition and integration costs	[1]	1,377	1,524		4,566	6,294
Non-cash stock compensation expense		4,612	3,014		11,110	9,177
Business reorganization costs	[2]	37	72		3,256	300
Other items		0	0	[3]	0	(222)	[3]
Other reconciling items [Member] | Other reconciling items [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization		512	561		1,529	1,838
Adjusted EBITDA		14,961	22,094		50,448	58,150
Operating segments [Member] | Geographic divisions [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization		19,941	17,974		59,218	51,121
Adjusted EBITDA		$ (114,149)	$ (96,752)		$ (300,991)	$ (260,537)

[1] Represents costs for acquisitions and related integration costs, as well as system integration and other costs related to the integration of BMHC and SBS as a result of the 2015 merger transaction.

[2] For the nine months ended September 30, 2019, represents income from a recovery made by the Company related to a fire at one of the Company’s facilities during 2015 and the effect of the settlement of pending litigation for an amount below what was previously accrued.

[3] For the three and nine months ended September 30, 2020, represents asset impairment and other charges related to the closure or relocation of the operations of certain of the Company’s facilities, which were not related to the COVID-19 pandemic, and severance expense related to permanent headcount reductions due to the impact of the COVID-19 pandemic. For the three and nine months ended September 30, 2019, represents asset impairment charges and the effect of certain customary post-closing adjustments related to the November 1, 2018 disposition of the Company’s Coleman Floor business.