Segments (Reconciliation of adjusted EBITDA to consolidated financial statements) (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Income before income taxes		$ 56,786	$ 46,189		$ 86,279	$ 72,539
Interest expense		6,204	5,574		12,136	11,612
Interest income		(339)	(844)		(922)	(1,785)
Depreciation and amortization		20,299	17,632		40,294	34,424
Merger and integration costs		357	1,382		1,525	4,172
Non-cash stock compensation expense		3,328	3,248		6,498	6,163
Acquisition costs		495	18		2,326	598
Business reorganization costs	[1]	3,219	228		3,219	228
Other items		0	(98)	[2]	0	(222)	[2]
Other reconciling items [Member] | Other reconciling items [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization		523	632		1,017	1,277
Adjusted EBITDA		16,117	16,688		35,487	36,056
Operating segments [Member] | Geographic divisions [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Depreciation and amortization		19,776	17,000		39,277	33,147
Adjusted EBITDA		$ (106,466)	$ (90,017)		$ (186,842)	$ (163,785)

[1] For the three and six months ended June 30, 2020, represents asset impairment charges related to the closure or relocation of the operations of certain of the Company’s facilities (“Impairment Charges”), 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 six months ended June 30, 2019, represents 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.

[2] For the three months ended June 30, 2019, represents income from a recovery made by the Company related to a fire at one of the Company’s facilities during 2015 (the “Recovery Income”). For the six months ended June 30, 2019, represents the Recovery Income and the effect of the settlement of pending litigation for an amount below what was previously accrued.