Reportable Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 29, 2018 USD ($) Segment	Sep. 30, 2017 USD ($)	Dec. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			2
Net sales	$ 611,120	$ 599,455	$ 1,659,803	$ 1,591,607
Operating income	53,626	57,719	84,372	87,302
Interest expense, net	2,522	1,764	7,375	3,761
Income before income taxes	51,104	55,955	76,997	83,541
Depreciation and amortization	18,607	18,060	55,887	54,524
Capital Expenditures (including capitalized software)	14,655	39,803	46,979	103,891
Identifiable assets	1,395,746		1,395,746		$ 1,391,550
Operating segments | Office Furniture
Segment Reporting Information [Line Items]
Net sales	471,687	465,312	1,276,480	1,231,737
Operating income	46,075	39,729	66,207	65,856
Depreciation and amortization	11,012	12,132	33,202	37,515
Capital Expenditures (including capitalized software)	10,324	27,102	35,321	64,467
Identifiable assets	817,753		817,753		821,767
Operating segments | Hearth Products
Segment Reporting Information [Line Items]
Net sales	139,433	134,143	383,323	359,870
Operating income	21,824	28,737	55,250	52,651
Depreciation and amortization	2,026	1,973	6,080	8,167
Capital Expenditures (including capitalized software)	2,150	5,606	6,317	12,818
Identifiable assets	360,609		360,609		347,189
General corporate
Segment Reporting Information [Line Items]
Operating income	(14,273)	(10,747)	(37,085)	(31,205)
Depreciation and amortization	5,569	3,955	16,605	8,842
Capital Expenditures (including capitalized software)	2,181	$ 7,095	5,341	$ 26,606
Identifiable assets	$ 217,384		$ 217,384		$ 222,594