Reportable Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Oct. 01, 2016 USD ($)	Sep. 30, 2017 USD ($) Segment	Oct. 01, 2016 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | Segment			2
Segment Reporting Information [Line Items]
Net sales	$ 599,455	$ 584,629	$ 1,591,607	$ 1,622,204
Income before income taxes	55,955	50,649	83,541	113,333
Depreciation and amortization	18,060	17,277	54,524	48,908
Capital expenditures (including capitalized software)	39,803	26,643	103,891	82,499
Identifiable assets	1,425,416		1,425,416		$ 1,330,234
Operating segments | Office Furniture
Segment Reporting Information [Line Items]
Net sales	465,312	454,946	1,231,737	1,270,398
Income before income taxes	39,729	44,729	65,856	109,396
Depreciation and amortization	12,132	10,889	37,515	32,709
Capital expenditures (including capitalized software)	27,102	13,875	64,467	43,923
Identifiable assets	838,094		838,094		749,145
Operating segments | Hearth Products
Segment Reporting Information [Line Items]
Net sales	134,143	129,683	359,870	351,806
Income before income taxes	28,737	19,108	52,651	41,623
Depreciation and amortization	1,973	3,034	8,167	9,012
Capital expenditures (including capitalized software)	5,606	1,957	12,818	8,969
Identifiable assets	361,241		361,241		340,494
General corporate
Segment Reporting Information [Line Items]
Income before income taxes	(12,511)	(13,188)	(34,966)	(37,686)
Depreciation and amortization	3,955	3,354	8,842	7,187
Capital expenditures (including capitalized software)	7,095	$ 10,811	26,606	$ 29,607
Identifiable assets	$ 226,081		$ 226,081		$ 240,595