Reportable Segment Information (Business Segment Information) (Details) (USD $)	3 Months Ended								12 Months Ended
	Jan. 03, 2015	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Jan. 03, 2015 Segment		Dec. 28, 2013		Dec. 29, 2012
Segment Reporting Information [Line Items]
Number of business segments									2
Net sales	$ 646,661,000	$ 614,690,000	$ 509,143,000	$ 452,201,000	$ 541,263,000	$ 565,706,000	$ 510,698,000	$ 442,297,000	$ 2,222,695,000		$ 2,059,964,000		$ 2,004,003,000
Operating profit									164,119,000		144,001,000		118,326,000
Income before income taxes	22,937,000	50,868,000	14,868,000	16,258,000	36,118,000	42,447,000	17,588,000	554,000	104,931,000		96,707,000		77,604,000
Depreciation and amortization expense									56,722,000		46,621,000		43,360,000
Capital expenditures									112,713,000		78,895,000		60,270,000
Identifiable assets	1,239,334,000				1,134,705,000				1,239,334,000		1,134,705,000		1,077,066,000
Office Furniture [Member]
Segment Reporting Information [Line Items]
Net sales									1,739,049,000		1,685,205,000		1,687,302,000
Operating profit									87,053,000	[1]	97,339,000	[1]	91,849,000	[1]
Depreciation and amortization expense									45,891,000		36,992,000		34,491,000
Capital expenditures									62,696,000		51,954,000		36,080,000
Identifiable assets	724,293,000				722,697,000				724,293,000		722,697,000		700,665,000
Segment reporting information restructuring and impairment charges									33,000,000		300,000		1,900,000
Hearth Products [Member]
Segment Reporting Information [Line Items]
Net sales									483,646,000		374,759,000		316,701,000
Operating profit									77,066,000		46,662,000		26,477,000
Depreciation and amortization expense									5,415,000		5,288,000		5,958,000
Capital expenditures									6,342,000		4,220,000		2,008,000
Identifiable assets	341,315,000				255,978,000				341,315,000		255,978,000		254,835,000
Unallocated Amount to Segment [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expense									(59,188,000)		(47,294,000)		(40,722,000)
Depreciation and amortization expense									5,416,000		4,341,000		2,911,000
Capital expenditures									43,675,000		22,721,000		22,182,000
Identifiable assets	$ 173,726,000				$ 156,030,000				$ 173,726,000		$ 156,030,000		$ 121,566,000

[1] Included in operating profit for the office furniture segment are pretax charges of $33.0 million, $0.3 million and $1.9 million, for closing of facilities and impairment charges in 2014, 2013 and 2012, respectively.