Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 625,386	$ 611,120	$ 1,630,868	$ 1,659,803
Office Furniture \| Supplies-driven channel
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	260,359	265,971	649,380	680,656
Office Furniture \| Contract channel
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	224,396	205,716	598,398	595,824
Hearth Products \| Hearth
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 140,631	$ 139,433	$ 383,090	$ 383,323

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration