Recently Adopted Accounting Standards (Policies)	3 Months Ended
Mar. 28, 2020
Accounting Changes and Error Corrections [Abstract]
Revenue	Performance Obligations The Corporation recognizes revenue for sales of office furniture and hearth products at a point in time following the transfer of control of such products to the customer, which typically occurs upon shipment of the product. In certain circumstances, transfer of control to the customer does not occur until the goods are received by the customer or upon installation and/or customer acceptance, depending on the terms of the underlying contracts. Contracts typically have a duration of less than one year and normally do not include a significant financing component. Generally, payment is due within 30 days of invoicing. The Corporation's backlog orders are typically cancelable for a period of time and almost all contracts have an original duration of one year or less. As a result, the Corporation has elected the practical expedient permitted in the revenue accounting standard not to disclose the unsatisfied performance obligation as of period end. The backlog is typically fulfilled within a quarter. Significant Judgments The amount of consideration the Corporation receives and revenue recognized varies with changes in rebate and marketing program incentives, as well as early pay discounts, offered to customers. The Corporation uses significant judgment throughout the year in estimating the reduction in net sales driven by variable consideration for rebate and marketing programs. Judgments made include expected sales levels and utilization of funds. However, this judgment factor is significantly reduced at the end of each year when sales volumes and the impact to rebate and marketing programs are known and recorded as the programs typically end near the Corporation's fiscal year end.
Inventories	The Corporation values its inventory at the lower of cost or net realizable value.
Goodwill and Other Intangible Assets	Impairment Analysis The Corporation evaluates its goodwill and indefinite-lived intangible assets for impairment on an annual basis during the fourth quarter, or whenever indicators of impairment exist. The Corporation also evaluates long-lived assets (which include definite-lived intangible assets) for impairment if indicators exist. At the end of the first quarter of 2020, the Corporation determined that a triggering event occurred, resulting in quantitative impairment tests performed over the goodwill, indefinite-lived intangible assets, and long-lived asset groups related to three reporting units in the office furniture segment. This determination was made considering the reduced sales and profitability projections for these reporting units, driven by the COVID-19 pandemic and related economic disruption. Management also considered the relative difference between the fair values and carrying values of the respective reporting units and indefinite-lived intangible assets in the most recent annual test performed during the fourth quarter of 2019. For the Corporation's remaining reporting units, management determined that the likelihood of the current fair value being less than the current carrying value was remote, and thus no quantitative impairment testing was performed. As a result of the long-lived asset impairment testing, it was determined the carrying value of one long-lived asset group was not recoverable based on an analysis of the undiscounted estimated future cash flows of the group. Consequently, the Corporation recorded charges of $0.6 million and $8.2 million to fully impair the carrying values of a definite-lived tradename and customer list, respectively, within this asset group. As a result of the indefinite-lived intangible asset impairment testing, it was determined the carrying value of one of the Corporation's indefinite-lived tradenames exceeded the estimated fair value. Therefore, a $2.3 million impairment charge was recorded to reduce the carrying value to estimated fair value of $5.3 million. The fair value of this tradename is considered a Level 3 measurement which utilizes a relief-from-royalty discounted cash flows approach. Key inputs and assumptions involved include the estimated near-term revenue growth (ranging from -28 percent to +12 percent), long-term growth rate (3 percent), royalty rate (2 percent), and discount rate (16 percent). For the goodwill impairment testing, management utilized a combination of both a discounted cash flows approach and market approach. Projections used in the impairment models reflected management's assumptions regarding revenue growth rates, economic and market trends including deterioration from the current COVID-19 pandemic, cost structure, investments required for product enhancements, and other expectations about the anticipated short-term and long-term operating results of the reporting units. As a result of the impairment testing, two reporting units were determined to have carrying values in excess of their fair values, resulting in goodwill impairment charges of $14.1 million and $7.5 million, respectively. These two reporting units have no remaining goodwill. The third reporting unit, which has goodwill of $6.9 million, was determined to have a fair value that exceeded carrying value by approximately 21 percent. For this reporting unit, the Corporation assumed a discount rate of 15.5 percent, near-term growth rates ranging from -24 percent to +17 percent, and a terminal growth rate of 4 percent. Holding other assumptions constant, a 100 basis point increase in the discount rate would result in a $3.7 million decrease in the estimated fair value of the reporting unit. Holding other assumptions constant, a 100 basis point decrease in the long-term growth rate would result in a $1.9 million decrease in the estimated fair value of the reporting unit. Both of these scenarios individually would result in the estimated fair value exceeding the carrying value. All impairment charges described above are reflected in "Impairment charges" in the Condensed Consolidated Statements of Comprehensive Income.
Product Warranties	The Corporation issues certain warranty policies on its office furniture and hearth products that provide for repair or replacement of any covered product or component that fails during normal use because of a defect in design, materials, or workmanship. Allowances have been established for the anticipated future costs associated with the Corporation's warranty programs. A warranty allowance is determined by recording a specific allowance for known warranty issues and an additional allowance for unknown claims expected to be incurred based on historical claims experience. Actual costs incurred could differ from the original estimates, requiring adjustments to the allowance.
Fair Value Measurements	For recognition purposes, on a recurring basis, the Corporation is required to measure at fair value its marketable securities, derivative financial instruments, and deferred stock-based compensation. The marketable securities are comprised of money market funds, government securities, and corporate bonds. When available, the Corporation uses quoted market prices to determine fair value and classifies such measurements within Level 1. Where market prices are not available, the Corporation makes use of observable market-based inputs (prices or quotes from published exchanges and indexes) to calculate fair value using the market approach, in which case the measurements are classified within Level 2.
Share-based Compensation, Option and Incentive Plans	The Corporation measures stock-based compensation expense at grant date, based on the fair value of the award. Forms of awards issued under shareholder approved plans include stock options, restricted stock units based on a service condition ("restricted stock units"), restricted stock units based on both performance and service conditions ("performance stock units"), and shares issued under member stock purchase plans. Stock-based compensation expense related to stock options, restricted stock units, and performance stock units is recognized over the employees' requisite service periods. However, expense related to performance stock units is adjusted for the probability that the Corporation will perform within an established target range of cumulative profitability over a multi-year period. The Corporation has not accrued compensation expense for performance stock units granted to date, based on the current determination that it is not probable that the minimum cumulative profitability target will be achieved.
Recently Adopted Accounting Standards	In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments and also issued subsequent amendments to the initial guidance: ASU 2018-19, ASU 2019-04, and ASU 2019-05 (collectively, Topic 326). Topic 326 replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses by requiring consideration of a broader range of reasonable and supportable information and is intended to provide financial statement users with more useful information about expected credit losses on financial instruments. The Corporation adopted Topic 326 in the first quarter of fiscal 2020 using a modified retrospective transition approach. The adoption resulted in a cumulative effect decrease to retained earnings of $0.1 million to reflect a change in the allowance for doubtful accounts. Additionally, Topic 326 requires the allowance for doubtful accounts balance (contra-asset) to be presented separately in the Condensed Consolidated Balance Sheets. No other financial statement line items were materially impacted by the adoption. The Corporation's allowance for doubtful accounts is developed based on several factors, including overall customer credit quality, historical write-off experience, and specific account analyses projecting the ultimate collectability of the account. The adoption of Topic 326 did not significantly impact the Corporation's accounting policies or estimation methods related to the allowance for doubtful accounts. Topic 326 also introduced new accounting and reporting requirements related to available-for-sale debt securities, including consideration of whether an allowance for credit losses should be established. The Corporation has determined that such an allowance is not required with respect to its available-for-sale debt security portfolio. See "Note 9. Fair Value Measurements" for fair value information of the Corporation's available-for-sale debt securities and where such are recorded in the Condensed Consolidated Balance Sheets. The amortized cost of this portfolio was $13.0 million and $12.5 million as of March 28, 2020 and December 28, 2019, respectively. Immaterial amounts of accrued interest receivable related to the Corporation's portfolio are recorded in "Prepaid expenses and other current assets" and "Other assets"
Business Segment Information	Management views the Corporation as being in two reportable segments based on industries: office furniture and hearth products, with the former being the principal segment. The aggregated office furniture segment manufactures and markets a broad line of commercial and home office furniture which includes panel-based and freestanding furniture systems, seating, storage, tables, and architectural products. The hearth products segment manufactures and markets a full array of gas, wood, electric, and pellet fueled fireplaces, inserts, stoves, facings, and accessories. For purposes of segment reporting, intercompany sales between segments are not material, and operating profit is income before income taxes exclusive of certain unallocated general corporate expenses. These unallocated general corporate expenses include the net costs of the Corporation's corporate operations. Management views interest income and expense as corporate financing costs and not as a reportable segment cost. In addition, management applies an effective income tax rate to its consolidated income before income taxes so income taxes are not reported or viewed internally on a segment basis. Identifiable assets by segment are those assets applicable to the respective industry segments. Corporate assets consist principally of cash and cash equivalents, short-term investments, long-term investments, IT infrastructure, and corporate office real estate and related equipment. No geographic information for revenues from external customers or for long-lived assets is disclosed since the Corporation's primary market and capital investments are concentrated in the United States.

Recently Adopted Accounting Standards (Policies)

3 Months Ended

Mar. 28, 2020

Accounting Changes and Error Corrections [Abstract]

Performance Obligations

The Corporation recognizes revenue for sales of office furniture and hearth products at a point in time following the transfer of control of such products to the customer, which typically occurs upon shipment of the product. In certain circumstances, transfer of control to the customer does not occur until the goods are received by the customer or upon installation and/or customer acceptance, depending on the terms of the underlying contracts. Contracts typically have a duration of less than one year and normally do not include a significant financing component. Generally, payment is due within 30 days of invoicing.

The Corporation's backlog orders are typically cancelable for a period of time and almost all contracts have an original duration of one year or less. As a result, the Corporation has elected the practical expedient permitted in the revenue accounting standard not to disclose the unsatisfied performance obligation as of period end. The backlog is typically fulfilled within a quarter.

Significant Judgments

The amount of consideration the Corporation receives and revenue recognized varies with changes in rebate and marketing program incentives, as well as early pay discounts, offered to customers. The Corporation uses significant judgment throughout the year in estimating the reduction in net sales driven by variable consideration for rebate and marketing programs. Judgments made include expected sales levels and utilization of funds. However, this judgment factor is significantly reduced at the end of each year when sales volumes and the impact to rebate and marketing programs are known and recorded as the programs typically end near the Corporation's fiscal year end.

Inventories

The Corporation values its inventory at the lower of cost or net realizable value.

Goodwill and Other Intangible Assets

Impairment Analysis

The Corporation evaluates its goodwill and indefinite-lived intangible assets for impairment on an annual basis during the fourth quarter, or whenever indicators of impairment exist. The Corporation also evaluates long-lived assets (which include definite-lived intangible assets) for impairment if indicators exist. At the end of the first quarter of 2020, the Corporation determined that a triggering event occurred, resulting in quantitative impairment tests performed over the goodwill, indefinite-lived intangible assets, and long-lived asset groups related to three reporting units in the office furniture segment. This determination was made considering the reduced sales and profitability projections for these reporting units, driven by the COVID-19 pandemic and related economic disruption. Management also considered the relative difference between the fair values and carrying values of the respective reporting units and indefinite-lived intangible assets in the most recent annual test performed during the fourth quarter of 2019. For the Corporation's remaining reporting units, management determined that the likelihood of the current fair value being less than the current carrying value was remote, and thus no quantitative impairment testing was performed.

As a result of the long-lived asset impairment testing, it was determined the carrying value of one long-lived asset group was not recoverable based on an analysis of the undiscounted estimated future cash flows of the group. Consequently, the Corporation recorded charges of $0.6 million and $8.2 million to fully impair the carrying values of a definite-lived tradename and customer list, respectively, within this asset group.

As a result of the indefinite-lived intangible asset impairment testing, it was determined the carrying value of one of the Corporation's indefinite-lived tradenames exceeded the estimated fair value. Therefore, a $2.3 million impairment charge was recorded to reduce the carrying value to estimated fair value of $5.3 million. The fair value of this tradename is considered a Level 3 measurement which utilizes a relief-from-royalty discounted cash flows approach. Key inputs and assumptions involved include the estimated near-term revenue growth (ranging from -28 percent to +12 percent), long-term growth rate (3 percent), royalty rate (2 percent), and discount rate (16 percent).

For the goodwill impairment testing, management utilized a combination of both a discounted cash flows approach and market approach. Projections used in the impairment models reflected management's assumptions regarding revenue growth rates, economic and market trends including deterioration from the current COVID-19 pandemic, cost structure, investments required for product enhancements, and other expectations about the anticipated short-term and long-term operating results of the reporting units. As a result of the impairment testing, two reporting units were determined to have carrying values in excess of their fair values, resulting in goodwill impairment charges of $14.1 million and $7.5 million, respectively. These two reporting units have no remaining goodwill. The third reporting unit, which has goodwill of $6.9 million, was determined to have a fair value that exceeded carrying value by approximately 21 percent. For this reporting unit, the Corporation assumed a discount rate of 15.5 percent, near-term growth rates ranging from -24 percent to +17 percent, and a terminal growth rate of 4 percent. Holding other assumptions constant, a 100 basis point increase in the discount rate would result in a $3.7 million decrease in the estimated fair value of the reporting unit. Holding other assumptions constant, a 100 basis point decrease in the long-term growth rate would result in a $1.9 million decrease in the estimated fair value of the reporting unit. Both of these scenarios individually would result in the estimated fair value exceeding the carrying value.

All impairment charges described above are reflected in "Impairment charges" in the Condensed Consolidated Statements of Comprehensive Income.

Product Warranties

The Corporation issues certain warranty policies on its office furniture and hearth products that provide for repair or replacement of any covered product or component that fails during normal use because of a defect in design, materials, or workmanship. Allowances have been established for the anticipated future costs associated with the Corporation's warranty programs.

A warranty allowance is determined by recording a specific allowance for known warranty issues and an additional allowance for unknown claims expected to be incurred based on historical claims experience. Actual costs incurred could differ from the original estimates, requiring adjustments to the allowance.

Fair Value Measurements

For recognition purposes, on a recurring basis, the Corporation is required to measure at fair value its marketable securities, derivative financial instruments, and deferred stock-based compensation. The marketable securities are comprised of money market funds, government securities, and corporate bonds. When available, the Corporation uses quoted market prices to determine fair value and classifies such measurements within Level 1. Where market prices are not available, the Corporation makes use of observable market-based inputs (prices or quotes from published exchanges and indexes) to calculate fair value using the market approach, in which case the measurements are classified within Level 2.

Share-based Compensation, Option and Incentive Plans

The Corporation measures stock-based compensation expense at grant date, based on the fair value of the award. Forms of awards issued under shareholder approved plans include stock options, restricted stock units based on a service condition ("restricted stock units"), restricted stock units based on both performance and service conditions ("performance stock units"), and shares issued under member stock purchase plans. Stock-based compensation expense related to stock options, restricted stock units, and performance stock units is recognized over the employees' requisite service periods. However, expense related to performance stock units is adjusted for the probability that the Corporation will perform within an established target range of cumulative profitability over a multi-year period. The Corporation has not accrued compensation expense for performance stock units granted to date, based on the current determination that it is not probable that the minimum cumulative profitability target will be achieved.

Recently Adopted Accounting Standards

In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments and also issued subsequent amendments to the initial guidance: ASU 2018-19, ASU 2019-04, and ASU 2019-05 (collectively, Topic 326). Topic 326 replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses by requiring consideration of a broader range of reasonable and supportable information and is intended to provide financial statement users with more useful information about expected credit losses on financial instruments.

The Corporation adopted Topic 326 in the first quarter of fiscal 2020 using a modified retrospective transition approach. The adoption resulted in a cumulative effect decrease to retained earnings of $0.1 million to reflect a change in the allowance for doubtful accounts. Additionally, Topic 326 requires the allowance for doubtful accounts balance (contra-asset) to be presented separately in the Condensed Consolidated Balance Sheets. No other financial statement line items were materially impacted by the adoption.

The Corporation's allowance for doubtful accounts is developed based on several factors, including overall customer credit quality, historical write-off experience, and specific account analyses projecting the ultimate collectability of the account. The adoption of Topic 326 did not significantly impact the Corporation's accounting policies or estimation methods related to the allowance for doubtful accounts.

Topic 326 also introduced new accounting and reporting requirements related to available-for-sale debt securities, including consideration of whether an allowance for credit losses should be established. The Corporation has determined that such an allowance is not required with respect to its available-for-sale debt security portfolio. See "Note 9. Fair Value Measurements" for fair value information of the Corporation's available-for-sale debt securities and where such are recorded in the Condensed Consolidated Balance Sheets. The amortized cost of this portfolio was $13.0 million and $12.5 million as of March 28, 2020 and December 28, 2019, respectively. Immaterial amounts of accrued interest receivable related to the Corporation's portfolio are recorded in "Prepaid expenses and other current assets" and "Other assets"

Business Segment Information

Management views the Corporation as being in two reportable segments based on industries: office furniture and hearth products, with the former being the principal segment.

The aggregated office furniture segment manufactures and markets a broad line of commercial and home office furniture which includes panel-based and freestanding furniture systems, seating, storage, tables, and architectural products. The hearth products segment manufactures and markets a full array of gas, wood, electric, and pellet fueled fireplaces, inserts, stoves, facings, and accessories.

For purposes of segment reporting, intercompany sales between segments are not material, and operating profit is income before income taxes exclusive of certain unallocated general corporate expenses. These unallocated general corporate expenses include the net costs of the Corporation's corporate operations. Management views interest income and expense as corporate financing costs and not as a reportable segment cost. In addition, management applies an effective income tax rate to its consolidated income before income taxes so income taxes are not reported or viewed internally on a segment basis. Identifiable assets by segment are those assets applicable to the respective industry segments. Corporate assets consist principally of cash and cash equivalents, short-term investments, long-term investments, IT infrastructure, and corporate office real estate and related equipment.

No geographic information for revenues from external customers or for long-lived assets is disclosed since the Corporation's primary market and capital investments are concentrated in the United States.