The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions about future events. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities, and reported amounts of revenues and expenses. Such estimates include the valuation of accounts receivable, inventories, goodwill, intangible assets, and other long-lived assets; legal contingencies; guarantee obligations; indemnifications; assumptions used in retirement, medical, and workers' compensation benefits; assumptions used in the determination of right-of-use assets and related lease liabilities; stock-based compensation; fair value measurements; income taxes; and vendor and customer rebates, among others. These estimates and assumptions are based on management's best estimates and judgment. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, which management believes to be reasonable under the circumstances. We adjust such estimates and assumptions when facts and circumstances dictate. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Changes in these estimates resulting from continuing changes in the economic environment will be reflected in the consolidated financial statements in future periods.

Cash equivalents consist of short-term investments that have a maturity of three months or less at the date of purchase. At December 31, 2020 and 2019, the majority of our cash and cash equivalents were invested in money market funds that are broadly diversified and invested in high-quality, short-duration securities, including commercial paper, certificates of deposit, U.S. government agency securities, and similar instruments. We have significant amounts of cash and cash equivalents that are in excess of federally insured limits. Though we have not experienced any losses on our cash and cash equivalents to date and we do not anticipate incurring any losses, we cannot be assured that we will not experience losses on our cash and cash equivalents.

Trade accounts receivable are stated at the amount we expect to collect. Trade accounts receivable do not bear interest. We make ongoing estimates relating to the collectability of our accounts receivable and maintain a reserve for estimated losses resulting from the inability of our customers to meet their financial obligations to us. At December 31, 2020 and 2019, we had $1.1 million and $0.6 million, respectively, recorded as allowances for doubtful accounts. In determining the amount of the reserve and in order to manage credit risk, we consider our historical level of credit losses, customer concentrations, and current economic trends and monitor the creditworthiness of significant customers based on ongoing credit evaluations. Our sales are principally to customers in the building products industry located in the U.S. and Canada. A significant portion of our sales are concentrated with a relatively small number of customers. In 2020, our top ten customers represented approximately 42% of sales, with one customer accounting for approximately 11% of total sales. At December 31, 2020, receivables from two customers accounted for approximately 13% and 12% of total receivables. At December 31, 2019, receivables from these two customers accounted for approximately 14% and 12% of total receivables. No other customer accounted for 10% or more of total receivables. Adjustments to the valuation allowance are charged to income. Trade accounts receivable balances that remain outstanding after we have used reasonable collection efforts are written off through a charge to the valuation allowance and a credit to accounts receivable. Although we have not experienced material credit losses in recent years, our actual future losses from uncollectable accounts may differ materially from our current estimates. As additional information becomes known, we may change our estimates. In the event we determine that a change in the reserve is appropriate, we will record a charge to "Selling and distribution expenses" in our Consolidated Statements of Operations in the period we make such a determination.

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy under GAAP gives the highest priority to quoted market prices (Level 1) and the lowest priority to unobservable inputs (Level 3). In general, and where applicable, we use quoted prices in active markets for identical assets or liabilities to determine fair value (Level 1). If quoted prices in active markets for identical assets or liabilities are not available to determine fair value, we use quoted prices for similar assets and liabilities or inputs that are observable either directly or indirectly (Level 2). If quoted prices for identical or similar assets are not available or are unobservable, we may use internally developed valuation models, whose inputs include bid prices, and third-party valuations utilizing underlying asset assumptions (Level 3). See Note 12, Retirement and Benefit Plans, for the fair value measurements of our defined benefit plans' assets.

Our financial instruments are cash and cash equivalents, accounts receivable, accounts payable, long-term debt, and interest rate swaps. Our cash is recorded at cost, which approximates fair value, and our cash equivalents are money market funds. As of December 31, 2020 and 2019, we held $371.8 million and $259.5 million, respectively, in money market funds that are measured at fair value on a recurring basis using Level 1 inputs. The recorded values of accounts receivable and accounts payable approximate fair values based on their short-term nature. At December 31, 2020 and 2019, the book value of our fixed-rate debt was $400.0 million and $350.0 million, respectively, and the fair value was estimated to be $432.0 million and $364.7 million, respectively. The difference between the book value and the fair value is derived from the difference between the period-end market interest rate and the stated rate of our fixed-rate, long-term debt. We estimated the fair value of our fixed-rate debt using quoted market prices of our debt in inactive markets (Level 2 inputs). The interest rate on our variable-rate debt is based on market conditions such as the London Interbank Offered Rate (LIBOR) or a base rate. Because the interest rate on the variable-rate debt is based on current market conditions, we believe that the estimated fair value of the outstanding balance on our variable-rate debt approximates book value.

We are exposed to financial risks such as changes in commodity prices, interest rates, and foreign currency exchange rates. We employ a variety of practices to manage these risks, including operating and financing activities and, where deemed appropriate, the use of derivative instruments. As discussed in Note 16, Financial Instrument Risk, we use interest rate swaps to mitigate our variable interest rate exposure, the fair value of which is measured based on Level 2 inputs.

We receive rebates and allowances from our vendors under a number of different programs, including vendor marketing programs. At December 31, 2020 and 2019, we had $9.9 million and $9.2 million, respectively, of vendor rebates and allowances recorded in "Receivables, Other" on the Consolidated Balance Sheets. Rebates and allowances received from our vendors are recognized as a reduction of "Materials, labor, and other operating expenses (excluding depreciation)" when the product is sold, unless the rebates and allowances are linked to a specific incremental cost to sell a vendor's product. Amounts

The functional currency for our operations outside the United States is the U.S. dollar. Nonmonetary assets and liabilities and related depreciation and amortization for these foreign operations are remeasured into U.S. dollars using historical exchange rates. Monetary assets and liabilities are remeasured into U.S. dollars using the exchange rates as of the Consolidated Balance Sheet date. Revenue and expense items are remeasured into U.S. dollars using an average exchange rate prevailing during the year.

We primarily lease land, building, and equipment under operating and finance leases. We determine if an arrangement is a lease at inception and assess lease classification as either operating or finance at lease inception or upon modification. Substantially all of our leases with initial terms greater than one year are for real estate, including distribution centers, corporate headquarters, land, and other office space. Substantially all of these lease agreements have fixed payment terms based on the passage of time and are recorded in our Building Materials Distribution segment. Many of our leases include fixed escalation clauses, renewal options and/or termination options that are factored into our determination of lease term and lease payments when appropriate. Renewal options generally range from one to ten years with fixed payment terms similar to those in the original lease agreements. Some lease agreements provide us with the option to purchase the leased property at market value. Our lease agreements do not contain any residual value guarantees.

Right-of-use (ROU) assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the lease commencement date based on the estimated present value of fixed lease payments over the lease term. The current portion of our operating and finance lease liabilities are recorded in "Accrued liabilities, Other" on our Consolidated Balance Sheets.

For purposes of determining straight-line rent expense, the lease term is calculated from the date we first take possession of the facility, including any periods of free rent and any renewal option periods we are reasonably certain of exercising. Variable lease expense generally includes reimbursement of actual costs for common area maintenance, property taxes, and insurance on leased real estate and are recorded as incurred. Most of our operating lease expense was recorded in "Selling and distribution expenses" in our Consolidated Statements of Operations. In addition, we do not separate lease and non-lease components for all of our leases.

We account for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and respective tax bases and operating loss and tax credit carryforwards, as measured using enacted tax rates expected to be in effect in the periods where temporary differences are expected to be realized or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.

We recognize deferred tax assets to the extent that we believe that these assets are more likely than not to be realized. In making such a determination, we consider all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If we determine that we would be unable to realize our deferred tax assets in the future, we would make an adjustment to the deferred tax asset valuation allowance, which would increase the provision for income taxes.

We review and update our tax positions as necessary to add any new uncertain tax positions taken, or to remove previously identified uncertain positions that have been adequately resolved. Additionally, uncertain positions may be remeasured as warranted by changes in facts or law. Accounting for uncertain tax positions requires estimating the amount, timing and likelihood of ultimate settlement. Although we believe that these estimates are reasonable, actual results could differ from these estimates.

Property and equipment are recorded at cost. Cost includes expenditures for major improvements and replacements and the amount of interest cost associated with significant capital additions. For the years ended December 31, 2020, 2019, and 2018, an insignificant amount of interest was capitalized. We expense all repair and maintenance costs as incurred. When property and equipment are retired, sold, or otherwise disposed of, the asset's carrying amount and related accumulated depreciation are removed from the accounts and any gain or loss is included in income (loss). We use the straight-line method of depreciation.


	December 31, 2020		December 31, 2019		General Range of Estimated Useful Lives in Years
	(thousands)
Land	$	47,099	$	39,304
Buildings	151,718		140,008		20	-	40
Improvements	64,178		61,187		10	-	15
Mobile equipment, information technology, and office furniture	178,271		165,445		3	-	7
Machinery and equipment	687,768		666,467		7	-	12
Construction in progress	40,606		34,846
	1,169,640		1,107,257
Less accumulated depreciation	(708,184)		(630,308)
	$	461,456	$	476,949

We review long-lived assets for impairment when events or changes in circumstances indicate that the carrying amount of assets may not be recoverable (triggering event). An impairment of long-lived assets exists when the carrying value is not recoverable through future undiscounted cash flows from operations and when the carrying value of an asset or asset group exceeds its fair value. No triggering event was identified during the years ended December 31, 2020 and 2019. For a description of the impairment losses recorded during the year ended December 31, 2018, see Note 7, Sale of Manufacturing Facilities.

We maintain two reporting units for purposes of our goodwill impairment testing, Wood Products and Building Materials Distribution, which are the same as our operating segments discussed in Note 17, Segment Information. We test goodwill in each of our reporting units and intangible assets with indefinite lives for impairment annually in the fourth quarter or sooner if events or changes in circumstances indicate that the carrying value of the asset may exceed fair value. We also evaluate the remaining useful lives of our finite-lived purchased intangible assets to determine whether any adjustments to the useful lives are necessary.

We completed our annual assessment of goodwill in fourth quarter 2020 using a qualitative approach. The qualitative goodwill impairment assessment requires evaluating factors, based on the weight of evidence, to determine whether a reporting unit's carrying value would more likely than not exceed its fair value. As part of our goodwill qualitative testing process for each reporting unit, we evaluate various factors that are specific to the reporting unit as well as industry and macroeconomic factors in order to determine whether they are reasonably likely to have a material impact on the fair value of our reporting units. Based on the qualitative analysis performed in 2020, we concluded that there were no changes that were reasonably likely to cause the fair value of the reporting units to be less than the reporting units' carrying value and determined that there was no impairment of our goodwill. In the event we were to determine that a reporting unit's carrying value would more likely than not exceed its fair value, quantitative testing would be performed comparing carrying values to estimated fair values. See Note 9, Goodwill and Intangible Assets, for additional information.

We recognize our asset retirement obligations in the period in which they are incurred if sufficient information is available to reasonably estimate the fair value of the obligation. Fair value estimates are determined using Level 3 inputs in the fair value hierarchy. The fair values of our asset retirement obligations are measured using expected future cash outflows discounted using the company's credit-adjusted risk-free interest rate. When we record the liability, we capitalize the cost by increasing the carrying amount of the related long-lived asset. Over time, the liability is accreted to its settlement value, and the capitalized cost is depreciated over the useful life of the related asset. Upon settlement of the liability, we will recognize a gain or loss for any difference between the settlement amount and the liability recorded.

At December 31, 2020 and 2019, we had $2.3 million and $2.2 million, respectively, of asset retirement obligations recorded in "Other long-term liabilities" on our Consolidated Balance Sheets. These liabilities related primarily to landfill closure costs. The liabilities are based on the best estimate of current costs and are updated periodically to reflect current technology, laws and regulations, inflation, and other economic factors. We do not have any assets legally restricted for purposes of settling asset retirement obligations.

We have additional asset retirement obligations with indeterminate settlement dates. The fair value of these asset retirement obligations cannot be estimated due to the lack of sufficient information to estimate the settlement dates of the obligations. These asset retirement obligations include, for example, (i) removal and disposal of potentially hazardous materials on equipment and/or an operating facility if the equipment and/or facility were to undergo major maintenance, renovation, or demolition; (ii) retention ponds that may be required to be drained and/or cleaned if the related operating facility is closed; and (iii) storage sites or owned facilities for which removal and/or disposal of chemicals and other related materials are required if the operating facility is closed. We will recognize a liability in the period in which sufficient information becomes available to reasonably estimate the fair value of these obligations.

Several estimates and assumptions are required to record pension costs and liabilities, including discount rates, expected return on plan assets, expected rate of compensation increases, retirement and mortality rates, expected contributions, and other factors. We review and update these assumptions annually unless a plan curtailment or other event occurs requiring that we update the estimates on an interim basis. See Note 12, Retirement and Benefit Plans, for additional information related to our pension plan.

We defer internal-use software costs that benefit future years. These costs are amortized using the straight-line method over the expected life of the software, typically three to five years. "Other assets" in the Consolidated Balance Sheets includes $4.1 million and $4.6 million, respectively, of deferred software costs at December 31, 2020 and 2019. During the year ended December 31, 2020, we amortized $1.9 million of deferred software costs. We amortized $2.0 million of deferred software costs for both of the years ended December 31, 2019 and 2018.

As of December 31, 2020, we had approximately 5,970 employees. Approximately 22% of these employees work pursuant to collective bargaining agreements. As of December 31, 2020, we had ten collective bargaining agreements. Two agreements covering approximately 740 employees at our Oakdale and Florien plywood plants are set to expire on July 15, 2021. If any of these agreements are not renewed or extended upon their termination, we could experience a material labor disruption, strike, or significantly increased labor costs at one or more of our facilities, either in the course of negotiations of a labor agreement or otherwise. Labor disruptions or shortages could prevent us from meeting customer demands or result in increased costs, thereby reducing our sales and profitability.

We are self-insured for certain losses related to workers' compensation and medical claims, general and auto liability, as well as property and business interruption losses. The expected ultimate costs for claims incurred are recognized as liabilities in the Consolidated Balance Sheets and are estimated based principally on an analysis of historical claims data and estimates of claims incurred but not reported. Losses are accrued and charged to operations when it is probable that a loss has been incurred and the amount can be reasonably estimated. We maintain third-party stop-loss insurance policies to cover these liability costs in excess of predetermined retained amounts. Costs related to the administration of the plans and related claims are expensed as incurred. At December 31, 2020 and 2019, self-insurance related liabilities of $9.5 million and $9.9 million, respectively, were classified within "Accrued liabilities," and $10.0 million and $10.0 million, respectively, were classified within "Other long-term liabilities" on our Consolidated Balance Sheets.

In March 2020, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting, which provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments apply only to contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. Our current contracts that reference LIBOR include certain debt instruments and interest rate swaps. The amendments are effective for eligible contract modifications subsequent to March 12, 2020, and through December 31, 2022. The adoption of this standard did not have a material effect on our financial statements, but we will assess any eligible contract modifications in the future.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which is intended to reduce complexity in accounting for income taxes. This ASU removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. The updated guidance is effective for interim and annual reporting periods beginning after December 15, 2020, with early adoption permitted. We adopted this standard in first quarter of 2021 and it did not have a material effect on our financial statements.

disclosures, and adds disclosure requirements identified as relevant related to defined benefit pension and other postretirement plans. The ASU's changes related to disclosures are part of the FASB's disclosure framework project. The updated guidance is effective retrospectively for annual reporting periods ending after December 15, 2020, with early adoption permitted. We adopted this standard in fourth quarter of 2020 and it did not have a material effect on our financial statement disclosures.