Significant Accounting Policies

Nature of Operations

USG, through our subsidiaries and joint ventures, is a leading manufacturer of building materials and innovative solutions. We produce a wide range of products for use in new residential, new nonresidential, and residential and nonresidential repair and remodel construction as well as products used in certain industrial processes. Our products are distributed through building materials dealers, home improvement centers and other retailers and specialty wallboard distributors and sold directly to contractors.

Segments

During the fourth quarter of 2017, we realigned our operating structure to reflect changes in our organizational structure and management's operation and view of our businesses. Our realigned operating structure is generally aligned by product type and consists of three divisions, in addition to our USG Boral Building Products, or UBBP, our joint ventures in Asia, Australasia and the Middle East: Gypsum, Performance Materials and Ceilings. The operations of the divisions are similar throughout North America.

This change to our operating structure modified how the business is managed and the financial information received by the chief operating decision maker to assess operating performance and allocate resources, and thus, triggered a review of our segment structure. Effective for the quarter ended December 31, 2017, we changed the composition of our reportable segments to reflect this change. We now have five reportable segments: U.S. Wallboard and Surfaces, U.S. Performance Materials, U.S. Ceilings, Canada, and UBBP. Our prior period results have been recast to reflect these changes and present comparative year over year information by segment. See Note 14, Segments.

Our reportable segments are determined considering both qualitative and quantitative metrics for aggregation of the product type within geographies for which discrete financial information is available. Our U.S. Wallboard and Surfaces, U.S. Performance Materials and U.S. Ceilings reportable segments were identified based on products manufactured and marketed. Our Canada segment is a separately reportable segment, as while it has similar qualitative factors to U.S. operations, it has different quantitative metrics and, therefore, cannot be aggregated. Our operating segments in Mexico and Latin America, as well as our mining operation in Little Narrows, Nova Scotia, Canada, which we indefinitely idled in 2016, and our shipping company, which we exited in 2015, are now included in Other as reconciling items to our consolidated segments. There has been no change to our UBBP segment.

Consolidation and Presentation

Our consolidated financial statements include the accounts of USG Corporation and its majority-owned subsidiaries. Entities in which we have more than a 20% but not more than 50% ownership interest are accounted for using the equity method of accounting. All intercompany balances and transactions are eliminated in consolidation.

Certain other reclassifications have been made to prior year amounts in order to conform with current year presentation. On our consolidated balance sheet, we reclassified the balance of our intangible assets from '"Other assets" to "Goodwill and intangible assets."

Use of Estimates

The preparation of our consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions. These estimates and assumptions affect the reported amounts of assets, liabilities, revenues and expenses. Actual results could differ from these estimates.

Revenue Recognition

We recognize revenue when shipment is received by the customer. We enter into agreements with customers to offer rebates, generally based on achievement of specified sales levels and various marketing allowances that are common industry practice. Estimated reductions to revenue for customer programs and incentive offerings, including promotions and other volume–based incentives, are recorded in the period in which the sale occurs. Provisions for early payment discounts are accrued in the same period in which the sale occurs.

Shipping and Handling Costs

Shipping and handling costs billed to customers are included in net sales and the related costs are presented in cost of products sold.

Advertising

Advertising expenses consist of media advertising and related production costs and sponsorships. We charge advertising expenses to earnings as incurred. These expenses amounted to $10 million, $12 million and $16 million for the years ended December 31, 2017, 2016 and 2015, respectively, and are included in "Selling and administrative expenses" in our consolidated statements of income.

Research and Development

We charge research and development expenditures to earnings as incurred. These expenditures amounted to $23 million, $24 million and $23 million for the years ended December 31, 2017, 2016 and 2015, respectively, and are included in "Cost of products sold" and "Selling and administrative expenses" in our consolidated statements of income.

Legal Costs

We expense legal costs as incurred.

Income Taxes

We record income tax expense (benefit) under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized based on temporary differences between the financial statement carrying values of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply in the years in which the temporary differences are expected to be recovered or paid. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in earnings in the period when the change is enacted. Valuation allowances are recorded to reduce deferred tax assets when it is more likely than not that a tax benefit will not be realized.

A reduction of the carrying values of deferred tax assets by a valuation allowance is required if, based on all available evidence, it is more likely than not that such assets will not be realized. The need to establish valuation allowances for deferred tax assets is assessed at each reporting date. In assessing the requirement for, and amount of, a valuation allowance in accordance with the more-likely-than-not standard, we give appropriate consideration to all positive and negative evidence related to the realization of the deferred tax assets. This assessment considers, among other matters, the nature, frequency and severity of current and cumulative losses, forecasts of future profitability, the duration of statutory carryforward periods, our experience with operating loss and tax credit carryforwards not expiring unused and tax planning strategies.

A history of cumulative losses for a certain threshold period is a significant form of negative evidence used in the assessment, and we are required to have a policy regarding the duration of the threshold period. We believe the historical cyclical nature of our operations show economic cycles ranging from 7 to 10 years with demand troughs historically showing recovery over four years. Accordingly, we have a policy of four years as our threshold period for cumulative losses.

Inventory Valuation

All of our inventories are stated at the lower of cost or net realizable value and are valued under the average cost method. Our inventories include materials, labor and applicable factory overhead costs. Depreciation associated with manufacturing assets is excluded from inventory cost but is included in cost of products sold.

Earnings per Share

Basic earnings per share is based on the weighted average number of common shares outstanding. Diluted earnings per share is based on the weighted average number of common shares outstanding plus the dilutive effect, if any, of market share units, or MSUs, restricted stock units, or RSUs, performance shares, stock options and the deferred shares associated with our deferred compensation program for non-employee directors. The shares that were not included in the computation of diluted earnings per share for those periods because their inclusion would be anti-dilutive were as follows:



(millions, common shares)	2017	2016	2015
Stock options, RSUs, MSUs and performance shares	0.7	1.5	1.9
Deferred shares associated with a deferred compensation program for non-employee directors	0.2	0.2	—

Business Combinations

Business combinations are accounted for using the acquisition method of accounting. The purchase price of the acquisition is allocated to the tangible and intangible assets acquired and liabilities assumed based on their fair values at the acquisition date. The calculation of fair value of the identified intangible assets are determined using cash flow models following the income approach or a discounted market-based methodology approach. Significant inputs include projected revenues, gross margins, operating expenses, estimated attrition rate and discount rates. The excess of fair value of the purchase price over the fair values of the tangible and identifiable intangible assets acquired and liabilities assumed is recorded as goodwill. During the measurement period, which may be up to one year from the acquisition date, we may record adjustments to the net assets with the corresponding offset to goodwill. The results of operations of the acquired business are included in our consolidated results of operations beginning on the date of the acquisition. Acquisition-related expenses, including legal costs, due diligence costs and business valuation costs, are expensed as incurred.

Cash and Cash Equivalents

Cash and cash equivalents include highly liquid investments, primarily money market funds, with maturities of three months or less at the time of purchase.

Marketable Securities

Marketable securities are classified as available-for-sale securities and reported at fair value, with unrealized gains and losses excluded from earnings and reported in accumulated other comprehensive income (loss), or AOCI. If it is deemed that marketable securities have unrealized losses that are other than temporary, these losses will be recorded in earnings immediately. Situations in which losses may be considered other than temporary include when we have decided to sell a security or when it is more likely than not that we will be required to sell the security before we recover its amortized cost basis. Cost basis for securities sold are determined on a first-in-first-out basis.

Receivables

Receivables are recorded at net realizable value, which includes allowances for cash discounts and doubtful accounts. We review the collectability of receivables on an ongoing basis and reserve for receivables determined to be uncollectible. This determination is based on the delinquency of the account, the financial condition of the customer and our collection experience.

We include short-term financing receivables in "Receivables" and long-term financing and loan receivables in "Other assets" on our consolidated balance sheets. Financing and loan receivables are recorded at net realizable value which includes an allowance for credit losses. We review the collectability of financing and loan receivables on an ongoing basis and reserve for financing and loan receivables determined to be uncollectible. This determination is based on the delinquency of the account and the financial condition of the other party. As of December 31, 2017, the allowance for credit losses was immaterial.

Investments in Unconsolidated Joint Ventures

The equity method of accounting is used for investments in joint ventures that we do not consolidate, but over which we have the ability to exercise significant influence. These investments are initially recorded at cost and subsequently adjusted for our share of the net income or loss and cash contributions and distributions to or from these entities. If the underlying net assets in our investments are denominated in a foreign currency, we adjust the value of our investment for translation gains or losses with a corresponding adjustment to our AOCI.

We are required to pay Boral, our UBBP joint venture partner, an earnout of $50 million in 2019 if certain financial metrics are met. At least quarterly, we review the probability of this earnout payment to Boral. At December 31, 2017, we concluded that it is currently not probable that the earnout target will be achieved. If our conclusion on the probability of achievement were to change, we will record a liability representing the present value of the second earnout payment with a corresponding increase to our investment.

Losses in the value of an equity method investment that are other than temporary are recognized when the current fair value of the investment is less than its carrying value. We review our investments in equity method investments for impairment whenever factors indicate an other than temporary loss in value. If we conclude a loss in value is other than temporary, an impairment charge is recognized for the difference between the investment’s carrying value and its estimated fair value.

Property, Plant and Equipment

Property, plant and equipment is recorded at cost. We record depreciation of property, plant and equipment on a straight-line basis over the expected useful lives of the assets. We have determined estimated useful lives to be 50 years for buildings and improvements, a range of 10 to 25 years for machinery and equipment, and a range of 5 to 7 years for computer software and systems development costs. Leasehold improvements are capitalized and amortized over the shorter of the remaining lease term or remaining economic useful life. We compute depletion on a basis calculated to spread the cost of gypsum and other applicable resources over the estimated quantities of material recoverable.

We capitalize interest during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying assets and is depreciated over the useful lives of those assets. We recorded capitalized interest of $3 million, $1 million and $3 million for the years ended December 31, 2017, 2016 and 2015, respectively. Facility start-up costs that cannot be capitalized are expensed as incurred and recorded in cost of products sold.

Property, plant and equipment is reviewed for impairment when indicators of a potential impairment are present by comparing the carrying values of the assets with their estimated future undiscounted cash flows. If we determine an impairment exists, the asset is written down to fair value.

Intangible Assets

We perform impairment tests for intangible assets with indefinite useful lives once a year, or more frequently if events occur or circumstances change that would more likely than not reduce the fair value of an intangible asset below its carrying value. The impairment test for assets with indefinite lives consists of a comparison of the fair value of the asset with its carrying value. If the carrying value of an intangible asset exceeds its fair value, an impairment loss is recognized in an amount equal to that excess. Intangible assets determined to have indefinite useful lives, primarily composed of trade names, are not amortized. An income approach is used for valuing trade names. Assumptions used in the income approach include projected revenues and assumed royalty, long-term growth and discount rates. As of December 31, 2017 and 2016, our indefinite lived intangibles, which are included in "Goodwill and intangible assets" on our consolidated balance sheets, totaled $19 million and $8 million, respectively.

We perform impairment tests on definite lived intangible assets upon identification of events or circumstances that may indicate the carrying value of the assets might be unrecoverable by comparing their undiscounted cash flows with their carrying value. If we determine impairment exists, the assets are written down to estimated fair value. As of December 31, 2017 and 2016, our definite lived intangibles, which are included in "Goodwill and intangible assets" on our consolidated balance sheets, totaled $8 million and $0 million, respectively.

Goodwill

We perform an impairment test on goodwill as of October 1, or more frequently if events occur or circumstances change that would more likely than not reduce the fair value below its carrying value. In testing goodwill for impairment, we have the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the estimated fair value of a reporting unit is less than its carrying value. If we elect to perform a qualitative assessment and determine that an impairment is more likely than not, we are then required to perform a quantitative impairment test, otherwise no further analysis is required. We also may elect not to perform the qualitative assessment and, instead, proceed directly to the quantitative impairment test. We perform a quantitative analysis which involves comparing the current fair value of each reporting unit to its carrying value, including goodwill. If the carrying value of a reporting unit exceeds its fair value, we recognize an impairment loss equal to the difference between the carrying value and the estimated fair value of the reporting unit. As of December 31, 2017 and 2016, goodwill totaled $16 million and $0 million, respectively, and is included in "Goodwill and intangible assets" on our consolidated balance sheets.

Asset Retirement Obligations

Our asset retirement obligations include reclamation requirements as regulated by government authorities related principally to assets such as our mines, quarries, landfills, ponds and wells. The accounting for asset retirement obligations requires estimates by management about the timing of asset retirements, the cost of retirement obligations, discount and inflation rates used in determining fair values and the methods of remediation associated with our asset retirement obligations. We generally use assumptions and estimates that reflect the most likely remediation method on a site-by-site basis. Our estimated liability for asset retirement obligations is revised annually, and whenever events or changes in circumstances indicate that a revision to the estimate is necessary.

In instances where a decrease in the asset retirement obligation is in excess of the related remaining net book value of the asset retirement costs, the excess is recorded to the consolidated statement of income as a reduction in "Cost of products sold." Asset retirement obligations are included in "Other liabilities" on the consolidated balance sheets.

Share-Based Compensation

We award share-based compensation to employees in the form of MSUs, performance shares and RSUs and to non-employee directors in the form of shares of our common stock. All grants under share-based payment programs are accounted for at fair value at the date of grant. We recognize expense on all share-based awards to employees expected to vest over the service period, which is the shorter of the period until the employees’ retirement eligibility dates or the service period of the award. We record forfeitures as they occur.

Derivative Instruments

We use derivative instruments to manage selected commodity price and foreign currency exposures. We do not use derivative instruments for speculative trading purposes, and we typically do not hedge beyond six years. All derivative instruments are recorded on the balance sheet at fair value. For derivatives designated as cash flow hedges, the effective portion of changes in the fair value of the derivative is recorded to AOCI, and is reclassified to earnings when the underlying forecasted transaction affects earnings. The ineffective portion of changes in the fair value of the derivative is reported in cost of products sold in the current period. For contracts designated as cash flow hedges, we reassess the probability of the underlying forecasted transactions occurring on a quarterly basis. For derivatives designated as net investment hedges, we record changes in fair value to AOCI. For derivatives not designated as hedging instruments, all changes in fair value are recorded to earnings in the current period. Cash flows from derivative instruments are included in operating activities in our consolidated statements of cash flows.

We use swaps to hedge a significant portion of our anticipated purchases of natural gas to be used in our manufacturing operations. Generally, we hedge the cost of a majority of our anticipated purchases of natural gas over the next 12 months. However, we review our positions regularly and make adjustments as market conditions warrant. The majority of contracts currently in place are designated as cash flow hedges and the remainder are not designated as hedging instruments.

We have operations outside of the United States and use forward contracts to hedge the risk of changes in cash flows resulting from selected forecasted intercompany and third-party sales or purchases, as well as intercompany loans, denominated in non-U.S. currencies, or to hedge the risk of selected changes in our net investment in foreign subsidiaries. These contracts are designated as either cash flow or net investment hedges or are not designated as hedging instruments.

Foreign Currency Translation

We translate foreign-currency-denominated assets and liabilities into U.S. Dollars at the exchange rates existing as of the respective balance sheet dates. We translate income and expense items at the average exchange rates during the respective periods. We record translation adjustments resulting from fluctuations in exchange rates to AOCI on our consolidated balance sheets.

We record transaction gains and losses to earnings. We recorded a total transaction loss of $4 million in 2017, a gain of $3 million in 2016 and a loss of $7 million in 2015. Transaction gains and losses are included in "Other (expense) income, net" in our consolidated statements of income.

Fair Value Measurements

Certain assets and liabilities are required to be recorded at fair value. The estimated fair values of those assets and liabilities have been determined using market information and valuation methodologies. Changes in assumptions or estimation methods could affect the fair value estimates. However, we do not believe any such changes would have a material impact on our financial condition, results of operations or cash flows. There are three levels of inputs that may be used to measure fair value:


•	Level 1 – Quoted prices for identical assets and liabilities in active markets;


•	Level 2 – Quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets; and


•	Level 3 – Valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.

Certain assets and liabilities are measured at fair value on a nonrecurring basis rather than on an ongoing basis, but are subject to fair value adjustments in certain circumstances, such as an acquisition, when evidence of impairment or when a new liability is being established that requires fair value measurement.