Usg (USG) 10-K 14 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	USG CORP
Entity Central Index Key	757,011
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 3,488,342,026
Entity Common Stock, Shares Outstanding		140,099,470
Entity Emerging Growth company	false
Entity Small Business	false
Entity Shell Company	false

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 3,336	$ 3,204	$ 3,017
Cost of products sold	2,730	2,548	2,317
Gross profit	606	656	700
Selling and administrative expenses	379	303	297
Long-lived asset impairment charges	0	0	10
Recovery of receivable	0	0	(3)
Operating profit	227	353	396
Income from equity method investments	42	59	49
Interest expense	(57)	(69)	(145)
Interest income	7	4	4
Loss on extinguishment of debt	0	(22)	(37)
Other income, net	8	10	7
Income from continuing operations before income taxes	227	335	274
Income tax expense	(34)	(238)	(63)
Income from continuing operations	193	97	211
Income (loss) from discontinued operations, net of tax	3	(9)	20
Gain on sale of discontinued operations, net of tax	0	0	279
Net income	$ 196	$ 88	$ 510
Earnings per common share - basic:
Income from continuing operations (in dollars per share)	$ 1.38	$ 0.67	$ 1.45
Income (loss) from and gain on sale of discontinued operations (in dollars per share)	0.02	(0.06)	2.04
Net income (in dollars per share)	1.40	0.61	3.49
Earnings per common share - diluted:
Income from continuing operations (in dollars per share)	1.36	0.66	1.44
Income (loss) from and gain on sale of discontinued operations (in dollars per share)	0.02	(0.06)	2.02
Net income (in dollars per share)	$ 1.38	$ 0.60	$ 3.46
Average common shares (in shares)	140,250,482	144,447,488	145,929,506
Dilutive awards under long-term incentive plan (in shares)	2,360,818	2,263,358	1,731,473
Average diluted common shares (in shares)	142,611,300	146,710,846	147,660,979
Cash dividend declared per share (in dollars per share)	$ 0.50	$ 0	$ 0

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 196	$ 88	$ 510
Derivatives qualifying as cash flow hedges:
Gain (loss) on derivatives qualifying as cash flow hedges, net of tax (benefit) of $1, ($10), and $2, respectively	6	(14)	1
Less: Reclassification adjustment for loss on derivatives included in net income, net of tax (benefit) of $0, ($3), and ($4), respectively	(2)	(3)	(6)
Net derivatives qualifying as cash flow hedges	8	(11)	7
Pension and postretirement benefits:
Changes in pension and postretirement benefits, net of tax (benefit) of $9, ($27), and ($19), respectively	28	(65)	(34)
Less: Amortization of prior service cost included in net periodic benefit cost, net of tax (benefit) of ($2), ($10), and ($7), respectively	(6)	(14)	(9)
Net pension and postretirement benefits	34	(51)	(25)
Foreign currency translation:
Changes in foreign currency translation, net of tax of $0 in all periods	(40)	58	(53)
Less: Translation loss realized upon sale of foreign equity method investment, net of tax (benefit) of ($2), $0, and $0, respectively	(4)	0	0
Net foreign currency translation	(36)	58	(53)
Other comprehensive income (loss), net of tax	6	(4)	(71)
Comprehensive income	$ 202	$ 84	$ 439

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivatives qualifying as cash flow hedges:
Gain (loss) on derivatives qualifying as cash flow hedges, tax (benefit)	$ 1	$ (10)	$ 2
Less: Reclassification adjustment for loss on derivatives included in net income, tax (benefit)	0	(3)	(4)
Pension and postretirement benefits:
Changes in pension and postretirement benefits, tax (benefit)	9	(27)	(19)
Less: Amortization of prior service cost included in net periodic pension cost, tax (benefit)	(2)	(10)	(7)
Foreign currency translation:
Changes in foreign currency translation, tax (benefit)	0	0	0
Less: Translation loss realized upon sale of foreign equity method investment tax (benefit)	$ (2)	$ 0	$ 0

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 328	$ 394
Short-term marketable securities	55	62
Receivables (net of reserves: 2018 - $10 and 2017 - $9)	233	233
Inventories	290	252
Income taxes receivable	21	15
Other current assets	44	35
Total current assets	971	991
Long-term marketable securities	43	37
Property, plant and equipment, net	1,838	1,762
Deferred income taxes	246	287
Equity method investments	662	686
Goodwill and intangible assets	40	43
Other assets	42	45
Total assets	3,842	3,851
Liabilities and Stockholders’ Equity
Accounts payable	290	280
Accrued expenses	129	135
Income taxes payable	2	0
Total current liabilities	421	415
Long-term debt	1,079	1,078
Deferred income taxes	5	4
Pension and other postretirement benefits	254	326
Other liabilities	164	183
Total liabilities	1,923	2,006
Stockholders’ Equity:
Preferred stock – $1 par value, authorized 36,000,000 shares; outstanding - none	0	0
Common stock – $0.10 par value; authorized 200,000,000 shares; issued: 2018 and 2017 - 146,513,000 shares	15	15
Treasury stock at cost; 2018 - 6,442,000 shares and 2017 - 5,571,000 shares	(200)	(169)
Additional paid-in capital	3,030	3,057
Accumulated other comprehensive loss	(383)	(389)
Retained earnings (accumulated deficit)	(543)	(669)
Total stockholders’ equity	1,919	1,845
Total liabilities and stockholders’ equity	$ 3,842	$ 3,851

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Reserves on receivables	$ 10	$ 9
Preferred stock - par value (in dollars per share)	$ 1	$ 1
Preferred stock - authorized shares (in shares)	36,000,000	36,000,000
Preferred stock - outstanding shares (in shares)	0	0
Common stock - par value (in dollars per share)	$ 0.1	$ 0.1
Common stock - authorized shares (in shares)	200,000,000	200,000,000
Common stock - issued shares (in shares)	146,513,000	146,513,000
Treasury stock, shares (in shares)	6,442,000	5,571,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Operating Activities
Net income	$ 196	$ 88	$ 510
Less: Income (loss) from discontinued operations, net of tax	3	(9)	20
Less: Gain on sale of discontinued operations, net of tax	0	0	279
Income from continuing operations	193	97	211
Adjustments to reconcile income from continuing operations to net cash:
Depreciation, depletion, amortization, and accretion	150	132	134
Loss on extinguishment of debt	0	22	37
Long-lived asset impairment charges	0	0	10
Recovery of receivable	0	0	(3)
Share-based compensation expense	21	18	18
Deferred income taxes	28	255	57
(Gain) loss on asset dispositions	(12)	1	(9)
Loss on sale of equity method investment	8	0	0
Income from equity method investments	(42)	(59)	(49)
Dividends received from equity method investments	30	42	47
Pension settlement	0	12	20
(Increase) decrease in working capital
Receivables	(5)	(32)	6
Income taxes receivable, net	(4)	(12)	3
Inventories	(42)	(13)	(20)
Other current assets	1	(3)	9
Payables	7	20	21
Accrued expenses	(2)	(36)	(39)
Increase in other assets	0	4	0
Decrease in pension and other postretirement benefits	(40)	(57)	(142)
Decrease in other liabilities	(23)	(13)	(6)
Other, net	13	4	9
Net cash provided by operating activities of continuing operations	281	382	314
Net cash provided by operating activities of discontinued operations	3	0	59
Net cash provided by operating activities	284	382	373
Investing Activities
Purchases of marketable securities	(102)	(105)	(274)
Sales or maturities of marketable securities	103	97	413
Capital expenditures	(219)	(168)	(83)
Net proceeds from asset dispositions	14	2	12
Net proceeds from sale of equity method investment	3	0	0
Acquisition of business, including working capital adjustment	2	(52)	0
Receipt of collection on loan from former joint venture	4	0	0
Return of capital	0	0	1
Insurance proceeds	0	1	1
Net cash (used for) provided by investing activities of continuing operations	(195)	(225)	70
Net cash provided by investing activities of discontinued operations	0	6	667
Net cash (used for) provided by investing activities	(195)	(219)	737
Financing Activities
Issuance of debt	0	500	0
Repayment of debt	0	(521)	(1,131)
Payment of debt issuance fees	0	(8)	0
Issuance of common stock	11	15	4
Repurchase of common stock	(76)	(184)	0
Repurchases of common stock to satisfy employee tax withholding obligations	(15)	(4)	(2)
Conditional special dividend	(70)	0	0
Net cash used for financing activities of continuing operations	(150)	(202)	(1,129)
Effect of exchange rate changes on cash	(5)	6	(5)
Net decrease in cash and cash equivalents from continuing operations	(69)	(39)	(750)
Net increase in cash and cash equivalents from discontinued operations	3	6	726
Net decrease in cash and cash equivalents	(66)	(33)	(24)
Cash, cash equivalents, and restricted cash at beginning of period	394	427	451
Cash, cash equivalents, and restricted cash at end of period	328	394	427
Supplemental Cash Flow Disclosures:
Interest paid, net of interest capitalized	53	82	153
Income taxes paid, net of refunds received	9	10	4
Noncash Investing and Financing Activities:
Amount in accounts payable for capital expenditures	23	18	15
Reversal of USG Boral Building Products earnout	0	0	(24)
Dividends Payable	$ 2	$ 0	$ 0

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Deficit)	Total Stockholders' Equity
Balance at beginning of period (in shares) at Dec. 31, 2015		145,667	0
Balance at beginning of period at Dec. 31, 2015		$ 15	$ 0	$ 3,027	$ (314)	$ (1,292)	$ 1,436
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 510					510	510
Other comprehensive loss	(71)				(71)		(71)
Share-based compensation				18			18
Tax deficiencies in share-based compensation				(11)			(11)
Stock issuances (in shares)		500	85
Stock issuances			$ 2	4			6
Repurchase of common stock (in shares)			(85)
Repurchase of common stock			$ (2)				(2)
Balance at end of period (in shares) at Dec. 31, 2016		146,167	0
Balance at end of period at Dec. 31, 2016		$ 15	$ 0	3,038	(385)	(782)	1,886
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	88					88	88
Other comprehensive loss	(4)				(4)		(4)
Share-based compensation				18			18
Stock issuances (in shares)		346	577
Stock issuances			$ 19	(5)			14
Repurchase of common stock (in shares)			(6,148)
Repurchase of common stock			$ (188)				(188)
Other				6			6
Balance at end of period (in shares) at Dec. 31, 2017		146,513	(5,571)
Balance at end of period at Dec. 31, 2017	1,845	$ 15	$ (169)	3,057	(389)	(669)	1,845
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	196					196	196
Other comprehensive loss	6				6		6
Share-based compensation				21			21
Stock issuances (in shares)			1,682
Stock issuances			$ 60	(48)			12
Repurchase of common stock (in shares)			(2,553)
Repurchase of common stock			$ (91)				(91)
Conditional special dividend						(72)	(72)
Balance at end of period (in shares) at Dec. 31, 2018		146,513	(6,442)
Balance at end of period at Dec. 31, 2018	$ 1,919	$ 15	$ (200)	$ 3,030	$ (383)	$ (543)	$ 1,919

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	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, specialty wallboard distributors, home improvement centers, other retailers and sold directly to contractors. Segments Our operating structure is generally aligned by product type and consists of three divisions, in addition to 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. Our reportable segments reflect the operating structure and align with how we manage our business, review operating performance and allocate resources considering the discrete information available for the geographies within the divisions. We have five reportable segments: U.S. Wallboard and Surfaces, U.S. Performance Materials, U.S. Ceilings, Canada, and UBBP. 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; 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, are included in Other, as reconciling items to our consolidated segments. 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. 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 upon transfer of control of our products to the customer which generally occurs upon shipment. 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. Reductions to revenue for customer programs and incentive offerings, including promotions and other volume-based incentives, are estimated using the most likely amount method and 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. We do not have any material payment terms as payment is received shortly after the point of sale. We pay commissions to third parties to obtain contracts. As these contracts are less than one year, these costs are expensed as incurred. Shipping and Handling Costs We include shipping and handling costs billed to customers in net sales and account for related costs as fulfillment activities and present the expenses in "Cost of products sold" when control of our products transfers to the customer. 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 $ 15 million , $ 10 million and $12 million for the years ended December 31, 2018 , 2017 and 2016 , 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 $22 million , $23 million and $24 million for the years ended December 31, 2018 , 2017 and 2016 , 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 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) 2018 2017 2016 Stock options, RSUs, MSUs and performance shares — 0.7 1.5 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 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 Our marketable securities, which meet the definition of debt 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, 2018 and 2017, the allowance for credit losses was immaterial. Equity Method Investments 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. 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 economic useful life. We record depletion 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 $6 million , $3 million and $1 million for the years ended December 31, 2018 , 2017 and 2016 , 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, 2018 and 2017 , our indefinite lived intangibles, which are included in "Goodwill and intangible assets" on our consolidated balance sheets, totaled $18 million and $19 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, 2018 and 2017 , our definite lived intangibles, which are included in "Goodwill and intangible assets" on our consolidated balance sheets, totaled $7 million and $8 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, including goodwill. 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. Our assessment compares 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, 2018 and 2017 , goodwill totaled $15 million and $16 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 or contractual obligations 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 Our current long-term incentive plan authorizes the Board’s Compensation and Organization Committee to provide equity-based compensation in the form of stock options, stock appreciation rights, restricted stock, RSUs, MSUs, performance shares and units, and other cash incentive and share-based awards for the purpose of providing our employees, officers and non-employee directors incentives and rewards for performance. We award share-based compensation to employees in the form RSUs, MSUs and performance shares and to non-employee directors in the form of shares of our common stock. We last granted stock options in 2012. All grants under share-based payment programs are accounted for at fair value at the date of grant. We recognize expense on 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 five 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. Purchase Obligations In the ordinary course of business we have entered into unconditional purchase obligations, which include noncancelable purchase commitments and take-or-pay arrangements with suppliers for the purchase of goods and services. On an ongoing basis, we review our agreements and assess the likelihood of a shortfall compared to the commitments and record a liability if the shortfall is probable and estimable. 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 $6 million in 2018 , a loss of $4 million in 2017 and a gain of $3 million in 2016 . Transaction gains and losses are included in "Other 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 there is evidence of impairment or when a new liability is being established that requires fair value measurement.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements We adopted Accounting Standard Update, or ASU, 2014-09, “Revenue from Contracts with Customers (Topic 606),” and all related amendments on January 1, 2018 using the modified retrospective method and practical expedients. Topic 606 supersedes the revenue recognition requirements in "Revenue Recognition (Topic 605)" and requires entities to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. On January 1, 2018, we recorded an increase of $2 million to our opening balance of retained earnings for the cumulative effect of adopting Topic 606. The adjustment related to a change to the point in time at which we record revenue for most customers. Prior period amounts have not been restated and continue to be reported under the legacy accounting guidance of Topic 605. As of and for the year ended December 31, 2018, the impact of applying Topic 606 as compared to applying Topic 605 is immaterial to our financial statements. We adopted ASU 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” on January 1, 2018 using the practical expedient. This ASU required us to disaggregate and present current service cost along with other current compensation costs for employees while presenting other net benefit cost components below operating profit. In addition, only the service cost component of net benefit cost is eligible for capitalization in our inventory and fixed assets. We retrospectively adopted the presentation of service cost and prospectively adopted the capitalization of only service cost into inventory and fixed assets. The effect of the adoption of ASU 2017-07 on our consolidated statements of income for the year ended December 31, 2017 and 2016 was as follows. (millions) Year ended December 31, 2017 Year ended December 31, 2016 As Restated Adjustment for Adoption of ASU 2017-07 As Previously Reported As Restated Adjustment for Adoption of ASU 2017-07 As Previously Reported Gross profit $ 656 $ (9 ) $ 665 $ 700 $ (5 ) $ 705 Operating profit 353 (14 ) 367 396 2 394 Other income, net 10 14 (4 ) 7 (2 ) 9 Net income 88 — 88 510 — 510 In the fourth quarter of 2018 we early adopted ASU 2018-14, "Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans," which modifies the disclosure requirements for defined benefit pension plans and other post-retirement plans. The adoption resulted in new disclosures, including comparative information for all years presented and the removal of certain disclosures no longer required. We adopted ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash,” which requires amounts generally described as restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling beginning-of-period and end-of-period total amounts shown on the statement of cash flows using the retrospective approach. The adoption resulted in a $9 million reduction of our net cash provided by investing activities on our consolidated statement of cash flows for the year ended December 31, 2016. We adopted ASU 2016-09, "Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting," on January 1, 2017. This ASU simplifies certain aspects of accounting for employee share-based payments. Upon adoption, we recorded to retained earnings a $25 million cumulative-effect adjustment for previously unrecognized excess tax benefits and an immaterial cumulative-effect adjustment for the reversal of cumulative forfeiture estimates to record forfeitures as they occur. We adopted ASU 2018-02, "Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," in the first quarter of 2018. The ASU allows for the reclassification of stranded tax effects on items resulting from the Tax Cuts and Jobs Act, or the 2017 Tax Act, from accumulated other comprehensive income, or AOCI, to retained earnings. We elected not to reclassify the income tax effects of the 2017 Tax Act. We adopted ASU 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments" on January 1, 2018 using the retrospective transition method. Topic 230 addresses specific cash flow issues with the stated objective of reducing the existing diversity in practice. There was no impact on adoption to our consolidated cash flow statements and disclosures as we were already compliant with the provisions of the standard. Recently Issued Accounting Pronouncements The Financial Accounting Standards Board, or FASB, issued ASU 2016-02, “Leases (Topic 842),” which supersedes existing lease guidance. The new standard requires lessees to recognize assets and liabilities on the balance sheet for the rights and obligations created by long-term leases and to disclose additional quantitative and qualitative information about leasing arrangements. Subsequently, the FASB has issued various ASUs to provide further clarification around certain aspects of Topic 842. We will adopt the new standard on January 1, 2019 using the modified retrospective transition method and will record a cumulative-effect adjustment to the opening balance of retained earnings at the adoption date. At transition, we will elect the package of practical expedients that allow us not to reassess under the new standard prior conclusions about lease identification, lease classification and initial direct costs. We expect to make the election to treat lease and non-lease components as a single lease component at the transition date. We are continuing to assess the completeness of our portfolio of leases, determine changes required in our lease accounting processes, and in the process of inputting our active leases into our new accounting software. The adoption of Topic 842 is expected to have a significant impact on our consolidated balance sheets and increase our disclosures on leases. In August 2018, the FASB, issued ASU 2018-15, "Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract," which clarifies the accounting for implementation costs in cloud computing arrangements. ASU 2018-15 is effective for us on January 1, 2020, and earlier adoption is permitted. We are currently evaluating the impact of this standard on our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments". Topic 326 eliminates the probable initial recognition threshold and, instead, requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. This standard is effective for us on January 1, 2020, and earlier adoption is permitted. We are currently evaluating the impact of Topic 326 on our consolidated financial position, results of operations and disclosures. We do not expect the adoption of Topic 326 to have a significant impact to our consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities,” which expands and refines hedge accounting for both non-financial and financial risk components and aligns the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The new standard is effective for us on January 1, 2019. We do not expect the adoption of ASU 2017-12 to have a significant impact to our consolidated financial statements or disclosures. In August 2018, the FASB issued ASU 2018-13, "Fair Value Measurement - Disclosure Framework (Topic 820)". The updated guidance improves the disclosure requirements on fair value measurements. The ASU is effective for us on January 1, 2020. Early adoption is permitted for any removed or modified disclosures. We are currently assessing the timing and impact of adoption.

Acquisition and Dispositions

Acquisition and Dispositions	12 Months Ended
	Dec. 31, 2018
Business Combinations And Discontinued Operations and Disposal Groups [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions Acquisition of Ceilings Plus On November 30, 2017, we completed our acquisition of Ceilings Plus for $50 million , net of working capital adjustments. The addition of Ceilings Plus to our U.S. Ceilings segment expands our operations in the specialty ceilings markets. We finalized our valuation in the second quarter of 2018. The fair value of tangible assets acquired, less liabilities assumed, in connection with the Ceilings Plus acquisition was $15 million . The fair value of intangible assets acquired, which included customer relationships and trade names, totaled $20 million . The resulting goodwill recorded was $15 million and all is expected to be deductible for tax purposes. The goodwill consists largely of Ceilings Plus' expected future product sales and synergies with the existing U.S. Ceilings product offerings. No impairment was recorded in 2018. Discontinued Operations On October 31, 2016, we completed the sale of our L&W distribution business to ABC Supply for total cash consideration of $675 million inclusive of the final working capital adjustment and recorded a gain on the sale of $279 million . For the year ended December 31, 2016, L&W met the criteria to be classified as held for sale and to be presented as a discontinued operation. The summarized financial information related to L&W that has been excluded from continuing operations and reported as a discontinued operation is as follows: (millions) Ten months ended October 31, 2016 Net sales $ 1,252 Cost of products sold 1,196 Gross profit 56 Selling and administrative expenses (a) 22 Operating profit 34 Income tax expense 12 Net income from discontinued operations $ 22 Gain on sale of discontinued operations $ 279 (a) The ten month period ended October 31, 2016 included transaction costs of $8 million . For the twelve months ended December 31, 2017 and 2016, we recorded a net loss of $9 million and net income of $22 million , respectively, to "Income (loss) from discontinued operations." The 2017 amounts reflected a $8 million loss for L&W primarily due to a pension settlement and a loss of $1 million for our European operations which were sold in December 2012. The 2016 net income from discontinued operations was comprised of the $22 million net income for L&W operations for the ten months prior to the disposition and expense of $2 million for our European operations which were sold in December 2012. Upon the close of the sale, we entered into a supply agreement with L&W. For the year ended December 31, 2018 and 2017, we recorded sales of $471 million and $510 million , respectively, and cash inflows related to payments on trade receivables of $467 million and $489 million , respectively. For the year ended December 31, 2016, the sales sold by L&W to third party customers totaled $568 million , and for the two months in 2016 after the sale of L&W, we recorded a cash inflow of $102 million related to payments on trade receivables.

Equity Method Investments

Equity Method Investments	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method Investments Equity method investments were as follows: December 31, 2018 December 31, 2017 (millions) Carrying Value Ownership Percentage Carrying Value Ownership Percentage USG Boral Building Products $ 660 50% $ 679 50% Other equity method investments 2 50% $ 7 33% - 50% Total equity method investments $ 662 $ 686 Investments in USG Boral Building Products (UBBP) UBBP is our 50 / 50 joint ventures with Boral Limited, or Boral. We account for our investment in UBBP using the equity method of accounting. During 2018 , UBBP paid cash dividends on earnings through December 2018 of which our 50% share totaled $30 million . As of December 31, 2018 , the amount of our consolidated retained earnings which represents undistributed earnings from UBBP is $72 million . The satisfaction by UBBP of certain U.S. Dollar denominated performance targets for the 5 years ended December 31, 2018 would have required us to pay Boral an earnout payment of up to $50 million . The performance targets were not satisfied by UBBP. At December 31, 2018 and 2017, there is no liability recorded for the earnout payment. UBBP is operated in accordance with the terms of a Shareholders Agreement. The Shareholders Agreement provides that a change of control, which includes the signing of the Merger Agreement, with respect to one party constitutes an event of default that allows the non-defaulting party the opportunity to purchase the defaulting shareholder's interest in UBBP for fair market value, as determined in accordance with the Shareholders Agreement. On August 28, 2018, Boral delivered a default notice under the Shareholders Agreement to commence the process to establish the fair market value of our 50% interest in UBBP. Once fair market value is established, Boral will have the right to purchase our 50% interest in UBBP in accordance with the Shareholders Agreement. Boral’s exercise of its right to purchase our 50% interest in UBBP could occur prior to the closing of the Merger Agreement (as defined in Note 19, Merger Agreement), in which case we would receive the cash proceeds for our interest, and we would no longer own an interest in UBBP. Our underlying net assets in our investments are denominated in a foreign currency, and translation gains or losses will impact the recorded value of our investments. Translation gains and losses recorded in other comprehensive income were as follows: (millions) 2018 2017 2016 Translation (loss) gain $ (31 ) $ 40 $ (30 ) Transactions with UBBP Our U.S. Wallboard and Surfaces and U.S. Performance Materials segments sell products to UBBP. Total sales to UBBP for each of the years ended December 31, 2018 , 2017 and 2016 were immaterial. In 2014, in connection with the formation of UBBP, we contributed our ownership interest in a joint venture in China to UBBP but retained our loan receivable from this joint venture. As of December 31, 2018 and 2017 , the loan receivable, including interest, totaled $9 million and $13 million , respectively, and is included in "Other assets" on our consolidated balance sheets. Summarized Financial Information Statements of Income For the year ended December 31, (millions) 2018 2017 2016 USG Boral Building Products: Net sales $ 1,182 $ 1,200 $ 1,052 Gross profit (a) 317 369 337 Operating profit 117 160 133 Net income from continuing operations before taxes 131 174 142 Net income 86 121 95 Net income attributable to USG Boral Building Products 84 117 99 USG share of income from investment accounted for using the equity method (b) 42 59 49 (a) Year ended December 31, 2016 includes long-lived asset impairment charges of $8 million for China and of $14 million for Oman. (b) Year ended December 31, 2016 includes long-lived asset impairment charges of $4 million for China and of $4 million for Oman. Balance Sheets (millions) December 31, 2018 December 31, 2017 USG Boral Building Products: Current assets $ 392 $ 438 Non-current assets 964 981 Current liabilities (a) 232 255 Long-term debt 10 10 Other non-current liabilities 22 12 Shareholders' equity (b) 1,092 1,142 (a) Includes the current portion of long-term debt of $15 million and $16 million as of December 31, 2018 and 2017 , respectively. (b) Shareholders' equity includes $64 million and $66 million related to non-controlling interests as of December 31, 2018 and 2017 , respectivel y. Investment in South Africa Joint Venture During the second quarter of 2018, we completed the sale of our 33% interest in a joint venture in South Africa for approximately $3 million . We recorded a loss on the sale of $8 million in "Other income, net" on our accompanying consolidated income statements. The loss, which totaled $5 million net of tax, was driven primarily by foreign currency losses included in equity that were recognized upon the disposition of the joint venture and was recorded within Other, as it does not relate to a reportable segment.

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	Marketable Securities Our investments in marketable securities as of December 31, 2018 and 2017 consisted of the following: 2018 2017 (millions) Amortized Cost Fair Value Amortized Cost Fair Value Corporate debt securities $ 73 $ 73 $ 68 $ 68 U.S. government and agency debt securities 5 5 6 6 Asset-backed debt securities 15 15 11 11 Certificates of deposit 5 5 13 13 Municipal debt securities — — 1 1 Total marketable securities $ 98 $ 98 $ 99 $ 99 The realized and unrealized gains and losses as of and for the years ended December 31, 2018 , 2017 and 2016 were immaterial. Contractual maturities of marketable securities as of December 31, 2018 were as follows: (millions) Amortized Cost Fair Value Due in 1 year or less $ 55 $ 55 Due in 1-5 years 43 43 Total marketable securities $ 98 $ 98 Actual maturities may differ from the contractual maturities because issuers of the securities may have the right to prepay them.

Debt

Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt	Debt Total debt as of December 31 consisted of the following: (millions) 2018 2017 4.875% senior notes due 2027 $ 500 $ 500 5.5% senior notes due 2025 350 350 Industrial revenue bonds (due 2028 through 2034) 239 239 Total $ 1,089 $ 1,089 Less: Unamortized debt issuance costs 10 11 Total $ 1,079 $ 1,078 Issuance of Senior Notes During 2017, we issued $500 million of 4.875% senior notes due 2027, referred to as our 4.875% Notes. The net proceeds from the issuance of these notes and cash on hand were used to fund the repurchase of our 7.75% senior notes due 2018, referred to as our 7.75% Notes, and all related costs and expenses. We deferred $7 million of debt issuance costs that are being amortized to interest expense over the term of the 4.875% Notes. Repurchases and Redemptions of Senior Notes During 2017, we repurchased $500 million of our 7.75% Notes through a cash tender offer and subsequent redemption for aggregate consideration of $536 million , including premiums of $20 million and accrued interest of $16 million . For the year ended December 31, 2017, we recorded a pre-tax loss on the early extinguishment of debt of $21 million . During 2016, we repaid $500 million of our 6.3% senior notes due 2016, referred to as the 6.3% Notes, $250 million of our 7.875% senior notes due 2020, referred to as the 7.875% Notes, and $350 million of our 5.875% senior notes due 2021, referred to as the 5.875% Notes. The retirement of the 6.3% Notes, the 7.875% Notes and the 5.875% Notes included premiums of $30 million and accrued interest of $9 million . As a result of these transactions, we recorded a loss on the early extinguishment of debt, before tax, of $37 million including premiums, write-off of deferred financing fees, debt discount and broker fees. Senior Notes Our senior notes are senior unsecured obligations, rank equally with all of our other existing and future unsecured senior indebtedness and are guaranteed by certain of our domestic subsidiaries. The indentures governing the notes contain events of default, covenants and restrictions that are customary for similar securities, including a limitation on our ability and the ability of certain of our subsidiaries to create or incur secured indebtedness. Interest rate 5.5% 4.875% Principal net of discount (in millions) (a) $350 $500 Maturity March 1, 2025 June 1, 2027 Call date (b) March 1, 2020 June 1, 2022 Mandatory redemption offer at 101% plus accrued and unpaid interest in the event of a change in control at 101% plus accrued and unpaid interest in the event of a change in control (a) Principal amounts exclude unamortized debt issuance costs. (b) Callable at any time, in whole or in part, prior to the call date at a redemption price equal to 100% of the principal plus a premium (as outlined in the respective indentures), plus any accrued and unpaid interest on the principal amount being called. Callable after the call date at stated redemption prices (as outlined in the applicable indenture), plus any accrued and unpaid interest on the principal amount being called. Credit Facility In 2017, we amended and restated our credit facility agreement to, among other things, increase the maximum borrowing limit from $180 million to $220 million . As a result, we recorded a pre-tax loss on extinguishment of debt of $1 million for the year ended December 31, 2017 and incurred $1 million of debt issuance costs. Our credit facility requires us to maintain a minimum fixed charge coverage ratio in the event excess availability falls below a minimum threshold. Because our excess borrowing availability as of December 31, 2018 of $171 million exceeds this threshold, the requirement to maintain the minimum fixed charge coverage ratio is not applicable. As of December 31, 2018 , we were in compliance with the covenants contained in our credit facility. As of December 31, 2018 and during the year then ended, there were no borrowings under the credit facility. Outstanding letters of credit as of December 31, 2018 totaled $19 million . Industrial Revenue Bonds Our $239 million of industrial revenue bonds have fixed interest rates ranging from 5.5% to 6.4% . The weighted average rate of interest on our industrial revenue bonds is 5.875% . These bonds mature during the years 2028 through 2034 . OTHER INFORMATION (millions) December 31, 2018 December 31, 2017 Fair value of debt $ 1,099 $ 1,134 Accrued interest 12 12 The fair value of our debt was determined using the fair value hierarchy of inputs described in Note 1. The fair values were determined utilizing prices from independent pricing services. The vendors’ methodologies utilize various forms of market data, including but not limited to, trade data, yield, spreads, bids and offers. We review the values provided by the independent pricing service for reasonableness. We have not adjusted the prices obtained from the independent pricing service. As a result, the fair values are classified as Level 2. See Note 8 , Fair Value Measurements, for further discussion on fair value measurements. As of December 31, 2018 , the amounts of total debt outstanding maturing in each of the next five years and beyond were as follows: (millions) 2019 through 2023 After 2023 Debt maturities (principal amounts) $ — $ 1,089

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments We use derivative instruments to manage selected commodity price and foreign currency exposures as described below. Derivative Instruments Type Hedged Item Aggregate Notional Amount Contracts Maturing Through Commodity Natural gas swaps Purchases of natural gas 41 million mmBTUs* December 31, 2022 Foreign Exchange Forward contracts Purchases of products and services denominated in a foreign currency $98 million December 31, 2019 * - millions of British Thermal Units COUNTERPARTY RISK, MASTER NETTING ARRANGEMENTS AND BALANCE SHEET OFFSETTING We are exposed to credit losses in the event of nonperformance by the counterparties to our derivative instruments. As of December 31, 2018 , our derivatives were in a $6 million net liability position. All of our counterparties have investment grade credit ratings; accordingly, we anticipate that they will be able to fully satisfy their obligations under the contracts. All of our derivative contracts are governed by master netting agreements negotiated between us and the counterparties that reduce our counterparty credit exposure. The agreements outline the conditions (such as credit ratings and net derivative fair values) upon which we, or the counterparties, are required to post collateral. As required by certain of our agreements, we had $7 million of collateral posted with our counterparties related to our derivatives as of December 31, 2018 . Amounts paid as cash collateral are included in "Receivables" on our consolidated balance sheets. We have not adopted an accounting policy to offset fair value amounts related to derivative contracts under our master netting arrangements; therefore, individual derivative contracts are reflected on a gross basis, as either assets or liabilities, on our consolidated balance sheets, based on their fair value as of the balance sheet date. FINANCIAL STATEMENT INFORMATION The following are the pre-tax effects of derivative instruments on our consolidated statements of income and our consolidated statements of comprehensive income for the years ended December 31, 2018 , 2017 and 2016 : Amount of Gain or (Loss) Recognized in Other Comprehensive Income (Loss) on Derivatives (Effective Portion) Location of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion) (millions) 2018 2017 2016 2018 2017 2016 Derivatives in Cash Flow Hedging Relationships Commodity contracts $ (1 ) $ (19 ) $ 6 Cost of products sold $ (2 ) $ (4 ) $ (15 ) Foreign exchange contracts 8 (5 ) (3 ) Cost of products sold — (2 ) 5 Total $ 7 $ (24 ) $ 3 $ (2 ) $ (6 ) $ (10 ) Location of Gain or (Loss) Recognized in Income on Derivatives Amount of Gain or (Loss) Recognized in Income on Derivatives (millions) 2018 2017 2016 Derivatives Not Designated as Hedging Instruments Commodity contracts Cost of products sold $ 1 $ (1 ) $ 1 Total $ 1 $ (1 ) $ 1 For both commodity contracts and foreign exchange contracts, no ineffectiveness was recorded in 2018 , 2017 or 2016 . The fair values of derivative instruments on the consolidated balance sheets are as follows: Balance Sheet Location Fair Value Balance Sheet Location Fair Value (millions) 12/31/18 12/31/17 12/31/18 12/31/17 Derivatives in Cash Flow Hedging Relationships Commodity contracts Other current assets $ 2 $ 1 Accrued expenses $ 6 $ 6 Commodity contracts Other assets 2 1 Other liabilities 10 8 Foreign exchange contracts Other current assets 6 — Accrued expenses — 3 Total derivatives in hedging relationships $ 10 $ 2 $ 16 $ 17 Derivatives Not Designated as Hedging Instruments Commodity contracts Other current assets $ — $ — Accrued expenses $ — $ — Commodity contracts Other assets — — Other liabilities — — Total derivatives not designated as hedging instruments $ — $ — $ — $ — Total derivatives Total assets $ 10 $ 2 Total liabilities $ 16 $ 17 As of December 31, 2018 and 2017, we had no derivatives designated as net investment or fair value hedges.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are required to be recorded at fair value. The fair values of our cash equivalents, equity mutual funds, marketable securities and derivatives were determined using the fair value hierarchy of inputs described in Note 1 , Significant Accounting Policies. USG Valuation Method Level 1 Cash equivalents and equity mutual funds consist of money market funds that are valued based on quoted prices in active markets. Level 2 Marketable securities, including certain cash equivalents, are valued using a "market value" approach. Values are based on quoted prices and other observable market inputs received from data providers. Derivatives are valued using the "income" approach such as discounted-cash-flow models and readily observable market data. The inputs for the valuation models are obtained from data providers and include end-of-period spot and forward natural gas prices, foreign currency exchange rates, natural gas price volatility and LIBOR and swap rates for discounting the cash flows implied from the derivative contracts. Level 3 No level 3 investments. Our assets and liabilities measured at fair value on a recurring basis were as follows: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (millions) 12/31/18 12/31/17 12/31/18 12/31/17 12/31/18 12/31/17 12/31/18 12/31/17 Cash equivalents $ 121 $ 124 $ 36 $ 24 $ — $ — $ 157 $ 148 Equity mutual funds 5 6 — — — — 5 6 Marketable securities: Corporate debt securities — — 73 68 — — 73 68 U.S. government and agency debt securities — — 5 6 — — 5 6 Asset-backed debt securities — — 15 11 — — 15 11 Certificates of deposit — — 5 13 — — 5 13 Municipal debt securities — — — 1 — — — 1 Derivative assets — — 10 2 — — 10 2 Derivative liabilities — — (16 ) (17 ) — — (16 ) (17 )

Employee Retirement Plans

Employee Retirement Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Retirement Plans	Employee Retirement Plans We maintain defined benefit pension plans for most of our employees. Most of these plans require employee contributions in order to accrue benefits. Benefits payable under the plans are based on employees’ years of service and compensation during specified years of employment. Effective December 31, 2010, we amended the USG Corporation defined benefit pension plan to replace the final average pay formula with a cash balance formula for employees hired after that date. In November 2016, we amended the U.S. pension plan to allow retirees and all terminated vested employees to take a lump-sum at all times without restriction. We also maintain plans that provide postretirement benefits (retiree health care and life insurance) for eligible employees. Employees hired before January 1, 2002 generally become eligible for the postretirement benefit plans when they meet minimum retirement age and service requirements. The cost of providing most postretirement benefits is shared with retirees. Upon the sale of L&W, we retained responsibility for the benefits payable to employees of L&W for the benefits accrued while employed by USG under the USG pension and postretirement plans. All L&W employees had the option to receive a lump sum benefit payment from the USG Corporation pension plan upon termination of their employment from USG. The total of the lump sum distributions made by the USG Corporation pension plan to both L&W employees and USG retirees or terminated vested employees during both 2017 and 2016 exceeded the settlement threshold and, as a result, we incurred settlement expense of $25 million and $26 million , respectively. The benefits payable to employees of L&W who did not take lump sum distributions in connection with their termination or retirement from USG are included in our benefit obligation as of December 31, 2018. The location of the pre-tax settlement expense within our consolidated statements of income and the group of employees for which it is related is presented in the following chart. There was no settlement expense in 2018. (millions) 2017 2016 Other income, net USG retirees or terminated vested employees $ 12 $ 11 Income (loss) from discontinued operations Terminated employees of L&W 13 — Gain on sale of discontinued operations Terminated employees of L&W — 15 Total $ 25 $ 26 Additionally, as a result of the sale of L&W, we recorded a curtailment gain of $20 million for the year ended December 31, 2016 for our postretirement plan to "Gain on sale of discontinued operations" in our consolidated statement of income, for those benefits no longer accruable to the employees of L&W who were not retirement eligible or did not elect retirement upon employment termination from USG. We previously amended our U.S. postretirement benefit plan to require retiree medical plan participants to begin purchasing individual coverage in the Affordable Insurance Exchanges or individual Medicare marketplace beginning January 1, 2016 using a company-funded subsidy. The subsidy is determined based upon years of service at retirement and Medicare eligibility. As a result of the amendments, the measurement of the accumulated postretirement benefit obligation, or APBO, was reduced and a credit to unrecognized prior service cost is being amortized into the statement of income over the average remaining service of active plan participants to retirement eligibility. This is reflected in net amortization of postretirement benefits in the table below and included in "Other income, net" in the consolidated statements of income. The subsidy provided to retirees eligible for Medicare will end December 31, 2019 at which time there will be no remaining credit to be amortized to the income statement for the unrecognized prior service cost. The components of the pre-tax total recognized in net pension and postretirement costs and other comprehensive income are summarized in the following table: Pension Postretirement (millions) 2018 2017 2016 2018 2017 2016 Service cost of benefits earned $ 50 $ 44 $ 45 $ 2 $ 2 $ 2 Interest cost on projected benefit obligation 62 61 66 5 5 6 Expected return on plan assets (97 ) (93 ) (89 ) — — — Settlement (a) — 25 35 — — — Curtailment — — — — — (20 ) Net amortization 31 22 22 (23 ) (23 ) (27 ) Net pension & postretirement cost (b) $ 46 $ 59 $ 79 $ (16 ) $ (16 ) $ (39 ) Net actuarial (loss) gain $ (14 ) $ 77 $ 58 $ (15 ) $ 10 $ (6 ) Net amortization (31 ) (22 ) (22 ) 23 23 27 Settlement — (25 ) (35 ) — — — Curtailment — — — — — 20 Deferred currency exchange (7 ) 4 2 (1 ) 1 (7 ) Total recognized in other comprehensive income $ (52 ) $ 34 $ 3 $ 7 $ 34 $ 34 Total recognized in net pension & postretirement cost and other comprehensive income $ (6 ) $ 93 $ 82 $ (9 ) $ 18 $ (5 ) (a) In 2016, $26 million of the settlement charge reflects the increase in lump sum benefits paid largely driven by the sale of L&W and $9 million reflected payments from our supplemental plan. (b) Net pension costs, excluding settlement costs, includes amounts allocated to income (loss) from discontinued operations for L&W totaling a benefit of $1 million for 2018, a benefit of $1 million for 2017, and an expense of $7 million for 2016. Net postretirement benefit, excluding curtailment gain, includes a net benefit allocated to income (loss) from discontinued operations for L&W of $3 million for 2018, $1 million for 2017 and $3 million for 2016. We use a December 31 measurement date for our plans. The accumulated benefit obligation, or ABO, for the defined benefit pension plans was $ 1.374 billion as of December 31, 2018 and $ 1.506 billion as of December 31, 2017 . As of December 31, (millions) 2018 2017 Selected information for pension plans with accumulated benefit obligations in excess of plan assets: Accumulated benefit obligation $ (35 ) $ (35 ) Fair value of plan assets 3 3 Selected information for pension plans with benefit obligations in excess of plan assets: Benefit obligation $ (1,568 ) $ (1,769 ) Fair value of plan assets 1,431 1,576 Selected information for postretirement plans with benefit obligations in excess of plan assets: Benefit obligation $ (132 ) $ (150 ) Fair value of plan assets — — The following table summarizes projected benefit obligations, plan assets and funded status as of December 31: Pension Postretirement (millions) 2018 2017 2018 2017 Change in Benefit Obligation: Benefit obligation as of January 1 $ 1,770 $ 1,610 $ 150 $ 135 Service cost 50 44 2 2 Interest cost 62 61 5 5 Settlements — (121 ) — — Participant contributions 10 9 — — Benefits paid (110 ) (51 ) (6 ) (6 ) Actuarial (gain) loss (192 ) 202 (15 ) 10 Foreign currency translation (21 ) 16 (4 ) 4 Benefit obligation as of December 31 $ 1,569 $ 1,770 $ 132 $ 150 Change in Plan Assets: Fair value as of January 1 $ 1,577 $ 1,435 $ — $ — Actual return on plan assets (81 ) 217 — — Employer contributions 56 71 6 6 Participant contributions 10 9 — — Benefits paid (110 ) (51 ) (6 ) (6 ) Settlements — (121 ) — — Foreign currency translation (20 ) 17 — — Fair value as of December 31 $ 1,432 $ 1,577 $ — $ — Funded status $ (137 ) $ (193 ) $ (132 ) $ (150 ) Components on the Consolidated Balance Sheets: Noncurrent assets $ 1 $ — $ — $ — Current liabilities (7 ) (8 ) (9 ) (9 ) Noncurrent liabilities (131 ) (185 ) (123 ) (141 ) Net liability as of December 31 $ (137 ) $ (193 ) $ (132 ) $ (150 ) Pretax Components in AOCI: Net actuarial loss (gain) $ 369 $ 421 $ (5 ) $ 11 Prior service credit — — (19 ) (42 ) Total as of December 31 $ 369 $ 421 $ (24 ) $ (31 ) For our defined benefit pension and postretirement plans, the 2018 actuarial gain of $192 million and $15 million , respectively, was primarily due to an increase in the discount rates. ASSUMPTIONS The following tables reflect the assumptions used in the accounting for our plans: Pension Postretirement 2018 2017 2018 2017 Weighted average assumptions used to determine benefit obligations as of December 31: Discount rate 4.21 % 3.55 % 4.09 % 3.42 % Compensation increase rate 3.55 % 3.54 % N/A N/A Interest crediting rate 4.00 % 4.00 % N/A N/A Weighted average assumptions used to determine net cost for years ended December 31: Discount rate 3.55 % 4.02 % 3.42 % 3.90 % Expected return on plan assets 6.55 % 6.54 % N/A N/A Compensation increase rate 3.54 % 3.55 % N/A N/A We no longer have significant exposure to health care cost trend rates due to the modifications we made to our U.S. postretirement health care plan to limit the increase in the annual amount we pay for retiree health care coverage for certain current and future retirees to 3% and to require retiree medical plan participants to begin purchasing individual coverage in the Affordable Insurance Exchanges or individual Medicare marketplace beginning January 1, 2016 using a company-funded subsidy based upon years of service at retirement. For the measurement of the APBO at December 31, 2018 for our Canadian postretirement health care plan, the assumed health care cost trend rates start with a 5.92% increase in 2019 , followed by a gradual decline in increases to 4% for 2046 and beyond. For the measurement of the APBO at December 31, 2017 , the assumed health care cost trend rates started with a 5.95% increase in 2018 , followed by a gradual decline in increases to 4% for 2046 and beyond. RETIREMENT PLAN ASSETS Investment Policies and Strategies : We have established investment policies and strategies for the defined benefit pension plans’ assets with a long-term objective of maintaining the plans’ assets at a level equal to or greater than that of their liabilities (as measured by a funded ratio of 100% or more of the PBO) and maximizing returns on the plans’ assets consistent with our moderate tolerance for risk. Contributions are made to the plans periodically as needed to meet funding targets or requirements. Factors influencing our determination to accept a moderate degree of risk include the timing of plan participants’ retirements and the resulting disbursement of retirement benefits, the liquidity requirements of the plans and our financial condition. Our overall long-term objective is to achieve a 6.6% rate of return on plan assets with a moderate level of risk as indicated by the volatility of investment returns. This rate of return target was established using a “building block” approach. In this approach, ranges of long-term expected returns for the various asset classes in which the plans invest are estimated. The estimated ranges are primarily based on observations of historical asset returns and their historical volatility. In determining the expected returns, we also consider consensus forecasts of certain market and economic factors that influence returns, such as inflation, gross domestic product trends and dividend yields. We then calculate an overall range of likely expected rates of return by applying the expected asset returns to the plans’ target asset allocation. The most likely rate of return is then determined and is adjusted to account for investment management fees. Our investment strategy is to invest in a diversified mix of asset classes in accordance with an asset allocation that we believe is likely to achieve our long-term target return while prudently considering risk. In order to manage risk, the plans’ pension and investment committees periodically rebalance the asset allocations as outlined by our investment policy statements. Our investment policy statements include glide paths which outline how our asset allocation would increase the portion of liability-hedging assets, such as fixed income, as our funded status improves in the future. This liability-driven investing approach is carried out by professional investment managers who help the committees in this process. The committees also monitor the investment performance of the individual investment managers compared to their benchmark returns and investment guidelines on an ongoing basis, in part through the use of quarterly investment portfolio reviews and compliance reporting by investment managers. The pension and investment committees also evaluate risk by periodically conducting asset/liability studies to assess the correlation of the plans’ assets and liabilities and the degree of risk in the target asset allocations. The plans limit the use of leverage to select investment strategies where leverage is typically employed, such as private equity and real estate. Certain investment managers may utilize derivatives, such as swaps, bond futures, and options, as part of their investment strategies. This is done primarily to gain a desired market exposure or manage factors such as interest rate risk or duration of a bond portfolio. The following table shows the aggregate target asset allocation on a weighted average basis for all the plans and the acceptable ranges around the targets as of December 31, 2018 . Investment Policy Asset Categories Asset Category Description Target Range Equity Institutional commingled/pooled equity funds, equity mutual funds and direct holdings of the common stock of U.S. and non-U.S. companies; equity funds and direct holdings are invested in companies with a range of market capitalizations 35% 32%-39% Fixed income U.S. Treasury securities, non-U.S. government debt securities such as Canadian federal bonds, corporate bonds of companies from diversified industries and mortgage-backed securities 55% 43%-66% Limited partnerships Investments in funds that follow any of several different strategies, including investing in distressed debt, energy development, infrastructure, and hedge funds. These investments use strategies with returns normally expected to have a reduced correlation to the return of equities as compared to other asset classes and often provide a current income component that is a meaningful portion of the investment’s total return. 5% 2%-8% Other real assets Primarily investments in large core, private real estate funds that directly own a diverse portfolio of properties located in the United States. It also includes an allocation to funds investing in equities of real estate and infrastructure companies 5% 2%-9% Cash equivalents and short-term investments Primarily short-term investment funds or registered money market funds with daily liquidity —% 0%-5% Total 100% Fair Values of Plan Assets : Pension assets are classified based on the valuation methodologies and inputs used to determine the fair value as described in Note 1. Level 1 investments include direct investments in common stocks of U.S. and non-U.S. companies that trade on liquid exchanges. These investments are valued based on the closing price on these exchanges. Level 2 investments include primarily fixed income securities such as corporate, or government debentures, mortgage- and asset-backed securities. They are valued primarily using income and market approaches, such as pricing based on recent market transactions, and values are based on quoted prices or other observable market inputs received from data providers. Commingled funds not traded on an exchange, even though their underlying investments are common stocks traded on liquid exchanges, are also included in the Level 2 category. The net asset value of commingled funds investing in either stocks or fixed income securities is calculated by subtracting the value of any liabilities from the market value of all securities owned by a fund. Level 3 investments include real estate, infrastructure, or direct energy investments as well as distressed securities or hedge funds. These are valued using income approach methodologies such as discounted cash flows, or market approach methodologies such as relative value (specific to equity securities), direct capitalization and comparable sales (specific to real estate investments). Some of the key inputs used to value these securities include discount rate, EBITDA multiple, yield-to-worst, yield-to-maturity, and cap rate (specific to real estate investments). The fair values by hierarchy of inputs as of December 31 were as follows: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (millions) 2018 2017 2018 2017 2018 2017 2018 2017 Asset Categories: Equity: Common and preferred stock $ 88 $ 92 $ — $ — $ — $ — $ 88 $ 92 Commingled/pooled/mutual funds (a) — — 450 553 — — 450 553 Total equity 88 92 450 553 — — 538 645 Fixed income: U.S. government and agency debt securities — — 11 8 — — 11 8 Non-U.S. government and agency debt securities — — 55 68 — — 55 68 Investment-grade debt securities — — 268 334 — — 268 334 High-yield debt securities — — 40 42 — — 40 42 Commingled/pooled funds (a) — — 362 305 — — 362 305 Mortgaged backed securities — — 5 1 — — 5 1 Other — — 12 13 1 1 13 14 Total fixed income — — 753 771 1 1 754 772 Limited partnerships — — — — 83 91 83 91 Other real estate assets — — 16 18 35 39 51 57 Cash equivalents and short-term investments — — 10 14 — — 10 14 Total $ 88 $ 92 $ 1,229 $ 1,356 $ 119 $ 131 $ 1,436 $ 1,579 Cash on hand 1 — Receivables 5 2 Accounts payable (10 ) (4 ) Total $ 1,432 $ 1,577 (a) Certain investments in commingled/pooled equity funds have been classified as Level 2 because observable quoted prices for these institutional funds are not available. A reconciliation of the change in the fair value measurement of the defined benefit plans’ consolidated assets using significant unobservable inputs (Level 3) between January 1, 2017 and December 31, 2018 is as follows: (millions) Fixed Income Other Real Estate Assets Limited Partnerships Total Balance as of January 1, 2017 $ 1 $ 38 $ 103 $ 142 Realized losses — 1 15 16 Unrealized gains — 2 (1 ) 1 Purchases, sales and settlements: Purchases — — 9 9 Sales — (2 ) (35 ) (37 ) Settlements — — — — Net transfers into (out of) Level 3 — — — — Balance as of December 31, 2017 $ 1 $ 39 $ 91 $ 131 Realized gains — 1 4 5 Unrealized gains (losses) — 1 (8 ) (7 ) Purchases, sales and settlements: Purchases — — 14 14 Sales — (6 ) (18 ) (24 ) Settlements — — — — Net transfers into (out of) Level 3 — — — — Balance as of December 31, 2018 $ 1 $ 35 $ 83 $ 119 CASH FLOWS We are evaluating our level of funding for pension plans and currently estimate that we will contribute approximately $62 million to our pension plans in 2019 . Our cash payments for postretirement plans are estimated to be $9 million in 2019 . Total benefit payments we expect to make to participants, which include payments funded from USG’s assets as well as payments from our pension plans' assets, are as follows (in millions): Years ended December 31 Pension Benefits Postretirement Benefits 2019 $ 115 $ 9 2020 117 8 2021 114 8 2022 117 8 2023 121 8 2024 - 2028 581 40 DEFINED CONTRIBUTION PLANS Total charges for our defined contribution plans amounted to approximately $12 million , $8 million and $5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. USG’s contributions are charged to cost of products sold and selling and administrative expenses.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation We grant share-based compensation to eligible participants under our 2016 Long-Term Incentive Plan, or New LTIP, which was approved by our Board of Directors and stockholders in 2016, and prior thereto under our prior Long-Term Incentive Plan, which, together with the New LTIP, is referred to as the LTIP. As of December 31, 2018 , a total of 6 million shares of common stock were reserved for future grants under the New LTIP. We may issue shares of our common stock upon option exercises and upon the vesting or grant of other awards under the LTIP from our authorized but unissued shares or from treasury shares. Our expense in continuing operations for share-based arrangements was $21 million in 2018 , $ 18 million in 2017 and $ 18 million in 2016 and is included in "Selling and administrative expenses" in our consolidated statements of income. In 2018 we recognized a $7 million net income tax benefit for share-based arrangements in the consolidated statement of income; no income tax effects were recognized in 2017 or 2016 . MARKET SHARE UNITS We granted MSUs with the following weighted average grant date fair values: 2018 2017 2016 Weighted average grant date fair values $ 34.22 $ 35.79 $ 19.59 MSUs generally vest after a three -year period based on our actual stock price performance during such period. The number of MSUs earned will vary from 0% to 150% of the number of MSUs awarded depending on the actual performance of our stock price. In the case of termination of employment due to death, disability or retirement during the performance period, vesting will be pro-rated based on the number of full months employed in the grant year. Awards earned will be issued at the end of the three -year period. Each MSU earned will be settled in shares of our common stock. We estimated the fair value of each MSU granted on the date of grant using a Monte Carlo simulation that used the assumptions noted in the following table. Volatility was based on stock price history immediately prior to grant for a period commensurate with the expected term. The risk-free rate was based on zero-coupon U.S. government issues at the time of grant. The expected term represents the period from the valuation date to the end of the performance period. Assumptions: 2018 2017 2016 Expected volatility 32.62 % 32.10 % 34.02 % Risk-free rate 2.37 % 1.39 % 0.86 % Expected term (in years) 2.95 2.96 2.95 Expected dividends — — — Nonvested MSUs outstanding as of December 31, 2018 and MSU activity during 2018 were as follows: Number of MSUs (000) Weighted Average Grant Date Fair Value Nonvested at January 1, 2018 1,097 $ 25.01 Granted 429 34.22 Vested (730 ) 19.59 Forfeited (8 ) 35.79 Nonvested at December 31, 2018 788 $ 34.93 With respect to the MSUs granted in 2016 , for which the three -year period ended December 31, 2018 , 730,145 vested for approximately 1,095,218 shares of common stock based on the actual performance of our stock price. Total unrecognized compensation cost related to nonvested share-based compensation awards represented by MSUs granted under the LTIP was $ 5 million as of December 31, 2018 . We expect that cost to be recognized over a weighted average period of 1.7 years. PERFORMANCE SHARES We granted performance shares with the following weighted average grant date fair values: 2018 2017 2016 Weighted average grant date fair values $ 34.21 $ 39.42 $ 21.10 The performance shares generally vest after a three -year period based on our total stockholder return relative to the performance of the Dow Jones U.S. Construction and Materials Index, with adjustments to that index in certain circumstances, for the three-year period. The number of performance shares earned will vary from 0% to 200% of the number of performance shares awarded depending on that relative performance. Vesting will be pro-rated based on the number of full months employed during the performance period in the case of death, disability or retirement, and pro-rated awards earned will be settled in common stock at the end of the three -year period. We estimated the fair value of each performance share granted on the date of grant using a Monte Carlo simulation that uses the assumptions noted in the following table. Volatility was based on stock price history immediately prior to grant for a period commensurate with the expected term. The risk-free rate was based on zero-coupon U.S. government issues at the time of grant. The expected term represents the period from the grant date to the end of the three -year performance period. Assumptions: 2018 2017 2016 Expected volatility 32.61 % 32.10 % 34.02 % Risk-free rate 2.37 % 1.39 % 0.86 % Expected term (in years) 2.95 2.96 2.95 Expected dividends — — — Nonvested performance shares outstanding as of December 31, 2018 and performance share activity during 2018 were as follows: Number of Performance Shares (000) Weighted Average Grant Date Fair Value Nonvested at January 1, 2018 256 $ 29.14 Granted 104 34.21 Vested (143 ) 21.10 Forfeited (2 ) 33.35 Nonvested at December 31, 2018 215 $ 36.93 With respect to the performance shares granted in 2016 , for which the three -year performance period ended December 31, 2018 , 143,033 of the performance awards vested for 286,066 common shares. Total unrecognized compensation cost related to nonvested share-based compensation awards represented by performance shares granted under the LTIP was $4 million as of December 31, 2018 . We expect that cost to be recognized over a weighted average period of 1.6 years. RESTRICTED STOCK UNITS We granted RSUs with the following weighted average grant date fair values: 2018 2017 2016 Weighted average grant date fair values $ 36.92 $ 31.57 $ 23.94 RSUs granted as special retention awards generally vest after a specified number of years from the date of grant or at a specified date and RSUs granted with performance goals vest if those goals are attained. RSUs may vest earlier in the case of death, disability, retirement or a change in control. Each RSU is settled in a share of our common stock after the vesting period. The fair value of each RSU granted is equal to the closing market price of our common stock on the date of grant. RSUs outstanding as of December 31, 2018 and RSU activity during the year then ended were as follows: Number of RSUs (000) Weighted Average Grant Date Fair Value Nonvested at January 1, 2018 304 $ 14.67 Granted 44 36.92 Vested (50 ) 26.64 Forfeited (10 ) 28.29 Nonvested at December 31, 2018 288 $ 30.05 As of December 31, 2018 , there was $4 million of total unrecognized compensation cost related to nonvested share-based compensation awards represented by RSUs granted under the LTIP. We expect that cost to be recognized over a weighted average period of 1.6 years . The total fair value of RSUs that vested was $1 million during 2018 , $ 2 million during 2017 and $ 2 million during 2016 . STOCK OPTIONS All outstanding stock options are exercisable. The stock options generally expire ten years from the date of grant, or earlier in the event of death, disability or retirement. A summary of stock options outstanding as of December 31, 2018 and of stock option activity during the year then ended is presented below: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2018 1,261 $ 15.72 2.48 $ 28 Exercised (677 ) 16.02 Canceled (50 ) 34.67 Outstanding, exercisable and vested at December 31, 2018 534 $ 13.55 1.89 $ 16 (millions) 2018 2017 2016 Intrinsic value of stock options exercised $ 17 $ 7 $ 4 Cash received from stock options exercised $ 11 $ 14 $ 4 Fair value of stock options vested $ — $ — $ 1 Intrinsic value for stock options is defined as the difference between the current market value of our common stock and the exercise price of the stock options. NON-EMPLOYEE DIRECTOR DEFERRED STOCK UNITS Our non-employee directors may elect to receive a portion of their compensation as deferred stock units. In August 2017, we amended this program to remove the election to receive cash or shares of USG common stock upon termination of board service and, as a result, all deferred stock units granted after August 2017 will be paid in shares of USG common stock. Also in August 2017, four of our non-employee directors elected to receive shares of stock for previously granted deferred stock units, and as a result, in 2017, we recorded a reclassification from a liability to equity of $6 million for these previously deferred awards. KNAUF TRANSACTION At the effective time of the Merger (as defined in Note 19, Merger Agreement), subject to certain exceptions, each MSU, performance share, and RSU that is outstanding immediately prior to the Merger will become fully vested. At the effective time of the Merger, these awards, along with each deferred stock unit, will be converted into the right to receive a cash payment equal to (i) the number of shares of our common stock earned on each underlying share, determined by substituting the closing consideration of $43.50 for the market value or the ending stock price in determining the achievement of the performance goal as applicable, multiplied by (ii) the closing consideration of $43.50 per share. Each stock option that is outstanding immediately prior to the Merger will be converted into the right to receive a cash payment equal to the (i) the number of shares of our common stock subject to such option at the effective time of the Merger, multiplied by (ii) the excess, if any, of the closing consideration of $43.50 per share over the exercise price of the option. A Dividend Make-Whole Amount Plan was approved by USG in connection with the Merger. See Note 19 , Merger Agreement, for further discussion.

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Balance Sheet Information	Supplemental Balance Sheet Information INVENTORIES Inventories as of December 31 consisted of the following: (millions) 2018 2017 Finished goods $ 168 $ 140 Work in progress 42 39 Raw materials 80 73 Total $ 290 $ 252 PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment as of December 31 consisted of the following: (millions) 2018 2017 Land and mineral deposits $ 206 $ 120 Buildings and improvements 1,022 1,100 Machinery and equipment 2,717 2,595 3,945 3,815 Reserves for depreciation and depletion (2,107 ) (2,053 ) Total $ 1,838 $ 1,762 Annual depreciation and depletion expense $ 133 $ 129 ACCRUED EXPENSES Accrued expenses as of December 31 consisted of the following: (millions) 2018 2017 Self-insurance reserves $ 13 $ 12 Employee compensation 17 17 Interest 12 12 Derivatives 6 9 Pension and other postretirement benefits 16 17 Environmental 13 17 Other 52 51 Total $ 129 $ 135 ASSET RETIREMENT OBLIGATIONS Changes in our liability for asset retirement obligations consisted of the following: (millions) 2018 2017 Balance as of January 1 $ 118 $ 113 Accretion expense 7 7 Liabilities incurred — 3 Changes in estimated cash flows (9 ) (4 ) Liabilities settled (1 ) (3 ) Reclass to accrued expenses (2 ) — Foreign currency translation (2 ) 2 Balance as of December 31 $ 111 $ 118 ASSET DISPOSITIONS In the second quarter of 2018, we recorded a gain of $13 million , or $9 million net of tax, on the sale of a surplus property. The pre-tax gain was recorded in "Cost of products sold" within the U.S. Wallboard and Surfaces segment. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Changes in the balances of each component of AOCI are summarized in the following table: (millions) Derivatives Pension and Other Postretirement Benefit Plans Foreign Total AOCI Balance as of January 1, 2016 $ 20 $ (221 ) $ (113 ) $ (314 ) Other comprehensive income (loss) before reclassifications, net of tax 1 (34 ) (53 ) (86 ) Less: Amounts reclassified from AOCI, net of tax (6 ) (9 ) — (15 ) Other comprehensive income (loss), net of tax 7 (25 ) (53 ) (71 ) Balance as of December 31, 2016 $ 27 $ (246 ) $ (166 ) $ (385 ) Other comprehensive income (loss) before reclassifications, net of tax (14 ) (65 ) 58 (21 ) Less: Amounts reclassified from AOCI, net of tax (3 ) (14 ) — (17 ) Other comprehensive income (loss), net of tax (11 ) (51 ) 58 (4 ) Balance as of December 31, 2017 $ 16 $ (297 ) $ (108 ) $ (389 ) Other comprehensive income (loss) before reclassifications, net of tax 6 28 (40 ) (6 ) Less: Amounts reclassified from AOCI, net of tax (2 ) (6 ) (4 ) (12 ) Other comprehensive income (loss), net of tax 8 34 (36 ) 6 Balance as of December 31, 2018 $ 24 $ (263 ) $ (144 ) $ (383 ) Amounts reclassified from AOCI, net of tax, for the years ended December 31, 2018 , 2017 and 2016 were as follows: (millions) 2018 2017 2016 Derivatives Net reclassification from AOCI for cash flow hedges included in cost of products sold $ (2 ) $ (6 ) $ (10 ) Less: Income tax benefit on reclassification from AOCI included in income tax expense — (3 ) (4 ) Net amount reclassified from AOCI $ (2 ) $ (3 ) $ (6 ) Defined Benefit Plans Net reclassification from AOCI for amortization of prior service (benefit) cost included in other income, net $ (8 ) $ (13 ) $ (13 ) Net reclassification from AOCI for amortization of prior service benefit included in income (loss) from discontinued operations, net of tax — (11 ) (3 ) Less: Income tax benefit on reclassification from AOCI included in income tax expense (2 ) (10 ) (7 ) Net amount reclassified from AOCI $ (6 ) $ (14 ) $ (9 ) Foreign Currency Translation Net reclassification from AOCI for translation loss realized upon the sale of foreign equity method investment included in other income, net $ (6 ) $ — $ — Less: Income tax benefit on reclassification from AOCI included in income tax benefit (2 ) — — Net amount reclassified from AOCI $ (4 ) $ — $ — We estimate that we will reclassify a net $2 million after-tax gain on derivatives from AOCI to earnings within the next 12 months.

Long-Lived Asset Impairment Cha

Long-Lived Asset Impairment Charges	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Long-Lived Asset Impairment Charges	Long-Lived Asset Impairment Charges In 2016, we indefinitely idled our mining operations in Little Narrows, Nova Scotia, Canada after completing a review of our gypsum sourcing needs. At such time, we assessed the property, plant and equipment for potential impairment. We compared the carrying values of those assets with their future undiscounted cash flows for their remaining useful lives. We measured the fair value of the machinery, equipment and buildings using measurements classified as Level 3. As a result we recorded long-lived asset impairment charges of $10 million , which are included in our consolidated statements of income in "Long-lived asset impairment charges". We also recorded severance and other charges of $2 million for the termination of employees at the Little Narrows location, which are included in "Costs of products sold" on our consolidated statements of income. Both the impairment and severance charges are included in Other.

Segments

Segments	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segments	Segments Our operations are organized into five reportable segments: U.S. Wallboard and Surfaces, U.S. Performance Materials, U.S. Ceilings, Canada, and UBBP. See Note 1, Significant Accounting Policies, for additional information regarding our reportable segments. The results of our five reportable segments are as follows: CONSOLIDATED SEGMENTS For the year ended December 31, (millions) 2018 2017 2016 Net Sales: U.S. Wallboard and Surfaces $ 1,927 $ 1,916 $ 1,778 U.S. Performance Materials 392 373 357 U.S. Ceilings 541 477 467 Canada 448 405 389 Other 252 245 220 Eliminations (224 ) (212 ) (194 ) Total $ 3,336 $ 3,204 $ 3,017 Operating Profit (Loss): U.S. Wallboard and Surfaces $ 248 $ 306 $ 328 U.S. Performance Materials (8 ) 24 40 U.S. Ceilings 78 92 98 Canada 19 13 27 Other 14 11 (4 ) Corporate (124 ) (92 ) (93 ) Eliminations — (1 ) — Total $ 227 $ 353 $ 396 Depreciation, Depletion, Amortization and Accretion: U.S. Wallboard and Surfaces $ 97 $ 91 $ 87 U.S. Performance Materials 10 9 9 U.S. Ceilings 24 15 15 Canada 8 6 6 Other 5 5 7 Corporate 6 6 10 Total $ 150 $ 132 $ 134 Capital Expenditures: U.S. Wallboard and Surfaces $ 131 $ 104 $ 60 U.S. Performance Materials 36 31 11 U.S. Ceilings 27 17 4 Canada 8 10 4 Other 10 5 3 Corporate 7 1 1 Total $ 219 $ 168 $ 83 CONSOLIDATED NET SALES DISAGGREGATED BY PRODUCT TYPE For the year ended December 31, 2018 (millions) U.S. Wallboard and Surfaces U.S. Performance Materials U.S. Ceilings Canada Other Total Wallboard $ 994 $ — $ — $ 258 $ 70 $ 1,322 Surfaces and industrial products 580 — — 89 28 697 Underlayment — 303 — 10 38 351 Building envelope and structural — 81 — 2 1 84 Ceiling tile and grid — — 464 44 34 542 Specialty ceilings — — 20 8 — 28 Other products 103 — 3 13 78 197 Total product sales 1,677 384 487 424 249 3,221 Other miscellaneous sales (a) 250 8 54 24 3 339 Total sales before eliminations 1,927 392 541 448 252 3,560 Eliminations (124 ) (20 ) (48 ) (31 ) (1 ) (224 ) Total net sales $ 1,803 $ 372 $ 493 $ 417 $ 251 $ 3,336 (a) Other miscellaneous sales primarily includes shipping and handling costs billed to customers. CONSOLIDATED GEOGRAPHIC INFORMATION For the year ended December 31, (millions) 2018 2017 2016 Net Sales: United States $ 2,871 $ 2,787 $ 2,625 Canada 448 406 389 Other Foreign 211 204 189 Geographic transfers (194 ) (193 ) (186 ) Total $ 3,336 $ 3,204 $ 3,017 Consolidated long-lived assets, consisting of property, plant and equipment, net, by geographic location were as follows: As of December 31, (millions) 2018 2017 2016 Long-Lived Assets: United States $ 1,680 $ 1,604 $ 1,563 Canada 84 90 80 Other Foreign 74 68 64 Total $ 1,838 $ 1,762 $ 1,707 UBBP For the year ended December 31, (millions) 2018 2017 2016 Net sales $ 1,182 $ 1,200 $ 1,052 Operating profit 117 160 133 Net income attributable to UBBP 84 117 99 Depreciation, depletion, and amortization 50 45 43 Capital expenditures 84 49 45 UBBP GEOGRAPHIC INFORMATION For the year ended December 31, (millions) 2018 2017 2016 Net Sales: Australia $ 438 $ 431 $ 381 South Korea 253 287 223 Thailand 161 150 141 China 131 119 103 Other 267 271 255 Geographic transfers (68 ) (58 ) (51 ) Total $ 1,182 $ 1,200 $ 1,052 Long-lived assets, consisting of property, plant and equipment, net, by geographic location for UBBP were as follows: As of December 31, (millions) 2018 2017 2016 Long-Lived Assets: Australia $ 209 $ 229 $ 217 South Korea 118 123 107 China 93 101 97 Oman 83 85 86 Thailand 86 86 75 Other 102 86 71 Total $ 691 $ 710 $ 653 OTHER SEGMENT INFORMATION Information on segment assets is not disclosed as our chief operating decision maker does not evaluate operating segments using asset information. Segment operating profit (loss) includes all costs and expenses directly related to the segment involved and an allocation of expenses that benefit more than one segment. Revenues are attributed to geographic areas based on the location of the assets producing the revenues. Transactions between reportable segments and geographic areas are accounted for at transfer prices that are approximately equal to market value. Geographic transfers largely reflect intercompany sales from our domestic segments of U.S. Wallboard and Surfaces, U.S. Performance Materials and U.S. Ceilings to Canada and Mexico. Sales to our significant customers were as follows: Significant Customer Segment with Sales to Significant Customer 2018 2017 2016 The Home Depot U.S. Wallboard and Surfaces, U.S. Performance Materials, U.S. Ceilings, and Canada 24 % 23 % 23 % L&W U.S. Wallboard and Surfaces, U.S. Performance Materials and U.S. Ceilings 14 % 16 % 19 %

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the President of the United States signed into law the 2017 Tax Act. The 2017 Tax Act amended the Internal Revenue Code of 1986, as amended (the "Code"), to reduce tax rates and modify policies, credits and deductions. For businesses, the 2017 Tax Act reduced the corporate federal tax rate from a maximum of 35% to a flat 21% . The provisional effect on deferred tax assets and liabilities of the change in tax rates was recognized in earnings in the period ended December 31, 2017, which was when the change was enacted. As part of the 2017 Tax Act's change to a quasi-territorial system, a transition tax was imposed on our accumulated foreign earnings, partially offset by foreign tax credits, which was also recognized in the period ending December 31, 2017. In December 2017, the SEC staff issued Staff Accounting Bulletin 118 (“SAB 118”), which provided relief for companies to record provisional amounts in the period of enactment not to exceed one year from the 2017 Tax Act enactment date. The estimate recorded as of December 31, 2017 was updated and finalized in the fourth quarter of 2018 to reflect our decision to elect not to apply our existing net operating losses, or NOLs, against the accumulated earnings that were subject to the transition tax. As a result of that election, in the fourth quarter of 2018 we recorded a tax benefit of $9 million for the release of a portion of the valuation allowance on our foreign tax credit carryforward. We also reversed $2 million of anticipated sequestration of our corporate alternative minimum tax, or AMT, credits based upon guidance released by the United States Office of Management and Budget (OMB). Ongoing guidance and accounting interpretation for the 2017 Tax Act are expected over the coming months and years and we will consider any changes in the accounting for the 2017 Tax Act in the period in which such additional guidance is issued. We do not expect the ongoing guidance and interpretations to have a material impact on our financial statements. The 2017 Tax Act also repealed the corporate AMT for tax years beginning January 1, 2018, and provides that existing AMT credit carryovers are refundable beginning in 2018. As of December 31, 2018, we recorded a $17 million receivable, which is included in "Income taxes receivable" on our consolidated balance sheet. We have approximately $17 million of AMT credit carryovers that are expected to be refunded by 2022. Income from continuing operations before income taxes consisted of the following: (millions) 2018 2017 2016 U.S. $ 168 $ 272 $ 201 Foreign 59 63 73 Total $ 227 $ 335 $ 274 Income tax expense (benefit) on continuing operations consisted of the following: (millions) 2018 2017 2016 Current: Federal $ (3 ) $ (21 ) $ — Foreign 7 2 5 State 2 2 1 Total current $ 6 $ (17 ) $ 6 Deferred: Federal $ 23 $ 243 $ 41 Foreign — — 2 State 5 12 14 Total deferred $ 28 $ 255 $ 57 Total $ 34 $ 238 $ 63 For our continuing operations, differences between actual provisions for income taxes and provisions for income taxes at the U.S. federal statutory rate ( 21% in 2018 and 35% in 2017 and 2016) were as follows: (millions) 2018 2017 2016 Taxes on income from continuing operations at U.S. federal statutory rate $ 48 $ 117 $ 96 Foreign earnings subject to different tax rates 4 3 (3 ) State income tax, net of federal benefit 6 9 10 Income from equity method investments (9 ) (21 ) (17 ) Law changes (a) (11 ) 145 — Stock compensation (5 ) — — Prior year return adjustments — (7 ) — Foreign tax credits — — (21 ) Global Intangible Low-Taxed Income 5 — — Other, net (4 ) (8 ) (2 ) Provision for income tax expense (benefit) $ 34 $ 238 $ 63 Effective income tax rate 15 % 71 % 23 % (a) In 2017, we recorded the impact of the 2017 Tax Act which included the transition tax on deferred foreign earnings, net of foreign tax credits, of $9 million , an increase in the valuation allowance related to foreign tax credits of $106 million , an increase in the valuation allowance of our state NOLs due to the change in federal benefit related to those assets of $18 million , anticipated sequestration of our AMT credits of $3 million and the impact of the corporate rate change on deferred tax assets and liabilities of $9 million . In 2018, we reversed $2 million of anticipated sequestration of our AMT credits based upon guidance released by the OMB and had a decrease in the valuation allowance of $9 million related to anticipated future realization of foreign tax credits. Significant components of deferred tax assets and liabilities were as follows: As of December 31, (millions) 2018 2017 Deferred Tax Assets: Net operating loss and tax credit carryforwards $ 389 $ 477 Pension and postretirement benefits 68 86 Reserves not deductible until paid 15 14 Self insurance 4 2 Capitalized interest 8 7 Inventories 4 4 Share-based compensation 13 14 Other 9 7 Deferred tax assets before valuation allowance 510 611 Valuation allowance (112 ) (175 ) Total deferred tax assets $ 398 $ 436 Deferred Tax Liabilities: Property, plant and equipment 157 153 Total deferred tax liabilities $ 157 $ 153 Net deferred tax assets $ 241 $ 283 During 2018, we recorded a decrease in the valuation allowance against our deferred tax assets of $63 million . The decrease was primarily related to the impact of the 2017 Tax Act on our ability to realize foreign tax credits and the expiration of certain state NOL carryforwards. During 2017, we recorded an increase in the valuation allowance against our deferred tax assets of $124 million . The increase was primarily related to law changes under the 2017 Tax Act, including the federal rate change, from 35% to 21%, and the ability to realize foreign tax credits. In 2016, we recorded a decrease in the valuation allowance related to the expiration of the state NOL carryforwards. As of December 31, 2018 , we had net deferred tax assets of $241 million , which included a valuation allowance of $112 million . The components of the valuation allowance relate to certain state NOL carryforwards and foreign tax credit carryforwards that we anticipate will not be used prior to their expiration. As of December 31, 2018 , we had federal NOL carryforwards of approximately $559 million that are available to offset future federal taxable income and will expire in the years 2030 through 2032 . In addition, as of that date, we had federal AMT credit carryforwards of approximately $17 million that are available to reduce future regular federal income taxes with the full benefit being realized by 2022 as described in the 2017 Tax Act. We have foreign tax credit carryforwards of $135 million that are available to offset future federal taxable income and expire in the years 2022 through 2027. The foreign tax credits are attributable to tax planning strategies to optimize foreign tax credit utilization and management’s intention to amend its tax returns for the tax years 2012-2013 in order to claim credits for previously deducted foreign tax. In 2018, additional foreign tax credits were attributed to the transition tax as enacted by the 2017 Tax Act. In order to fully realize the U.S. federal net deferred tax assets, taxable income of approximately $1.285 billion would need to be generated during the period before their expiration based on our current interpretation of the 2017 Tax Act. As of December 31, 2018 , we had a deferred tax asset of $152 million related to state NOLs and tax credit carryforwards. The NOLs will expire if unused in years 2019 through 2036 . To the extent that we do not generate sufficient state taxable income within the statutory carryforward periods to utilize the NOL and tax credit carryforwards in these states, they will expire unused. The Code imposes limitations on a corporation’s ability to utilize NOLs if it experiences an “ownership change.” See Note 15, Stockholder Rights Plan, for further explanation. If we were to experience an ownership change, utilization of our NOLs would be subject to an annual limitation that may be carried over to later years within the allowed NOL carryforward period. If an ownership change had occurred as of December 31, 2018 , our annual U.S. federal NOL utilization would have been limited to approximately $150 million per year. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: (millions) 2018 2017 2016 Balance as of January 1 $ 12 $ 15 $ 18 Tax positions related to the current period: Gross increase — — — Gross decrease — — — Tax positions related to prior periods: Gross increase 4 — — Gross decrease — (1 ) (3 ) Settlements (1 ) — — Lapse of statutes of limitations (1 ) (2 ) — Balance as of December 31 $ 14 $ 12 $ 15 We classify interest expense and penalties related to unrecognized tax benefits and interest income on tax overpayments as components of income tax expense. We do no t have amounts related to interest expense and penalties recognized on our consolidated balance sheets as of December 31, 2018 and 2017 . We recorded no interest and penalties in our consolidated statements of income in the years ended December 31, 2018 , 2017 and 2016 . The total amounts of unrecognized tax benefit that, if recognized, would affect our effective tax rate were $14 million , $12 million and $14 million for 2018 , 2017 and 2016 , respectively. Our federal income tax returns for 2014, 2008 and prior years have been examined by the Internal Revenue Service. The U.S. federal statute of limitations remains open for 2006 -2012 and 2015 to the present. We are under examination in various U.S. state and foreign jurisdictions. We do not believe our gross unrecognized tax benefits will change as a result of the conclusion of these examinations. There are statutes, however, that are expiring within the next 12 months that could result in recognition of approximately $1 million of tax benefit. Foreign and U.S. state jurisdictions have statutes of limitations generally ranging from three to five years. We do not provide for U.S. income taxes on the portion of undistributed earnings of foreign subsidiaries that is intended to be permanently reinvested. It is not practical to calculate the residual income tax which would result if basis differences reversed or previously-taxed earnings were distributed. This is due to the complexities of the tax law impacted by the 2017 Tax Act and the hypothetical nature of the calculations.

Stockholder Rights Plan

Stockholder Rights Plan	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Stockholder Rights Plan	Stockholder Rights Plan NOL Protective Provisions of our Rights Plan We have a stockholder rights plan that is intended to protect our NOL carryforwards and related tax benefits. See Note 14 , Income Taxes, for a description of our NOL carryforwards. Under federal tax laws, we generally can use our pre-2018 NOLs and certain related tax credits to reduce ordinary income tax paid in our prior two tax years or on our future taxable income for up to 20 years (10 years for tax credits), when they “expire” for such purposes. Our ability to use our NOLs could be substantially limited if we experience an “ownership change,” as defined under Section 382 of the Code, and the rights plan has been designed to help prevent such an “ownership change.” Under Section 382 of the Code, an “ownership change” occurs if, over a rolling three -year period, there has been an aggregate increase of 50 percentage points or more in the percentage of our common stock owned by one or more of our “ 5 -percent stockholders” (as determined under Section 382 of the Code). The Merger is expected to constitute an “ownership change.” The rights plan provides that if any person becomes the beneficial owner (as defined in the Code) of 4.9% or more of our common stock, stockholders other than the triggering stockholder will have the right to purchase additional shares of our common stock at half the market price, thereby diluting the triggering stockholder; provided that stockholders whose beneficial ownership, as defined in Section 382 of the Code, exceeded 4.9% of our common stock outstanding on February 11, 2015 will not be deemed to have triggered the rights plan, so long as they do not thereafter acquire beneficial ownership of additional common stock other than in certain specified exempt transactions. At our 2016 annual meeting our stockholders ratified, on an advisory basis, the extension of the term of the rights plan and the NOL protective provisions to May 31, 2019. In connection with the Merger, we entered into an amendment to the rights plan on November 13, 2018, which provides that no person or entity will become a triggering stockholder under the terms of the rights plan as a result of the transactions contemplated by the Merger Agreement and the Voting Agreement, dated as of June 10, 2018, among Knauf, Merger Sub and Berkshire Hathaway Inc., a Delaware corporation, on behalf of itself and its subsidiaries listed on Exhibit A thereto, or the Voting Agreement. The amendment also accelerates the expiration of the rights issued pursuant to the rights plan to the earliest of May 31, 2019 and the effective time of the transactions contemplated by the Merger Agreement, unless earlier redeemed or exchanged. Subject to the limitations of the Merger Agreement, our Board of Directors has the power to accelerate or extend the expiration date of the rights. The NOL protective provisions of the rights plan described above will be effective until the earliest of the close of business on (i) May 31, 2019, (ii) the date on which our Board of Directors determines that these provisions are no longer necessary for the protection of certain tax benefits because of the repeal of Section 382 of the Code, (iii) the first day of a taxable year as to which our Board of Directors determines that no tax benefits may be carried forward, or (iv) such other date as our Board of Directors determines that these provisions are no longer necessary for the preservation of tax benefits, or the Special Period. After the end of the Special Period, the triggering threshold for the rights issued pursuant to the rights plan will revert to 15% of our outstanding common stock and the definition of “beneficial owner” will revert to definitions that do not track Section 382 of the Code. A board committee composed solely of independent directors reviews the rights plan at least once every three years to determine whether to modify the rights plan in light of all relevant factors. This review was most recently conducted in November 2018. Restated Certificate of Incorporation Our Restated Certificate of Incorporation also restricts certain transfers of our common stock and includes provisions intended to further protect the tax benefits of our NOL carryforwards. Subject to certain limited exceptions, these transfer restrictions restrict any person from transferring our common stock (or any interest in our common stock) if the transfer would result in a stockholder (or several stockholders, in the aggregate, who hold their stock as a “group” under Section 382 of the Code) owning 4.9% or more of our common stock. Any direct or indirect transfer attempted in violation of these transfer restrictions would be void as of the date of the prohibited transfer as to the purported transferee, and the purported transferee would not be recognized as the owner of the shares attempted to be owned in violation of the transfer restrictions for any purpose, including for purposes of voting and receiving dividends or other distributions in respect of that common stock, or in the case of options, receiving our common stock in respect of their exercise. These restrictions are effective until the earliest of (i) the close of business on May 31, 2019, (ii) the repeal of Section 382 of the Code if our Board of Directors determines that the restrictions are no longer necessary or desirable for the preservation of tax benefits, (iii) the close of business on the first day of a taxable year as to which our Board of Directors determines that no tax benefits may be carried forward, or (iv) such other date as determined by our Board of Directors pursuant to the provisions described above. Pursuant to our Restated Certificate of Incorporation, our Board of Directors approved the transactions contemplated by the Merger Agreement and the Voting Agreement and determined that the transfer restrictions described above do not apply to such transactions. Treatment of Berkshire Hathaway under Rights Plan and Restated Certificate of Incorporation Pursuant to a Shareholder’s Agreement reached in 2006, Berkshire Hathaway and certain of its affiliates may acquire beneficial ownership of up to 50% of our voting stock on a fully-diluted basis without triggering the ownership thresholds in our Restated Certificate of Incorporation or the rights plan, and may acquire beneficial ownership of more than 50% of our voting stock on a fully-diluted basis without triggering the ownership thresholds in our Restated Certificate of Incorporation or the rights plan through an offer to purchase all of our common stock that remains open for at least 60 days, in each case subject to specified exceptions.

Lease Commitments

Lease Commitments	12 Months Ended
	Dec. 31, 2018
Lease Commitments [Abstract]
Lease Commitments	Lease Commitments We lease some of our offices, buildings, machinery and equipment, and automobiles under noncancelable operating leases. These leases have various escalation terms and renewal options. Lease expense amounted to $48 million in 2018 , $37 million in 2017 and $36 million in 2016 . Future minimum lease payments required under operating leases with initial or remaining noncancelable terms in excess of one year as of December 31, 2018 were as follows: (millions) 2019 2020 2021 2022 2023 After 2023 Future minimum lease payments $ 46 $ 39 $ 27 $ 12 $ 6 $ 6

Litigation

Litigation	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Litigation	Litigation WALLBOARD PRICING CLASS ACTION LAWSUITS In 2015, USG, our subsidiary United States Gypsum Company, our former subsidiary L&W Supply Corporation, and seven other wallboard manufacturers were named as defendants in a lawsuit filed in federal court in California by twelve homebuilders alleging that since at least September 2011, U.S. wallboard manufacturers conspired to fix and raise the price of gypsum wallboard sold in the United States and to effectuate the alleged conspiracy by ending the practice of providing job quotes on wallboard. The lawsuit was transferred to the United States District Court for the Eastern District of Pennsylvania under the title In re: Domestic Drywall Antitrust Litigation, MDL No. 2437. In 2016, the Court dismissed with prejudice the portions of the homebuilders’ complaint alleging a conspiracy in 2014 and 2015, ruling that there were insufficient factual allegations to allow such a claim to go forward. The homebuilders' claims alleging a conspiracy prior to 2014 have not been dismissed, and the case proceeds as to those claims. USG has agreed to defend and indemnify L&W Supply Corporation with regard to this matter. Beginning in 2013, class action lawsuits making similar allegations with regard to Canada were filed in Quebec, Ontario and British Columbia courts on behalf of purchasers of wallboard in Canada and naming USG, our subsidiaries United States Gypsum Company and CGC Inc., and other wallboard manufacturers as defendants. We believe that the cost, if any, of resolving the homebuilders’ lawsuit and Canadian class action litigation will not have a material effect on our results of operations, financial position or cash flows. ENVIRONMENTAL LITIGATION We are involved in environmental cleanups of property that we own or have owned. In addition, we have previously been notified by state and federal environmental protection agencies of possible involvement as one of numerous “potentially responsible parties” in certain Superfund sites in the United States to pay for some part of the cleanup of hazardous waste. In most of these sites, our involvement is expected to be minimal. As of December 31, 2018 and 2017 , we had a liability of $13 million and $17 million , respectively, for our probable and reasonably estimable liability in connection with these matters. Our liability takes into account all known or estimated undiscounted costs associated with these sites, including site investigations and feasibility costs, site cleanup and remediation, certain legal costs, and fines and penalties, if any. However, we continue to review these liabilities as additional information becomes available and revise them as appropriate. Based on the information known to us, we believe these environmental matters will not have a material effect on our results of operations, financial position or cash flows. OTHER LITIGATION We are named as defendants in other claims and lawsuits arising from our operations, including lawsuits or claims arising from commercial disputes, product performance, product liabilities and worksite or vehicular accidents. We believe that we have properly accrued for our probable liability in connection with these claims and suits, taking into account the probability of liability, whether our exposure can be reasonably estimated and, if so, our estimate of our liability or the range of our liability. We do not expect these or any other litigation matters involving USG to have a material effect on our results of operations, financial position or cash flows.

Quarterly Financial Data (unaud

Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (unaudited)	Quarterly Financial Data (unaudited) Quarter (millions, except per-share data) First Second Third Fourth 2018 Net sales $ 786 $ 880 $ 851 $ 819 Gross profit 139 184 152 131 Operating profit 46 75 69 37 Income from continuing operations 36 58 58 41 Income from discontinued operations, net of tax 1 — 1 1 Net income 37 58 59 42 Income per average common share: Basic (a) $ 0.26 $ 0.41 $ 0.42 $ 0.31 Diluted (a) 0.25 0.41 0.41 0.30 2017 Net sales $ 767 $ 811 $ 795 $ 831 Gross profit 159 168 162 167 Operating profit 84 95 91 83 Income (loss) from continuing operations (b) 55 46 66 (70 ) (Loss) income from discontinued operations, net of tax — (10 ) — 1 Net income (loss) (b) 55 36 66 (69 ) Income per average common share: Basic (a) $ 0.38 $ 0.25 $ 0.47 $ (0.49 ) Diluted (a) 0.37 0.24 0.46 (0.49 ) (a) The sum of the four quarters is not necessarily the same as the total for the year. (b) Income from continuing operations and net income included a loss on extinguishment of debt of $22 million for the second quarter of 2017 and income tax expense of $145 million related to the 2017 Tax Act for the fourth quarter of 2017. See Notes 6 , Debt, and 14 , Income Taxes, respectively.

Merger Agreement

Merger Agreement	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Merger Agreement	Merger Agreement On June 10, 2018, we entered into an Agreement and Plan of Merger, as it may be amended from time to time, or the Merger Agreement, with Gebr. Knauf KG, a limited partnership ( Kommanditgesellschaft ) organized under the laws of Germany, or Knauf, and World Cup Acquisition Corporation, a Delaware corporation and an indirect, wholly-owned subsidiary of Knauf, or Merger Sub. The Merger Agreement provides that, subject to the satisfaction of customary closing conditions, Merger Sub will be merged with and into USG, or the Merger, with USG continuing as the surviving corporation and an indirect, wholly-owned subsidiary of Knauf. Pursuant to the terms of the Merger Agreement, at the effective time of the Merger, each share of common stock, par value $0.10 , of USG issued and outstanding immediately prior to the effective time of the Merger (other than shares of common stock owned by Knauf and its subsidiaries, USG and its subsidiaries and certain excluded holders) will be converted into the right to receive $43.50 in cash, without interest and subject to tax withholding. In addition, as contemplated by the Merger Agreement, we announced on August 9, 2018 that USG had declared a conditional special cash dividend of $0.50 per share, or the conditional special dividend, payable to holders of record of our common stock as of the close of business on August 21, 2018. Payment of the conditional special dividend was conditioned on adoption of the Merger Agreement by our stockholders at the special meeting held on September 26, 2018, or the special meeting. The Merger Agreement was adopted by our stockholders at the special meeting and following certification of the vote in favor of adoption, the conditional special dividend was paid on October 2, 2018. The conditional special dividend totaled $70 million and was declared from retained earnings. Pursuant to the Dividend Make-Whole Amount Plan approved by USG in connection with the Merger and the conditional special dividend, an additional $2 million is expected to be paid to holders of stock options, market share units and performance shares of USG, or Incentive Equity Awards, that were outstanding as of June 10, 2018, and are or become vested and paid out in connection with completion of the Merger or are or become vested and become payable following the record date of the special meeting, but prior to the closing of the Merger. These Incentive Equity Awards would not otherwise be entitled to dividend equivalent payments pursuant to their existing terms. The dividend payable is included in "Accounts payable" on our consolidated balance sheets. The Merger, which is currently expected to close in early 2019, is subject to the satisfaction or waiver of certain customary closing conditions, including, among others, receipt of certain regulatory approvals. The Merger Agreement contains certain termination rights for both USG and Knauf. If the Merger Agreement is terminated under certain specified circumstances, we will be required to pay Knauf a termination fee of $215 million . We have incurred $19 million , pre-tax, of Merger-related costs for the year ended December 31, 2018 which are included in "Selling and administrative expenses" on our consolidated statements of income. See Note 4, Equity Method Investments, for additional information regarding the default notice under the UBBP Shareholders Agreement delivered by Boral in connection with the Merger.

Schedule II - Valuation And Qua

Schedule II - Valuation And Qualifying Accounts	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation And Qualifying Accounts	SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS Additions (millions) Balance at beginning of period Charged to costs and expenses Charged to other accounts Deductions (a) Balance at end of period Year ended December 31, 2018: Doubtful accounts $ 6 $ 1 $ — $ — $ 7 Cash discounts 3 39 — (39 ) 3 Income tax valuation allowance 175 — — (63 ) 112 Year ended December 31, 2017: Doubtful accounts 5 2 — (1 ) 6 Cash discounts 3 34 — (34 ) 3 Income tax valuation allowance 51 124 — — 175 Year ended December 31, 2016: Doubtful accounts 7 1 — (3 ) 5 Cash discounts 2 34 — (33 ) 3 Income tax valuation allowance 70 — — (19 ) 51 (a) Reflects receivables written off as related to doubtful accounts, cash discounts allowed and reductions in the income tax valuation allowance.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Nature of Operations	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, specialty wallboard distributors, home improvement centers, other retailers and sold directly to contractors.
Segments	Segments Our operating structure is generally aligned by product type and consists of three divisions, in addition to 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. Our reportable segments reflect the operating structure and align with how we manage our business, review operating performance and allocate resources considering the discrete information available for the geographies within the divisions. We have five reportable segments: U.S. Wallboard and Surfaces, U.S. Performance Materials, U.S. Ceilings, Canada, and UBBP. 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; 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, are included in Other, as reconciling items to our consolidated segments.
Consolidation and Presentation	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.
Use of Estimates	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 and Shipping and Handling Costs	Revenue Recognition We recognize revenue upon transfer of control of our products to the customer which generally occurs upon shipment. 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. Reductions to revenue for customer programs and incentive offerings, including promotions and other volume-based incentives, are estimated using the most likely amount method and 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. We do not have any material payment terms as payment is received shortly after the point of sale. We pay commissions to third parties to obtain contracts. As these contracts are less than one year, these costs are expensed as incurred. Shipping and Handling Costs We include shipping and handling costs billed to customers in net sales and account for related costs as fulfillment activities and present the expenses in "Cost of products sold" when control of our products transfers to the customer.
Advertising	Advertising Advertising expenses consist of media advertising and related production costs and sponsorships. We charge advertising expenses to earnings as incurred.
Research and Development	Research and Development We charge research and development expenditures to earnings as incurred.
Legal Costs	Legal Costs We expense legal costs as incurred.
Income Taxes	Income Taxes We record income tax expense 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	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	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.
Business Combinations	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 are expensed as incurred.
Cash and Cash Equivalents	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 Our marketable securities, which meet the definition of debt 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 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.
Equity Method Investments	Equity Method Investments 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. 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 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 economic useful life. We record depletion 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 $6 million , $3 million and $1 million for the years ended December 31, 2018 , 2017 and 2016 , 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, Indefinite Lived	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.
Intangible Assets, Definite Lived	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.
Goodwill	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, including goodwill. 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. Our assessment compares 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.
Asset Retirement Obligations	Asset Retirement Obligations Our asset retirement obligations include reclamation requirements as regulated by government authorities or contractual obligations 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	Share-Based Compensation Our current long-term incentive plan authorizes the Board’s Compensation and Organization Committee to provide equity-based compensation in the form of stock options, stock appreciation rights, restricted stock, RSUs, MSUs, performance shares and units, and other cash incentive and share-based awards for the purpose of providing our employees, officers and non-employee directors incentives and rewards for performance. We award share-based compensation to employees in the form RSUs, MSUs and performance shares and to non-employee directors in the form of shares of our common stock. We last granted stock options in 2012. All grants under share-based payment programs are accounted for at fair value at the date of grant. We recognize expense on 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	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 five 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.
Purchase Obligations	Purchase Obligations In the ordinary course of business we have entered into unconditional purchase obligations, which include noncancelable purchase commitments and take-or-pay arrangements with suppliers for the purchase of goods and services. On an ongoing basis, we review our agreements and assess the likelihood of a shortfall compared to the commitments and record a liability if the shortfall is probable and estimable.
Foreign Currency Translation	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.
Fair Value Measurements	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 there is evidence of impairment or when a new liability is being established that requires fair value measurement.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements We adopted Accounting Standard Update, or ASU, 2014-09, “Revenue from Contracts with Customers (Topic 606),” and all related amendments on January 1, 2018 using the modified retrospective method and practical expedients. Topic 606 supersedes the revenue recognition requirements in "Revenue Recognition (Topic 605)" and requires entities to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. On January 1, 2018, we recorded an increase of $2 million to our opening balance of retained earnings for the cumulative effect of adopting Topic 606. The adjustment related to a change to the point in time at which we record revenue for most customers. Prior period amounts have not been restated and continue to be reported under the legacy accounting guidance of Topic 605. As of and for the year ended December 31, 2018, the impact of applying Topic 606 as compared to applying Topic 605 is immaterial to our financial statements. We adopted ASU 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” on January 1, 2018 using the practical expedient. This ASU required us to disaggregate and present current service cost along with other current compensation costs for employees while presenting other net benefit cost components below operating profit. In addition, only the service cost component of net benefit cost is eligible for capitalization in our inventory and fixed assets. We retrospectively adopted the presentation of service cost and prospectively adopted the capitalization of only service cost into inventory and fixed assets. The effect of the adoption of ASU 2017-07 on our consolidated statements of income for the year ended December 31, 2017 and 2016 was as follows. (millions) Year ended December 31, 2017 Year ended December 31, 2016 As Restated Adjustment for Adoption of ASU 2017-07 As Previously Reported As Restated Adjustment for Adoption of ASU 2017-07 As Previously Reported Gross profit $ 656 $ (9 ) $ 665 $ 700 $ (5 ) $ 705 Operating profit 353 (14 ) 367 396 2 394 Other income, net 10 14 (4 ) 7 (2 ) 9 Net income 88 — 88 510 — 510 In the fourth quarter of 2018 we early adopted ASU 2018-14, "Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans," which modifies the disclosure requirements for defined benefit pension plans and other post-retirement plans. The adoption resulted in new disclosures, including comparative information for all years presented and the removal of certain disclosures no longer required. We adopted ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash,” which requires amounts generally described as restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling beginning-of-period and end-of-period total amounts shown on the statement of cash flows using the retrospective approach. The adoption resulted in a $9 million reduction of our net cash provided by investing activities on our consolidated statement of cash flows for the year ended December 31, 2016. We adopted ASU 2016-09, "Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting," on January 1, 2017. This ASU simplifies certain aspects of accounting for employee share-based payments. Upon adoption, we recorded to retained earnings a $25 million cumulative-effect adjustment for previously unrecognized excess tax benefits and an immaterial cumulative-effect adjustment for the reversal of cumulative forfeiture estimates to record forfeitures as they occur. We adopted ASU 2018-02, "Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income," in the first quarter of 2018. The ASU allows for the reclassification of stranded tax effects on items resulting from the Tax Cuts and Jobs Act, or the 2017 Tax Act, from accumulated other comprehensive income, or AOCI, to retained earnings. We elected not to reclassify the income tax effects of the 2017 Tax Act. We adopted ASU 2016-15, "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments" on January 1, 2018 using the retrospective transition method. Topic 230 addresses specific cash flow issues with the stated objective of reducing the existing diversity in practice. There was no impact on adoption to our consolidated cash flow statements and disclosures as we were already compliant with the provisions of the standard. Recently Issued Accounting Pronouncements The Financial Accounting Standards Board, or FASB, issued ASU 2016-02, “Leases (Topic 842),” which supersedes existing lease guidance. The new standard requires lessees to recognize assets and liabilities on the balance sheet for the rights and obligations created by long-term leases and to disclose additional quantitative and qualitative information about leasing arrangements. Subsequently, the FASB has issued various ASUs to provide further clarification around certain aspects of Topic 842. We will adopt the new standard on January 1, 2019 using the modified retrospective transition method and will record a cumulative-effect adjustment to the opening balance of retained earnings at the adoption date. At transition, we will elect the package of practical expedients that allow us not to reassess under the new standard prior conclusions about lease identification, lease classification and initial direct costs. We expect to make the election to treat lease and non-lease components as a single lease component at the transition date. We are continuing to assess the completeness of our portfolio of leases, determine changes required in our lease accounting processes, and in the process of inputting our active leases into our new accounting software. The adoption of Topic 842 is expected to have a significant impact on our consolidated balance sheets and increase our disclosures on leases. In August 2018, the FASB, issued ASU 2018-15, "Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract," which clarifies the accounting for implementation costs in cloud computing arrangements. ASU 2018-15 is effective for us on January 1, 2020, and earlier adoption is permitted. We are currently evaluating the impact of this standard on our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, "Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments". Topic 326 eliminates the probable initial recognition threshold and, instead, requires the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. This standard is effective for us on January 1, 2020, and earlier adoption is permitted. We are currently evaluating the impact of Topic 326 on our consolidated financial position, results of operations and disclosures. We do not expect the adoption of Topic 326 to have a significant impact to our consolidated financial statements. In August 2017, the FASB issued ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities,” which expands and refines hedge accounting for both non-financial and financial risk components and aligns the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements. The new standard is effective for us on January 1, 2019. We do not expect the adoption of ASU 2017-12 to have a significant impact to our consolidated financial statements or disclosures. In August 2018, the FASB issued ASU 2018-13, "Fair Value Measurement - Disclosure Framework (Topic 820)". The updated guidance improves the disclosure requirements on fair value measurements. The ASU is effective for us on January 1, 2020. Early adoption is permitted for any removed or modified disclosures. We are currently assessing the timing and impact of adoption.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of ant-dilutive securities excluded from computation of diluted earnings (loss) per share	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) 2018 2017 2016 Stock options, RSUs, MSUs and performance shares — 0.7 1.5 Deferred shares associated with a deferred compensation program for non-employee directors — 0.2 0.2

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of new accounting pronouncement	The effect of the adoption of ASU 2017-07 on our consolidated statements of income for the year ended December 31, 2017 and 2016 was as follows. (millions) Year ended December 31, 2017 Year ended December 31, 2016 As Restated Adjustment for Adoption of ASU 2017-07 As Previously Reported As Restated Adjustment for Adoption of ASU 2017-07 As Previously Reported Gross profit $ 656 $ (9 ) $ 665 $ 700 $ (5 ) $ 705 Operating profit 353 (14 ) 367 396 2 394 Other income, net 10 14 (4 ) 7 (2 ) 9 Net income 88 — 88 510 — 510

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations And Discontinued Operations and Disposal Groups [Abstract]
Summarized financial information of discontinued operations	The summarized financial information related to L&W that has been excluded from continuing operations and reported as a discontinued operation is as follows: (millions) Ten months ended October 31, 2016 Net sales $ 1,252 Cost of products sold 1,196 Gross profit 56 Selling and administrative expenses (a) 22 Operating profit 34 Income tax expense 12 Net income from discontinued operations $ 22 Gain on sale of discontinued operations $ 279 (a) The ten month period ended October 31, 2016 included transaction costs of $8 million .

Equity Method Investments (Tabl

Equity Method Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Schedule of equity method investments	Equity method investments were as follows: December 31, 2018 December 31, 2017 (millions) Carrying Value Ownership Percentage Carrying Value Ownership Percentage USG Boral Building Products $ 660 50% $ 679 50% Other equity method investments 2 50% $ 7 33% - 50% Total equity method investments $ 662 $ 686
Schedule of translation gains or losses recorded in other comprehensive income	Translation gains and losses recorded in other comprehensive income were as follows: (millions) 2018 2017 2016 Translation (loss) gain $ (31 ) $ 40 $ (30 )
Statement of operations from equity method investments	Statements of Income For the year ended December 31, (millions) 2018 2017 2016 USG Boral Building Products: Net sales $ 1,182 $ 1,200 $ 1,052 Gross profit (a) 317 369 337 Operating profit 117 160 133 Net income from continuing operations before taxes 131 174 142 Net income 86 121 95 Net income attributable to USG Boral Building Products 84 117 99 USG share of income from investment accounted for using the equity method (b) 42 59 49 (a) Year ended December 31, 2016 includes long-lived asset impairment charges of $8 million for China and of $14 million for Oman. (b) Year ended December 31, 2016 includes long-lived asset impairment charges of $4 million for China and of $4 million for Oman.
Balance Sheet from equity method investments	Balance Sheets (millions) December 31, 2018 December 31, 2017 USG Boral Building Products: Current assets $ 392 $ 438 Non-current assets 964 981 Current liabilities (a) 232 255 Long-term debt 10 10 Other non-current liabilities 22 12 Shareholders' equity (b) 1,092 1,142 (a) Includes the current portion of long-term debt of $15 million and $16 million as of December 31, 2018 and 2017 , respectively. (b) Shareholders' equity includes $64 million and $66 million related to non-controlling interests as of December 31, 2018 and 2017 , respectivel y.

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of investments in marketable securities	Our investments in marketable securities as of December 31, 2018 and 2017 consisted of the following: 2018 2017 (millions) Amortized Cost Fair Value Amortized Cost Fair Value Corporate debt securities $ 73 $ 73 $ 68 $ 68 U.S. government and agency debt securities 5 5 6 6 Asset-backed debt securities 15 15 11 11 Certificates of deposit 5 5 13 13 Municipal debt securities — — 1 1 Total marketable securities $ 98 $ 98 $ 99 $ 99
Schedule of contractual maturities of marketable securities	Contractual maturities of marketable securities as of December 31, 2018 were as follows: (millions) Amortized Cost Fair Value Due in 1 year or less $ 55 $ 55 Due in 1-5 years 43 43 Total marketable securities $ 98 $ 98

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of total debt	Interest rate 5.5% 4.875% Principal net of discount (in millions) (a) $350 $500 Maturity March 1, 2025 June 1, 2027 Call date (b) March 1, 2020 June 1, 2022 Mandatory redemption offer at 101% plus accrued and unpaid interest in the event of a change in control at 101% plus accrued and unpaid interest in the event of a change in control (a) Principal amounts exclude unamortized debt issuance costs. (b) Callable at any time, in whole or in part, prior to the call date at a redemption price equal to 100% of the principal plus a premium (as outlined in the respective indentures), plus any accrued and unpaid interest on the principal amount being called. Callable after the call date at stated redemption prices (as outlined in the applicable indenture), plus any accrued and unpaid interest on the principal amount being called. Total debt as of December 31 consisted of the following: (millions) 2018 2017 4.875% senior notes due 2027 $ 500 $ 500 5.5% senior notes due 2025 350 350 Industrial revenue bonds (due 2028 through 2034) 239 239 Total $ 1,089 $ 1,089 Less: Unamortized debt issuance costs 10 11 Total $ 1,079 $ 1,078
Schedule of fair value of debt	(millions) December 31, 2018 December 31, 2017 Fair value of debt $ 1,099 $ 1,134 Accrued interest 12 12
Schedule of amounts of total debt outstanding maturing in each of next five years and beyond	As of December 31, 2018 , the amounts of total debt outstanding maturing in each of the next five years and beyond were as follows: (millions) 2019 through 2023 After 2023 Debt maturities (principal amounts) $ — $ 1,089

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivative Instruments used to manage commodity price and foreign currency exposure	We use derivative instruments to manage selected commodity price and foreign currency exposures as described below. Derivative Instruments Type Hedged Item Aggregate Notional Amount Contracts Maturing Through Commodity Natural gas swaps Purchases of natural gas 41 million mmBTUs* December 31, 2022 Foreign Exchange Forward contracts Purchases of products and services denominated in a foreign currency $98 million December 31, 2019 * - millions of British Thermal Units
Schedule of pretax effects of derivative instruments	The following are the pre-tax effects of derivative instruments on our consolidated statements of income and our consolidated statements of comprehensive income for the years ended December 31, 2018 , 2017 and 2016 : Amount of Gain or (Loss) Recognized in Other Comprehensive Income (Loss) on Derivatives (Effective Portion) Location of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion) Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion) (millions) 2018 2017 2016 2018 2017 2016 Derivatives in Cash Flow Hedging Relationships Commodity contracts $ (1 ) $ (19 ) $ 6 Cost of products sold $ (2 ) $ (4 ) $ (15 ) Foreign exchange contracts 8 (5 ) (3 ) Cost of products sold — (2 ) 5 Total $ 7 $ (24 ) $ 3 $ (2 ) $ (6 ) $ (10 ) Location of Gain or (Loss) Recognized in Income on Derivatives Amount of Gain or (Loss) Recognized in Income on Derivatives (millions) 2018 2017 2016 Derivatives Not Designated as Hedging Instruments Commodity contracts Cost of products sold $ 1 $ (1 ) $ 1 Total $ 1 $ (1 ) $ 1
Schedule of fair values of derivative instruments	The fair values of derivative instruments on the consolidated balance sheets are as follows: Balance Sheet Location Fair Value Balance Sheet Location Fair Value (millions) 12/31/18 12/31/17 12/31/18 12/31/17 Derivatives in Cash Flow Hedging Relationships Commodity contracts Other current assets $ 2 $ 1 Accrued expenses $ 6 $ 6 Commodity contracts Other assets 2 1 Other liabilities 10 8 Foreign exchange contracts Other current assets 6 — Accrued expenses — 3 Total derivatives in hedging relationships $ 10 $ 2 $ 16 $ 17 Derivatives Not Designated as Hedging Instruments Commodity contracts Other current assets $ — $ — Accrued expenses $ — $ — Commodity contracts Other assets — — Other liabilities — — Total derivatives not designated as hedging instruments $ — $ — $ — $ — Total derivatives Total assets $ 10 $ 2 Total liabilities $ 16 $ 17

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair value valuation method	USG Valuation Method Level 1 Cash equivalents and equity mutual funds consist of money market funds that are valued based on quoted prices in active markets. Level 2 Marketable securities, including certain cash equivalents, are valued using a "market value" approach. Values are based on quoted prices and other observable market inputs received from data providers. Derivatives are valued using the "income" approach such as discounted-cash-flow models and readily observable market data. The inputs for the valuation models are obtained from data providers and include end-of-period spot and forward natural gas prices, foreign currency exchange rates, natural gas price volatility and LIBOR and swap rates for discounting the cash flows implied from the derivative contracts. Level 3 No level 3 investments.
Schedule of assets and liabilities measured at fair value on a recurring basis	Our assets and liabilities measured at fair value on a recurring basis were as follows: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (millions) 12/31/18 12/31/17 12/31/18 12/31/17 12/31/18 12/31/17 12/31/18 12/31/17 Cash equivalents $ 121 $ 124 $ 36 $ 24 $ — $ — $ 157 $ 148 Equity mutual funds 5 6 — — — — 5 6 Marketable securities: Corporate debt securities — — 73 68 — — 73 68 U.S. government and agency debt securities — — 5 6 — — 5 6 Asset-backed debt securities — — 15 11 — — 15 11 Certificates of deposit — — 5 13 — — 5 13 Municipal debt securities — — — 1 — — — 1 Derivative assets — — 10 2 — — 10 2 Derivative liabilities — — (16 ) (17 ) — — (16 ) (17 )

Employee Retirement Plans (Tabl

Employee Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Schedule of settlement expense	The location of the pre-tax settlement expense within our consolidated statements of income and the group of employees for which it is related is presented in the following chart. There was no settlement expense in 2018. (millions) 2017 2016 Other income, net USG retirees or terminated vested employees $ 12 $ 11 Income (loss) from discontinued operations Terminated employees of L&W 13 — Gain on sale of discontinued operations Terminated employees of L&W — 15 Total $ 25 $ 26
Summary of components of net pension and postretirement benefits costs	The components of the pre-tax total recognized in net pension and postretirement costs and other comprehensive income are summarized in the following table: Pension Postretirement (millions) 2018 2017 2016 2018 2017 2016 Service cost of benefits earned $ 50 $ 44 $ 45 $ 2 $ 2 $ 2 Interest cost on projected benefit obligation 62 61 66 5 5 6 Expected return on plan assets (97 ) (93 ) (89 ) — — — Settlement (a) — 25 35 — — — Curtailment — — — — — (20 ) Net amortization 31 22 22 (23 ) (23 ) (27 ) Net pension & postretirement cost (b) $ 46 $ 59 $ 79 $ (16 ) $ (16 ) $ (39 ) Net actuarial (loss) gain $ (14 ) $ 77 $ 58 $ (15 ) $ 10 $ (6 ) Net amortization (31 ) (22 ) (22 ) 23 23 27 Settlement — (25 ) (35 ) — — — Curtailment — — — — — 20 Deferred currency exchange (7 ) 4 2 (1 ) 1 (7 ) Total recognized in other comprehensive income $ (52 ) $ 34 $ 3 $ 7 $ 34 $ 34 Total recognized in net pension & postretirement cost and other comprehensive income $ (6 ) $ 93 $ 82 $ (9 ) $ 18 $ (5 ) (a) In 2016, $26 million of the settlement charge reflects the increase in lump sum benefits paid largely driven by the sale of L&W and $9 million reflected payments from our supplemental plan. (b) Net pension costs, excluding settlement costs, includes amounts allocated to income (loss) from discontinued operations for L&W totaling a benefit of $1 million for 2018, a benefit of $1 million for 2017, and an expense of $7 million for 2016. Net postretirement benefit, excluding curtailment gain, includes a net benefit allocated to income (loss) from discontinued operations for L&W of $3 million for 2018, $1 million for 2017 and $3 million for 2016.
Schedule of accumulated benefit obligation for the defined benefit pension plans	As of December 31, (millions) 2018 2017 Selected information for pension plans with accumulated benefit obligations in excess of plan assets: Accumulated benefit obligation $ (35 ) $ (35 ) Fair value of plan assets 3 3 Selected information for pension plans with benefit obligations in excess of plan assets: Benefit obligation $ (1,568 ) $ (1,769 ) Fair value of plan assets 1,431 1,576 Selected information for postretirement plans with benefit obligations in excess of plan assets: Benefit obligation $ (132 ) $ (150 ) Fair value of plan assets — —
Summary of projected benefit obligations, plan assets and funded status	The following table summarizes projected benefit obligations, plan assets and funded status as of December 31: Pension Postretirement (millions) 2018 2017 2018 2017 Change in Benefit Obligation: Benefit obligation as of January 1 $ 1,770 $ 1,610 $ 150 $ 135 Service cost 50 44 2 2 Interest cost 62 61 5 5 Settlements — (121 ) — — Participant contributions 10 9 — — Benefits paid (110 ) (51 ) (6 ) (6 ) Actuarial (gain) loss (192 ) 202 (15 ) 10 Foreign currency translation (21 ) 16 (4 ) 4 Benefit obligation as of December 31 $ 1,569 $ 1,770 $ 132 $ 150 Change in Plan Assets: Fair value as of January 1 $ 1,577 $ 1,435 $ — $ — Actual return on plan assets (81 ) 217 — — Employer contributions 56 71 6 6 Participant contributions 10 9 — — Benefits paid (110 ) (51 ) (6 ) (6 ) Settlements — (121 ) — — Foreign currency translation (20 ) 17 — — Fair value as of December 31 $ 1,432 $ 1,577 $ — $ — Funded status $ (137 ) $ (193 ) $ (132 ) $ (150 ) Components on the Consolidated Balance Sheets: Noncurrent assets $ 1 $ — $ — $ — Current liabilities (7 ) (8 ) (9 ) (9 ) Noncurrent liabilities (131 ) (185 ) (123 ) (141 ) Net liability as of December 31 $ (137 ) $ (193 ) $ (132 ) $ (150 ) Pretax Components in AOCI: Net actuarial loss (gain) $ 369 $ 421 $ (5 ) $ 11 Prior service credit — — (19 ) (42 ) Total as of December 31 $ 369 $ 421 $ (24 ) $ (31 )
Schedule of assumptions used in the accounting for the plans	The following tables reflect the assumptions used in the accounting for our plans: Pension Postretirement 2018 2017 2018 2017 Weighted average assumptions used to determine benefit obligations as of December 31: Discount rate 4.21 % 3.55 % 4.09 % 3.42 % Compensation increase rate 3.55 % 3.54 % N/A N/A Interest crediting rate 4.00 % 4.00 % N/A N/A Weighted average assumptions used to determine net cost for years ended December 31: Discount rate 3.55 % 4.02 % 3.42 % 3.90 % Expected return on plan assets 6.55 % 6.54 % N/A N/A Compensation increase rate 3.54 % 3.55 % N/A N/A
Schedule of aggregate target asset allocation on a weighted average basis for all the plans and the acceptable ranges around the targets	The following table shows the aggregate target asset allocation on a weighted average basis for all the plans and the acceptable ranges around the targets as of December 31, 2018 . Investment Policy Asset Categories Asset Category Description Target Range Equity Institutional commingled/pooled equity funds, equity mutual funds and direct holdings of the common stock of U.S. and non-U.S. companies; equity funds and direct holdings are invested in companies with a range of market capitalizations 35% 32%-39% Fixed income U.S. Treasury securities, non-U.S. government debt securities such as Canadian federal bonds, corporate bonds of companies from diversified industries and mortgage-backed securities 55% 43%-66% Limited partnerships Investments in funds that follow any of several different strategies, including investing in distressed debt, energy development, infrastructure, and hedge funds. These investments use strategies with returns normally expected to have a reduced correlation to the return of equities as compared to other asset classes and often provide a current income component that is a meaningful portion of the investment’s total return. 5% 2%-8% Other real assets Primarily investments in large core, private real estate funds that directly own a diverse portfolio of properties located in the United States. It also includes an allocation to funds investing in equities of real estate and infrastructure companies 5% 2%-9% Cash equivalents and short-term investments Primarily short-term investment funds or registered money market funds with daily liquidity —% 0%-5% Total 100%
Schedule of fair values by hierarchy of inputs	The fair values by hierarchy of inputs as of December 31 were as follows: Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total (millions) 2018 2017 2018 2017 2018 2017 2018 2017 Asset Categories: Equity: Common and preferred stock $ 88 $ 92 $ — $ — $ — $ — $ 88 $ 92 Commingled/pooled/mutual funds (a) — — 450 553 — — 450 553 Total equity 88 92 450 553 — — 538 645 Fixed income: U.S. government and agency debt securities — — 11 8 — — 11 8 Non-U.S. government and agency debt securities — — 55 68 — — 55 68 Investment-grade debt securities — — 268 334 — — 268 334 High-yield debt securities — — 40 42 — — 40 42 Commingled/pooled funds (a) — — 362 305 — — 362 305 Mortgaged backed securities — — 5 1 — — 5 1 Other — — 12 13 1 1 13 14 Total fixed income — — 753 771 1 1 754 772 Limited partnerships — — — — 83 91 83 91 Other real estate assets — — 16 18 35 39 51 57 Cash equivalents and short-term investments — — 10 14 — — 10 14 Total $ 88 $ 92 $ 1,229 $ 1,356 $ 119 $ 131 $ 1,436 $ 1,579 Cash on hand 1 — Receivables 5 2 Accounts payable (10 ) (4 ) Total $ 1,432 $ 1,577 (a) Certain investments in commingled/pooled equity funds have been classified as Level 2 because observable quoted prices for these institutional funds are not available.
Reconciliation of the change in the fair value measurement of the defined benefit plans’ consolidated assets	A reconciliation of the change in the fair value measurement of the defined benefit plans’ consolidated assets using significant unobservable inputs (Level 3) between January 1, 2017 and December 31, 2018 is as follows: (millions) Fixed Income Other Real Estate Assets Limited Partnerships Total Balance as of January 1, 2017 $ 1 $ 38 $ 103 $ 142 Realized losses — 1 15 16 Unrealized gains — 2 (1 ) 1 Purchases, sales and settlements: Purchases — — 9 9 Sales — (2 ) (35 ) (37 ) Settlements — — — — Net transfers into (out of) Level 3 — — — — Balance as of December 31, 2017 $ 1 $ 39 $ 91 $ 131 Realized gains — 1 4 5 Unrealized gains (losses) — 1 (8 ) (7 ) Purchases, sales and settlements: Purchases — — 14 14 Sales — (6 ) (18 ) (24 ) Settlements — — — — Net transfers into (out of) Level 3 — — — — Balance as of December 31, 2018 $ 1 $ 35 $ 83 $ 119
Schedule of expected benefit payments	Total benefit payments we expect to make to participants, which include payments funded from USG’s assets as well as payments from our pension plans' assets, are as follows (in millions): Years ended December 31 Pension Benefits Postretirement Benefits 2019 $ 115 $ 9 2020 117 8 2021 114 8 2022 117 8 2023 121 8 2024 - 2028 581 40

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted average grant date fair values of MSUs	We granted MSUs with the following weighted average grant date fair values: 2018 2017 2016 Weighted average grant date fair values $ 34.22 $ 35.79 $ 19.59
Schedule of MSUs valuation assumptions	We estimated the fair value of each MSU granted on the date of grant using a Monte Carlo simulation that used the assumptions noted in the following table. Volatility was based on stock price history immediately prior to grant for a period commensurate with the expected term. The risk-free rate was based on zero-coupon U.S. government issues at the time of grant. The expected term represents the period from the valuation date to the end of the performance period. Assumptions: 2018 2017 2016 Expected volatility 32.62 % 32.10 % 34.02 % Risk-free rate 2.37 % 1.39 % 0.86 % Expected term (in years) 2.95 2.96 2.95 Expected dividends — — —
Schedule of nonvested MSUs outstanding and activity	Nonvested MSUs outstanding as of December 31, 2018 and MSU activity during 2018 were as follows: Number of MSUs (000) Weighted Average Grant Date Fair Value Nonvested at January 1, 2018 1,097 $ 25.01 Granted 429 34.22 Vested (730 ) 19.59 Forfeited (8 ) 35.79 Nonvested at December 31, 2018 788 $ 34.93
Weighted average grant date fair values of performance shares	We granted performance shares with the following weighted average grant date fair values: 2018 2017 2016 Weighted average grant date fair values $ 34.21 $ 39.42 $ 21.10
Schedule of performance based units valuation assumptions	We estimated the fair value of each performance share granted on the date of grant using a Monte Carlo simulation that uses the assumptions noted in the following table. Volatility was based on stock price history immediately prior to grant for a period commensurate with the expected term. The risk-free rate was based on zero-coupon U.S. government issues at the time of grant. The expected term represents the period from the grant date to the end of the three -year performance period. Assumptions: 2018 2017 2016 Expected volatility 32.61 % 32.10 % 34.02 % Risk-free rate 2.37 % 1.39 % 0.86 % Expected term (in years) 2.95 2.96 2.95 Expected dividends — — —
Summary of nonvested performance share outstanding and performance share activity	Nonvested performance shares outstanding as of December 31, 2018 and performance share activity during 2018 were as follows: Number of Performance Shares (000) Weighted Average Grant Date Fair Value Nonvested at January 1, 2018 256 $ 29.14 Granted 104 34.21 Vested (143 ) 21.10 Forfeited (2 ) 33.35 Nonvested at December 31, 2018 215 $ 36.93
Weighted average grant date fair values of RSUs	We granted RSUs with the following weighted average grant date fair values: 2018 2017 2016 Weighted average grant date fair values $ 36.92 $ 31.57 $ 23.94
Summary of nonvested RSUs outstanding and activity	RSUs outstanding as of December 31, 2018 and RSU activity during the year then ended were as follows: Number of RSUs (000) Weighted Average Grant Date Fair Value Nonvested at January 1, 2018 304 $ 14.67 Granted 44 36.92 Vested (50 ) 26.64 Forfeited (10 ) 28.29 Nonvested at December 31, 2018 288 $ 30.05
Summary of stock options outstanding and stock option activity	A summary of stock options outstanding as of December 31, 2018 and of stock option activity during the year then ended is presented below: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2018 1,261 $ 15.72 2.48 $ 28 Exercised (677 ) 16.02 Canceled (50 ) 34.67 Outstanding, exercisable and vested at December 31, 2018 534 $ 13.55 1.89 $ 16 (millions) 2018 2017 2016 Intrinsic value of stock options exercised $ 17 $ 7 $ 4 Cash received from stock options exercised $ 11 $ 14 $ 4 Fair value of stock options vested $ — $ — $ 1

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of inventories	Inventories as of December 31 consisted of the following: (millions) 2018 2017 Finished goods $ 168 $ 140 Work in progress 42 39 Raw materials 80 73 Total $ 290 $ 252
Schedule of property, plant and equipment	Property, plant and equipment as of December 31 consisted of the following: (millions) 2018 2017 Land and mineral deposits $ 206 $ 120 Buildings and improvements 1,022 1,100 Machinery and equipment 2,717 2,595 3,945 3,815 Reserves for depreciation and depletion (2,107 ) (2,053 ) Total $ 1,838 $ 1,762 Annual depreciation and depletion expense $ 133 $ 129
Schedule of accrued expenses	Accrued expenses as of December 31 consisted of the following: (millions) 2018 2017 Self-insurance reserves $ 13 $ 12 Employee compensation 17 17 Interest 12 12 Derivatives 6 9 Pension and other postretirement benefits 16 17 Environmental 13 17 Other 52 51 Total $ 129 $ 135
Schedule of change in asset retirement obligation	Changes in our liability for asset retirement obligations consisted of the following: (millions) 2018 2017 Balance as of January 1 $ 118 $ 113 Accretion expense 7 7 Liabilities incurred — 3 Changes in estimated cash flows (9 ) (4 ) Liabilities settled (1 ) (3 ) Reclass to accrued expenses (2 ) — Foreign currency translation (2 ) 2 Balance as of December 31 $ 111 $ 118
Schedule of changes in balances of each component of accumulated other comprehensive income (loss)	Changes in the balances of each component of AOCI are summarized in the following table: (millions) Derivatives Pension and Other Postretirement Benefit Plans Foreign Total AOCI Balance as of January 1, 2016 $ 20 $ (221 ) $ (113 ) $ (314 ) Other comprehensive income (loss) before reclassifications, net of tax 1 (34 ) (53 ) (86 ) Less: Amounts reclassified from AOCI, net of tax (6 ) (9 ) — (15 ) Other comprehensive income (loss), net of tax 7 (25 ) (53 ) (71 ) Balance as of December 31, 2016 $ 27 $ (246 ) $ (166 ) $ (385 ) Other comprehensive income (loss) before reclassifications, net of tax (14 ) (65 ) 58 (21 ) Less: Amounts reclassified from AOCI, net of tax (3 ) (14 ) — (17 ) Other comprehensive income (loss), net of tax (11 ) (51 ) 58 (4 ) Balance as of December 31, 2017 $ 16 $ (297 ) $ (108 ) $ (389 ) Other comprehensive income (loss) before reclassifications, net of tax 6 28 (40 ) (6 ) Less: Amounts reclassified from AOCI, net of tax (2 ) (6 ) (4 ) (12 ) Other comprehensive income (loss), net of tax 8 34 (36 ) 6 Balance as of December 31, 2018 $ 24 $ (263 ) $ (144 ) $ (383 )
Schedule of amounts reclassified from accumulated other comprehensive income, net of tax	Amounts reclassified from AOCI, net of tax, for the years ended December 31, 2018 , 2017 and 2016 were as follows: (millions) 2018 2017 2016 Derivatives Net reclassification from AOCI for cash flow hedges included in cost of products sold $ (2 ) $ (6 ) $ (10 ) Less: Income tax benefit on reclassification from AOCI included in income tax expense — (3 ) (4 ) Net amount reclassified from AOCI $ (2 ) $ (3 ) $ (6 ) Defined Benefit Plans Net reclassification from AOCI for amortization of prior service (benefit) cost included in other income, net $ (8 ) $ (13 ) $ (13 ) Net reclassification from AOCI for amortization of prior service benefit included in income (loss) from discontinued operations, net of tax — (11 ) (3 ) Less: Income tax benefit on reclassification from AOCI included in income tax expense (2 ) (10 ) (7 ) Net amount reclassified from AOCI $ (6 ) $ (14 ) $ (9 ) Foreign Currency Translation Net reclassification from AOCI for translation loss realized upon the sale of foreign equity method investment included in other income, net $ (6 ) $ — $ — Less: Income tax benefit on reclassification from AOCI included in income tax benefit (2 ) — — Net amount reclassified from AOCI $ (4 ) $ — $ —

Segments (Tables)

Segments (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of reportable segment results	The results of our five reportable segments are as follows: CONSOLIDATED SEGMENTS For the year ended December 31, (millions) 2018 2017 2016 Net Sales: U.S. Wallboard and Surfaces $ 1,927 $ 1,916 $ 1,778 U.S. Performance Materials 392 373 357 U.S. Ceilings 541 477 467 Canada 448 405 389 Other 252 245 220 Eliminations (224 ) (212 ) (194 ) Total $ 3,336 $ 3,204 $ 3,017 Operating Profit (Loss): U.S. Wallboard and Surfaces $ 248 $ 306 $ 328 U.S. Performance Materials (8 ) 24 40 U.S. Ceilings 78 92 98 Canada 19 13 27 Other 14 11 (4 ) Corporate (124 ) (92 ) (93 ) Eliminations — (1 ) — Total $ 227 $ 353 $ 396 Depreciation, Depletion, Amortization and Accretion: U.S. Wallboard and Surfaces $ 97 $ 91 $ 87 U.S. Performance Materials 10 9 9 U.S. Ceilings 24 15 15 Canada 8 6 6 Other 5 5 7 Corporate 6 6 10 Total $ 150 $ 132 $ 134 Capital Expenditures: U.S. Wallboard and Surfaces $ 131 $ 104 $ 60 U.S. Performance Materials 36 31 11 U.S. Ceilings 27 17 4 Canada 8 10 4 Other 10 5 3 Corporate 7 1 1 Total $ 219 $ 168 $ 83
Schedule of rvenue by product	CONSOLIDATED NET SALES DISAGGREGATED BY PRODUCT TYPE For the year ended December 31, 2018 (millions) U.S. Wallboard and Surfaces U.S. Performance Materials U.S. Ceilings Canada Other Total Wallboard $ 994 $ — $ — $ 258 $ 70 $ 1,322 Surfaces and industrial products 580 — — 89 28 697 Underlayment — 303 — 10 38 351 Building envelope and structural — 81 — 2 1 84 Ceiling tile and grid — — 464 44 34 542 Specialty ceilings — — 20 8 — 28 Other products 103 — 3 13 78 197 Total product sales 1,677 384 487 424 249 3,221 Other miscellaneous sales (a) 250 8 54 24 3 339 Total sales before eliminations 1,927 392 541 448 252 3,560 Eliminations (124 ) (20 ) (48 ) (31 ) (1 ) (224 ) Total net sales $ 1,803 $ 372 $ 493 $ 417 $ 251 $ 3,336 (a) Other miscellaneous sales primarily includes shipping and handling costs billed to customers.
Schedule of geographic information	CONSOLIDATED GEOGRAPHIC INFORMATION For the year ended December 31, (millions) 2018 2017 2016 Net Sales: United States $ 2,871 $ 2,787 $ 2,625 Canada 448 406 389 Other Foreign 211 204 189 Geographic transfers (194 ) (193 ) (186 ) Total $ 3,336 $ 3,204 $ 3,017 Consolidated long-lived assets, consisting of property, plant and equipment, net, by geographic location were as follows: As of December 31, (millions) 2018 2017 2016 Long-Lived Assets: United States $ 1,680 $ 1,604 $ 1,563 Canada 84 90 80 Other Foreign 74 68 64 Total $ 1,838 $ 1,762 $ 1,707
UBBP reporting	UBBP For the year ended December 31, (millions) 2018 2017 2016 Net sales $ 1,182 $ 1,200 $ 1,052 Operating profit 117 160 133 Net income attributable to UBBP 84 117 99 Depreciation, depletion, and amortization 50 45 43 Capital expenditures 84 49 45 UBBP GEOGRAPHIC INFORMATION For the year ended December 31, (millions) 2018 2017 2016 Net Sales: Australia $ 438 $ 431 $ 381 South Korea 253 287 223 Thailand 161 150 141 China 131 119 103 Other 267 271 255 Geographic transfers (68 ) (58 ) (51 ) Total $ 1,182 $ 1,200 $ 1,052 Long-lived assets, consisting of property, plant and equipment, net, by geographic location for UBBP were as follows: As of December 31, (millions) 2018 2017 2016 Long-Lived Assets: Australia $ 209 $ 229 $ 217 South Korea 118 123 107 China 93 101 97 Oman 83 85 86 Thailand 86 86 75 Other 102 86 71 Total $ 691 $ 710 $ 653
Schedule of revenue by major customers	Sales to our significant customers were as follows: Significant Customer Segment with Sales to Significant Customer 2018 2017 2016 The Home Depot U.S. Wallboard and Surfaces, U.S. Performance Materials, U.S. Ceilings, and Canada 24 % 23 % 23 % L&W U.S. Wallboard and Surfaces, U.S. Performance Materials and U.S. Ceilings 14 % 16 % 19 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of income from continuing operations before income taxes	Income from continuing operations before income taxes consisted of the following: (millions) 2018 2017 2016 U.S. $ 168 $ 272 $ 201 Foreign 59 63 73 Total $ 227 $ 335 $ 274
Schedule of income tax expense (benefit) on continuing operations	Income tax expense (benefit) on continuing operations consisted of the following: (millions) 2018 2017 2016 Current: Federal $ (3 ) $ (21 ) $ — Foreign 7 2 5 State 2 2 1 Total current $ 6 $ (17 ) $ 6 Deferred: Federal $ 23 $ 243 $ 41 Foreign — — 2 State 5 12 14 Total deferred $ 28 $ 255 $ 57 Total $ 34 $ 238 $ 63
Schedule of differences between actual provisions for income taxes and provisions for income taxes at the U.S. federal statutory rate	For our continuing operations, differences between actual provisions for income taxes and provisions for income taxes at the U.S. federal statutory rate ( 21% in 2018 and 35% in 2017 and 2016) were as follows: (millions) 2018 2017 2016 Taxes on income from continuing operations at U.S. federal statutory rate $ 48 $ 117 $ 96 Foreign earnings subject to different tax rates 4 3 (3 ) State income tax, net of federal benefit 6 9 10 Income from equity method investments (9 ) (21 ) (17 ) Law changes (a) (11 ) 145 — Stock compensation (5 ) — — Prior year return adjustments — (7 ) — Foreign tax credits — — (21 ) Global Intangible Low-Taxed Income 5 — — Other, net (4 ) (8 ) (2 ) Provision for income tax expense (benefit) $ 34 $ 238 $ 63 Effective income tax rate 15 % 71 % 23 % (a) In 2017, we recorded the impact of the 2017 Tax Act which included the transition tax on deferred foreign earnings, net of foreign tax credits, of $9 million , an increase in the valuation allowance related to foreign tax credits of $106 million , an increase in the valuation allowance of our state NOLs due to the change in federal benefit related to those assets of $18 million , anticipated sequestration of our AMT credits of $3 million and the impact of the corporate rate change on deferred tax assets and liabilities of $9 million .
Schedule of components of deferred tax assets and liabilities	Significant components of deferred tax assets and liabilities were as follows: As of December 31, (millions) 2018 2017 Deferred Tax Assets: Net operating loss and tax credit carryforwards $ 389 $ 477 Pension and postretirement benefits 68 86 Reserves not deductible until paid 15 14 Self insurance 4 2 Capitalized interest 8 7 Inventories 4 4 Share-based compensation 13 14 Other 9 7 Deferred tax assets before valuation allowance 510 611 Valuation allowance (112 ) (175 ) Total deferred tax assets $ 398 $ 436 Deferred Tax Liabilities: Property, plant and equipment 157 153 Total deferred tax liabilities $ 157 $ 153 Net deferred tax assets $ 241 $ 283
Reconciliation of the beginning and ending amount of unrecognized tax benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: (millions) 2018 2017 2016 Balance as of January 1 $ 12 $ 15 $ 18 Tax positions related to the current period: Gross increase — — — Gross decrease — — — Tax positions related to prior periods: Gross increase 4 — — Gross decrease — (1 ) (3 ) Settlements (1 ) — — Lapse of statutes of limitations (1 ) (2 ) — Balance as of December 31 $ 14 $ 12 $ 15

Lease Commitments (Tables)

Lease Commitments (Tables)	12 Months Ended
	Dec. 31, 2018
Lease Commitments [Abstract]
Schedule of future minimum lease payments required under operating leases	Future minimum lease payments required under operating leases with initial or remaining noncancelable terms in excess of one year as of December 31, 2018 were as follows: (millions) 2019 2020 2021 2022 2023 After 2023 Future minimum lease payments $ 46 $ 39 $ 27 $ 12 $ 6 $ 6

Quarterly Financial Data (una_2

Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information	Quarter (millions, except per-share data) First Second Third Fourth 2018 Net sales $ 786 $ 880 $ 851 $ 819 Gross profit 139 184 152 131 Operating profit 46 75 69 37 Income from continuing operations 36 58 58 41 Income from discontinued operations, net of tax 1 — 1 1 Net income 37 58 59 42 Income per average common share: Basic (a) $ 0.26 $ 0.41 $ 0.42 $ 0.31 Diluted (a) 0.25 0.41 0.41 0.30 2017 Net sales $ 767 $ 811 $ 795 $ 831 Gross profit 159 168 162 167 Operating profit 84 95 91 83 Income (loss) from continuing operations (b) 55 46 66 (70 ) (Loss) income from discontinued operations, net of tax — (10 ) — 1 Net income (loss) (b) 55 36 66 (69 ) Income per average common share: Basic (a) $ 0.38 $ 0.25 $ 0.47 $ (0.49 ) Diluted (a) 0.37 0.24 0.46 (0.49 ) (a) The sum of the four quarters is not necessarily the same as the total for the year. (b) Income from continuing operations and net income included a loss on extinguishment of debt of $22 million for the second quarter of 2017 and income tax expense of $145 million related to the 2017 Tax Act for the fourth quarter of 2017. See Notes 6 , Debt, and 14 , Income Taxes, respectively.

Significant Accounting Polici_4

Significant Accounting Policies - Segments (Details)	12 Months Ended
	Dec. 31, 2018divisionssegment
Accounting Policies [Abstract]
Number of divisions | divisions	3
Number of reportable segments | segment	5

Significant Accounting Polici_5

Significant Accounting Policies - Consolidation and Presentation (Details)	Dec. 31, 2018
Minimum
Schedule of Equity Method Investments [Line Items]
Ownership percentage interest	20.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Ownership percentage interest	50.00%

Significant Accounting Polici_6

Significant Accounting Policies - Advertising (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Advertising expense	$ 15	$ 10	$ 12

Significant Accounting Polici_7

Significant Accounting Policies - Research and Development (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Research and development expenditures	$ 22	$ 23	$ 24

Significant Accounting Polici_8

Significant Accounting Policies - Income Taxes (Details)	12 Months Ended
	Dec. 31, 2018
Valuation Allowance [Line Items]
Recovery of demand troughs	4 years
Threshold period for cumulative losses	4 years
Minimum
Valuation Allowance [Line Items]
Economic cycle	7 years
Maximum
Valuation Allowance [Line Items]
Economic cycle	10 years

Significant Accounting Polici_9

Significant Accounting Policies - Earnings Per Share (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock options, RSUs, MSUs and performance shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted earnings (loss) per share (in shares)	0	0.7	1.5
Deferred shares associated with a deferred compensation program for non-employee directors
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted earnings (loss) per share (in shares)	0	0.2	0.2

Significant Accounting Polic_10

Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Capitalized interest	$ 6	$ 3	$ 1
Buildings and improvements
Property, Plant and Equipment [Line Items]
Expected useful life	50 years
Machinery and equipment | Minimum
Property, Plant and Equipment [Line Items]
Expected useful life	10 years
Machinery and equipment | Maximum
Property, Plant and Equipment [Line Items]
Expected useful life	25 years
Computer software and systems development costs | Minimum
Property, Plant and Equipment [Line Items]
Expected useful life	5 years
Computer software and systems development costs | Maximum
Property, Plant and Equipment [Line Items]
Expected useful life	7 years

Significant Accounting Polic_11

Significant Accounting Policies - Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Indefinite-lived intangible assets	$ 18	$ 19
Finite-lived intangible assets	$ 7	$ 8

Significant Accounting Polic_12

Significant Accounting Policies - Goodwill (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Goodwill	$ 15	$ 16

Significant Accounting Polic_13

Significant Accounting Policies - Derivative instruments (Details)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Typical hedging period	5 years
Period of anticipated natural gas purchases typically hedged	12 months

Significant Accounting Polic_14

Significant Accounting Policies - Foreign Currency Translation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Transaction gain (loss)	$ (6)	$ (4)	$ 3

Recent Accounting Pronounceme_3

Recent Accounting Pronouncements - Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	Jan. 01, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings (accumulated deficit)	$ (543)				$ (669)				$ (543)	$ (669)
Gross profit	131	$ 152	$ 184	$ 139	167	$ 162	$ 168	$ 159	606	656	$ 700
Operating profit	37	69	75	46	83	91	95	84	227	353	396
Other income, net									8	10	7
Net income	$ 42	$ 59	$ 58	$ 37	$ (69)	$ 66	$ 36	$ 55	196	88	510
Reduction in net cash provided by investing activities									195	219	(737)
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction in net cash provided by investing activities											9
Adjustment for Adoption of ASU 2017-07 | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gross profit										(9)	(5)
Operating profit										(14)	2
Other income, net										14	(2)
Net income										0	0
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gross profit										665	705
Operating profit										367	394
Other income, net										(4)	9
Net income										88	510
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings (accumulated deficit)												$ 2
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income									$ 196	$ 88	$ 510
Impact due to adoption of ASU												$ 2	$ 25
Retained Earnings | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impact due to adoption of ASU													$ 25

Acquisitions and Dispositions -

Acquisitions and Dispositions - Acquisition of Ceilings Plus (Details) - Ceilings Plus - USD ($) $ in Millions	Nov. 30, 2017	Jun. 30, 2018
Business Acquisition [Line Items]
Purchase price of acquisition		$ 50
Fair value of tangible assets acquired, less liabilities assumed	$ 15
Fair value of intangible assets acquired	20
Goodwill, acquired	$ 15

Acquisitions and Dispositions_2

Acquisitions and Dispositions - Discontinued Operations (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended								10 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Oct. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of discontinued operations, net of tax											$ 0	$ 0	$ 279
Loss from discontinued operations, net of tax		$ (1)	$ (1)	$ 0	$ (1)	$ (1)	$ 0	$ 10	$ 0		(3)	9	(20)
Cash inflow from discontinued operations	$ 102
L&W Supply
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales sold to third party customers											471	510	568
Cash inflow from discontinued operations											$ 467	489
L&W Supply | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration for discontinued operations										$ 675
Gain on sale of discontinued operations, net of tax										279
Loss from discontinued operations, net of tax												8
Net income from discontinued operations										$ 22			22
European Operations | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations, net of tax												$ 1	$ 2

Acquisitions and Dispositions_3

Acquisitions and Dispositions - Summarized Financial Information Related to Discontinued Operations (Details) - USD ($) $ in Millions	10 Months Ended	12 Months Ended
	Oct. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of discontinued operations		$ 0	$ 0	$ 279
L&W Supply | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales	$ 1,252
Cost of products sold	1,196
Gross profit	56
Selling and administrative expenses	22
Operating profit	34
Income tax expense	12
Net income from discontinued operations	22			$ 22
Gain on sale of discontinued operations	279
Transaction costs related to sale	$ 8

Equity Method Investments - Sch

Equity Method Investments - Schedule of Investments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 662	$ 686
Minimum
Schedule of Equity Method Investments [Line Items]
Ownership percentage interest	20.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Ownership percentage interest	50.00%
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 660	$ 679
Ownership percentage interest	50.00%	50.00%
Other equity method investments
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 2	$ 7
Ownership percentage interest	50.00%
Other equity method investments | Minimum
Schedule of Equity Method Investments [Line Items]
Ownership percentage interest		33.00%
Other equity method investments | Maximum
Schedule of Equity Method Investments [Line Items]
Ownership percentage interest		50.00%

- Equity Method Investments - N

- Equity Method Investments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Cash dividends received		$ 30	$ 42	$ 47
Years in performance target		5 years
Interest in joint venture	33.00%
Proceeds from divestiture of interest in joint venture	$ 3
Loss on sale of investments	8
Loss on sale of investments, net of tax	$ 5
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Loan receivable from related party		$ 9	$ 13
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Ownership percentage interest		50.00%	50.00%
Cash dividends received		$ 30
Consolidated retained earnings which represents undistributed earnings		72
Contingent consideration amount (up to)		$ 50

Equity Method Investments - Tr

Equity Method Investments - Translation Gains and Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Translation (loss) gain	$ (40)	$ 58	$ (53)
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Translation (loss) gain	$ (31)	$ 40	$ (30)

Equity Method Investments - Sum

Equity Method Investments - Summarized Statements of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ 42	$ 59	$ 49
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Net sales	1,182	1,200	1,052
Gross profit	317	369	337
Operating profit	117	160	133
Net income from continuing operations before taxes	131	174	142
Net income	86	121	95
Net income attributable to USG Boral Building Products	84	117	99
Income (loss) from equity method investments	$ 42	$ 59	49
China | Operating profit
Schedule of Equity Method Investments [Line Items]
Long-lived asset impairment charges			8
China | Equity Method Income
Schedule of Equity Method Investments [Line Items]
Long-lived asset impairment charges			4
Oman | Operating profit
Schedule of Equity Method Investments [Line Items]
Long-lived asset impairment charges			14
Oman | Equity Method Income
Schedule of Equity Method Investments [Line Items]
Long-lived asset impairment charges			$ 4

Equity Method Investments - S_2

Equity Method Investments - Summarized Balance Sheets (Details) - USG Boral Building Products - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Current assets	$ 392	$ 438
Non-current assets	964	981
Current liabilities	232	255
Long-term debt	10	10
Other non-current liabilities	22	12
Shareholders' equity	1,092	1,142
Current portion of long-term debt	15	16
Shareholders' equity related to non-controlling interests	$ 64	$ 66

Marketable Securities - Investm

Marketable Securities - Investments in Marketable Securities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 98	$ 99
Fair Value	98	99
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	73	68
Fair Value	73	68
U.S. government and agency debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5	6
Fair Value	5	6
Asset-backed debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	15	11
Fair Value	15	11
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5	13
Fair Value	5	13
Municipal debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	0	1
Fair Value	$ 0	$ 1

Marketable Securities - Contrac

Marketable Securities - Contractual Maturities of Marketable Securities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost
Due in 1 year or less	$ 55
Due in 1-5 years	43
Total marketable securities	98	$ 99
Fair Value
Due in 1 year or less	55
Due in 1-5 years	43
Total marketable securities	$ 98	$ 99

Debt - Total Debt (Details)

Debt - Total Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,089	$ 1,089
Less: Unamortized debt issuance costs	10	11
Total	1,079	1,078
4.875% senior notes due 2027
Debt Instrument [Line Items]
Long-term debt, gross	$ 500	500
Less: Unamortized debt issuance costs		$ 7
Stated interest rate	4.875%	4.875%
5.5% senior notes due 2025
Debt Instrument [Line Items]
Long-term debt, gross	$ 350	$ 350
Stated interest rate	5.50%	5.50%
Industrial revenue bonds (due 2028 through 2034)
Debt Instrument [Line Items]
Long-term debt, gross	$ 239	$ 239

Debt - Issuance, Repurchases an

Debt - Issuance, Repurchases and Redemptions of Senior Notes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt issuance cost		$ 10	$ 11
Premiums paid on early redemption of debt				$ 30
Accrued interest on early redemption of debt				9
Gain (loss) on early extinguishment of debt	$ (22)	$ 0	(22)	$ (37)
4.875% senior notes due 2027
Debt Instrument [Line Items]
Face amount of notes			$ 500
Stated interest rate		4.875%	4.875%
Debt issuance cost			$ 7
7.75% senior notes due 2018
Debt Instrument [Line Items]
Stated interest rate			7.75%
Repurchase amount			$ 500
Aggregate consideration			536
Premiums paid on early redemption of debt			20
Accrued interest on early redemption of debt			16
Gain (loss) on early extinguishment of debt			$ (21)
6.3% senior notes due 2016
Debt Instrument [Line Items]
Stated interest rate				6.30%
Repurchase amount				$ 500
7.875% senior notes due 2020
Debt Instrument [Line Items]
Stated interest rate				7.875%
Repurchase amount				$ 250
5.875% senior notes due 2021
Debt Instrument [Line Items]
Stated interest rate				5.875%
Repurchase amount				$ 350

Debt - Senior Notes (Details)

Debt - Senior Notes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal net of discount	$ 1,089	$ 1,089
5.5% senior notes due 2025
Debt Instrument [Line Items]
Stated interest rate	5.50%	5.50%
Principal net of discount	$ 350	$ 350
Percentage of purchase price of notes at their principal amount	101.00%
Percentage of principal amount of the notes being redeemed	100.00%
4.875% senior notes due 2027
Debt Instrument [Line Items]
Stated interest rate	4.875%	4.875%
Principal net of discount	$ 500	$ 500
Percentage of purchase price of notes at their principal amount	101.00%
Percentage of principal amount of the notes being redeemed	100.00%

Debt - Credit Facility (Details

Debt - Credit Facility (Details) - USD ($)	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Loss on extinguishment of debt	$ 22,000,000	$ 0	$ 22,000,000	$ 37,000,000
Debt issuance cost		10,000,000	11,000,000
Line of credit
Line of Credit Facility [Line Items]
Maximum borrowing limit			220,000,000	$ 180,000,000
Loss on extinguishment of debt			1,000,000
Debt issuance cost			$ 1,000,000
Line of credit | Line of credit
Line of Credit Facility [Line Items]
Current borrowing capacity		171,000,000
Letters of credit outstanding		$ 19,000,000

Debt - Industrial Revenue Bonds

Debt - Industrial Revenue Bonds (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Long-term debt, gross	$ 1,089	$ 1,089
Industrial revenue bonds
Line of Credit Facility [Line Items]
Long-term debt, gross	$ 239	$ 239
Weighted average interest rate	5.875%
Minimum | Industrial revenue bonds
Line of Credit Facility [Line Items]
Stated interest rate	5.50%
Maximum | Industrial revenue bonds
Line of Credit Facility [Line Items]
Stated interest rate	6.40%

Debt - Other Information (Detai

Debt - Other Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Fair value of debt	$ 1,099	$ 1,134
Accrued interest	12	$ 12
Debt maturities (principal amounts)
2019 through 2023	0
After 2,023	$ 1,089

- Derivative Instruments - Narr

- Derivative Instruments - Narrative (Details) MMBTU in Millions	12 Months Ended
	Dec. 31, 2018USD ($)MMBTU	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Net liability position of derivatives	$ 6,000,000
Collateral provided to counterparties related to derivatives	7,000,000
Foreign exchange contracts | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Loss on cash flow hedge ineffectiveness	$ 0	$ 0	$ 0
Commodity contracts | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of commodity instruments (in mmbtu) | MMBTU	41
Loss on cash flow hedge ineffectiveness	$ 0	$ 0	$ 0
Purchases of products and services | Foreign exchange contracts | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of FX instruments	$ 98,000,000

Derivative Instruments - Pretax

Derivative Instruments - Pretax Effects of Derivative Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	$ 7	$ (24)	$ 3
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	(2)	(6)	(10)
Derivatives in Cash Flow Hedging Relationships | Commodity contracts | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	(1)	(19)	6
Derivatives in Cash Flow Hedging Relationships | Commodity contracts | Cost of products sold | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	(2)	(4)	(15)
Derivatives in Cash Flow Hedging Relationships | Foreign exchange contracts | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Other Comprehensive Income (Loss) on Derivatives (Effective Portion)	8	(5)	(3)
Derivatives in Cash Flow Hedging Relationships | Foreign exchange contracts | Cost of products sold | Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	0	(2)	5
Derivatives Not Designated as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives	1	(1)	1
Derivatives Not Designated as Hedging Instruments | Commodity contracts | Cost of products sold
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives	$ 1	$ (1)	$ 1

Derivative Instruments - Fair V

Derivative Instruments - Fair Values of Derivative Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair values of derivative instruments on the consolidated balance sheets
Total assets	$ 10	$ 2
Total liabilities	16	17
Derivatives Not Designated as Hedging Instruments
Fair values of derivative instruments on the consolidated balance sheets
Total assets	0	0
Total liabilities	0	0
Commodity contracts | Other current assets | Derivatives Not Designated as Hedging Instruments
Fair values of derivative instruments on the consolidated balance sheets
Total assets	0	0
Commodity contracts | Other assets | Derivatives Not Designated as Hedging Instruments
Fair values of derivative instruments on the consolidated balance sheets
Total assets	0	0
Commodity contracts | Accrued expenses | Derivatives Not Designated as Hedging Instruments
Fair values of derivative instruments on the consolidated balance sheets
Total liabilities	0	0
Commodity contracts | Other liabilities | Derivatives Not Designated as Hedging Instruments
Fair values of derivative instruments on the consolidated balance sheets
Total liabilities	0	0
Derivatives in Cash Flow Hedging Relationships | Derivatives in Cash Flow Hedging Relationships
Fair values of derivative instruments on the consolidated balance sheets
Total assets	10	2
Total liabilities	16	17
Derivatives in Cash Flow Hedging Relationships | Commodity contracts | Other current assets | Derivatives in Cash Flow Hedging Relationships
Fair values of derivative instruments on the consolidated balance sheets
Total assets	2	1
Derivatives in Cash Flow Hedging Relationships | Commodity contracts | Other assets | Derivatives in Cash Flow Hedging Relationships
Fair values of derivative instruments on the consolidated balance sheets
Total assets	2	1
Derivatives in Cash Flow Hedging Relationships | Commodity contracts | Accrued expenses | Derivatives in Cash Flow Hedging Relationships
Fair values of derivative instruments on the consolidated balance sheets
Total liabilities	6	6
Derivatives in Cash Flow Hedging Relationships | Commodity contracts | Other liabilities | Derivatives in Cash Flow Hedging Relationships
Fair values of derivative instruments on the consolidated balance sheets
Total liabilities	10	8
Derivatives in Cash Flow Hedging Relationships | Foreign exchange contracts | Other current assets | Derivatives in Cash Flow Hedging Relationships
Fair values of derivative instruments on the consolidated balance sheets
Total assets	6	0
Derivatives in Cash Flow Hedging Relationships | Foreign exchange contracts | Accrued expenses | Derivatives in Cash Flow Hedging Relationships
Fair values of derivative instruments on the consolidated balance sheets
Total liabilities	$ 0	$ 3

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 157	$ 148
Equity mutual funds	5	6
Derivative assets	10	2
Derivative liabilities	(16)	(17)
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	73	68
U.S. government and agency debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	5	6
Asset-backed debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	15	11
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	5	13
Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	1
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	121	124
Equity mutual funds	5	6
Derivative assets	0	0
Derivative liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government and agency debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Asset-backed debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	36	24
Equity mutual funds	0	0
Derivative assets	10	2
Derivative liabilities	(16)	(17)
Significant Other Observable Inputs (Level 2) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	73	68
Significant Other Observable Inputs (Level 2) | U.S. government and agency debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	5	6
Significant Other Observable Inputs (Level 2) | Asset-backed debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	15	11
Significant Other Observable Inputs (Level 2) | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	5	13
Significant Other Observable Inputs (Level 2) | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	1
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Equity mutual funds	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Significant Unobservable Inputs (Level 3) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Significant Unobservable Inputs (Level 3) | U.S. government and agency debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Significant Unobservable Inputs (Level 3) | Asset-backed debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Significant Unobservable Inputs (Level 3) | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Significant Unobservable Inputs (Level 3) | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 0	$ 0

- Employee Retirement Plans - N

- Employee Retirement Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plans Disclosure [Abstract]
Total charges for defined contribution plans	$ 12	$ 8	$ 5
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	0	25	35
Curtailment gain	0	0	0
Net periodic benefit cost (credit)	(46)	(59)	(79)
Accumulated benefit obligation	1,374	1,506
Actuarial gain (loss)	$ 192	$ (202)
Minimum funded percentage of ABO	100.00%
Expected return on plan assets (as a percent)	6.55%	6.54%
Estimated future employer benefit plan contribution	$ 62
Expected future benefit payments in next twelve months	115
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	0	$ 0	0
Curtailment gain	0	0	20
Net periodic benefit cost (credit)	16	16	39
Actuarial gain (loss)	15	$ (10)
Expected future benefit payments in next twelve months	$ 9
Gain on sale of discontinued operations | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Curtailment gain			20
United States
Defined Benefit Plan Disclosure [Line Items]
Annual increase to contributions health care cost (as a percent)	3.00%
Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate	5.92%	5.95%
Ultimate health care cost trend rate	4.00%	4.00%
USG Corporation Pension Plan - L&W Supply | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		$ 25	26
Net periodic benefit cost (credit)	$ 1	1	(7)
USG Corporation Pension Plan - L&W Supply | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (credit)	$ 3	1	3
USG Corporation Pension Plan - L&W Supply | Gain on sale of discontinued operations | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		$ 0	$ 15

Employee Retirement Plans - Sch

Employee Retirement Plans - Schedule of Settlement Expense (Details) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	$ 0	$ 25	$ 35
USG Corporation Pension Plan - L&W Supply
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		25	26
Other income, net | USG Corporation Pension Plan - L&W Supply
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		12	11
Income (loss) from discontinued operations | USG Corporation Pension Plan - L&W Supply
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		13	0
Gain on sale of discontinued operations | USG Corporation Pension Plan - L&W Supply
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		$ 0	$ 15

Employee Retirement Plans - Com

Employee Retirement Plans - Components of Net Pension and Postretirement Benefit Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost of benefits earned	$ 50	$ 44	$ 45
Interest cost on projected benefit obligation	62	61	66
Expected return on plan assets	(97)	(93)	(89)
Settlement	0	25	35
Curtailment	0	0	0
Net amortization	31	22	22
Net pension & postretirement cost	46	59	79
Net actuarial (loss) gain	(14)	77	58
Net amortization	(31)	(22)	(22)
Settlement	0	(25)	(35)
Curtailment	0	0	0
Deferred currency exchange	(7)	4	2
Total recognized in other comprehensive income	(52)	34	3
Total recognized in net pension & postretirement cost and other comprehensive income	(6)	93	82
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost of benefits earned	2	2	2
Interest cost on projected benefit obligation	5	5	6
Expected return on plan assets	0	0	0
Settlement	0	0	0
Curtailment	0	0	(20)
Net amortization	(23)	(23)	(27)
Net pension & postretirement cost	(16)	(16)	(39)
Net actuarial (loss) gain	(15)	10	(6)
Net amortization	23	23	27
Settlement	0	0	0
Curtailment	0	0	20
Deferred currency exchange	(1)	1	(7)
Total recognized in other comprehensive income	7	34	34
Total recognized in net pension & postretirement cost and other comprehensive income	(9)	18	(5)
USG Corporation Pension Plan - L&W Supply | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Settlement		25	26
Net pension & postretirement cost	(1)	(1)	7
USG Corporation Pension Plan - L&W Supply | Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net pension & postretirement cost	$ (3)	$ (1)	(3)
USG Corporation Pension Plan - Other | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Settlement			$ 9

Employee Retirement Plans - Acc

Employee Retirement Plans - Accumulated Benefit Obligation (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Pension
Selected information for pension plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligation	$ (35)	$ (35)
Fair value of plan assets	3	3
Selected information for pension and postretirement plans with benefit obligations in excess of plan assets:
Benefit obligation	(1,568)	(1,769)
Fair value of plan assets	1,431	1,576
Postretirement
Selected information for pension and postretirement plans with benefit obligations in excess of plan assets:
Benefit obligation	(132)	(150)
Fair value of plan assets	$ 0	$ 0

Employee Retirement Plans - Pro

Employee Retirement Plans - Projected Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Plan Assets:
Fair value as of beginning of period	$ 1,577
Fair value as of end of period	1,432	$ 1,577
Components on the Consolidated Balance Sheets:
Current liabilities	(16)	(17)
Noncurrent liabilities	(254)	(326)
Pension
Change in Benefit Obligation:
Benefit obligation as of beginning of period	1,770	1,610
Service cost	50	44	$ 45
Interest cost	62	61	66
Settlements	0	(121)
Participant contributions	10	9
Benefits paid	(110)	(51)
Actuarial (gain) loss	(192)	202
Foreign currency translation	(21)	16
Benefit obligation as of end of period	1,569	1,770	1,610
Change in Plan Assets:
Fair value as of beginning of period	1,577	1,435
Actual return on plan assets	(81)	217
Employer contributions	56	71
Participant contributions	10	9
Benefits paid	(110)	(51)
Settlements	0	(121)
Foreign currency translation	(20)	17
Fair value as of end of period	1,432	1,577	1,435
Funded status	(137)	(193)
Components on the Consolidated Balance Sheets:
Noncurrent assets	1	0
Current liabilities	(7)	(8)
Noncurrent liabilities	(131)	(185)
Net liability as of December 31	(137)	(193)
Pretax Components in AOCI:
Net actuarial loss (gain)	369	421
Prior service credit	0	0
Total as of end of year	369	421
Postretirement
Change in Benefit Obligation:
Benefit obligation as of beginning of period	150	135
Service cost	2	2	2
Interest cost	5	5	6
Settlements	0	0
Participant contributions	0	0
Benefits paid	(6)	(6)
Actuarial (gain) loss	(15)	10
Foreign currency translation	(4)	4
Benefit obligation as of end of period	132	150	135
Change in Plan Assets:
Fair value as of beginning of period	0	0
Actual return on plan assets	0	0
Employer contributions	6	6
Participant contributions	0	0
Benefits paid	(6)	(6)
Settlements	0	0
Foreign currency translation	0	0
Fair value as of end of period	0	0	$ 0
Funded status	(132)	(150)
Components on the Consolidated Balance Sheets:
Noncurrent assets	0	0
Current liabilities	(9)	(9)
Noncurrent liabilities	(123)	(141)
Net liability as of December 31	(132)	(150)
Pretax Components in AOCI:
Net actuarial loss (gain)	(5)	11
Prior service credit	(19)	(42)
Total as of end of year	$ (24)	$ (31)

Employee Retirement Plans - Ass

Employee Retirement Plans - Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension
Weighted average assumptions used to determine benefit obligations as of December 31:
Discount rate	4.21%	3.55%
Compensation increase rate	3.55%	3.54%
Interest crediting rate	4.00%	4.00%
Weighted average assumptions used to determine net cost for years ended December 31:
Discount rate	3.55%	4.02%
Expected return on plan assets (as a percent)	6.55%	6.54%
Compensation increase rate	3.54%	3.55%
Postretirement
Weighted average assumptions used to determine benefit obligations as of December 31:
Discount rate	4.09%	3.42%
Weighted average assumptions used to determine net cost for years ended December 31:
Discount rate	3.42%	3.90%

Employee Retirement Plans - Tar

Employee Retirement Plans - Target Asset Allocation and Acceptable Ranges (Details)	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	100.00%
Equity
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	35.00%
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	55.00%
Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	5.00%
Other real assets
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	5.00%
Cash equivalents and short-term investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	0.00%
Minimum | Equity
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	32.00%
Minimum | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	43.00%
Minimum | Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	2.00%
Minimum | Other real assets
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	2.00%
Minimum | Cash equivalents and short-term investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	0.00%
Maximum | Equity
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	39.00%
Maximum | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	66.00%
Maximum | Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	8.00%
Maximum | Other real assets
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	9.00%
Maximum | Cash equivalents and short-term investments
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations (as a percent)	5.00%

Employee Retirement Plans - Fai

Employee Retirement Plans - Fair Values by Hierarchy of Inputs (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,432	$ 1,577
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	119	131	$ 142
Common and preferred stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	88	92
Common and preferred stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	88	92
Common and preferred stock | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Common and preferred stock | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Commingled/pooled/mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	450	553
Commingled/pooled/mutual funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Commingled/pooled/mutual funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	450	553
Commingled/pooled/mutual funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Total equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	538	645
Total equity | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	88	92
Total equity | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	450	553
Total equity | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. government and agency debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	8
U.S. government and agency debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
U.S. government and agency debt securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	8
U.S. government and agency debt securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. government and agency debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55	68
Non-U.S. government and agency debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Non-U.S. government and agency debt securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55	68
Non-U.S. government and agency debt securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Investment-grade debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	268	334
Investment-grade debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Investment-grade debt securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	268	334
Investment-grade debt securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
High-yield debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40	42
High-yield debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
High-yield debt securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	40	42
High-yield debt securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Commingled/pooled funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	362	305
Commingled/pooled funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Commingled/pooled funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	362	305
Commingled/pooled funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mortgaged backed securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	1
Mortgaged backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mortgaged backed securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	1
Mortgaged backed securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	14
Other | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12	13
Other | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
Total fixed income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	754	772
Total fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Total fixed income | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	753	771
Total fixed income | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1	1
Limited partnerships
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	83	91
Limited partnerships | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Limited partnerships | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Limited partnerships | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	83	91	103
Other Real Estate Assets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	51	57
Other Real Estate Assets | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Real Estate Assets | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	16	18
Other Real Estate Assets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	35	39	$ 38
Cash equivalents and short-term investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	14
Cash equivalents and short-term investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash equivalents and short-term investments | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	14
Cash equivalents and short-term investments | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Total
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,436	1,579
Total | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	88	92
Total | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,229	1,356
Total | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	119	131
Cash on hand
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	0
Receivables
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	2
Accounts payable
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ (10)	$ (4)

Employee Retirement Plans - Rec

Employee Retirement Plans - Reconciliation of Change in Fair Value Measurement of Defined Benefit Plans' Consolidated Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in Plan Assets:
Fair value as of beginning of period	$ 1,577
Fair value as of end of period	1,432	$ 1,577
Significant Unobservable Inputs (Level 3)
Change in Plan Assets:
Fair value as of beginning of period	131	142
Realized gains (losses)	5	16
Unrealized gains (losses)	(7)	1
Purchases	14	9
Sales	(24)	(37)
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Fair value as of end of period	119	131
Fixed income
Change in Plan Assets:
Fair value as of beginning of period	772
Fair value as of end of period	754	772
Fixed income | Significant Unobservable Inputs (Level 3)
Change in Plan Assets:
Fair value as of beginning of period	1	1
Realized gains (losses)	0	0
Unrealized gains (losses)	0	0
Purchases	0	0
Sales	0	0
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Fair value as of end of period	1	1
Other Real Estate Assets
Change in Plan Assets:
Fair value as of beginning of period	57
Fair value as of end of period	51	57
Other Real Estate Assets | Significant Unobservable Inputs (Level 3)
Change in Plan Assets:
Fair value as of beginning of period	39	38
Realized gains (losses)	1	1
Unrealized gains (losses)	1	2
Purchases	0	0
Sales	(6)	(2)
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Fair value as of end of period	35	39
Limited partnerships
Change in Plan Assets:
Fair value as of beginning of period	91
Fair value as of end of period	83	91
Limited partnerships | Significant Unobservable Inputs (Level 3)
Change in Plan Assets:
Fair value as of beginning of period	91	103
Realized gains (losses)	4	15
Unrealized gains (losses)	(8)	(1)
Purchases	14	9
Sales	(18)	(35)
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Fair value as of end of period	$ 83	$ 91

Employee Retirement Plans - Exp

Employee Retirement Plans - Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2018USD ($)
Pension Benefits
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	$ 115
2,020	117
2,021	114
2,022	117
2,023	121
2024 - 2028	581
Postretirement Benefits
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	9
2,020	8
2,021	8
2,022	8
2,023	8
2024 - 2028	$ 40

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) - USD ($)	Feb. 14, 2019	Jun. 10, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Number of shares reserved for future grant under the LTIP (in shares)			6,000,000
Expense for share-based arrangements			$ 21,000,000	$ 18,000,000	$ 18,000,000
Income tax benefits on share based arrangements			$ 7,000,000	0	0
Reclassification to equity				6,000,000
MSUs
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Vesting period			3 years
Minimum number of performance shares earned (as a percent)			0.00%
Maximum number of performance shares earned (as a percent)			150.00%
Awards vested (in shares)			730,145
Number of shares vested (in shares)			1,095,218
Unrecognized compensation cost			$ 5,000,000
Weighted average period for recognition of unrecognized compensation cost			1 year 8 months 12 days
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Vesting period			3 years
Minimum number of performance shares earned (as a percent)			0.00%
Maximum number of performance shares earned (as a percent)			200.00%
Awards vested (in shares)			143,033
Number of shares vested (in shares)			286,066
Unrecognized compensation cost			$ 4,000,000
Weighted average period for recognition of unrecognized compensation cost			1 year 7 months 12 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Awards vested (in shares)			50,000
Unrecognized compensation cost			$ 4,000,000
Weighted average period for recognition of unrecognized compensation cost			1 year 7 months 12 days
Fair value of RSUs that vested in period			$ 1,000,000	$ 2,000,000	$ 2,000,000
Employee stock option
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Expiration period of stock options			10 years
Knauf And World Cup Acquisition Corporation
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Conversion price (in dollars per share)		$ 43.50
Scenario, Forecast | Knauf And World Cup Acquisition Corporation
Share-based Compensation Arrangement by Share-based Payment Award [lLine Items]
Conversion price (in dollars per share)	$ 43.50

Share-Based Compensation - MSUs

Share-Based Compensation - MSUs Assumptions (Details) - MSUs - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assumptions:
Weighted average grant date fair value (in dollars per share)	$ 34.22	$ 35.79	$ 19.59
Expected volatility	32.62%	32.10%	34.02%
Risk-free rate	2.37%	1.39%	0.86%
Expected term (in years)	2 years 11 months 12 days	2 years 11 months 14 days	2 years 11 months 12 days
Expected dividends	$ 0	$ 0	$ 0

Share-Based Compensation - MS_2

Share-Based Compensation - MSUs Activity (Details) - MSUs - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted Number of Shares
Nonvested at beginning of period (in shares)	1,097,000
Granted (in shares)	429,000
Vested (in shares)	(730,145)
Forfeited (in shares)	(8,000)
Nonvested at end of period (in shares)	788,000	1,097,000
Weighted Average Grant Date Fair Value
Nonvested at January 1 (in dollars per share)	$ 25.01
Granted (in dollars per share)	34.22	$ 35.79	$ 19.59
Vested (in dollars per share)	19.59
Forfeited (in dollars per share)	35.79
Nonvested at December 31 (in dollars per share)	$ 34.93	$ 25.01

Share-Based Compensation - Perf

Share-Based Compensation - Performance Shares Assumptions (Details) - Performance shares - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assumptions:
Weighted average grant date fair value (in dollars per share)	$ 34.21	$ 39.42	$ 21.10
Expected volatility	32.61%	32.10%	34.02%
Risk-free rate	2.37%	1.39%	0.86%
Expected term (in years)	2 years 11 months 12 days	2 years 11 months 14 days	2 years 11 months 12 days
Expected dividends	$ 0	$ 0	$ 0

Share-Based Compensation - Pe_2

Share-Based Compensation - Performance Shares Activity (Details) - Performance shares - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted Number of Shares
Nonvested at beginning of period (in shares)	256,000
Granted (in shares)	104,000
Vested (in shares)	(143,033)
Forfeited (in shares)	(2,000)
Nonvested at end of period (in shares)	215,000	256,000
Weighted Average Grant Date Fair Value
Nonvested at January 1 (in dollars per share)	$ 29.14
Granted (in dollars per share)	34.21	$ 39.42	$ 21.10
Vested (in dollars per share)	21.10
Forfeited (in dollars per share)	33.35
Nonvested at December 31 (in dollars per share)	$ 36.93	$ 29.14

Share-Based Compensation - RSU

Share-Based Compensation - RSU Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
RSUs
Assumptions:
Weighted average grant date fair value (in dollars per share)	$ 36.92	$ 31.57	$ 23.94

Share-Based Compensation - RSUs

Share-Based Compensation - RSUs Activity (Details) - RSUs - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Nonvested at beginning of period (in shares)	304
Granted (in shares)	44
Vested (in shares)	(50)
Forfeited (in shares)	(10)
Nonvested at end of period (in shares)	288	304
Weighted Average Grant Date Fair Value
Nonvested at January 1 (in dollars per share)	$ 14.67
Granted (in dollars per share)	36.92	$ 31.57	$ 23.94
Vested (in dollars per share)	26.64
Forfeited (in dollars per share)	28.29
Nonvested at December 31 (in dollars per share)	$ 30.05	$ 14.67

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Stock Options (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Options
Outstanding at beginning of period (in shares)	1,261
Exercised (in shares)	(677)
Canceled (in shares)	(50)
Outstanding at end of period (in shares)	534	1,261
Exercisable (in shares)	534
Vested (in shares)	534
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 15.72
Exercised (in dollars per share)	16.02
Canceled (in dollars per share)	34.67
Outstanding at end of period (in dollars per share)	13.55	$ 15.72
Exercisable (in dollars per share)	13.55
Vested (in dollars per share)	$ 13.55
Options Activity, Weighted Remaining Contractual Term and Aggregate Intrisic Value
Outstanding weighted average remaining contractual term	1 year 10 months 20 days	2 years 5 months 22 days
Exercisable weighted average remaining contractual term	1 year 10 months 20 days
Vested weighted average remaining contractual term	1 year 10 months 20 days
Outstanding aggregate intrinsic value	$ 16	$ 28
Exercisable aggregate intrinsic value	16
Vested aggregate intrinsic value	16
Employee stock option
Options Activity, Weighted Remaining Contractual Term and Aggregate Intrisic Value
Intrinsic value of stock options exercised	17	7	$ 4
Cash received from stock options exercised	11	14	4
Fair value of stock options vested	$ 0	$ 0	$ 1

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Inventory, Net [Abstract]
Finished goods	$ 168	$ 140
Work in progress	42	39
Raw materials	80	73
Total	$ 290	$ 252

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Land and mineral deposits	$ 206	$ 120
Buildings and improvements	1,022	1,100
Machinery and equipment	2,717	2,595
Property, plant and equipment, gross	3,945	3,815
Reserves for depreciation and depletion	(2,107)	(2,053)
Total	1,838	1,762
Annual depreciation and depletion expense	$ 133	$ 129

Supplemental Balance Sheet In_5

Supplemental Balance Sheet Information - Accrued Expenses (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities, Current [Abstract]
Self-insurance reserves	$ 13	$ 12
Employee compensation	17	17
Interest	12	12
Derivatives	6	9
Pension and other postretirement benefits	16	17
Environmental	13	17
Other	52	51
Total	$ 129	$ 135

Supplemental Balance Sheet In_6

Supplemental Balance Sheet Information - Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance as of beginning of period	$ 118	$ 113
Accretion expense	7	7
Liabilities incurred	0	3
Changes in estimated cash flows	(9)	(4)
Liabilities settled	(1)	(3)
Reclass to accrued expenses	(2)	0
Foreign currency translation	(2)	2
Balance as of end of period	$ 111	$ 118

Supplemental Balance Sheet In_7

Supplemental Balance Sheet Information - Asset Disposition and AOCI - Narrative (Details) $ in Millions	3 Months Ended
	Jun. 30, 2018USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Gain on disposition of assets	$ 13
Gain on disposition of assets, net of tax	$ 9

Supplemental Balance Sheet In_8

Supplemental Balance Sheet Information - Changes in Balances of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	$ 1,845
Other comprehensive income (loss) before reclassifications, net of tax	(6)	$ (21)	$ (86)
Less: Amounts reclassified from AOCI, net of tax	(12)	(17)	(15)
Other comprehensive income (loss), net of tax	6	(4)	(71)
Balance at end of period	1,919	1,845
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	16	27	20
Other comprehensive income (loss) before reclassifications, net of tax	6	(14)	1
Less: Amounts reclassified from AOCI, net of tax	(2)	(3)	(6)
Other comprehensive income (loss), net of tax	8	(11)	7
Balance at end of period	24	16	27
Pension and Other Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(297)	(246)	(221)
Other comprehensive income (loss) before reclassifications, net of tax	28	(65)	(34)
Less: Amounts reclassified from AOCI, net of tax	(6)	(14)	(9)
Other comprehensive income (loss), net of tax	34	(51)	(25)
Balance at end of period	(263)	(297)	(246)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(108)	(166)	(113)
Other comprehensive income (loss) before reclassifications, net of tax	(40)	58	(53)
Less: Amounts reclassified from AOCI, net of tax	(4)	0	0
Other comprehensive income (loss), net of tax	(36)	58	(53)
Balance at end of period	(144)	(108)	(166)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(389)	(385)	(314)
Other comprehensive income (loss), net of tax	6	(4)	(71)
Balance at end of period	$ (383)	$ (389)	$ (385)

Supplemental Balance Sheet In_9

Supplemental Balance Sheet Information - Amounts Reclassified from AOCI (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of products sold									$ 2,730	$ 2,548	$ 2,317
Other income, net									8	10	7
Gain on sale of discontinued operations, net of tax									0	0	(279)
Less: Income tax benefit on reclassification from AOCI included in income tax expense or benefit									(34)	(238)	(63)
Net income	$ (42)	$ (59)	$ (58)	$ (37)	$ 69	$ (66)	$ (36)	$ (55)	(196)	(88)	(510)
Gain on reclassification from AOCI									2
Derivatives | Reclassification out of accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Cost of products sold									(2)	(6)	(10)
Less: Income tax benefit on reclassification from AOCI included in income tax expense or benefit									0	(3)	(4)
Net income									(2)	(3)	(6)
Defined Benefit Plans | Reclassification out of accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income, net									(8)	(13)	(13)
Gain on sale of discontinued operations, net of tax									0	(11)	(3)
Less: Income tax benefit on reclassification from AOCI included in income tax expense or benefit									(2)	(10)	(7)
Net income									(6)	(14)	(9)
Foreign Currency Translation | Reclassification out of accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income, net									(6)	0	0
Less: Income tax benefit on reclassification from AOCI included in income tax expense or benefit									(2)	0	0
Net income									$ (4)	$ 0	$ 0

Long-Lived Asset Impairment C_2

Long-Lived Asset Impairment Charges - Impairment Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring and Related Activities [Abstract]
Long-lived asset impairment charges	$ 0	$ 0	$ 10
Severance and other charges			$ 2

Segments - Narrative (Details)

Segments - Narrative (Details)	12 Months Ended
	Dec. 31, 2018segment
Segment Reporting [Abstract]
Number of reportable segments	5

Segments - Consolidated Segment

Segments - Consolidated Segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Sales:
Net sales	$ 819	$ 851	$ 880	$ 786	$ 831	$ 795	$ 811	$ 767	$ 3,336	$ 3,204	$ 3,017
Operating Profit (Loss):
Operating profit	$ 37	$ 69	$ 75	$ 46	$ 83	$ 91	$ 95	$ 84	227	353	396
Depreciation, Depletion and Amortization:
Depreciation, depletion, amortization, and accretion									150	132	134
Capital Expenditures:
Capital expenditures									219	168	83
U.S. Wallboard and Surfaces
Net Sales:
Net sales									1,803
U.S. Performance Materials
Net Sales:
Net sales									372
U.S. Ceilings
Net Sales:
Net sales									493
Canada
Net Sales:
Net sales									417
Other
Net Sales:
Net sales									251
Operating Segments
Net Sales:
Net sales									3,560
Operating Segments | U.S. Wallboard and Surfaces
Net Sales:
Net sales									1,927	1,916	1,778
Operating Profit (Loss):
Operating profit									248	306	328
Depreciation, Depletion and Amortization:
Depreciation, depletion, amortization, and accretion									97	91	87
Capital Expenditures:
Capital expenditures									131	104	60
Operating Segments | U.S. Performance Materials
Net Sales:
Net sales									392	373	357
Operating Profit (Loss):
Operating profit									(8)	24	40
Depreciation, Depletion and Amortization:
Depreciation, depletion, amortization, and accretion									10	9	9
Capital Expenditures:
Capital expenditures									36	31	11
Operating Segments | U.S. Ceilings
Net Sales:
Net sales									541	477	467
Operating Profit (Loss):
Operating profit									78	92	98
Depreciation, Depletion and Amortization:
Depreciation, depletion, amortization, and accretion									24	15	15
Capital Expenditures:
Capital expenditures									27	17	4
Operating Segments | Canada
Net Sales:
Net sales									448	405	389
Operating Profit (Loss):
Operating profit									19	13	27
Depreciation, Depletion and Amortization:
Depreciation, depletion, amortization, and accretion									8	6	6
Capital Expenditures:
Capital expenditures									8	10	4
Operating Segments | Other
Net Sales:
Net sales									252	245	220
Operating Profit (Loss):
Operating profit									14	11	(4)
Depreciation, Depletion and Amortization:
Depreciation, depletion, amortization, and accretion									5	5	7
Capital Expenditures:
Capital expenditures									10	5	3
Corporate
Operating Profit (Loss):
Operating profit									(124)	(92)	(93)
Depreciation, Depletion and Amortization:
Depreciation, depletion, amortization, and accretion									6	6	10
Capital Expenditures:
Capital expenditures									7	1	1
Eliminations
Net Sales:
Net sales									(224)	(212)	(194)
Operating Profit (Loss):
Operating profit									0	$ (1)	$ 0
Eliminations | U.S. Wallboard and Surfaces
Net Sales:
Net sales									(124)
Eliminations | U.S. Performance Materials
Net Sales:
Net sales									(20)
Eliminations | U.S. Ceilings
Net Sales:
Net sales									(48)
Eliminations | Canada
Net Sales:
Net sales									(31)
Eliminations | Other
Net Sales:
Net sales									$ (1)

Segments - Product Information

Segments - Product Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net sales	$ 819	$ 851	$ 880	$ 786	$ 831	$ 795	$ 811	$ 767	$ 3,336	$ 3,204	$ 3,017
U.S. Wallboard and Surfaces
Segment Reporting Information [Line Items]
Net sales									1,803
U.S. Performance Materials
Segment Reporting Information [Line Items]
Net sales									372
U.S. Ceilings
Segment Reporting Information [Line Items]
Net sales									493
Canada
Segment Reporting Information [Line Items]
Net sales									417
Other
Segment Reporting Information [Line Items]
Net sales									251
Operating Segments
Segment Reporting Information [Line Items]
Net sales									3,560
Operating Segments | Wallboard
Segment Reporting Information [Line Items]
Net sales									1,322
Operating Segments | Surfaces and industrial products
Segment Reporting Information [Line Items]
Net sales									697
Operating Segments | Underlayment
Segment Reporting Information [Line Items]
Net sales									351
Operating Segments | Building envelope and structural
Segment Reporting Information [Line Items]
Net sales									84
Operating Segments | Ceiling tile and grid
Segment Reporting Information [Line Items]
Net sales									542
Operating Segments | Specialty ceilings
Segment Reporting Information [Line Items]
Net sales									28
Operating Segments | Other products
Segment Reporting Information [Line Items]
Net sales									197
Operating Segments | Total product sales
Segment Reporting Information [Line Items]
Net sales									3,221
Operating Segments | Other miscellaneous sales
Segment Reporting Information [Line Items]
Net sales									339
Operating Segments | U.S. Wallboard and Surfaces
Segment Reporting Information [Line Items]
Net sales									1,927	1,916	1,778
Operating Segments | U.S. Wallboard and Surfaces | Wallboard
Segment Reporting Information [Line Items]
Net sales									994
Operating Segments | U.S. Wallboard and Surfaces | Surfaces and industrial products
Segment Reporting Information [Line Items]
Net sales									580
Operating Segments | U.S. Wallboard and Surfaces | Underlayment
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Wallboard and Surfaces | Building envelope and structural
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Wallboard and Surfaces | Ceiling tile and grid
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Wallboard and Surfaces | Specialty ceilings
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Wallboard and Surfaces | Other products
Segment Reporting Information [Line Items]
Net sales									103
Operating Segments | U.S. Wallboard and Surfaces | Total product sales
Segment Reporting Information [Line Items]
Net sales									1,677
Operating Segments | U.S. Wallboard and Surfaces | Other miscellaneous sales
Segment Reporting Information [Line Items]
Net sales									250
Operating Segments | U.S. Performance Materials
Segment Reporting Information [Line Items]
Net sales									392	373	357
Operating Segments | U.S. Performance Materials | Wallboard
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Performance Materials | Surfaces and industrial products
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Performance Materials | Underlayment
Segment Reporting Information [Line Items]
Net sales									303
Operating Segments | U.S. Performance Materials | Building envelope and structural
Segment Reporting Information [Line Items]
Net sales									81
Operating Segments | U.S. Performance Materials | Ceiling tile and grid
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Performance Materials | Specialty ceilings
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Performance Materials | Other products
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Performance Materials | Total product sales
Segment Reporting Information [Line Items]
Net sales									384
Operating Segments | U.S. Performance Materials | Other miscellaneous sales
Segment Reporting Information [Line Items]
Net sales									8
Operating Segments | U.S. Ceilings
Segment Reporting Information [Line Items]
Net sales									541	477	467
Operating Segments | U.S. Ceilings | Wallboard
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Ceilings | Surfaces and industrial products
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Ceilings | Underlayment
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Ceilings | Building envelope and structural
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | U.S. Ceilings | Ceiling tile and grid
Segment Reporting Information [Line Items]
Net sales									464
Operating Segments | U.S. Ceilings | Specialty ceilings
Segment Reporting Information [Line Items]
Net sales									20
Operating Segments | U.S. Ceilings | Other products
Segment Reporting Information [Line Items]
Net sales									3
Operating Segments | U.S. Ceilings | Total product sales
Segment Reporting Information [Line Items]
Net sales									487
Operating Segments | U.S. Ceilings | Other miscellaneous sales
Segment Reporting Information [Line Items]
Net sales									54
Operating Segments | Canada
Segment Reporting Information [Line Items]
Net sales									448	405	389
Operating Segments | Canada | Wallboard
Segment Reporting Information [Line Items]
Net sales									258
Operating Segments | Canada | Surfaces and industrial products
Segment Reporting Information [Line Items]
Net sales									89
Operating Segments | Canada | Underlayment
Segment Reporting Information [Line Items]
Net sales									10
Operating Segments | Canada | Building envelope and structural
Segment Reporting Information [Line Items]
Net sales									2
Operating Segments | Canada | Ceiling tile and grid
Segment Reporting Information [Line Items]
Net sales									44
Operating Segments | Canada | Specialty ceilings
Segment Reporting Information [Line Items]
Net sales									8
Operating Segments | Canada | Other products
Segment Reporting Information [Line Items]
Net sales									13
Operating Segments | Canada | Total product sales
Segment Reporting Information [Line Items]
Net sales									424
Operating Segments | Canada | Other miscellaneous sales
Segment Reporting Information [Line Items]
Net sales									24
Operating Segments | Other
Segment Reporting Information [Line Items]
Net sales									252	245	220
Operating Segments | Other | Wallboard
Segment Reporting Information [Line Items]
Net sales									70
Operating Segments | Other | Surfaces and industrial products
Segment Reporting Information [Line Items]
Net sales									28
Operating Segments | Other | Underlayment
Segment Reporting Information [Line Items]
Net sales									38
Operating Segments | Other | Building envelope and structural
Segment Reporting Information [Line Items]
Net sales									1
Operating Segments | Other | Ceiling tile and grid
Segment Reporting Information [Line Items]
Net sales									34
Operating Segments | Other | Specialty ceilings
Segment Reporting Information [Line Items]
Net sales									0
Operating Segments | Other | Other products
Segment Reporting Information [Line Items]
Net sales									78
Operating Segments | Other | Total product sales
Segment Reporting Information [Line Items]
Net sales									249
Operating Segments | Other | Other miscellaneous sales
Segment Reporting Information [Line Items]
Net sales									3
Eliminations
Segment Reporting Information [Line Items]
Net sales									(224)	$ (212)	$ (194)
Eliminations | U.S. Wallboard and Surfaces
Segment Reporting Information [Line Items]
Net sales									(124)
Eliminations | U.S. Performance Materials
Segment Reporting Information [Line Items]
Net sales									(20)
Eliminations | U.S. Ceilings
Segment Reporting Information [Line Items]
Net sales									(48)
Eliminations | Canada
Segment Reporting Information [Line Items]
Net sales									(31)
Eliminations | Other
Segment Reporting Information [Line Items]
Net sales									$ (1)

Segments - Geographic Informati

Segments - Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Geographic Areas, Revenues from External Customers [Abstract]
Net sales	$ 819	$ 851	$ 880	$ 786	$ 831	$ 795	$ 811	$ 767	$ 3,336	$ 3,204	$ 3,017
Geographic Areas, Long-Lived Assets [Abstract]
Long-lived assets	1,838				1,762				1,838	1,762	1,707
Reportable geographical components | United States
Geographic Areas, Revenues from External Customers [Abstract]
Net sales									2,871	2,787	2,625
Geographic Areas, Long-Lived Assets [Abstract]
Long-lived assets	1,680				1,604				1,680	1,604	1,563
Reportable geographical components | Canada
Geographic Areas, Revenues from External Customers [Abstract]
Net sales									448	406	389
Geographic Areas, Long-Lived Assets [Abstract]
Long-lived assets	84				90				84	90	80
Reportable geographical components | Other Foreign
Geographic Areas, Revenues from External Customers [Abstract]
Net sales									211	204	189
Geographic Areas, Long-Lived Assets [Abstract]
Long-lived assets	$ 74				$ 68				74	68	64
Geographic transfers
Geographic Areas, Revenues from External Customers [Abstract]
Net sales									$ (194)	$ (193)	$ (186)

Segments - UBBP (Details)

Segments - UBBP (Details) - USG Boral Building Products - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net sales	$ 1,182	$ 1,200	$ 1,052
Operating profit	117	160	133
Net income attributable to UBBP	84	117	99
Depreciation, depletion, and amortization	50	45	43
Capital expenditures	84	49	45
Geographic Areas, Long-Lived Assets [Abstract]
Long-Lived Assets	691	710	653
Reportable geographical components | Australia
Segment Reporting Information [Line Items]
Net sales	438	431	381
Geographic Areas, Long-Lived Assets [Abstract]
Long-Lived Assets	209	229	217
Reportable geographical components | South Korea
Segment Reporting Information [Line Items]
Net sales	253	287	223
Geographic Areas, Long-Lived Assets [Abstract]
Long-Lived Assets	118	123	107
Reportable geographical components | Thailand
Segment Reporting Information [Line Items]
Net sales	161	150	141
Geographic Areas, Long-Lived Assets [Abstract]
Long-Lived Assets	86	86	75
Reportable geographical components | China
Segment Reporting Information [Line Items]
Net sales	131	119	103
Geographic Areas, Long-Lived Assets [Abstract]
Long-Lived Assets	93	101	97
Reportable geographical components | Oman
Geographic Areas, Long-Lived Assets [Abstract]
Long-Lived Assets	83	85	86
Reportable geographical components | Other
Segment Reporting Information [Line Items]
Net sales	267	271	255
Geographic Areas, Long-Lived Assets [Abstract]
Long-Lived Assets	102	86	71
Geographic transfers
Segment Reporting Information [Line Items]
Net sales	$ (68)	$ (58)	$ (51)

Segments - Revenues from Signif

Segments - Revenues from Significant Customers (Details) - Net Sales	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
The Home Depot
Segment Reporting Information [Line Items]
Concentration risk, percentage	24.00%	23.00%	23.00%
L&W
Segment Reporting Information [Line Items]
Concentration risk, percentage	14.00%	16.00%	19.00%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Examination [Line Items]
Foreign tax credit valuation allowance released	$ 9,000,000
Sequestration of AMT credits		$ (2,000,000)	$ 3,000,000
Income taxes receivable	17,000,000	17,000,000
Increase / decrease in valuation allowance against deferred tax assets		(63,000,000)	124,000,000
Net deferred tax assets	241,000,000	241,000,000	283,000,000
Valuation allowance	112,000,000	112,000,000	175,000,000
Approximate federal net operating loss carryforwards	559,000,000	559,000,000
Foreign deferred tax assets	135,000,000	135,000,000
Minimum taxable income needed to fully realize the U.S. federal net deferred tax assets	1,285,000,000	1,285,000,000
State deferred tax assets	152,000,000	152,000,000
Annual U.S. federal NOL utilization	150,000,000	150,000,000
Unrecognized tax benefits, income tax penalties and interest	0	0	0
Total amounts of interest and penalties recognized in consolidated statements of operations		0	0	$ 0
Total amount of unrecognized tax benefit that would affect our effective tax rate	14,000,000	$ 14,000,000	$ 12,000,000	$ 14,000,000
Income tax examinations, possible period for resolution		12 months
Lapse of statutes of limitations	1,000,000	$ 1,000,000
Minimum
Income Tax Examination [Line Items]
Period of statutes of limitations		3 years
Maximum
Income Tax Examination [Line Items]
Period of statutes of limitations		5 years
Domestic Tax Authority
Income Tax Examination [Line Items]
Approximate federal alternative minimum tax credit carryforwards	17,000,000	$ 17,000,000
OMB
Income Tax Examination [Line Items]
Sequestration of AMT credits	$ 2,000,000

Income Taxes - Income from Cont

Income Taxes - Income from Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income (loss) before income taxes
U.S.	$ 168	$ 272	$ 201
Foreign	59	63	73
Total	$ 227	$ 335	$ 274

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Benefit) on Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ (3)	$ (21)	$ 0
Foreign	7	2	5
State	2	2	1
Total current	6	(17)	6
Deferred:
Federal	23	243	41
Foreign	0	0	2
State	5	12	14
Total deferred	28	255	57
Provision for income tax expense (benefit)	$ 34	$ 238	$ 63

Income Taxes - Differences Betw

Income Taxes - Differences Between Provisions for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Valuation Allowance [Line Items]
Transition tax for accumulated foreign earnings			$ 9
Change in tax rate, deferred tax asset, valuation allowance		$ (9)
Sequestration of AMT credits		(2)	3
Change in tax rate, provisional income tax expense (benefit)			9
Differences between actual provisions for income taxes and provisions for income taxes at the U.S. federal statutory rate (35%)
Taxes on income from continuing operations at U.S. federal statutory rate		48	117	$ 96
Foreign earnings subject to different tax rates		4	3	(3)
State income tax, net of federal benefit		6	9	10
Income from equity method investments		(9)	(21)	(17)
Law changes	$ 145	(11)	145	0
Stock compensation		(5)	0	0
Prior year return adjustments		0	(7)	0
Foreign tax credits		0	0	(21)
Global Intangible Low-Taxed Income		5	0	0
Other, net		(4)	(8)	(2)
Provision for income tax expense (benefit)		$ 34	$ 238	$ 63
Effective income tax rate		15.00%	71.00%	23.00%
Foreign Tax Credits
Valuation Allowance [Line Items]
Change in tax rate, deferred tax asset, valuation allowance			$ 106
State Net Operating Losses
Valuation Allowance [Line Items]
Change in tax rate, deferred tax asset, valuation allowance			$ 18

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets:
Net operating loss and tax credit carryforwards	$ 389	$ 477
Pension and postretirement benefits	68	86
Reserves not deductible until paid	15	14
Self insurance	4	2
Capitalized interest	8	7
Inventories	4	4
Share-based compensation	13	14
Other	9	7
Deferred tax assets before valuation allowance	510	611
Valuation allowance	(112)	(175)
Total deferred tax assets	398	436
Deferred Tax Liabilities:
Property, plant and equipment	157	153
Total deferred tax liabilities	157	153
Net deferred tax assets	$ 241	$ 283

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance as of beginning of period	$ 12	$ 15	$ 18
Tax positions related to the current period:
Gross increase	0	0	0
Gross decrease	0	0	0
Tax positions related to prior periods:
Gross increase	4	0	0
Gross decrease	0	(1)	(3)
Settlements	(1)	0	0
Lapse of statutes of limitations	(1)	(2)	0
Balance as of end of period	$ 14	$ 12	$ 15

Stockholder Rights Plan (Detail

Stockholder Rights Plan (Details)	12 Months Ended
	Dec. 31, 2018	Feb. 11, 2015
Equity [Abstract]
Period of cumulative change in ownership	3 years
Aggregate increase in common stock owned	50.00%
Ownership interest to cause cumulative change in ownership (or more than) (as a percent)	5.00%
Beneficial owner of common stock percentage (or more than)		4.90%
Triggering threshold for rights issued pursuant to the plan	15.00%
Period of review	3 years
Beneficial ownership percentage post standstill period (up to)	50.00%
Beneficial owner of common stock percentage in future (more than)	50.00%
Period of offer to purchase common stock	60 days

Lease Commitments - Textuals (D

Lease Commitments - Textuals (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Lease Commitments [Abstract]
Lease expense	$ 48	$ 37	$ 36

Lease Commitments - Future Mini

Lease Commitments - Future Minimum Lease Payments (Details) $ in Millions	Dec. 31, 2018USD ($)
Future minimum lease payments
2,019	$ 46
2,020	39
2,021	27
2,022	12
2,023	6
After 2,023	$ 6

Litigation (Details)

Litigation (Details) $ in Millions	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2015HomebuilderDefendants
Commitments and Contingencies Disclosure [Abstract]
Number of other wallboard manufacturer defendants named in lawsuit | Defendants			7
Number of homebuilders asserting individual claims | Homebuilder			12
Accrual potential liability for environmental cleanup | $	$ 13	$ 17

Quarterly Financial Data (una_3

Quarterly Financial Data (unaudited) - Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 819	$ 851	$ 880	$ 786	$ 831	$ 795	$ 811	$ 767	$ 3,336	$ 3,204	$ 3,017
Gross profit	131	152	184	139	167	162	168	159	606	656	700
Operating profit	37	69	75	46	83	91	95	84	227	353	396
Income (loss) from continuing operations	41	58	58	36	(70)	66	46	55	193	97	211
(Loss) income from discontinued operations, net of tax	1	1	0	1	1	0	(10)	0	3	(9)	20
Net income (loss)	$ 42	$ 59	$ 58	$ 37	$ (69)	$ 66	$ 36	$ 55	$ 196	$ 88	$ 510
Income per average common share, basic (in dollars per share)	$ 0.31	$ 0.42	$ 0.41	$ 0.26	$ (0.49)	$ 0.47	$ 0.25	$ 0.38	$ 1.40	$ 0.61	$ 3.49
Income per average common share, diluted (in dollars per share)	$ 0.30	$ 0.41	$ 0.41	$ 0.25	$ (0.49)	$ 0.46	$ 0.24	$ 0.37	$ 1.38	$ 0.60	$ 3.46
Income per average common share:
Loss on extinguishment of debt							$ 22		$ 0	$ 22	$ 37
Income tax expense related to 2017 Tax Act					$ 145				$ (11)	$ 145	$ 0

Merger Agreement - Narrative (D

Merger Agreement - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 14, 2019	Oct. 02, 2018	Aug. 09, 2018	Jun. 10, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Common stock - par value (in dollars per share)					$ 0.1	$ 0.1
Conditional special dividend, additional amount paid to holders of stock options					$ 2
Knauf And World Cup Acquisition Corporation
Business Acquisition [Line Items]
Common stock - par value (in dollars per share)				$ 0.10
Conversion price (in dollars per share)				$ 43.50
Special cash dividend (in dollars per share)			$ 0.50
Conditional special dividend, amount		$ 70
Merger related costs					$ 19
Scenario, Forecast | Knauf And World Cup Acquisition Corporation
Business Acquisition [Line Items]
Conversion price (in dollars per share)	$ 43.50
Termination fee, contingency of merger agreement	$ 215

Schedule II - Valuation And Q_2

Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 6	$ 5	$ 7
Charged to costs and expenses	1	2	1
Charged to other accounts	0	0	0
Deductions	0	(1)	(3)
Balance at end of period	7	6	5
Cash discounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	3	3	2
Charged to costs and expenses	39	34	34
Charged to other accounts	0	0	0
Deductions	(39)	(34)	(33)
Balance at end of period	3	3	3
Income tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	175	51	70
Charged to costs and expenses	0	124	0
Charged to other accounts	0	0	0
Deductions	(63)	0	(19)
Balance at end of period	$ 112	$ 175	$ 51

Uncategorized Items - usg-20181

Label	Element	Value
Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 25,000,000
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 2,000,000