United States Steel (X) 10-K 15 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Feb. 12, 2019	Jun. 29, 2018
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	X
Entity Registrant Name	UNITED STATES STEEL CORP
Entity Central Index Key	1,163,302
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Smaller Reporting Company	false
Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		173,222,678
Entity Public Float			$ 6.1

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net sales:
Net sales		$ 12,758	$ 11,046	$ 9,045
Net sales to related parties (Note 23)		1,420	1,204	1,216
Total		14,178	12,250	10,261
Operating expenses (income):
Cost of sales (excludes items shown below)		12,305	10,858	9,608
Selling, general and administrative expenses		336	320	306
Depreciation, depletion and amortization (Notes 13 and 14)		521	501	507
Earnings from investees (Note 12)		(61)	(44)	(98)
Gain on equity investee transactions		(38)	(2)	0
Gain associated with U. S. Steel Canada Inc. (Note 5)		0	(72)	0
Restructuring and other charges (Note 25)		0	31	122
Impairment of intangible assets (Note 14)		0	0	14
Net (gain) loss on disposals of assets		(6)	(5)	5
Other income, net		(3)	(6)	(2)
Total		13,054	11,581	10,462
Earnings (loss) before interest and income taxes		1,124	669	(201)
Interest expense (Note 7)		168	226	230
Interest income		(23)	(17)	(5)
Loss on debt extinguishment (Note 7)		98	54	22
Other financial costs (Note 7)		0	44	4
Net periodic benefit cost (other than service cost) (Note 3) (a)	[1]	69	61	(36)
Net interest and other financial costs		312	368	215
Earnings (loss) before income taxes		812	301	(416)
Income tax (benefit) provision (Note 11)		(303)	(86)	24
Net earnings (loss)		1,115	387	(440)
Less: Net earnings attributable to noncontrolling interests		0	0	0
Earnings (loss) attributable to United States Steel Corporation		$ 1,115	$ 387	$ (440)
Earnings (loss) per share attributable to United States Steel Corporation stockholders:
— Basic (in dollars per share)		$ 6.31	$ 2.21	$ (2.81)
— Diluted (in dollars per share)		$ 6.25	$ 2.19	$ (2.81)
[1]	Represents postretirement benefit expense as a result of the adoption of Accounting Standards Update 2017-07, Compensation - Retirement Benefits on January 1, 2018 (see Note 3 for further details).

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net earnings (loss)	$ 1,115	$ 387	$ (440)
Other comprehensive income (loss), net of tax:
Changes in foreign currency translation adjustments	(60)	189	(38)
Changes in pension and other employee benefit accounts	(107)	462	(292)
Changes in derivative financial instruments	(14)	1	2
Total other comprehensive (loss) income, net of tax	(181)	652	(328)
Comprehensive income (loss) including noncontrolling interest	934	1,039	(768)
Comprehensive income attributable to noncontrolling interest	0	0	0
Comprehensive income (loss) attributable to United States Steel Corporation	$ 934	$ 1,039	$ (768)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 1,000	$ 1,553
Receivables, less allowance of $29 and $28	1,435	1,173
Receivables from related parties (Note 23)	224	206
Inventories (Note 10)	2,092	1,738
Other current assets	79	85
Total current assets	4,830	4,755
Investments and long-term receivables, less allowance of $5 and $11 (Note 12)	513	480
Property, plant and equipment, net (Note 13)	4,865	4,280
Intangibles — net (Note 14)	158	167
Deferred income tax benefits (Note 11)	445	56
Other noncurrent assets	171	124
Total assets	10,982	9,862
Current liabilities:
Accounts payable and other accrued liabilities	2,454	2,148
Accounts payable to related parties (Note 23)	81	74
Payroll and benefits payable	440	347
Accrued taxes	118	132
Accrued interest	39	69
Short-term debt and current maturities of long-term debt (Note 17)	65	3
Total current liabilities	3,197	2,773
Long-term debt, less unamortized discount and debt issuance costs (Note 17)	2,316	2,700
Employee benefits (Note 18)	980	759
Deferred income tax liabilities (Note 11)	14	6
Deferred credits and other noncurrent liabilities	272	303
Total liabilities	6,779	6,541
Contingencies and commitments (Note 26)
Stockholders’ Equity
Common stock issued — 177,386,430 and 176,424,554 shares issued (par value $1 per share, authorized 400,000,000 shares) (Note 8)	177	176
Treasury stock, at cost (2,857,578 shares and 1,203,344 shares)	(78)	(76)
Additional paid-in capital	3,917	3,932
Retained earnings	1,212	133
Accumulated other comprehensive loss (Note 21)	(1,026)	(845)
Total United States Steel Corporation stockholders’ equity	4,202	3,320
Noncontrolling interests	1	1
Total liabilities and stockholders’ equity	$ 10,982	$ 9,862

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$ 29	$ 28
Other noncurrent assets, allowance	$ 5	$ 11
Common stock, par value (usd per share)	$ 1	$ 1
Common stock, shares issued	177,386,430	176,424,554
Common stock, shares authorized	400,000,000	400,000,000
Treasury stock, shares	2,857,578	1,203,344

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities:
Net earnings (loss)	$ 1,115	$ 387	$ (440)
Adjustments to reconcile net cash provided by operating activities:
Depreciation, depletion and amortization (Notes 13 and 14)	521	501	507
Impairment of intangible assets (Note 14)	0	0	14
Gain associated with U. S. Steel Canada Inc. (Note 5)	0	(72)	0
Gain on equity investee transactions	(38)	(2)	0
Restructuring and other charges (Note 25)	0	31	122
Loss on debt extinguishment (Note 17)	98	54	22
Provision for doubtful accounts	4	1	0
Pensions and other post-employment benefits	77	(16)	(62)
Deferred income taxes (Note 11)	(329)	(72)	9
Net (gain) loss on disposal of assets	(6)	(5)	5
Equity investees earnings, net of distributions received	(47)	(32)	(89)
Changes in:
Current receivables	(312)	(36)	(182)
Inventories	(374)	(117)	491
Current accounts payable and accrued expenses	282	225	287
Income taxes receivable/payable	(8)	(52)	10
Bank checks outstanding	1	(2)	0
All other, net	(46)	33	60
Net cash provided by operating activities	938	826	754
Investing activities:
Capital expenditures	(1,001)	(505)	(306)
Disposal of assets	10	5	12
Proceeds from sale of ownership interests in equity investees	30	116	0
Investments, net	(2)	(2)	(21)
Net cash used in investing activities	(963)	(386)	(315)
Financing activities:
Revolving credit facilities - borrowings, net	228	0	0
Issuance of long-term debt, net of financing costs (Note 17)	640	737	958
Repayment of long-term debt (Note 17)	(1,299)	(1,127)	(1,093)
Settlement of contingent consideration	0	0	(15)
Net proceeds from public offering of common stock (Note 27)	0	0	482
Common stock repurchased (Note 27)	(75)	0	0
Receipts from exercise of stock options (Note 15)	35	20	35
Taxes paid for equity compensation plans (Note 15)	(8)	(10)	(4)
Dividends paid	(36)	(35)	(31)
Net cash (used in) provided by financing activities	(515)	(415)	332
Effect of exchange rate changes on cash	(17)	17	(8)
Net (decrease) increase in cash, cash equivalents and restricted cash	(557)	42	763
Cash, cash equivalents and restricted cash at beginning of year	1,597	1,555	792
Cash, cash equivalents and restricted cash at end of year	$ 1,040	$ 1,597	$ 1,555

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Millions	Total	Common stock:	Treasury stock:	Additional paid-in capital:	Retained earnings:	Accumulated other comprehensive (loss) income:	Pension and other benefit adjustments (Note 18):	Foreign currency translation adjustments:	Derivative financial instruments:	Total stockholders’ equity	Noncontrolling interests:
Balance at beginning of year at Dec. 31, 2015		$ 151	$ (339)	$ 3,603	$ 190		$ (1,479)	$ 312	$ (2)		$ 1
Balance at beginning of year (in shares) at Dec. 31, 2015		150,926	(4,645)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued		$ 25
Common stock issued (in shares)		25,499
Common stock repurchased	$ 0		$ 0
Common Stock Repurchased (in shares)			0
Common stock reissued for employee/non-employee director stock plans			$ 157
Common stock reissued for employee/non-employee director stock plans (in shares)			2,031
Common stock issued				557
Dividends on common stock				(31)	0
Employee stock plans				(102)
Net earnings (loss) attributable to United States Steel Corporation	(440)				(440)
Other					0
Changes during year, net of taxes	(292)						(288)
Changes during year, equity investee net of taxes							(4)
Changes during year								(38)	2
Net loss	0										0
Balance at end of year at Dec. 31, 2016		$ 176	$ (182)	4,027	(250)	$ (1,497)	(1,771)	274	0	$ 2,274	1
Balance at end of year (in shares) at Dec. 31, 2016		176,425	(2,614)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income including noncontrolling interest	(768)
Common stock issued		$ 0
Common stock issued (in shares)		0
Common stock repurchased	0		$ 0
Common Stock Repurchased (in shares)			0
Common stock reissued for employee/non-employee director stock plans			$ 106
Common stock reissued for employee/non-employee director stock plans (in shares)			1,411
Common stock issued				0
Dividends on common stock				(26)	(9)
Employee stock plans				(69)
Net earnings (loss) attributable to United States Steel Corporation	387				387
Other					5
Changes during year, net of taxes	462						454
Changes during year, equity investee net of taxes							8
Changes during year								189	1
Net loss	0										0
Balance at end of year at Dec. 31, 2017	3,320	$ 176	$ (76)	3,932	133	(845)	(1,309)	463	1	3,320	1
Balance at end of year (in shares) at Dec. 31, 2017		176,425	(1,203)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income including noncontrolling interest	1,039
Common stock issued		$ 1
Common stock issued (in shares)		961
Common stock repurchased	75		$ 75
Common Stock Repurchased (in shares)			(2,760)
Common stock reissued for employee/non-employee director stock plans			$ 73
Common stock reissued for employee/non-employee director stock plans (in shares)			1,105
Common stock issued				0
Dividends on common stock				0	(36)
Employee stock plans				(15)
Net earnings (loss) attributable to United States Steel Corporation	1,115				1,115
Other					0
Changes during year, net of taxes	(107)						(108)
Changes during year, equity investee net of taxes							1
Changes during year								(60)	(14)
Net loss	0										0
Balance at end of year at Dec. 31, 2018	4,202	$ 177	$ (78)	$ 3,917	$ 1,212	$ (1,026)	$ (1,416)	$ 403	$ (13)	$ 4,202	$ 1
Balance at end of year (in shares) at Dec. 31, 2018		177,386	(2,858)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income including noncontrolling interest	$ 934

Nature of Business and Signific

Nature of Business and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Nature of Business and Significant Accounting Policies	Nature of Business and Significant Accounting Policies Nature of Business U. S. Steel produces and sells steel products, including flat-rolled and tubular products, in North America and Europe. Operations in the United States also include iron ore and coke production facilities, railroad services and real estate operations. Operations in Europe also include coke production facilities. Significant Accounting Policies Principles applied in consolidation These financial statements include the accounts of U. S. Steel and its majority-owned subsidiaries. Additionally, variable interest entities for which U. S. Steel is the primary beneficiary are included in the Consolidated Financial Statements and their impacts are either partially or completely offset by noncontrolling interests. Intercompany accounts, transactions and profits have been eliminated in consolidation. Investments in entities over which U. S. Steel has significant influence are accounted for using the equity method of accounting and are carried at U. S. Steel’s share of net assets plus loans, advances and our share of earnings less distributions. Earnings or loss from investees includes U. S. Steel’s share of earnings or loss from equity method investments, which is generally recorded a month in arrears, except for significant and unusual items which are recorded in the period of occurrence. Use of estimates Generally accepted accounting principles require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at year-end and the reported amounts of revenues and expenses during the year. Significant items subject to such estimates and assumptions include the carrying value of property, plant and equipment; intangible assets; valuation allowances for receivables, inventories and deferred income tax assets and liabilities; environmental liabilities; liabilities for potential tax deficiencies; potential litigation claims and settlements; and assets and obligations related to employee benefits. Actual results could differ materially from the estimates and assumptions used. Sales recognition Sales are recognized when U. S. Steel's performance obligations are satisfied. Generally, U. S. Steel’s performance obligations are satisfied, control of our products is transferred, and revenue is recognized at a single point in time, when title transfers to our customer for product shipped or when services are provided. Revenues are recorded net of any sales incentives. Shipping and other transportation costs charged to customers are treated as fulfillment activities and are recorded in both revenue and cost of sales at the time control is transferred to the customer. See Note 6 for further details on U. S. Steel’s revenue. Inventories Inventories are carried at the lower of cost or market. Fixed costs related to abnormal production capacity are expensed in the period incurred rather than capitalized into inventory. LIFO (last-in, first-out) is the predominant method of inventory costing for inventories in the United States and FIFO (first-in, first-out) is the predominant method in Europe. The LIFO method of inventory costing was used on 74 percent and 75 percent of consolidated inventories at December 31, 2018 and 2017 , respectively. Derivative instruments From time to time, U. S. Steel may use fixed price forward physical purchase contracts to partially manage our exposure to price risk. Generally, forward physical purchase contracts qualify for the normal purchase normal sales exclusion in Accounting Standards Codification (ASC) 815, Derivatives and Hedging , and are not subject to mark-to-market accounting. U. S. Steel also uses derivatives such as commodity-based financial swaps and foreign currency exchange forward contracts to manage its exposure to purchase and sale price fluctuations and foreign currency exchange rate risk. U. S. Steel elects hedge accounting for some of its derivatives. Under hedge accounting, fluctuations in the value of the derivative are recognized in Accumulated Other Comprehensive Income (AOCI) until the associated underlying is recognized in earnings. When the associated underlying is recognized in earnings, the value of the derivative is reclassified to earnings from AOCI. We recognize fair value changes for derivatives where hedge accounting has not been elected immediately in earnings. See Note 16 for further details on U. S. Steel’s derivatives. Property, plant and equipment Property, plant and equipment is carried at cost and is depreciated on a straight-line basis over the estimated useful lives of the assets. Depletion of mineral properties is based on rates which are expected to amortize cost over the estimated tonnage of minerals to be removed. When property, plant and equipment is sold or otherwise disposed of, any gains or losses are reflected in income. If a loss on disposal is expected, such losses are recognized when the assets are reclassified as assets held for sale or when impaired as part of an asset group’s impairment. U. S. Steel evaluates impairment of its property, plant and equipment whenever circumstances indicate that the carrying value may not be recoverable. We evaluate the impairment of long-lived assets at the asset group level. Our asset groups are Flat-Rolled, welded tubular, seamless tubular and U. S. Steel Europe (USSE). Asset impairments are recognized when the carrying value of an asset grouping exceeds its recoverable amount as determined by the asset group's aggregate projected undiscounted cash flows. During 2018 and 2017, there were no triggering events that required fixed assets to be evaluated for impairment. During 2016, the permanent shutdown of certain Lorain, Lone Star and Bellville (sold in 2018) tubular assets, was considered a triggering event for our welded and seamless tubular asset groups. U. S. Steel completed a quantitative analysis of its long-lived assets for these asset groups within the Tubular segment and determined that the remaining assets were not impaired. The welded tubular asset group had a carrying value of $410 million at December 31, 2016 and the recoverable amount exceeded this carrying value by approximately $93 million , or 23 percent . The seamless tubular asset group had a carrying value of $210 million at December 31, 2016 and the recoverable amount exceeded this carrying value by $220 million , or 106 percent . The key assumption used to estimate the recoverable amounts for both the welded and seamless tubular asset groups was the forecasted price of oil over the 11 -year average remaining useful lives of the assets within the asset groups. Management will continue to monitor market and economic conditions for triggering events that may warrant further review of long-lived assets. Change in Accounting Estimate - Capitalization and Depreciation Method During 2017, U. S. Steel completed a review of its accounting policy for property, plant and equipment depreciated on a group basis. As a result of this review, U. S. Steel changed its accounting method for property, plant and equipment from the group method of depreciation to the unitary method of depreciation, effective as of January 1, 2017. The Company believes the change from the group method to the unitary method of depreciation is preferable under U.S. GAAP as it results in a more precise estimate of depreciation expense. Additionally, the change to the unitary method of depreciation is consistent with the depreciation method applied by our competitors, and improves the comparability of our results to the results of our competitors. Our change in the method of depreciation was considered a change in accounting estimate effected by a change in accounting principle and has been applied prospectively. Due to the application of the unitary method of depreciation and resultant change in our capitalization policy, maintenance and outage spending that had previously been expensed as well as capital investments associated with our asset revitalization program are now capitalized if the useful life of the related asset is extended. When property, plant, and equipment are disposed of by sale, retirement, or abandonment, the gross value of the property, plant and equipment and corresponding accumulated depreciation are removed from the Company’s financial accounting records. Due to the application of the unitary method of depreciation, any gain or loss resulting from an asset disposal by sale is now immediately recognized as a gain or loss on the disposal of assets line in our consolidated statement of operations. Assets that are retired or abandoned are reflected as an immediate charge to depreciation expense for any remaining book value in our consolidated statement of operations. Gains (losses) on disposals of assets for the year ended December 31, 2017 and 2018 were immaterial. U. S. Steel's property, plant and equipment totaled $3,979 million at December 31, 2016. U. S. Steel allocated the existing net book value of group assets at the transition date to approximate a unitary depreciation methodology, and the fixed assets are being depreciated over their estimated remaining useful lives as follows: (In millions) Remaining Useful Life of Assets Net Book Value at December 31, 2016 Under 5 years $ 597 6-10 years 629 11-15 years 765 16-20 years 654 21-25 years 363 Over 25 years 479 Assets not subject to depreciation 492 Total $ 3,979 Environmental remediation Environmental expenditures are capitalized if the costs mitigate or prevent future contamination or if the costs improve existing assets’ environmental safety or efficiency. U. S. Steel provides for remediation costs and penalties when the responsibility to remediate is probable and the amount of associated costs is reasonably estimable. The timing of remediation accruals typically coincides with completion of studies defining the scope of work to be undertaken or when it is probable that a formal plan of action will be approved by the oversight agency. Remediation liabilities are accrued based on estimates of believed environmental exposure and are discounted if the amount and timing of the cash disbursements are readily determinable. Asset retirement obligations Asset retirement obligations (AROs) are initially recorded at fair value and are capitalized as part of the cost of the related long-lived asset and depreciated in accordance with U. S. Steel’s depreciation policies for property, plant and equipment. The fair value of the obligation is determined as the discounted value of expected future cash flows. Accretion expense is recorded each month to increase this discounted obligation over time. Certain AROs related to disposal costs of the majority of assets at our integrated steel facilities are not recorded because they have an indeterminate settlement date. These AROs will be initially recognized in the period in which sufficient information exists to estimate their fair value. See Note 19 for further details on U. S. Steel's AROs. Pensions and other post-employment benefits U. S. Steel has defined contribution or multi-employer arrangements for pension benefits for more than three-quarters of its employees in the United States and defined benefit pension plans covering the remaining employees. For hires before January 1, 2016, U. S. Steel has defined benefit retiree health care and life insurance plans (Other Benefits) that cover its represented employees in North America upon their retirement. Government-sponsored programs into which U. S. Steel makes required contributions cover the majority of U. S. Steel’s European employees. For more details regarding pension and other post-employment benefits see Note 18 of the Consolidated Financial Statements. The pension and other benefits obligations and the related net periodic benefit costs are based on, among other things, assumptions of the discount rate, estimated return on plan assets, salary increases, the projected mortality of participants and the current level and future escalation of health care costs. Additionally, U. S. Steel recognizes an obligation to provide post-employment benefits for disability-related claims covering indemnity and medical payments for certain employees in North America. The obligation for these claims and the related periodic costs are measured using actuarial techniques and assumptions. Actuarial gains and losses occur when actual experience differs from any of the many assumptions used to value the benefit plans, or when assumptions change. For pension and other benefits, the Company recognizes into income on an annual basis any unrecognized actuarial net gains or losses that exceed 10 percent of the larger of projected benefit obligations or plan assets (the corridor). These unrecognized amounts in excess of the corridor are amortized over the plan participants' average life expectancy or average future service, depending on the demographics of the plan. Unrecognized actuarial net gains and losses for disability-related claims are immediately recognized into income. Deferred taxes Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. The realization of deferred tax assets is assessed quarterly based on several interrelated factors. These factors include U. S. Steel’s expectation to generate sufficient future taxable income and the projected time period over which these deferred tax assets will be realized. U. S. Steel records a valuation allowance when necessary to reduce deferred tax assets to the amount that will more likely than not be realized. See Note 11 for further details of deferred taxes. Reclassifications and Adjustments Certain reclassifications of prior years' data have been made to conform to the current year presentation including the following: U. S. Steel reclassified certain prior year data as a result of the retrospective adoption on January 1, 2018 of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments and ASU 2017-07, Compensation - Retirement Benefits . See Note 3 for further details. U. S. Steel made an adjustment of $52 million to correct the classification in the December 31, 2017 Consolidated Balance Sheet to reflect a previously reported non-current liability as a current liability. This adjustment had no impact on the Statement of Operations and resulted in a decrease to Deferred Credits and Other Non-Current Liabilities and an increase to Accounts Payable and Other Accrued Liabilities on the Consolidated Balance Sheets.

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Standards	New Accounting Standards In August 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (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 (ASU 2018-15). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing internal-use software. ASU 2018-15 is effective for annual and interim reporting periods beginning after December 15, 2019, with early adoption permitted. U. S. Steel is currently assessing the impact of the ASU but does not believe this ASU will have a material impact on its overall Consolidated Financial Statements. In August 2018, the FASB issued ASU 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20), Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans (ASU 2018-14). ASU 2018-14 removes certain disclosures that the FASB no longer considers cost beneficial, adds certain disclosure requirements and clarifies others. ASU 2018-14 is effective for public companies for fiscal years beginning after December 15, 2020, with early adoption permitted. U. S. Steel is currently assessing the impact of the ASU on its defined benefit plan disclosures. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13), which adds an impairment model that is based on expected losses rather than incurred losses. Under ASU 2016-13, an entity recognizes as an allowance its estimate of expected credit losses, which the FASB believes will result in more timely recognition of such losses. ASU 2016-13 is effective for public companies for fiscal years beginning after December 15, 2019 including interim reporting periods, with early adoption permitted. U. S. Steel is currently assessing the impact of the ASU, but does not believe this ASU will have a material impact on its overall Consolidated Financial Statements. In February 2016, the FASB issued ASU 2016-02, Leases (ASU 2016-02). ASU 2016-02 supersedes prior lease accounting guidance. Under ASU 2016-02, for operating leases, a lessee should recognize in its statement of financial position a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term; recognize a single lease cost, which is allocated over the lease term, generally on a straight line basis, and classify all cash payments within operating activities in the statement of cash flows. For financing leases, a lessee is required to recognize a right-of-use asset and a lease liability; recognize interest on the lease liability separately from amortization of the right-of-use asset, and classify repayments of the principal portion of the lease liability within financing activities and payments of interest on the lease liability within operating activities in the statement of cash flows. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election not to recognize lease assets and lease liabilities. In addition, at the inception of a contract, an entity should determine whether the contract is or contains a lease. ASU 2016-02 is effective for public entities for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842) - Targeted Improvements (ASU 2018-11), which provides an option to use a modified retrospective transition method at the adoption date. U. S. Steel will adopt the new lease accounting standard at the adoption date using the optional modified retrospective transition method outlined in ASU 2018-11. We anticipate that the impact of adoption will result in an insignificant cumulative effect of adoption and the recognition of a right of use asset and total operating lease liability in the range of $230 million to $250 million .

Recently Adopted Accounting Sta

Recently Adopted Accounting Standards	12 Months Ended
	Dec. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (ASU 2018-02) . ASU 2018-02 allows a reclassification from Accumulated Other Comprehensive Income to Retained Earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act (2017 Act). The amendments in this ASU are effective for fiscal years beginning after December 15, 2018 and for interim periods therein; early adoption is permitted. U. S. Steel adopted ASU 2018-02 on July 1, 2018, and elected not to reclassify the stranded tax effects related to the 2017 Act. As a result, the adoption did not have an impact on the Company's Consolidated Financial Statements. U. S. Steel's accounting policy is to release stranded income tax effects from AOCI when the circumstances upon which the stranded tax effects are premised cease to exist. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities (ASU 2017-12), which amends and simplifies hedge accounting guidance so that companies could more accurately present the economic effects of risk management activities in the financial statements. ASU 2017-12 is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years with early adoption permitted. U. S. Steel adopted the provisions of ASU 2017-12 on January 1, 2018. The adoption did not result in a material impact to our financial results; however, we expanded our use of hedge accounting effective January 1, 2018 as well as our disclosures of derivative activity. See Note 16 for further details. In May 2017, the FASB issued ASU 2017-09, Compensation – Stock Compensation: Scope of Modification Accounting (ASU 2017-09). The amendments included in ASU 2017-09 provide guidance about which changes to the terms and conditions of a share-based payment award require an entity to apply modification accounting. The amendments in this update will be applied prospectively to an award modified on or after the adoption date. On January 1, 2018, U. S. Steel adopted the provisions of ASU 2017-09 and the adoption did not have an impact on its Consolidated Financial Statements. In March 2017, the FASB issued ASU 2017-07, Compensation - Retirement Benefits (ASU 2017-07). ASU 2017-07 requires an employer who offers defined benefit and postretirement benefit plans to report the service cost component of the net periodic benefit cost in the same line item or items as other compensation cost arising from services rendered by employees during the period. The other components of net periodic benefit costs are required to be presented on a retrospective basis in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. The ASU also allows for the service cost component of net periodic benefit cost to be eligible for capitalization into inventory when applicable. ASU 2017-07 was effective for periods beginning after December 15, 2017, including interim periods within those annual periods; early adoption was permitted. U. S. Steel adopted ASU 2017-07 on January 1, 2018. U. S. Steel has historically capitalized the service cost component of net periodic benefit cost into inventory, when applicable, and will continue to do so prospectively. The effect of the retrospective presentation change related to the net periodic benefit cost of our defined benefit pension and other post-employment benefits (OPEB) plans on our consolidated statement of operations was as follows: Year Ended December 31, 2017 Statement of Operations (In millions) As Revised Previously Reported Effect of Change Higher/(Lower) Cost of Sales $ 10,858 $ 10,864 $ (6 ) Selling, general and administrative expenses 320 375 (55 ) Net periodic benefit cost (other than service cost) 61 — 61 Year Ended December 31, 2016 Statement of Operations (In millions) As Revised Previously Reported Effect of Change Higher/(Lower) Cost of Sales $ 9,608 $ 9,623 $ (15 ) Selling, general and administrative expenses 306 255 51 Net periodic benefit cost (other than service cost) (36 ) — (36 ) In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (ASU 2016-18). The ASU reduced diversity in practice in the classification and presentation of changes in restricted cash on the statement of cash flows by including restricted cash and restricted cash equivalents with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. On January 1, 2018, U. S. Steel adopted the provisions of ASU 2016-18 using a retrospective transition method. As a result, a $3 million cash outflow was removed from the investing activities section in the Consolidated Statements of Cash Flows for the years ended December 31, 2017 and 2016 as changes in restricted cash are now included in the beginning-of-period and end-of-period total cash, cash equivalents and restricted cash amounts. Expanded disclosures have been included, which describe the components of cash shown on the Company's Consolidated Statements of Cash Flows. See Note 9 for further details. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (ASU 2016-15). ASU 2016-15 reduced diversity in practice in how certain transactions are classified in the statement of cash flows by addressing eight specific cash receipt and cash payment issues. On January 1, 2018, U. S. Steel adopted the provisions of ASU 2016-15 using a retrospective transition method. As a result, all payments to extinguish debt will now be presented as cash outflows from financing activities on our Consolidated Statements of Cash Flows in accordance with ASU 2016-15. U. S. Steel has historically presented make-whole premiums as cash outflows from operating activities. There were $23 million of cash outflows for make-whole premiums that were reclassified from cash provided by operating activities to the repayment of long-term debt line within the cash used in financing activities section on the Consolidated Statements of Cash Flows for the years-ended December 31, 2017 and December 31, 2016. The other cash receipt and cash payment items addressed in ASU 2016-15 did not have an impact on the Company’s Consolidated Statements of Cash Flows. Additionally, the Company has elected to use the cumulative earnings approach as defined in ASU 2016-15 to classify distributions received from equity method investees. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09). ASU 2014-09 and its related amendments (Revenue Recognition Standard) outline a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and superseded most previous revenue recognition guidance. On January 1, 2018, U. S. Steel adopted the Revenue Recognition Standard using the full retrospective method. Generally, U. S. Steel’s performance obligations are satisfied, control of our products is transferred, and revenue is recognized at a single point in time. The adoption did not have a financial statement impact to U. S. Steel but did result in expanded disclosures. See Note 6 for further details. On March 30, 2016, the FASB issued ASU 2016-09, Compensation - Stock Compensation (ASU 2016-09). ASU 2016-09 simplifies the accounting and reporting of certain aspects of share-based payment transactions, including income tax treatment of excess tax benefits, forfeitures, classification of share-based awards as either equity or liabilities, and classification in the statement of cash flows for certain share-based transactions related to tax benefits and tax payments. ASU 2016-09 was effective for public business entities for annual periods beginning after December 15, 2016. On January 1, 2017, the Company adopted the provisions of ASU 2016-09. The adoption of ASU 2016-09 did not have a significant impact on the Company’s Consolidated Financial Statements and included the following items: (1) adoption on a prospective basis of the recognition of excess tax benefits and tax deficiencies in the Company’s income tax expense line in the Consolidated Statements of Operations for vested and exercised equity awards as discrete items in the period in which they occur; (2) adoption on a prospective basis of the classification of excess tax benefits in cash flows from operations in the Company’s Consolidated Statements of Cash Flows; (3) adoption on a retrospective basis of the classification of cash paid by the Company for directly withholding shares for tax withholding purposes in cash flows from financing activities, and (4) adoption on a prospective basis for the exclusion of the amount of excess tax benefits when applying the treasury stock method for the Company’s diluted earnings per share calculation. Additionally, the Company continues to withhold the statutory minimum taxes for participants in the Company’s stock-based compensation plans and estimates forfeiture rates at the grant date and the expected term of its equity awards based on historical results. On July 22, 2015, the FASB issued ASU No. 2015-11, Simplifying the Measurement of Inventory (ASU 2015-11). ASU 2015-11 requires an entity to measure most inventory at the lower of cost and net realizable value, thereby simplifying the prior guidance under which an entity must measure inventory at the lower of cost or market. ASU 2015-11 does not apply to inventories that are measured using either the last-in, first-out (LIFO) method or the retail inventory method. ASU 2015-11 was effective for public entities for financial statements issued for fiscal years beginning after December 15, 2016. U. S. Steel adopted ASU 2015-11 on January 1, 2017. The adoption did not have a significant financial statement impact to U. S. Steel.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information U. S. Steel has three reportable segments: North American Flat-Rolled (Flat-Rolled), USSE and Tubular Products (Tubular). The results of our railroad and real estate businesses that do not constitute reportable segments are combined and disclosed in the Other Businesses category. The majority of U. S. Steel's customers are located in North America and Europe. No single customer accounted for more than 10 percent of gross annual revenues. The Flat-Rolled segment includes the operating results of U. S. Steel’s integrated steel plants and equity investees in the United States involved in the production of slabs, strip mill plates, sheets and tin mill products, as well as all iron ore and coke production facilities in the United States. These operations primarily serve North American customers in the service center, conversion, transportation (including automotive), construction, container, and appliance and electrical markets. Additionally, the Flat-Rolled segment is organized into the following three commercial entities to specifically address our customers and service their needs: (1) automotive solutions, (2) consumer solutions, and (3) industrial, service center and mining solutions. The USSE segment includes the operating results of U. S. Steel Košice (USSK), U. S. Steel’s integrated steel plant and coke production facilities in Slovakia, and its subsidiaries. USSE primarily serves customers in the Eastern European service center, conversion, transportation (including automotive), construction, container, appliance and electrical, and oil, gas and petrochemical markets. USSE produces and sells slabs, strip mill plates, sheets, tin mill products and spiral welded pipe, as well as heating radiators and refractory ceramic materials. The Tubular segment includes the operating results of U. S. Steel’s tubular production facilities and an equity investee in the United States. We sold our ownership interest in an equity investee in Brazil in December of 2017. These operations produce and sell seamless and electric resistance welded (welded) steel casing and tubing (commonly known as oil country tubular goods or OCTG), standard and line pipe and mechanical tubing and primarily serve customers in the oil, gas and petrochemical markets. During the fourth quarter of 2016, certain of our tubular assets within the Tubular segment were permanently shut down, including Pipe Mill #1 at our Lone Star facility, Pipe Mill #4 at our Lorain facility and our Bellville facility. We sold our Bellville facility in 2018 and the assets at our McKeesport tubular operations in 2016. On February 4, 2019, U. S. Steel announced plans to restart Pipe Mill #1 at our Lone Star facility. See Note 29 for further details. The chief operating decision maker evaluates performance and determines resource allocations based on a number of factors, the primary measure being earnings (loss) before interest and income taxes. Earnings (loss) before interest and income taxes for reportable segments and Other Businesses does not include net interest and other financial costs (income), income taxes, and certain other items that management believes are not indicative of future results. In 2018, U. S. Steel began allocating certain post-employment benefits to its segments. Prior year information was adjusted to conform with the current year presentation. The accounting principles applied at the operating segment level in determining earnings (loss) before interest and income taxes are generally the same as those applied at the consolidated financial statement level. Intersegment sales and transfers are accounted for at market-based prices and are eliminated at the corporate consolidation level. Corporate-level selling, general and administrative expenses and costs related to certain former businesses are allocated to the reportable segments and Other Businesses based on measures of activity that management believes are reasonable. The results of segment operations are as follows: (In millions) Customer Intersegment Net Earnings Earnings (Loss) before Interest and Income Taxes Depreciation, Capital 2018 Flat-Rolled $ 9,681 $ 231 $ 9,912 $ 54 $ 883 $ 367 $ 820 USSE 3,205 23 3,228 — 359 87 104 Tubular 1,231 5 1,236 7 (58 ) 47 45 Total reportable segments 14,117 259 14,376 61 1,184 501 969 Other Businesses 61 125 186 — 55 20 32 Reconciling Items and Eliminations — (384 ) (384 ) — (115 ) — — Total $ 14,178 $ — $ 14,178 $ 61 $ 1,124 $ 521 $ 1,001 2017 Flat-Rolled $ 8,297 $ 194 $ 8,491 $ 38 $ 375 $ 352 $ 388 USSE 2,949 25 2,974 — 327 76 83 Tubular 944 1 945 8 (99 ) 51 28 Total reportable segments 12,190 220 12,410 46 603 479 499 Other Businesses 60 119 179 (2 ) 44 22 6 Reconciling Items and Eliminations — (339 ) (339 ) — 22 — — Total $ 12,250 $ — $ 12,250 $ 44 $ 669 $ 501 $ 505 2016 Flat-Rolled $ 7,507 $ 25 $ 7,532 $ 106 $ 22 $ 349 $ 111 USSE 2,243 3 2,246 — 185 80 83 Tubular 449 2 451 6 (303 ) 68 88 Total reportable segments 10,199 30 10,229 112 (96 ) 497 282 Other Businesses 62 107 169 (2 ) 63 10 24 Reconciling Items and Eliminations — (137 ) (137 ) (12 ) (168 ) — — Total $ 10,261 $ — $ 10,261 $ 98 $ (201 ) $ 507 $ 306 A summary of total assets by segment is as follows: December 31, (In millions) 2018 2017 Flat-Rolled (a) $ 6,977 $ 5,823 USSE (a) 5,607 5,423 Tubular 1,076 1,076 Total reportable segments $ 13,660 $ 12,322 Other Businesses $ 329 $ 344 Corporate, reconciling items, and eliminations (b) (3,007 ) (2,804 ) Total assets $ 10,982 $ 9,862 (a) Included in segment assets for each year presented is goodwill for Flat-Rolled and USSE of $3 million and $4 million , respectively. (b) The majority of Corporate, reconciling items, and eliminations total assets is comprised of cash and the elimination of intersegment amounts. The detail of reconciling items to consolidated earnings (loss) before interest and income taxes is as follows: (In millions) 2018 2017 2016 Items not allocated to segments: United Steelworkers labor agreement signing bonus and related costs (Note 28) (81 ) — — Granite City Works restart and related costs (80 ) — — Loss on shutdown of certain tubular pipe mill assets (a) — (35 ) (126 ) Gain associated with U. S. Steel Canada Inc. (Note 5) — 72 — Restructuring and other charges (a) — — 2 Granite City Works temporary idling charges 8 (17 ) (18 ) Gain (loss) on equity investee transactions (Note 12) 38 2 (12 ) Impairment of intangible assets (Note 14) — — (14 ) Total reconciling items $ (115 ) $ 22 $ (168 ) (a) Included in Restructuring and other charges on the Consolidated Statements of Operations. See Note 25 to the Consolidated Financial Statements. Geographic Area: The information below summarizes external sales, property, plant and equipment and equity method investments based on the location of the operating segment to which they relate. (In millions) Year External Assets North America 2018 $ 10,973 $ 4,432 (a) 2017 9,301 3,831 (a) 2016 8,018 3,671 (a) Europe 2018 3,205 919 2017 2,949 906 2016 2,243 789 Other Foreign Countries 2018 — — 2017 — — 2016 — 18 Total 2018 14,178 5,351 2017 12,250 4,737 2016 $ 10,261 $ 4,478 (a) Assets with a book value of $4,432 million , $3,817 million and $3,670 million were located in the United States at December 31, 2018 , 2017 and 2016 , respectively.

USSC Retained Interest

USSC Retained Interest	12 Months Ended
	Dec. 31, 2018
USSC Retained Interest [Abstract]
USSC Retained Interest	U. S. Steel Canada Inc. Retained Interest On June 30, 2017, U. S. Steel completed the restructuring and disposition of U. S. Steel Canada Inc. (USSC) through a sale and transfer of all of the issued and outstanding shares in USSC to an affiliate of Bedrock Industries LLC. In accordance with the Second Amended and Restated Plan of Compromise, Arrangement and Reorganization, approved by the Ontario Superior Court of Justice on June 9, 2017, U. S. Steel received approximately $127 million in satisfaction of its secured claims, including interest, which resulted in a gain of $72 million on the Company's retained interest in USSC. U. S. Steel also agreed to the discharge and cancellation of its unsecured claims for nominal consideration. The terms of the settlement included mutual releases among key stakeholders, including a release of all claims against the Company regarding environmental, pension and other liabilities, and transition services agreements that superseded all prior arrangements among the parties, including the 2015 transition arrangements. Pursuant to the terms of these new transition services agreements, U. S. Steel will continue to provide various transition services for up to 24 months from June 30, 2017.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Revenue is generated primarily from contracts to produce, ship and deliver steel products, and to a lesser extent, to deliver raw materials such as iron ore pellets, to deliver coke by-products and for railroad services and real estate sales. Generally, U. S. Steel’s performance obligations are satisfied, control of our products is transferred, and revenue is recognized at a single point in time, when title transfers to our customer for product shipped or when services are provided. Revenues are recorded net of any sales incentives. Shipping and other transportation costs charged to customers are treated as fulfillment activities and are recorded in both revenue and cost of sales at the time control is transferred to the customer. Costs related to obtaining sales contracts are incidental and are expensed when incurred. Because customers are invoiced at the time title transfers and U. S. Steel’s right to consideration is unconditional at that time, U. S. Steel does not maintain contract asset balances. Additionally, U. S. Steel does not maintain contract liability balances, as performance obligations are satisfied prior to customer payment for product. U. S. Steel offers industry standard payment terms. U. S. Steel has three reportable segments: Flat-Rolled, USSE and Tubular. Flat-Rolled primarily generates revenue from sheet and coated product sales to North American customers. Flat-Rolled also sells iron ore pellets and coke making by-products. USSE sells slabs, sheets, strip mill plates, coated products and spiral welded pipe to customers primarily in the Eastern European market. Tubular sells seamless and electric resistance welded (ERW) steel casing and tubing (commonly known as oil country tubular goods or OCTG), standard and line pipe and mechanical tubing and primarily serves customers in the oil, gas and petrochemical markets. Revenue from our railroad and real estate businesses is reported in the Other Businesses category in our segment reporting structure. The following table disaggregates our revenue by product for each of our reportable business segments for the years ended December 31, 2018 , 2017 and 2016 , respectively: Customer Sales by Product: (In millions) Year Ended December 31, 2018 Flat-Rolled USSE Tubular Other Businesses Total Semi-finished $ 156 $ 174 $ — $ — $ 330 Hot-rolled sheets 2,816 1,313 — — 4,129 Cold-rolled sheets 2,709 384 — — 3,093 Coated sheets 3,090 1,164 — — 4,254 Tubular products — 48 1,195 — 1,243 All Other (a) 910 122 36 61 1,129 Total $ 9,681 $ 3,205 $ 1,231 $ 61 $ 14,178 (In millions) Year Ended December 31, 2017 Flat-Rolled USSE Tubular Other Businesses Total Semi-finished $ 72 $ 232 $ — $ — $ 304 Hot-rolled sheets 2,045 1,210 — — 3,255 Cold-rolled sheets 2,355 328 — — 2,683 Coated sheets 2,902 1,038 — — 3,940 Tubular products — 39 909 — 948 All Other (a) 923 102 35 60 1,120 Total $ 8,297 $ 2,949 $ 944 $ 60 $ 12,250 (In millions) Year Ended December 31, 2016 Flat-Rolled USSE Tubular Other Businesses Total Semi-finished $ 6 $ 165 $ — $ — $ 171 Hot-rolled sheets 1,495 907 — — 2,402 Cold-rolled sheets 2,405 230 — — 2,635 Coated sheets 2,932 834 — — 3,766 Tubular products — 32 430 — 462 All Other (a) 669 75 19 62 825 Total $ 7,507 $ 2,243 $ 449 $ 62 $ 10,261 (a) Consists primarily of sales of raw materials and coke making by-products.

Net Interest and Other Financia

Net Interest and Other Financial Costs	12 Months Ended
	Dec. 31, 2018
Other Income and Expenses [Abstract]
Net Interest and Other Financial Costs	Net Interest and Other Financial Costs (In millions) 2018 2017 2016 Interest income: Interest income $ (23 ) $ (17 ) $ (5 ) Interest expense and other financial costs: Interest incurred 175 229 234 Less interest capitalized 7 3 4 Total interest expense 168 226 230 Loss on debt extinguishment (a) 98 54 22 Net periodic benefit costs (other than service cost) (b) 69 61 (36 ) Foreign currency net (gain) loss (c) (19 ) 23 (14 ) Financial costs on: Amended Credit Agreement 5 6 6 USSK credit facilities 3 3 3 Other 3 2 — Amortization of discounts and deferred financing costs 8 10 9 Total other financial costs — 44 4 Net interest and other financial costs $ 312 $ 368 $ 215 (a) Represents a net pretax charge of a $98 million during 2018 related to the retirement of our 2020 Senior Notes and 2021 Senior Secured Notes, a net pretax charge of $54 million during 2017 related to the retirement of our 2018, 2021, and 2022 Senior Notes, partial redemption of our 2021 Senior Secured Notes, and redemption of the Lorain Recovery Zone Facility Bonds, and a net pretax charge of $22 million during 2016 related to the retirement of our 2017 Senior Notes, and partial redemption of our 2018, 2020 and 2021 Senior Notes. (b) Represents postretirement benefit expense as a result of the adoption of Accounting Standards Update 2017-07, Compensation - Retirement Benefits on January 1, 2018. See Note 3 to the Consolidated Financial Statements. (c) The functional currency for USSE is the euro. Foreign currency net (gain) loss is a result of transactions denominated in currencies other than the euro.

Earnings and Dividends Per Comm

Earnings and Dividends Per Common Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings and Dividends Per Common Share	Earnings and Dividends Per Common Share Earnings (Loss) per Share Attributable to United States Steel Corporation Stockholders Basic earnings (loss) per common share is based on the weighted average number of common shares outstanding during the period. Diluted earnings (loss) per common share assumes the exercise of stock options, the vesting of restricted stock units and performance awards, provided in each case the effect is dilutive. The computations for basic and diluted earnings (loss) per common share from continuing operations are as follows: (Dollars in millions, except per share amounts) 2018 2017 2016 Net earnings (loss) attributable to United States Steel Corporation stockholders $ 1,115 $ 387 $ (440 ) Weighted-average shares outstanding (in thousands): Basic 176,633 174,793 156,673 Effect of stock options, restricted stock units and performance awards 1,828 1,727 — Adjusted weighted-average shares outstanding, diluted 178,461 176,520 156,673 Basic earnings (loss) per common share $ 6.31 $ 2.21 $ (2.81 ) Diluted earnings (loss) per common share $ 6.25 $ 2.19 $ (2.81 ) The following table summarizes the securities that were antidilutive, and therefore, were not included in the computation of diluted earnings (loss) per common share: (In thousands) 2018 2017 2016 Securities granted under the 2005 Stock Incentive Plan $ 1,631 $ 1,579 $ 8,820 Dividends Paid per Share Quarterly dividends on common stock were five cent s per share for each quarter in 2018 , 2017 and 2016 .

Cash, Cash Equivalents, and Res

Cash, Cash Equivalents, and Restricted Cash	12 Months Ended
	Dec. 31, 2018
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within U. S. Steel's Consolidated Balance Sheets that sum to the total of the same amounts shown in the Consolidated Statement of Cash Flows: December 31, (In millions) 2018 2017 2016 Cash and cash equivalents $ 1,000 $ 1,553 $ 1,515 Restricted cash in other current assets 3 6 — Restricted cash in other noncurrent assets 37 38 40 Total cash, cash equivalents and restricted cash $ 1,040 $ 1,597 $ 1,555 Amounts included in restricted cash represent cash balances which are legally or contractually restricted, primarily for environmental capital expenditure projects and insurance purposes.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories (In millions) December 31, 2018 December 31, 2017 Raw materials $ 605 $ 527 Semi-finished products 1,021 796 Finished products 404 356 Supplies and sundry items 62 59 Total $ 2,092 $ 1,738 Current acquisition costs were estimated to exceed the above inventory values at December 31 by $1,038 million in 2018 and $802 million in 2017 . As a result of the liquidation of LIFO inventories, cost of sales decreased and earnings (loss) before interest and income taxes increased by $10 million in 2018. As a result of the liquidation of LIFO inventories, cost of sales increased and earnings (loss) before interest and income taxes decreased by $6 million and $77 million in 2017 and 2016 , respectively. Inventory includes $39 million and $42 million of land held for residential/commercial development as of December 31, 2018 and 2017 , respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Components of earnings (loss) (In millions) 2018 2017 2016 United States $ 434 $ 75 $ (588 ) Foreign 378 226 172 Earnings (loss) before income taxes $ 812 $ 301 $ (416 ) At the end of both 2018 and 2017, U. S. Steel does not have any undistributed foreign earnings and profits for which U.S. deferred taxes have not been provided. (Benefit) Provision for income taxes 2018 2017 2016 (In millions) Current Deferred Total Current Deferred Total Current Deferred Total Federal $ (40 ) $ (283 ) $ (323 ) $ (66 ) $ (81 ) $ (147 ) $ (18 ) $ — $ (18 ) State and local 2 (58 ) (56 ) (1 ) — (1 ) 1 — 1 Foreign 64 12 76 53 9 62 32 9 41 Total $ 26 $ (329 ) $ (303 ) $ (14 ) $ (72 ) $ (86 ) $ 15 $ 9 $ 24 A reconciliation of the federal statutory tax rate of 21 percent ( 35 percent in 2017 and 2016) to total provision follows: (In millions) 2018 2017 2016 Statutory rate applied to earnings (loss) before income taxes $ 171 $ 105 $ (146 ) Valuation allowance (412 ) 36 252 Excess percentage depletion (48 ) (68 ) (49 ) State and local income taxes after federal income tax effects 8 (28 ) (20 ) Effects of foreign operations 74 62 42 U.S. impact of foreign operations (21 ) (6 ) (6 ) Tax credits (71 ) (56 ) (39 ) Effect of tax reform — (81 ) — Alternative minimum tax credit refund — (48 ) (18 ) Other (4 ) (2 ) 8 Total (benefit) provision $ (303 ) $ (86 ) $ 24 In 2018, the tax benefit differs from the domestic statutory rate of 21 percent as a result of the items listed above. In particular, it includes a benefit of $374 million related to the reversal of a portion of the valuation allowance recorded against the Company's net domestic deferred tax asset, as well as a benefit of $38 million related to the reversal of the valuation allowance for current year activity. Included in the 2017 tax benefit is a benefit of $10 million related to corporate rate reduction provided by the 2017 Act, as well as a benefit of $71 million related to the reversal of the valuation allowance recorded against the remaining balance of the Company’s Alternative Minimum Tax (AMT) credits, which became fully refundable pursuant to the 2017 Act. Also included in the 2017 tax benefit is a benefit of $48 million related to the Company’s election to claim a refund of AMT credits pursuant to a provision in the Protecting Americans from Tax Hikes (PATH) Act. Included in the 2016 tax provision is a benefit of $18 million related to the Company's election to claim a refund of AMT credits pursuant to a provision in the PATH Act. The provision also reflects a write-off of certain deferred tax assets and liabilities related to branch operations pursuant to new regulations. However, the write-off did not impact the total provision because of the valuation allowance on the net domestic deferred tax asset. Deferred taxes Deferred tax assets and liabilities resulted from the following: December 31, (In millions) 2018 2017 Deferred tax assets: Federal tax loss carryforwards (expiring in 2035 through 2036) $ 220 $ 394 Federal capital loss carryforwards (expiring 2021) 33 36 State tax credit carryforwards (expiring in 2019 through 2027) 16 14 State tax loss carryforwards (expiring in 2019 through 2038) 137 155 Minimum tax credit carryforwards 38 76 General business credit carryforwards (expiring in 2027 through 2038) 85 86 Foreign tax loss and credit carryforwards (expiring in 2024 through 2028) 173 102 Employee benefits 337 266 Contingencies and accrued liabilities 62 70 Investments in subsidiaries and equity investees 59 33 Other temporary differences 26 1 Valuation allowance (214 ) (608 ) Total deferred tax assets 972 625 Deferred tax liabilities: Property, plant and equipment 468 516 Inventory 22 6 Receivables, payables and debt 33 14 Indefinite-lived intangible assets 18 18 Other temporary differences — 21 Total deferred tax liabilities 541 575 Net deferred tax asset $ 431 $ 50 U. S. Steel recognizes deferred tax assets and liabilities for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. The realization of deferred tax assets is assessed quarterly based on several interrelated factors. These factors include U. S. Steel’s expectation to generate sufficient future taxable income and the projected time period over which these deferred tax assets will be realized. At December 31, 2018, the net domestic deferred tax asset was $445 million , net of an established valuation allowance of $211 million . At December 31, 2017, the net domestic deferred tax asset was $53 million , net of an established valuation allowance of $604 million . At December 31, 2018 , the net foreign deferred tax liability was $14 million , net of an established valuation allowance of $3 million . At December 31, 2017, the net foreign deferred tax liability was $3 million , net of an established valuation allowance of $4 million . The net foreign deferred tax liability will fluctuate as the value of the U.S. dollar changes with respect to the euro. U. S. Steel will continue to monitor the realizability of its deferred tax assets on a quarterly basis taking into consideration, among other items, the uncertainty regarding the Company's continued ability to generate domestic income in the near term. In the future, if we determine that realization is more likely than not for a deferred tax asset with a valuation allowance, the related valuation allowance will be reduced, and we will record a non-cash benefit to earnings. Tax years subject to examination Below is a summary of the tax years open to examination by major tax jurisdiction: U.S. Federal – 2011 and forward* U.S. States – 2009 and forward Slovakia – 2008 and forward *U. S. Steel's 2011 federal tax year remains open to the extent of net operating losses carried back from 2013. Status of Internal Revenue Service (IRS) examinations The IRS audit of U. S. Steel’s 2014-2016 federal consolidated tax returns began in 2018 and is ongoing. The IRS audit of the Company's 2012-2013 tax returns began in 2015. Although the IRS and the Company have effectively agreed to adjustments to complete the 2012-2013 audit, final settlement is subject to Joint Committee approval. Unrecognized tax benefits Unrecognized tax benefits are the differences between a tax position taken, or expected to be taken, in a tax return and the benefit recognized for accounting purposes pursuant to the guidance in ASC Topic 740 on income taxes. The total amount of unrecognized tax benefits was $35 million , $42 million and $72 million as of December 31, 2018 , 2017 and 2016 , respectively. The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate was $2 million as of December 31, 2018 and $6 million as of December 31, 2017 . U. S. Steel records interest related to uncertain tax positions as a part of net interest and other financial costs in the Consolidated Statements of Operations. Any penalties are recognized as part of selling, general and administrative expenses. U. S. Steel had accrued liabilities of $2 million and $6 million for interest and penalties related to uncertain tax positions as of December 31, 2018 and 2017 , respectively. A tabular reconciliation of unrecognized tax benefits follows: (In millions) 2018 2017 2016 Unrecognized tax benefits, beginning of year $ 42 $ 72 $ 74 Increases – tax positions taken in prior years — 1 — Decreases – tax positions taken in prior years (2 ) (26 ) (4 ) Increases – current tax positions — — 3 Settlements — (4 ) — Lapse of statute of limitations (5 ) (1 ) (1 ) Unrecognized tax benefits, end of year $ 35 $ 42 $ 72 It is reasonably expected that during the next 12 months unrecognized tax benefits related to income tax issues will decrease by approximately $32 million .

Investments, Long-Term Receivab

Investments, Long-Term Receivables and Equity Investee Transactions	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investments, Long-Term Receivables and Equity Investee Transactions	Investments, Long-Term Receivables and Equity Investee Transactions December 31, (In millions) 2018 2017 Equity method investments $ 485 $ 457 Receivables due after one year, less allowance of $5 and $11 24 20 Other 4 3 Total $ 513 $ 480 Summarized financial information of all investees accounted for by the equity method of accounting is as follows (amounts represent 100% of investee financial information): (In millions) 2018 2017 2016 Income data – year ended December 31: (a) Net Sales $ 2,193 $ 2,485 $ 2,839 Operating income 157 132 345 Net earnings 134 109 323 Balance sheet date – December 31: Current Assets $ 642 $ 633 $ 771 Noncurrent Assets 853 710 989 Current liabilities 348 441 478 Noncurrent Liabilities 516 335 506 (a) Former equity affiliates, Swan Point Development Company, Inc., Tilden Mining Company and Apolo Tubulars S.A. were sold on February 6, 2017, September 29, 2017 and December 22, 2017, respectively. We exited Leeds Retail Center, LLC and sold Acero Prime, S.R.L. de CV on May 31, 2018, and October 23, 2018, respectively. The former equity affiliates are included in the income data through the month prior to the date of sale. U. S. Steel's portion of the equity in net earnings for its equity investments as reported in the income from investees line on the Consolidated Statements of Operations was $61 million , $44 million and $98 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Investees accounted for using the equity method include: Investee Country December 31, 2018 Interest Chrome Deposit Corporation United States 50 % Daniel Ross Bridge, LLC United States 50 % Double G Coatings Company, Inc. United States 50 % Feralloy Processing Company United States 49 % Hibbing Development Company United States 24.1 % Hibbing Taconite Company (a) United States 14.7 % Patriot Premium Threading Services, LLC United States 50 % PRO-TEC Coating Company, LLC United States 50 % Strategic Investment Fund Partners II (b) United States 5.2 % USS-POSCO Industries United States 50 % Worthington Specialty Processing United States 49 % (a) Hibbing Taconite Company (HTC) is an unincorporated joint venture that is owned, in part, by Hibbing Development Company (HDC), which is accounted for using the equity method. Through HDC we are able to influence the activities of HTC, and as such, its activities are accounted for using the equity method. (b) Strategic Investment Fund Partners II is a limited partnership and in accordance with ASC Topic 323, the financial activities are accounted for using the equity method. In 2018, we recognized pre-tax gains on equity investee transactions of approximately $18 million for the assignment of our ownership interest in Leeds Retail Center, LLC and $20 million from the sale of our 40 percent ownership interest in Acero Prime, S. R. L. de CV. In 2017, we recognized a total gain on equity investee transactions of $2 million primarily as a result of a gain on sale of our 15 percent ownership in Tilden Mining Company, L.C., partially offset by a loss on sale of our 50 percent ownership interest in Apolo Tubulars S.A. Dividends and partnership distributions received from equity investees were $13 million in 2018 , $12 million in 2017 and $9 million in 2016 . U. S. Steel evaluates impairment of its equity method investments whenever circumstances indicate that a decline in value below carrying value is other than temporary. Under these circumstances, we would adjust the investment down to its estimated fair value, which then becomes its new carrying value. During the fourth quarter of 2016, the Company completed a review of its equity method investments and determined there was an other than temporary impairment of an equity investee within our Tubular segment. Accordingly, U. S. Steel recorded an impairment charge of $12 million , which reduced the carrying value of the investment to $18 million at December 31, 2016. The equity investment was sold in 2017. We supply substrate to certain of our equity method investees and from time to time will extend the payment terms for their trade receivables. For discussion of transactions and related receivable and payable balances between U. S. Steel and its investees, see Note 23.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment December 31, (In millions) Useful Lives 2018 2017 Land and depletable property — $ 207 $ 208 Buildings 35 years 1,098 1,109 Machinery and equipment Steel producing 2-30 years 12,784 12,014 Transportation 3-40 years 268 239 Other 5-30 years 123 122 Information technology 5-6 years 786 782 Assets under capital lease 5-15 years 36 36 Construction in process — 706 576 Total 16,008 15,086 Less accumulated depreciation and depletion 11,143 10,806 Net $ 4,865 $ 4,280 Amounts in accumulated depreciation and depletion for assets acquired under capital leases (including sale-leasebacks accounted for as financings) were $20 million and $18 million at December 31, 2018 and 2017 , respectively.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets Intangible assets are being amortized on a straight-line basis over their estimated useful lives and are detailed below: As of December 31, 2018 As of December 31, 2017 (In millions) Useful Gross Accumulated Net Gross Accumulated Net Customer relationships 22 Years $ 132 $ 70 $ 62 $ 132 $ 64 $ 68 Patents 10-15 Years 22 7 15 22 5 17 Other 4-20 Years 14 8 6 15 8 7 Total amortizable intangible assets $ 168 $ 85 $ 83 $ 169 $ 77 $ 92 Identifiable intangible assets with finite lives are reviewed for impairment whenever events or circumstances indicate that the carrying value may not be recoverable. There were no triggering events in 2018 or 2017 that required a review for impairment. Amortization expense was $8 million and $9 million for years ended December 31, 2018 and December 31, 2017 , respectively. We expect a consistent level of annual amortization expense through 2023 . The carrying amount of acquired water rights with indefinite lives as of December 31, 2018 and December 31, 2017 totaled $75 million . The acquired water rights are tested for impairment annually in the third quarter, or whenever events or circumstances indicate the carrying value may not be recoverable. U. S. Steel performed a qualitative impairment evaluation of its acquired water rights during the third quarter of 2018 . Based on the results of the evaluation, the water rights were not impaired. The research and development activities of the Company's acquired indefinite lived in-process research and development patents was completed during the fourth quarter of 2016 and the carrying amount of the patents is being amortized over the useful lives of the patents (approximately 10 years). As a result of the quantitative impairment evaluation of its in-process research and development patents during 2016, an impairment charge of approximately $14 million was recorded during 2016. Key assumptions used in the discounted cash flow analysis for the evaluation of the patents consisted of a combination of Level 2 and Level 3 inputs, which included future cash flow projections, a royalty rate of 5% and a discount rate of 17% .

Stock-Based Compensation Plans

Stock-Based Compensation Plans	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans U. S. Steel has outstanding stock-based compensation awards that were granted by the Compensation & Organization Committee of the Board of Directors (the Committee) under the 2005 Stock Incentive Plan (the 2005 Plan) and the 2016 Omnibus Incentive Compensation Plan (the Omnibus Plan) (collectively the Plans). On April 26, 2016, the Company's stockholders approved the Omnibus Plan and authorized the Company to issue up to 7,200,000 shares of U. S. Steel common stock under the Omnibus Plan. The Company's stockholders authorized the issuance of an additional 6,300,000 shares under the Omnibus Plan on April 25, 2017. While awards that were previously granted under the 2005 Plan remain outstanding, all future awards will be granted under the Omnibus Plan. As of December 31, 2018 , there were 10,936,016 shares available for future grants under the Omnibus Plan. Generally, a share issued under the Omnibus Plan pursuant to an award other than a stock option will reduce the number of shares available under the Stock Plan by 1.73 shares. Also, shares related to awards under either plan (i) that are forfeited, (ii) that terminate without shares having been issued or (iii) for which payment is made in cash or property other than shares, are again available for awards under the Omnibus Plan; provided, however, that shares delivered to U. S. Steel or withheld for purposes of satisfying the exercise price or tax withholding obligations shall not be available for future awards. The purpose of the Plans is to attract, retain and motivate employees and non-employee directors of outstanding ability, and to align their interests with those of the stockholders of U. S. Steel. The Committee administers the plan pursuant to which they may make grants of stock options, restricted stock units (RSUs), performance awards, and other stock-based awards. The following table summarizes the total stock-based compensation awards granted during the years 2018 , 2017 and 2016 : Stock Options Restricted Stock Units TSR Performance Awards ROCE Performance Awards 2018 Grants — 824,195 79,190 247,510 2017 Grants 647,780 348,040 169,850 — 2016 Grants 1,333,210 1,120,332 308,130 — Stock-based compensation expense The following table summarizes the total compensation expense recognized for stock-based compensation awards: (In millions, except per share amounts) Year Ended December 31, 2018 Year Ended December 31, 2017 Year Ended December 31, 2016 Stock-based compensation expense recognized: Cost of sales $ 11 $ 10 $ 9 Selling, general and administrative expenses 21 17 13 Decrease in net income 32 27 22 Decrease in basic earnings per share 0.14 0.15 0.14 Decrease in diluted earnings per share 0.13 0.15 0.14 As of December 31, 2018 , total future compensation cost related to nonvested stock-based compensation arrangements was $23 million , and the average period over which this cost is expected to be recognized is approximately 16 months . Stock options Compensation expense for stock options is recorded over the vesting period based on the fair value on the date of grant, as calculated by U. S. Steel using the Black-Scholes model and the assumptions listed below. Awards generally vest ratably over a three -year service period and have a term of ten years . Stock options are generally issued at the market price of the underlying stock on the date of the grant. Upon exercise of stock options, shares of U. S. Steel stock are issued from treasury stock or from authorized, but unissued common stock. There were no stock options granted in 2018 . Black-Scholes Assumptions (a) 2017 Grants 2016 Grants Grant date price per share of option award $ 36.94 $ 14.78 Exercise price per share of option award $ 36.94 $ 14.78 Expected annual dividends per share $ 0.20 $ 0.20 Expected life in years 5.0 5.0 Expected volatility 57 % 53 % Risk-free interest rate 2.0 % 1.5 % Average grant date fair value per share of unvested option awards as calculated from above $ 17.28 $ 6.24 (a) The assumptions represent a weighted-average for all grants during the year. The expected annual dividends per share are based on the latest annualized dividend rate at the date of grant; the expected life in years is determined primarily from historical stock option exercise data; the expected volatility is based on the historical volatility of U. S. Steel stock; and the risk-free interest rate is based on the U.S. Treasury strip rate for the expected life of the option. The following table shows a summary of the status and activity of stock options for the year ended December 31, 2018 : Shares Weighted- Weighted- Aggregate Outstanding at January 1, 2018 4,612,940 $ 28.92 Granted — $ — Exercised (1,541,989 ) $ 22.65 Forfeited or expired (324,431 ) $ 72.15 Outstanding at December 31, 2018 2,746,520 $ 27.73 5.03 $ 2 Exercisable at December 31, 2018 2,174,000 $ 28.10 4.32 $ 1 Exercisable and expected to vest at December 31, 2018 2,640,308 $ 27.76 4.92 $ 2 The aggregate intrinsic value in the table above represents the total pretax intrinsic value (difference between our closing stock price on the last trading day of 2018 and the exercise price, multiplied by the number of in-the-money options). Intrinsic value changes are a function of the fair market value of our stock. The total intrinsic value of stock options exercised (i.e., the difference between the market price at exercise and the price paid by the employee to exercise the option) was $27 million during the year ended December 31, 2018 , $11 million during the year ended December 31, 2017 and $13 million during the year ended December 31, 2016 . The total amount of cash received by U. S. Steel from the exercise of options during the year ended December 31, 2018 and December 31, 2017 , was $35 million and $20 million , respectively, and the related net tax benefit realized from the exercise of these options was $3 million in 2018 and was immaterial in 2017. Stock awards Compensation expense for nonvested stock awards is recorded over the vesting period based on the fair value at the date of grant. RSUs awarded as part of annual grants generally vest ratably over 3 years . Their fair value is the market price of the underlying common stock on the date of grant. RSUs granted in connection with new-hire or retention awards generally cliff vest three years from the date of the grant. Total shareholder return (TSR) performance awards may vest at the end of a three -year performance period if U. S. Steel’s total shareholder return compared to the total shareholder return of a peer group of companies over the three -year performance period meets the performance criteria. Performance awards can vest at between zero and 200 percent of the target award. The fair value of the performance awards is calculated using a Monte-Carlo simulation. Performance awards based on the return on capital employed (ROCE) metric were granted in 2018 in equity and in 2017 and 2016 in cash. ROCE awards granted will be measured on a weighted average basis of the Company’s consolidated worldwide earnings (loss) before interest and income taxes, as adjusted, divided by consolidated worldwide capital employed, as adjusted, over a three year period. Weighted average ROCE is calculated based on the ROCE achieved in the first, second and third years of the performance period, weighted at 20 percent , 30 percent and 50 percent , respectively. The ROCE awards will payout 50 percent at the threshold level, 100 percent at the target level and 200 percent at the maximum level. Amounts in between the threshold percentages will be interpolated. Compensation expense associated with the ROCE awards will be contingent based upon the achievement of the specified ROCE performance goals and will be adjusted on a quarterly basis to reflect the probability of achieving the ROCE metric. ROCE performance awards may vest at the end of a three -year performance period contingent upon meeting ROCE performance goals approved by the Committee. The fair value of the ROCE performance awards is the average market price of the underlying common stock on the date of grant. The following table shows a summary of the performance awards outstanding as of December 31, 2018 , and their fair market value on the respective grant date: Performance Period Fair Value Minimum Target Maximum 2018 - 2020 $ 15 — 313,874 627,748 2017 - 2019 $ 4 — 105,479 210,958 2016 - 2018 $ 2 — 192,332 384,664 The following table shows a summary of the status and activity of nonvested stock awards for the year ended December 31, 2018 : Restricted TSR Performance (a) ROCE Performance (a) Total Weighted- Nonvested at January 1, 2018 1,188,746 515,531 — 1,704,277 $ 21.08 Granted 824,195 79,190 247,510 1,150,895 41.65 Vested (431,661 ) (150,133 ) — (581,794 ) 24.20 Performance adjustment factor (b) — (52,557 ) — (52,557 ) 24.95 Forfeited or expired (85,008 ) (16,244 ) (11,612 ) (112,864 ) 28.99 Nonvested at December 31, 2018 1,496,272 375,787 235,898 2,107,957 $ 30.92 (a) The number of shares shown for the performance awards is based on the target number of share awards. (b) Consists of adjustments to vested performance awards to reflect actual performance. The adjustments were required since the original grants of the awards were at 100 percent of the targeted amounts and the awards vested at less than target. The following table presents information on RSUs and performance awards granted: 2018 2017 2016 Number of awards granted 1,150,895 517,890 1,428,462 Weighted-average grant-date fair value per share $ 41.65 $ 37.68 $ 13.39 During the years ended December 31, 2018 , 2017 , and 2016 , the total fair value of shares vested was $14 million , $11 million , and $17 million , respectively.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments U. S. Steel is exposed to foreign currency exchange rate risks in our European operations. USSE’s revenues are primarily in euros and costs are primarily in euros and U.S. dollars (USD). U. S. Steel uses foreign exchange forward sales contracts (foreign exchange forwards) with maturities no longer than 12 months to exchange euros for USD to manage our currency requirements and exposure to foreign currency exchange rate fluctuations. Derivative instruments are required to be recognized at fair value in the Consolidated Balance Sheet. U. S. Steel has not elected to designate these contracts as hedges. Therefore, changes in their fair value are recognized immediately in the Consolidated Statements of Operations and are also shown in the tabular disclosure below. We mitigate the risk of concentration of counterparty credit risk by purchasing our forwards from several counterparties. In 2018, U. S. Steel entered into long-term freight contracts in its domestic operations that require payment in Canadian dollars (CAD). We entered into foreign exchange forward sales contracts with remaining maturities up to two years to exchange USD for CAD to mitigate a portion of the related risk of exchange rate fluctuations and to manage our currency requirements. We elected to designate these contracts as cash flow hedges. Accordingly, we record gains and losses on these contracts within Accumulated Other Comprehensive Income (AOCI) until the related contract impacts earnings. From time to time U. S. Steel may use fixed-price forward physical purchase contracts to partially manage our exposure to price risk related to the purchases of natural gas, zinc and tin used in the production process. Generally, forward physical purchase contracts qualify for the normal purchase and normal sales exceptions described in ASC Topic 815 and are not subject to mark-to-market accounting. U. S. Steel also uses financial swaps to protect from the commodity price risk associated with purchases of natural gas, zinc and tin (commodity purchase swaps) in both our domestic and European operations. Commodity purchase swaps did not have a significant impact on the Company's financial results and were classified as cash flow hedges in prior periods for our domestic operations. Commodity purchase swaps used in our European operations were not classified as hedges. The impacts of our commodity purchase swaps are included in the tabular disclosure below. Effective January 1, 2018, U. S. Steel adopted the provisions of ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities . The cumulative effect of the adoption of ASU 2017-12 was not material to U. S. Steel's financial results. See Note 3 for additional information on the recently adopted accounting standard. Financial swaps are also used to partially manage the sales price of certain hot-rolled coil and iron ore pellet contract sales (sales swaps). In prior periods, we did not elect hedge accounting for these financial swaps and changes in their fair value were immediately recognized in earnings. Effective January 1, 2018, U. S. Steel elected to designate its hot-rolled coil sales swaps as cash flow hedges. See the tabular disclosure below for further details. In accordance with the guidance in ASC Topic 820 on fair value measurements and disclosures, the fair value of our foreign exchange forwards, commodity purchase swaps and sales swaps was determined using Level 2 inputs, which are defined as "significant other observable" inputs. The inputs used are from market sources that aggregate data based upon market transactions. The table below shows the outstanding swap quantities used to hedge forecasted purchases and sales as of December 31, 2018 and December 31, 2017 : Hedge Contracts Classification December 31, 2018 December 31, 2017 Natural gas (in mmbtus) Commodity purchase swaps 33,951,016 22,049,500 Tin (in metric tons) Commodity purchase swaps 585 80 Zinc (in metric tons) Commodity purchase swaps 3,471 4,179 Hot-rolled coils (in tons) Sales swaps 9,000 38,000 Iron ore pellets (in metric tons) Sales swaps — 40,000 Foreign currency (in millions of euros) Foreign exchange forwards € 286 € 234 Foreign currency (in millions of CAD) Foreign exchange forwards C$ 50 C$ — The following summarizes the fair value amounts included in our Consolidated Balance Sheets as of December 31, 2018 and December 31, 2017 : (In millions) Designated as Hedging Instruments Balance Sheet Location December 31, 2018 December 31, 2017 Sales swaps Accounts payable $ 1 $ — Commodity purchase swaps Accounts receivable 2 4 Commodity purchase swaps Accounts payable 17 2 Commodity purchase swaps Investments and long-term receivables — 1 Commodity purchase swaps Other long-term liabilities 1 1 Foreign exchange forwards Accounts payable 1 — Foreign exchange forwards Other long-term liabilities 1 — Not Designated as Hedging Instruments Sales swaps Accounts payable — 2 Commodity purchase swaps Accounts payable — 1 Foreign exchange forwards Accounts receivable 12 11 The table below summarizes the effect of hedge accounting on AOCI and amounts reclassified from AOCI into earnings for 2018 , 2017 , and 2016 : Gain (Loss) on Derivatives in AOCI Amount of Gain (Loss) Recognized in Income (In millions) 2018 2017 2016 Location of Reclassification from AOCI (a) 2018 2017 2016 Sales swaps (b) $ — $ — $ — Net sales $ (13 ) $ — $ — Commodity purchase swaps (15 ) 1 2 Cost of sales (c) (8 ) (2 ) 13 Foreign exchange forwards (2 ) — — Cost of sales — — — (a) The earnings impact of our hedging instruments substantially offsets the earnings impact of the related hedged items since ineffectiveness is less than $1 million . (b) U. S. Steel has elected hedge accounting for hot-rolled coil sales swaps prospectively on January 1, 2018. Iron ore pellet sales swaps were not classified as hedges. (c) Costs for commodity purchase swaps are recognized in cost of sales as products are sold. The table below summarizes the impact of derivative activity where hedge accounting has not been elected on our Consolidated Statements of Operations for 2018 , 2017 and 2016 : Amount of Gain (Loss) Recognized in Income (In millions) Consolidated Statement of Operations Location 2018 2017 2016 Sales swaps (a) Net sales $ (1 ) $ 6 $ (3 ) Commodity purchase swaps (b) Cost of sales — 3 3 Foreign exchange forwards (c) Other financial costs 24 (23 ) 7 (a) U. S. Steel has elected hedge accounting for hot-rolled coil sales swaps prospectively on January 1, 2018. Iron ore pellet sales swaps were not classified as hedges. (b) The 2017 impacts were for de-designated zinc contracts for our domestic operations and the 2016 impacts were for zinc and tin contracts not elected for hedge accounting for our European operations. (c) U. S. Steel has elected hedge accounting for foreign exchange forwards to exchange USD for CAD. Foreign exchange forwards to exchange euro for USD were not classified as hedges. At current contract values, $16 million and $1 million currently in AOCI as of December 31, 2018 will be recognized as an increase in cost of sales and a decrease in net sales, respectively, over the next year as related hedged items are recognized in earnings. The maximum derivative contract duration for commodity purchase swaps is 24 months and the maximum duration for foreign exchange forwards is 24 months. There are no outstanding contracts for commodity sales swaps.

Debt

Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt	Debt December 31, (In millions) Interest Maturity 2018 2017 2037 Senior Notes 6.650 2037 $ 350 $ 350 2026 Senior Notes 6.250 2026 650 — 2025 Senior Notes 6.875 2025 750 750 2021 Senior Secured Notes 8.375 2021 — 780 2020 Senior Notes 7.375 2020 — 432 Environmental Revenue Bonds 5.750 - 6.875 2019 - 2042 400 400 Fairfield Caster Lease 2022 22 24 Other capital leases and all other obligations 2019 6 1 Fourth Amended and Restated Credit Agreement Variable 2023 — — USSK Credit Agreement Variable 2023 229 — USSK credit facilities Variable 2021 — — Total debt 2,407 2,737 Less unamortized discount and debt issuance costs 26 34 Less short-term debt and long-term debt due within one year 65 3 Long-term debt $ 2,316 $ 2,700 Senior Note Repurchases and Redemption Through a series of open market purchases, U. S. Steel repurchased approximately $75 million of its 7.375% Senior Notes due 2020 at a weighted average price of 107.119 percent of par during 2018. The aggregate cash flow for the open market purchases was $80 million which included approximately $5 million of premiums. U. S. Steel redeemed the remaining $357 million of 7.375% Senior Notes due 2020 for 105.307 percent of par. The aggregate cash flow for the redemption was approximately $376 million , which included approximately $19 million of premiums. Senior Secured Note Tender and Redemption In March 2018, pursuant to a cash tender offer, U. S. Steel repurchased approximately $499 million aggregate principal amount of its outstanding 8.375% Senior Secured Notes due 2021 (2021 Senior Secured Notes). The aggregate cash outflow from the tender was approximately $538 million , which included $39 million of premiums. The remaining approximately $281 million aggregate principal amount of 2021 Senior Secured Notes was redeemed in April 2018. The aggregate cash flow from the redemption was $302 million , which included $21 million of premiums. Issuance of Senior Notes due 2026 In March 2018, U. S. Steel issued $650 million aggregate principal amount of 6.250% Senior Notes due 2026 (2026 Senior Notes). U. S. Steel received net proceeds from the offering of approximately $640 million after fees of approximately $10 million related to underwriting and third-party expenses. The net proceeds from the issuance of the 2026 Senior Notes, together with cash on hand, were used to tender or otherwise redeem all of our outstanding 2021 Senior Secured Notes as discussed above. The 2026 Senior Notes are senior and unsecured obligations that rank equally in right of payment with all of our other existing and future senior and unsecured indebtedness. U. S. Steel will pay interest on the notes semi-annually in arrears on March 15th and September 15th of each year, commencing on September 15, 2018. Similar to our other senior notes, the indenture governing the 2026 Senior Notes restricts our ability to create certain liens, to enter into sale leaseback transactions and to consolidate, merge, transfer or sell all, or substantially all of our assets. It also contains provisions requiring the purchase of the 2026 Senior Notes upon a change of control under certain specified circumstances, as well as other customary provisions. U. S. Steel may redeem the 2026 Senior Notes, in whole or in part, at our option at any time, or from time to time, on or after March 15, 2021 at the redemption price for such notes set forth below as a percentage of the principal amount, plus accrued and unpaid interest, if any, to, but excluding the redemption date, if redeemed during the twelve-month period beginning March 15 of the years indicated below: Year Redemption Price 2021 103.125 % 2022 101.563 % 2023 and thereafter 100.000 % At any time prior to March 15, 2021, U. S. Steel may also redeem up to 35% of the original aggregate principal amount of the 2026 Senior Notes at 106.25% , plus accrued and unpaid interest, if any, up to, but excluding the applicable date of redemption, with proceeds from equity offerings. Fourth Amended and Restated Credit Agreement On February 26, 2018, U. S. Steel entered into the Fourth Amended and Restated Credit Agreement (Credit Facility Agreement), replacing the Company's Third Amended and Restated Credit Agreement. The Credit Facility Agreement maintains the facility size of $1.5 billion and extends the maturity date to 2023. As of December 31, 2018 , there were no amounts drawn under the $1.5 billion Credit Facility Agreement. U. S. Steel must maintain a fixed charge coverage ratio of at least 1.00 to 1.00 for the most recent four consecutive quarters when availability under the Credit Facility Agreement is less than the greater of 10 percent of the total aggregate commitments and $150 million . Based on the most recent four quarters as of December 31, 2018 , we would have met this covenant. If we are unable to meet this covenant in future periods, the amount available to the Company under this facility would be reduced by $150 million . The Credit Facility Agreement provides for borrowings at interest rates based on defined, short-term market rates plus a spread based on availability and includes other customary terms and conditions including restrictions on our ability to create certain liens and to consolidate, merge or transfer all, or substantially all, of our assets. The Credit Facility Agreement expires in February 2023. Maturity may be accelerated 91 days prior to the stated maturity of any outstanding senior debt if excess cash and credit facility availability do not meet the liquidity conditions set forth in the Credit Facility Agreement. Borrowings are secured by liens on certain North American inventory and trade accounts receivable. U. S. Steel Košice ( USSK) credit facilities On September 26, 2018, USSK and one of its wholly owned subsidiaries, as guarantor, entered into a €460 million unsecured revolving credit facility (USSK Credit Agreement), replacing USSK's €200 million revolving credit facility (Prior Facility). The USSK Credit Agreement has a maturity date of September 26, 2023 and contains terms and conditions substantially similar to the Prior Facility. Concurrent with the execution of the USSK Credit Agreement, USSK reduced the size of a separate €40 million unsecured credit facility to €20 million . At December 31, 2018 , USSK had borrowings of €200 million (approximately $229 million ) under its €460 million (approximately $527 million ) unsecured revolving credit facility. At December 31, 2017 , USSK had no borrowings under the Prior Facility. The USSK Credit Agreement contains certain USSK financial covenants, including a maximum net debt to EBITDA ratio and a minimum stockholders' equity to assets ratio. The covenants are measured semi-annually for the period covering the last twelve calendar months and calculated as set forth in the USSK Credit Agreement. If USSK does not comply with the USSK Credit Agreement financial covenants, it may not draw on the facility until the next measurement date, outstanding borrowings may be accelerated, or the margin on outstanding borrowings may be increased. At December 31, 2018 , USSK had availability of €260 million (approximately $ 298 million ) under the USSK Credit Agreement. At December 31, 2018 , USSK had no borrowings under its €20 million and €10 million unsecured credit facilities (collectively approximately $34 million ) and the availability was approximately $32 million due to approximately $2 million of customs and other guarantees outstanding. At December 31, 2017 , USSK had no borrowings under its €40 million and €10 million unsecured credit facilities (collectively approximately $60 million ) and the availability was approximately $57 million due to approximately $3 million of customs and other guarantees outstanding. During the fourth quarter of 2018, USSK amended its €20 million and €10 million credit facilities, extending the maturity of both credit facilities to December 2021. Each of these facilities bear interest at the applicable inter-bank offer rate plus a margin and contain customary terms and conditions. Change in control event If there is a change in control of U. S. Steel: (a) debt obligations totaling $1,979 million as of December 31, 2018 may be declared due and payable; (b) the Credit Facility Agreement and the USSK credit facilities may be terminated and any amounts outstanding declared due and payable; and (c) U. S. Steel may be required to either repurchase the leased Fairfield Works slab caster for $22 million or provide a letter of credit to secure the remaining obligation. Debt Maturities – Aggregate maturities of debt are as follows (in millions): 2019 2020 2021 2022 2023 Later Total $ 65 $ 4 $ 4 $ 10 $ 229 $ 2,095 $ 2,407

Pensions and Other Benefits

Pensions and Other Benefits	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Pensions and Other Benefits	Pensions and Other Benefits U. S. Steel has defined contribution or multi-employer retirement benefits for more than three-quarters of its employees in the United States and non-contributory defined benefit pension plans covering the remaining employees. Benefits under the defined benefit pension plans are based upon years of service and final average pensionable earnings, or a minimum benefit based upon years of service, whichever is greater. In addition, pension benefits for most non-represented employees under these plans are based upon a percent of total career pensionable earnings. Effective December 31, 2015, non-represented participants in the defined benefit plan no longer accrue additional benefits under the plan. For those without defined benefit coverage (defined benefit pension plan was closed to new participants in 2003) and those for which the defined benefit plan was frozen, the Company also provides a retirement account benefit based on salary and attained age. Most non-represented employees also participate in defined contribution plans (401(k) plans) whereby the Company matches a certain percentage of salary based on the amount contributed by the participant. At December 31, 2018 , more than two-thirds of U. S. Steel’s represented employees in the United States are covered by the Steelworkers Pension Trust (SPT), a multi-employer pension plan, to which U. S. Steel contributes on the basis of a fixed dollar amount for each hour worked. On November 13, 2018, the USW ratified successor four year Collective Bargaining Agreements with U. S. Steel and its U. S. Steel Tubular Products, Inc. subsidiary (the 2018 Labor Agreements). The 2018 Labor Agreements were effective as of September 1, 2018 and expire on September 1, 2022. As a result of the 2018 Labor Agreements, the defined benefit pension liability increased $26 million after considering higher wages on final average pay formulas and higher flat rate minimum multipliers. U. S. Steel’s defined benefit retiree health care and life insurance plans (Other Benefits) cover the majority of its represented employees in the United States upon their retirement. Health care benefits are provided for Medicare and pre-Medicare retirees, with Medicare retirees largely enrolled in Medicare Advantage Plans. Both are subject to various cost sharing features, and in most cases domestically, an employer cap on total costs. The Other Benefits plan was closed to represented employees hired or rehired under certain conditions on or after January 1, 2016. Per an amendment effective June 30, 2014 to the retiree medical and retiree life insurance plan, benefits for non-represented employees who retired after December 31, 2017 were eliminated. The majority of U. S. Steel’s European employees are covered by government-sponsored programs into which U. S. Steel makes required contributions. Also, U. S. Steel sponsors defined benefit plans for most European employees covering benefit payments due to employees upon their retirement, some of which are government mandated. These same employees receive service awards throughout their careers based on stipulated service and, in some cases, age and service. U. S. Steel uses a December 31 measurement date for its plans and may have an interim measurement date if significant events occur. Details relating to Pension Benefits and Other Benefits are below. Pension Benefits Other Benefits (In millions) 2018 2017 2018 2017 Change in benefit obligations Benefit obligations at January 1 $ 6,107 $ 6,214 $ 2,379 $ 2,432 Service cost 49 50 17 17 Interest cost 233 235 92 94 Plan amendments 26 — — — Actuarial (gains) losses (223 ) 214 (185 ) 8 Exchange rate loss (3 ) 4 — — Settlements, curtailments and termination benefits (18 ) (12 ) — — Benefits paid (545 ) (598 ) (182 ) (172 ) Benefit obligations at December 31 $ 5,626 $ 6,107 $ 2,121 $ 2,379 Change in plan assets Fair value of plan at January 1 $ 5,732 $ 5,482 $ 2,042 $ 1,984 Actual return on plan assets (228 ) 773 (49 ) 171 Employer contributions — 75 — — Benefits paid from plan assets (544 ) (598 ) (133 ) (113 ) Fair value of plan assets at December 31 $ 4,960 $ 5,732 $ 1,860 $ 2,042 Funded status of plans at December 31 (666 ) (375 ) (261 ) (337 ) Amounts recognized in accumulated other comprehensive loss: 2018 (In millions) 12/31/2017 Amortization Activity 12/31/2018 Pensions Prior Service Cost $ (8 ) $ — $ 26 $ 18 Actuarial Losses 2,238 (152 ) 356 2,442 Other Benefits Prior Service Cost (51 ) (29 ) — (80 ) Actuarial Losses 41 (4 ) (54 ) (17 ) As of December 31, 2018 and 2017 , the following amounts were recognized in the Consolidated Balance Sheet: Pension Benefits Other Benefits (In millions) 2018 2017 2018 2017 Current liabilities (2 ) (4 ) (52 ) (59 ) Noncurrent liabilities (664 ) (371 ) (209 ) (278 ) Accumulated other comprehensive loss (a) 2,460 2,230 (97 ) (10 ) Net amount recognized $ 1,794 $ 1,855 $ (358 ) $ (347 ) (a) Accumulated other comprehensive loss effects associated with accounting for pensions and other benefits in accordance with ASC Topic 715 at December 31, 2018 and December 31, 2017 , respectively, are reflected net of tax of $991 million and $958 million respectively, on the Consolidated Statements of Stockholders’ Equity. The Accumulated Benefit Obligation (ABO) for all defined benefit pension plans was $5,454 million and $5,937 million at December 31, 2018 and 2017 , respectively. December 31, (In millions) 2018 2017 Information for pension plans with an accumulated benefit obligation in excess of plan assets: Aggregate accumulated benefit obligations (ABO) $ (5,454 ) $ (5,937 ) Aggregate projected benefit obligations (PBO) (5,626 ) (6,107 ) Aggregate fair value of plan assets 4,960 5,732 The aggregate PBO in excess of plan assets reflected above is included in the payroll and benefits payable and employee benefits lines on the Consolidated Balance Sheet. Following are the details of net periodic benefit costs related to Pension and Other Benefits: Pension Benefits Other Benefits (In millions) 2018 2017 2016 2018 2017 2016 Components of net periodic benefit cost: Service cost $ 49 $ 50 $ 54 $ 17 $ 17 $ 20 Interest cost 233 235 258 92 94 98 Expected return on plan assets (361 ) (390 ) (422 ) (82 ) (65 ) (151 ) Amortization - prior service costs — — 11 29 29 26 - actuarial losses 152 148 129 4 3 3 Net periodic benefit cost (benefit), excluding below 73 43 30 60 78 (4 ) Multiemployer plans (a) 60 59 63 — — — Settlement, termination and curtailment losses/(gains) 10 7 13 — — (1 ) Net periodic benefit cost (benefit) $ 143 $ 109 $ 106 $ 60 $ 78 $ (5 ) (a) Primarily represents pension expense for the SPT covering USW employees hired from National Steel Corporation and new USW employees hired after May 21, 2003. Net periodic benefit cost for pensions and other benefits is projected to be approximately $158 million and approximately $57 million , respectively, in 2019 . The pension cost projection includes approximately $66 million of contributions to the SPT. The amounts in accumulated other comprehensive income that are expected to be recognized as components of net periodic benefit cost during 2019 are as follows: (In millions) Pension Benefits 2019 Other Benefits 2019 Amortization of actuarial loss $ 131 $ 3 Amortization of prior service cost 2 29 Total recognized from accumulated other comprehensive income $ 133 $ 32 Weighted average assumptions used to determine the benefit obligation at December 31 and net periodic benefit cost for the year ended December 31 are detailed below. Pension Benefits Other Benefits 2018 2017 2018 2017 U.S. and Europe U.S. and Europe U.S. U.S. Actuarial assumptions used to determine benefit obligations at December 31: Discount rate 4.41 % 4.00 % 4.47 % 4.03 % Increase in compensation rate 2.60 % 2.60 % N/A N/A Pension Benefits 2018 2017 2016 U.S. and Europe U.S. and Europe U.S. and Europe Actuarial assumptions used to determine net periodic benefit cost for the year ended December 31: Discount rate 4.00 % 4.00 % 4.25 % Expected annual return on plan assets 6.85 % 7.25 % 7.50 % Increase in compensation rate 2.60 % 2.60 % 2.60 % Other Benefits 2018 2017 2016 U.S. U.S. U.S. Discount rate 4.03 % 4.00 % 4.25 % Expected annual return on plan assets 4.25 % 3.25 % 7.50 % Increase in compensation rate N/A 3.50 % 3.50 % The discount rate reflects the current rate at which the pension and other benefit liabilities could be effectively settled at the measurement date. In 2016 and prior years, the discount rate for our U.S. plans was determined by utilizing several AAA and AA corporate bond indices as an indication of interest rate movements and levels. In 2017, we refined our discount rate determination process for our U.S. plans by using a bond matching approach to select specific bonds that would satisfy our projected benefit payments. We believe the bond matching approach more closely reflects the process we would employ to settle our pension and other benefits obligations. For our European pension plan, the discount rate is determined using a yield curve methodology based on European bonds. The discount rate assumptions are updated annually. 2018 2017 Assumed health care cost trend rates at December 31: U.S. U.S. Health care cost trend rate assumed for next year 7.00% 7.00% Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 5.00% 5.00% Year that the rate reaches the ultimate trend rate 2023 2022 A one-percentage-point change in the assumed return on plan assets, discount rate or health care cost trend rates would have the following effects: (In millions) 1-Percentage- 1-Percentage- Expected return on plan assets Incremental (decrease) increase in: Net periodic pension & other benefits costs for 2019 $ (69 ) $ 69 Discount rate Incremental (decrease) increase in: Net periodic pension & other benefits costs for 2019 $ (18 ) $ 8 Pension & other benefits liabilities at December 31, 2018 $ (650 ) $ 770 Health care cost escalation trend rates Incremental increase (decrease) in: Other post-employment benefit obligations $ 77 $ (66 ) Service and interest costs components for 2019 $ 4 $ (3 ) U. S. Steel reviews its actual historical rate experience and expectations of future health care cost trends to determine the escalation of per capita health care costs under U. S. Steel’s benefit plans. About three quarters of our costs for the domestic USW participants’ retiree health benefits in the Company’s main domestic benefit plan are limited to a per capita dollar maximum calculation based on 2006 base year actual costs incurred under the main U. S. Steel benefit plan for USW participants (cost cap). The full effect of the cost cap is expected to be realized around 2025. After 2025, the Company’s costs for a majority of USW retirees and their dependents are expected to remain fixed and as a result, the cost impact of health care escalation for the Company is projected to be limited for this group. Plan Assets On January 1, 2016, U. S. Steel adopted Accounting Standards Update 2015-07, Fair Value Measurement (Topic 820) Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share (or Its Equivalent) (ASU 2015-07). ASU 2015-07 removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share practical expedient. ASC Topic 820 establishes a single definition of fair value, creates a three-tier hierarchy as a framework for measuring fair value based on inputs used to value the Plan's investments, and requires additional disclosure about fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (level 1) and the lowest priority to unobservable inputs (level 3). The three levels of the fair value hierarchy are summarized below: • Level 1 – Inputs to the valuation methodology are unadjusted quoted prices for identical assets or liabilities in active markets that the Plan has the ability to access. • Level 2 – Inputs to the valuation methodology include: ◦ Quoted prices for similar assets or liabilities in active markets; ◦ Quoted prices for identical or similar assets or liabilities in inactive markets; ◦ Inputs other than quoted prices that are observable for the asset or liability; ◦ Inputs that are derived principally from or corroborated by observable market data by correlation or other means If the asset or liability has a specified (contractual) term, the level 2 input must be observable for substantially the full term of the asset or liability. • Level 3 – Inputs to the valuation methodology are unobservable and significant to the fair value measurement. U. S. Steel’s Pension plan and Other Benefits plan assets are classified as follows: Level 1 Level 2 Level 3 Short-term Investments Corporate Bonds - U.S. & Non U.S. Private Equities Equity Securities - U.S. & Non U.S. Government Bonds - U.S. & Non U.S. Real Estate Exchange-traded Funds Mortgage and asset-backed securities Mineral Interests Investment Trusts Timberlands An instrument’s level is based on the lowest level of any input that is significant to the fair value measurement. Valuation techniques maximize the use of relevant observable inputs and minimize the use of unobservable inputs. The following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the methodologies used at December 31, 2018 and 2017 . Short-term investments are valued at amortized cost which approximates fair value due to the short-term maturity of the instruments. Equity securities - U.S. & Non U.S., investments in investment trusts and exchange-traded funds are valued at the closing price reported on the active exchange on which the individual securities are traded. U.S. & Non U.S. government bonds are valued using pricing models maximizing the use of observable inputs for similar securities. Corporate U.S. & Non U.S. bonds are also valued using pricing models maximizing the use of observable inputs for similar securities, which includes basing value on yields currently available on comparable securities of issuers with similar credit ratings. When quoted prices are not available for identical or similar bonds, the bond is valued under a discounted cash flow approach that maximizes observable inputs, such as current yields of similar instruments, but includes adjustments for certain risks that may not be observable, such as credit and liquidity risks. Mortgage and asset-backed securities are valued using quotes from a broker dealer. Investments in non-public investment partnerships are valued using net asset value (NAV) as a practical expedient. Private equities and real estate are valued using information provided by external managers for each individual investment held in the fund or using NAV as a practical expedient. Timberland investments are either appraised or valued using the investment managers' assessment of the assets within the fund. Mineral Interests are valued at the present value of estimated future cash flows discounted at estimated market rates for assets of similar quality and duration. The following is a summary of U. S. Steel’s Pension plan assets carried at fair value at December 31, 2018 and 2017 : Fair Value Measurements at December 31, 2018 (in millions) Total Quoted Prices in Other Significant Observable Inputs Significant Asset Classes Short-term investments $ 7 $ 7 $ — $ — Equity Securities (a) 101 101 — — Corporate & Government Bonds (b) 2,143 — 2,143 — Mineral Interests 2 — — 2 Timberlands 294 — — 294 Private equities (c) 2 — — 2 Real Estate (d) 33 — — 33 All Other (e) 14 14 — — Total assets in the fair value hierarchy $ 2,596 $ 122 $ 2,143 $ 331 Investments measured at net asset value (f) 2,364 Investments at fair value $ 4,960 (a) Includes $95 million of U.S. equity securities and $6 million of Non U.S. equity securities. (b) Underlying investments include: Corporate Bonds – U.S. $ 933 Corporate Bonds - Non U.S. 149 Government Bonds – U.S. 858 Government Bonds - Non U.S. 67 Mortgage and asset-backed securities 136 Total $ 2,143 (c) Includes investments in CAI Partners and Company III LP, Clayton Dubilier Rice Fund VI and Epiris Club 2007. (d) Includes investments in the Avanti Funds and the Mariano Ranch properties. (e) Includes $32 million of cash, $57 million of investment sales, $21 million of accrued income, $(80) million of investment purchases and $(16) million of miscellaneous payables. (f) In accordance with ASC Topic 820, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The following table represents investments based on net asset value and the significant unobservable inputs and the ranges of values for those inputs: Net Asset Value at December 31, 2018 Unfunded Commitments Redemption Frequency Redemption Notice Period Private Equity Funds (a) $ 254 $ 68 Not redeemable NA Real Estate Funds (a) 236 93 Not redeemable NA Commingled Funds 1,874 NA NA NA Investments measured at net asset value $ 2,364 (a) The remaining lives of such investments range from approximately less than 1 year to up to 10 years. Fair Value Measurements at December 31, 2017 (in millions) Total Quoted Prices in Other Significant Observable Inputs (Level 2) Significant Asset Classes Short-term investments $ 155 $ 155 $ — $ — Equity Securities - U.S. (a) 260 260 — — Corporate & Government Bonds (b) 1,806 — 1,806 — Mineral Interests 3 — — 3 Timberlands 300 — — 300 Private equities (c) 4 — — 4 Real Estate (d) 33 — — 33 All Other (e) (39 ) (39 ) — — Total assets in the fair value hierarchy $ 2,522 $ 376 1,806 $ 340 Investments measured at net asset value (f) 3,210 Investments at fair value $ 5,732 (a) Includes U. S. Steel stock. (b) Underlying investments include: Corporate Bonds – U.S. $ 1,084 Government Bonds – U.S. 720 Agency Mortgages 2 Total $ 1,806 (c) Includes investments in CAI Partners and Company III LP, Clayton Dubilier Rice Fund VI, Epiris Club 2007 and FF&P Investor 8 ERISA LP. (d) Includes investments in the Avanti Funds and the Mariano Ranch properties. (e) Includes $157 million of investment sales, $19 million of accrued income, and $(197) million of investment purchases and $(18) million of miscellaneous payables. (f) In accordance with ASC Topic 820, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The following table represents investments based on net asset value and the significant unobservable inputs and the ranges of values for those inputs: Net Asset Value at December 31, 2017 Unfunded Commitments Redemption Frequency Redemption Notice Period Private Equity Funds (a) $ 252 $ 91 Not redeemable N/A Real Estate Funds (a) 260 117 ** N/A Interest in Investment Partnerships (b) 729 N/A N/A N/A Commingled Funds 1,969 N/A N/A N/A Investments measured at net asset value $ 3,210 ** Not redeemable, except for JP Morgan Real Estate Income & Growth, which has a quarterly redemption provision. (a) The remaining lives of such investments range from approximately less than 1 year to up to 11 years. (b) Investment partnerships whose investment objectives are to achieve long-term capital appreciation by investing in global equity markets. The following table sets forth a summary of changes in the fair value of U. S. Steel’s Pension plan Level 3 assets for the years ended December 31, 2018 and 2017 (in millions): (In millions) 2018 2017 Balance at beginning of period $ 340 $ 357 Transfers in and/or out of Level 3 — — Actual return on plan assets: Realized gain 11 2 Net unrealized loss (8 ) (16 ) Purchases, sales, issuances and settlements: Sales (12 ) (3 ) Balance at end of period $ 331 $ 340 The following is a summary of U. S. Steel’s Other Benefits plan assets carried at fair value at December 31, 2018 and 2017 . Fair Value Measurements at December 31, 2018 (in millions) Total Quoted Prices in Other Significant Observable Inputs (Level 2) Significant Asset Classes Short-term investments $ 42 $ 42 — $ — Equity Securities (a) 45 45 — — Corporate & Government Bonds (b) 1,631 — 1,631 — Timberlands 35 — — 35 All Other (c) 13 13 — — Total assets in the fair value hierarchy $ 1,766 $ 100 $ 1,631 $ 35 Investments measured at net asset value (d) 94 Investments at fair value $ 1,860 (a) Includes $27 million of U.S. equity securities and $18 million of Non U.S. equity securities. (b) Underlying investments include: Corporate Bonds – U.S. $ 1,052 Corporate Bonds - Non U.S. 271 Government Bonds – U.S. 270 Government Bonds - Non U.S. 8 Mortgage and asset-backed securities 30 Total $ 1,631 (c) Includes $16 million of accrued income and $(3) million of investment purchase payables. (d) In accordance with Subtopic 820-10, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The following table represents investments based on net asset value and the significant unobservable inputs and the ranges of values for those inputs: Net Asset Value at December 31, 2018 Unfunded Commitments Redemption Frequency Redemption Notice Period Private Equity Funds (a) $ 61 $ 10 Not redeemable NA Real Estate Funds (a) 33 12 Not redeemable NA Investments measured at net asset value $ 94 (a) The remaining lives of such investments range from approximately less than 1 year up to 10 years. Fair Value Measurements at December 31, 2017 (in millions) Total Quoted Prices in Other Significant Observable Inputs (Level 2) Significant Asset Classes Short-term investments 54 54 — — Equity Securities - U.S. 29 29 — — Corporate Bonds - U.S. 1,455 — 1,455 — Government bonds - U.S. 323 — 323 — Timberlands 34 — — 34 Private equities (a) 1 — — 1 All Other (b) 39 39 — — Total assets in the fair value hierarchy $ 1,935 $ 122 1,778 $ 35 Investments measured at net asset value (c) 107 Investments at fair value $ 2,042 (a) Includes investment in Epiris Club 2007 (formerly Electra Partners Club 2007 LP) and FF&P Investor 8 ERISA LP. (b) Includes $23 million of investment sales, $17 million of accrued income and $(1) million of investment purchase payables. (c) In accordance with Subtopic 820-10, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy. The following table represents investments based on net asset value and the significant unobservable inputs and the ranges of values for those inputs: Net Asset Value at December 31, 2017 Unfunded Commitments Redemption Frequency Redemption Notice Period Private Equity Funds (a) $ 62 $ 15 Not redeemable N/A Real Estate Funds (a) 33 15 ** N/A Interest in Investment Partnerships (b) 12 N/A N/A N/A Investments measured at net asset value $ 107 ** Not redeemable, except for JP Morgan U.S. Real Estate Income & Growth, which has a quarterly redemption provision. (a) The remaining lives of such investments range from approximately less than 1 year to up to 11 years. (b) Investment partnerships whose investment objectives are to achieve long-term capital appreciation by investing in global equity markets. The following table sets forth a summary of changes in the fair value of U. S. Steel’s Other Benefits plan Level 3 assets for the years ended December 31, 2018 and 2017 (in millions): (In millions) 2018 2017 Balance at beginning of period $ 35 $ 38 Transfers in and/or out of Level 3 — — Actual return on plan assets: Realized gain 1 — Net unrealized loss (1 ) (2 ) Purchases, sales, issuances and settlements: Sales — (1 ) Balance at end of period $ 35 $ 35 U. S. Steel’s investment strategy for its U.S. pension and other benefits plan assets provides for a diversified mix of high quality bonds, public equities and selected smaller investments in private equities, timber and mineral interests. For its U.S. pension, U. S. Steel has a target allocation for plan assets of 45 percent in corporate bonds, government bonds and mortgage and asset-backed securities. The balance is invested in equity securities, timber, private equity and real estate partnerships. U. S. Steel believes that returns on equities over the long term will be higher than returns from fixed-income securities as actual historical returns from U. S. Steel’s trusts have shown. Returns on bonds tend to offset some of the short-term volatility of stocks. Both equity and fixed-income investments are made across a broad range of industries and companies (both domestic and foreign) to provide protection against the impact of volatility in any single industry as well as company specific developments. U. S. Steel will use a 6.50 percent assumed rate of return on assets for the development of net periodic cost for the main defined benefit pension plan in 2019 . The 2019 assumed rate of return is lower than the rate of return used for 2018 domestic expense and was determined by taking into account the intended asset mix and some moderation of the historical premiums that fixed-income and equity investments have yielded above government bonds. Actual returns since the inception of the plan have exceeded this 6.50 percent rate and while recent annual returns have been volatile, it is U. S. Steel’s expectation that rates will achieve this level in future periods. For its Other Benefits Plan, U. S. Steel is now employing a liability driven investment strategy. The plan assets are allocated to match the plan cash flows with maturing investments. To achieve this strategy, U. S. Steel has a target allocation for plan assets of 90 percent in high quality bonds with the balance primarily invested in equity securities, timber, private equity and real estate partnerships. U. S. Steel will use a 4.25 percent assumed rate of return on assets for the development of net periodic cost for its Other Benefits Plan. The 2019 assumed rate of return has been conservatively set, taking into account the intended asset mix. Steelworkers Pension Trust For most bargaining unit employees participating in the SPT, U. S. Steel contributes to the SPT a fixed dollar amount for each hour worked of $2.65 through December 31, 2018. Please see Note 28 for increases to the fixed dollar contribution amount that are included in the 2018 Labor Agreement. U. S. Steel’s contributions to the SPT represented greater than 5% of the total combined contributions of all employers participating in the plan for the years ended December 31, 2018 , 2017 and 2016 . Participation in a multi-employer pension plan agreed to under the terms of a collective bargaining agreement differ from a traditional qualified single employer defined benefit pension plan. The SPT shares risks associated with the plan in the following respects: a. Contributions to the SPT by U. S. Steel may be used to provide benefits to employees of other participating employers; b. If a participating employer stops contributing to the SPT, the unfunded obligations of the plan may be borne by the remaining participating employers; c. If U. S. Steel chooses to stop participating in the SPT, U. S. Steel may be required to pay an amount based on the underfunded status of the plan, referred to as a withdrawal liability. On March 21, 2011 the Board of Trustees of the SPT elected funding relief which has the effect of decreasing the amount of required minimum contributions in near-term years, but will increase the minimum funding requirements during later plan years. As a result of the election of funding relief, the SPT’s zone funding under the Pension Protection Act may be impacted. In addition to the funding relief election, the Board of Trustees also elected a special amortization rule, which allows the SPT to separately amortize investment losses incurred during the SPT’s December 31, 2008 plan year-end over a 29 year period, whereas they were previously required to be amortized over a 15 year period. U. S. Steel’s participation in the SPT for the annual periods ended December 31, 2018 , 2017 and 2016 is outlined in the table below. Employer Pension Protection Act Zone (a) FIP/RP Status (b) U.S. Steel Surcharge (c) Expiration Date Pension Fund 2018 2017 2018 2017 2016 2018 2017 Steelworkers Pension Trust 23-6648508/499 Green Green No $ 60 $ 59 $ 63 No No September 1, 2022 (a) The zone status is based on information that U. S. Steel received from the plan and is certified by the plan’s actuary. Among other factors, plans in the green zone are at least 80 percent funded, while plans in the yellow zone are less than 80 percent funded and plans in the red zone are less than 65 percent funded. (b) Indicates if a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented. (c) Indicates whether there were charges to U. S. Steel from the plan. Cash Flows Employer Contributions – U. S. Steel did not make any voluntary contributions to the pension plan in 2018. In addition to the contributions to the SPT noted in the table above, on November 20, 2017, U. S. Steel made a voluntary contribution of $75 million to the U. S. Steel Retirement Plan Trust, which is the funding vehicle for the Company's main defined pension plan. In 2016, U. S. Steel made a voluntary contribution of 3,763,643 shares of common stock (the shares), par value of $1.00 per share, to the U. S. Steel Retirement Plan Trust. The shares were valued by an independent valuation firm for the purposes of the contribution at $26.57 per share, or approximately $100 million in the aggregate, which was the closing price of the Company's common stock on August 1, 2016. For pension plans not funded by trusts, U. S. Steel made $20 million , $13 million and $26 million of pension payments not funded by trusts in 2018 , 2017 and 2016 , respectively. Cash payments totaling $48 million , $59 million and $61 million were made for other post-employment benefit payments not funded by trusts in 2018 , 2017 and 2016 , respectively. In 2018 and 2017, U. S. Steel continued to use assets from our trust for represented retiree health care and life insurance benefits to pay USW post-employment benefit claims. Estimated Future Benefit Payments – The following benefit payments, which reflect expected future service as appropriate, are expected to be paid from U. S. Steel’s defined benefit plans: (In millions) Pension Other 2019 $ 498 $ 164 2020 470 184 2021 453 186 2022 440 186 2023 426 185 Years 2024 - 2027 1,962 755 Defined contribution plans U. S. Steel also contributes to several defined contribution plans for its salaried employees. Effective December 31, 2015, all non-represented salaried employees in North America receive pension benefits through a defined contribution pension plan with contribution percentages based upon age, for which company contributions totaled $23 million , $22 million and $23 million in 2018 , 2017 and 2016 , respectively. U. S. Steel’s matching contributions to salaried employees’ defined contribution savings fund plans, which for the most part are based on a percentage of the employees’ contributions, totaled $17 million each year for 2018 , 2017 and 2016 . U. S. Steel also maintains non-qualified defined contribution plans to provide benefits which are otherwise limited by the Internal Revenue Service for qualified plans. U. S. Steel’s contributions under these defined contribution plans totaled $4 million in 2018 , and $1 million each year for 2017 and 2016 . Most represented employees are eligible to participate in a defined contribution savings fund plan where there is no company match on savings except for certain Tubular hourly employees. Effective with the 2015 Labor Agreement, represented hires on or after January 1, 2016 are eligible for a $0.50 per hour savings account contribution. As a result of the 2018 Labor Agreement, increases to the savings account contribution for each hour worked will increase to $0.55 effective January 1, 2019, $0.60 effective January 1, 2020, and $0.65 effective January 1, 2021. These company contributions for represented employees totaled $ 2 million in 2018 and $1 million each year for 2017 and 2016 . Other post-employment benefits The Company provides benefits to former or inactive employees after employment but before retirement. Certain benefits including workers’ compensation and black lung benefits represent material obligations to the Company and under the guidance for nonretirement post-employment benefits, have historically been treated as accrued benefit obligations. Liabilities for these benefits reco

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations U. S. Steel’s asset retirement obligations (AROs) primarily relate to mine, landfill closure and post-closure costs. The following table reflects changes in the carrying values of AROs for the years ended December 31, 2018 and 2017 : December 31, (In millions) 2018 2017 Balance at beginning of year $ 69 $ 79 Obligations settled (12 ) (8 ) Change in estimate of obligations — (6 ) Foreign currency translation effects — 2 Accretion expense 3 2 Balance at end of period $ 60 $ 69 Certain AROs related to disposal costs of the majority of fixed assets at our integrated steel facilities have not been recorded because they have an indeterminate settlement date. These AROs will be initially recognized in the period in which sufficient information exists to estimate their fair value.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying value of cash and cash equivalents, current accounts and notes receivable, accounts payable, bank checks outstanding, and accrued interest included in the Consolidated Balance Sheet approximate fair value. See Note 16 for disclosure of U. S. Steel’s derivative instruments, which are accounted for at fair value on a recurring basis. The following table summarizes U. S. Steel’s financial assets and liabilities that were not carried at fair value at December 31, 2018 and 2017 . December 31, 2018 December 31, 2017 (In millions) Fair Value Carrying Fair Value Carrying Financial liabilities: Long-term debt (a) $ 2,182 $ 2,353 $ 2,851 $ 2,678 (a) Excludes capital lease obligations. The following methods and assumptions were used to estimate the fair value of financial instruments included in the table above: Long-term debt : Fair value was determined using Level 2 inputs which were derived from quoted market prices and is based on the yield on public debt where available or current borrowing rates available for financings with similar terms and maturities. Fair value of the financial assets and liabilities disclosed herein is not necessarily representative of the amount that could be realized or settled, nor does the fair value amount consider the tax consequences of realization or settlement. Financial guarantees are U. S. Steel’s only unrecognized financial instrument. For details relating to financial guarantees see Note 26.

Reclassifications from Accumula

Reclassifications from Accumulated Other Comprehensive Income (AOCI)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Reclassifications from Accumulated Other Comprehensive Income (AOCI)	Reclassifications from Accumulated Other Comprehensive Income (AOCI) (In millions) (a) Pension and Other Benefit Items Foreign Currency Items Unrealized Gain (Loss) on Derivatives Total Balance at December 31, 2016 $ (1,771 ) $ 274 $ — $ (1,497 ) Other comprehensive income before reclassifications 640 189 5 834 Amounts reclassified from AOCI (b) (187 ) — (4 ) (191 ) Sale of ownership interest in Tilden Mining Company L.C. 9 — — 9 Net current-period other comprehensive income 462 189 1 652 Balance at December 31, 2017 $ (1,309 ) $ 463 $ 1 $ (845 ) Other comprehensive income (loss) before reclassifications 41 (60 ) — (19 ) Amounts reclassified from AOCI (b) (148 ) — (14 ) (162 ) Net current-period other comprehensive loss (107 ) (60 ) (14 ) (181 ) Balance at December 31, 2018 $ (1,416 ) $ 403 $ (13 ) $ (1,026 ) (a) Amounts in 2017 and 2016 do not reflect a tax benefit as a result of a full valuation allowance on our domestic deferred tax assets. (b) See table below for further details. Amount reclassified (In millions) (a) Details about AOCI components 2018 2017 2016 Amortization of pension and other benefit items Prior service costs (a) $ (29 ) $ (29 ) $ (37 ) Actuarial losses (a) (156 ) (151 ) (132 ) Settlements, termination and curtailment losses (a) (10 ) (7 ) (12 ) Total pensions and other benefits items (195 ) (187 ) (181 ) Derivative reclassifications to Consolidated Statements of Operations (19 ) (4 ) (18 ) Total before tax (214 ) (191 ) (199 ) Tax benefit (b) 52 — — Net of tax $ (162 ) $ (191 ) $ (199 ) (a) These AOCI components are included in the computation of net periodic benefit cost (see Note 18 for additional details). (b) Amounts in 2017 and 2016 do not reflect a tax benefit as a result of a full valuation allowance on our domestic deferred tax assets.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Year Ended December 31, (In millions) 2018 2017 2016 Net cash used in operating activities included: Interest and other financial costs paid (net of amount capitalized) $ (207 ) $ (242 ) $ (193 ) Income taxes paid $ (39 ) $ (40 ) $ (6 ) Non-cash investing and financing activities: Change in accrued capital expenditures $ 135 $ 208 $ (110 ) U. S. Steel common stock issued for employee/non-employee director stock plans $ 21 $ 49 $ 32 U. S. Steel common stock issued for defined benefit pension plans $ — $ — $ 100

Transactions with Related Parti

Transactions with Related Parties	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Transactions with Related Parties	Transactions with Related Parties Net sales to related parties and receivables from related parties primarily reflect sales of raw materials and steel products to equity investees and USSC after the Canada's Companies' Creditors Arrangement Act (CCAA) filing on September 16, 2014, but before the sale to an affiliate of Bedrock on June 30, 2017. Generally, transactions are conducted under long-term contractual arrangements. Related party sales and service transactions were $1,420 million , $1,204 million and $1,216 million in 2018 , 2017 and 2016 , respectively. Purchases from related parties for outside processing services provided by equity investees and USSC after the CCAA filing on September 16, 2014, but before the sale to an affiliate of Bedrock on June 30, 2017, amounted to $29 million , $70 million and $80 million during 2018 , 2017 and 2016 , respectively. Purchases of iron ore pellets from related parties amounted to $91 million , $140 million and $177 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Accounts payable to related parties include balances due to PRO-TEC Coating Company (PRO-TEC) of $80 million and $72 million at December 31, 2018 and 2017 , respectively for invoicing and receivables collection services provided by U. S. Steel on PRO-TEC's behalf. U. S. Steel, as PRO-TEC’s exclusive sales agent, is responsible for credit risk related to those receivables. U. S. Steel also provides PRO-TEC marketing, selling and customer service functions. Payables to other related parties totaled $1 million and $2 million at December 31, 2018 and 2017 , respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Leases	Leases Future minimum commitments for capital leases (including sale-leasebacks accounted for as financings) and for operating leases having initial non-cancelable lease terms in excess of one year are as follows: (In millions) Capital Operating 2019 $ 5 $ 66 2020 5 55 2021 5 45 2022 11 37 2023 — 28 Later years — 72 Total minimum lease payments $ 26 $ 303 Less imputed interest costs 4 Present value of net minimum lease payments included in long-term debt (see Note 17) $ 22 Operating lease rental expense: Year Ended December 31, (In millions) 2018 2017 2016 Minimum rentals $ 114 $ 114 $ 115 Contingent rentals 19 10 8 Net rental expense $ 133 $ 124 $ 123 U. S. Steel leases a wide variety of facilities and equipment under operating leases, including land and building space, office equipment, production equipment and transportation equipment. Most long-term leases include renewal options and, in certain leases, purchase options. See the discussion of residual value guarantees under “Other contingencies” in Note 26. Contingent rental payments are determined based on operating lease agreements that include floating rental charges that are directly associated to variable operating components.

Restructuring and Other Charges

Restructuring and Other Charges	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring and Other Charges	Restructuring and Other Charges During 2018, restructuring charges recorded were immaterial. Cash payments were made related to severance and exit costs of $21 million . During 2017, U. S. Steel recorded net restructuring charges of approximately $31 million , which consists of charges of $37 million primarily related to the permanent shutdown and relocation of the No. 6 Quench & Temper Mill at Lorain Tubular Operations and a favorable adjustment of $6 million primarily associated with a change in estimate for previously recorded costs for environmental obligations and Company-wide headcount reductions. Cash payments were made related to severance and exit costs of $32 million . During 2016, U. S. Steel recorded net restructuring charges of approximately $122 million , which consists of: (1) charges of $124 million related to the permanent shutdown of the Lorain #4, Lone Star #1 and Bellville pipe mills within our Tubular segment; (2) charges of $24 million for Company-wide headcount reductions, including within our Flat-Rolled, Tubular and USSE segments; and (3) a favorable adjustment of $26 million primarily associated with a change in estimate for previously recorded costs for Company-wide headcount reductions. Cash payments were made related to severance and exit costs of $79 million . Charges for restructuring and ongoing cost reduction initiatives are recorded in the period U. S. Steel commits to a restructuring or cost reduction plan, or executes specific actions contemplated by the plan and all criteria for liability recognition have been met. Charges related to the restructuring and cost reductions are reported in restructuring and other charges in the Consolidated Statements of Operations. The activity in the accrued balances incurred in relation to restructuring and other cost reduction programs during the years ended December 31, 2018 and December 31, 2017 were as follows: (in millions) Employee Related Costs Exit Costs Non-cash Charges Total Balance at December 31, 2016 $ 14 $ 60 $ — $ 74 Additional charges 2 — 35 (a) 37 Cash payments/utilization (8 ) (24 ) (35 ) (67 ) Other adjustments and reclasses (4 ) (2 ) — (6 ) Balance at December 31, 2017 $ 4 $ 34 $ — $ 38 Cash payments/utilization (4 ) (17 ) — (21 ) Balance at December 31, 2018 $ — $ 17 $ — $ 17 (a) Charges are primarily related to the write down of assets associated with the permanent shutdown of the No. 6 Quench & Temper Mill at Lorain Tubular Operations. Accrued liabilities for restructuring and other cost reduction programs are included in the following balance sheet lines: (in millions) December 31, 2018 December 31, 2017 Accounts payable $ 11 $ 26 Payroll and benefits payable — 4 Deferred credits and other noncurrent liabilities 6 8 Total $ 17 $ 38

Contingencies and Commitments

Contingencies and Commitments	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingencies and Commitments	Contingencies and Commitments U. S. Steel is the subject of, or party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Certain of these matters are discussed below. The ultimate resolution of these contingencies could, individually or in the aggregate, be material to the Consolidated Financial Statements. However, management believes that U. S. Steel will remain a viable and competitive enterprise even though it is possible that these contingencies could be resolved unfavorably. U. S. Steel accrues for estimated costs related to existing lawsuits, claims and proceedings when it is probable that it will incur these costs in the future and the costs are reasonably estimable. Asbestos matters – As of December 31, 2018 , U. S. Steel was a defendant in approximately 755 active cases involving approximately 2,320 plaintiffs. The vast majority of these cases involve multiple defendants. About 1,540 , or approximately 66 percent , of these plaintiff claims are currently pending in jurisdictions which permit filings with massive numbers of plaintiffs. At December 31, 2017 , U. S. Steel was a defendant in approximately 820 cases involving approximately 3,315 plaintiffs. Based upon U. S. Steel’s experience in such cases, it believes that the actual number of plaintiffs who ultimately assert claims against U. S. Steel will likely be a small fraction of the total number of plaintiffs. The following table shows the number of asbestos claims in the current year and the prior two years: Period ended Opening Claims (a) New Closing December 31, 2016 3,315 225 250 3,340 December 31, 2017 3,340 275 250 3,315 December 31, 2018 3,315 1,285 290 2,320 (a) The period ending December 31, 2018 includes approximately 1,000 dismissed cases previously pending in the State of Texas. Historically, asbestos-related claims against U. S. Steel fall into three groups: (1) claims made by persons who allegedly were exposed to asbestos on the premises of U. S. Steel facilities; (2) claims made by persons allegedly exposed to products manufactured by U. S. Steel; and (3) claims made under certain federal and maritime laws by employees of former operations of U. S. Steel. The amount U. S. Steel accrues for pending asbestos claims is not material to U. S. Steel’s financial condition. However, U. S. Steel is unable to estimate the ultimate outcome of asbestos-related claims due to a number of uncertainties, including: (1) the rates at which new claims are filed, (2) the number of and effect of bankruptcies of other companies traditionally defending asbestos claims, (3) uncertainties associated with the variations in the litigation process from jurisdiction to jurisdiction, (4) uncertainties regarding the facts, circumstances and disease process with each claim, and (5) any new legislation enacted to address asbestos-related claims. Further, U. S. Steel does not believe that an accrual for unasserted claims is required. At any given reporting date, it is probable that there are unasserted claims that will be filed against the Company in the future. In the current year, the Company engaged an outside valuation consultant to assist in assessing its ability to estimate an accrual for unasserted claims. This assessment was based on the Company's settlement experience, including recent claims trends. The analysis focused on settlements made over the last several years as these claims are likely to best represent future claim characteristics. After review by the valuation consultant and U. S. Steel management, it was determined that the Company could not estimate an accrual for unasserted claims. Despite these uncertainties, management believes that the ultimate resolution of these matters will not have a material adverse effect on U. S. Steel’s financial condition. Environmental Matters – U. S. Steel is subject to federal, state, local and foreign laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites. Penalties may be imposed for noncompliance. Changes in accrued liabilities for remediation activities where U. S. Steel is identified as a named party are summarized in the following table: Year Ended December 31, (In millions) 2018 2017 Beginning of period $ 179 $ 179 Accruals for environmental remediation deemed probable and reasonably estimable 14 8 Obligations settled (6 ) (8 ) End of period $ 187 $ 179 Accrued liabilities for remediation activities are included in the following Consolidated Balance Sheet lines: (In millions) December 31, 2018 December 31, 2017 Accounts payable $ 37 $ 29 Deferred credits and other noncurrent liabilities 150 150 Total $ 187 $ 179 Expenses related to remediation are recorded in cost of sales and were immaterial for the years ended December 31, 2018 , December 31, 2017 and December 31, 2016 . It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties that may be imposed. Due to uncertainties inherent in remediation projects and the associated liabilities, it is reasonably possible that total remediation costs for active matters may exceed the accrued liabilities by as much as 15 to 25 percent . Remediation Projects U. S. Steel is involved in environmental remediation projects at or adjacent to several current and former U. S. Steel facilities and other locations that are in various stages of completion ranging from initial characterization through post-closure monitoring. Based on the anticipated scope and degree of uncertainty of projects, we categorize projects as follows: (1) Projects with Ongoing Study and Scope Development – Projects which are still in the development phase. For these projects, the extent of remediation that may be required is not yet known, the remediation methods and plans are not yet developed, and/or cost estimates cannot be determined. Therefore, significant costs, in addition to the accrued liabilities for these projects, are reasonably possible. There are five environmental remediation projects where additional costs for completion are not currently estimable, but could be material. These projects are at Fairfield Works, Lorain Tubular, USS-POSCO Industries (UPI), the Fairless Plant, and the former steelmaking plant at Joliet, Illinois. As of December 31, 2018 , accrued liabilities for these projects totaled $1 million for the costs of studies, investigations, interim measures, design and/or remediation. It is reasonably possible that additional liabilities associated with future requirements regarding studies, investigations, design and remediation for these projects could be as much as $25 million to $40 million . (2) Significant Projects with Defined Scope – Projects with significant accrued liabilities with a defined scope. As of December 31, 2018 , there are four significant projects with defined scope greater than or equal to $5 million each, with a total accrued liability of $144 million . These projects are: Gary Resource Conservation and Recovery Act (RCRA) (accrued liability of $25 million ), the former Geneva facility (accrued liability of $62 million ), the Cherryvale Zinc site (accrued liability of $11 million ) and the former Duluth facility St. Louis River Estuary (accrued liability of $46 million ). (3) Other Projects with a Defined Scope – Projects with relatively small accrued liabilities for which we believe that, while additional costs are possible, they are not likely to be significant, and also include those projects for which we do not yet possess sufficient information to estimate potential costs to U. S. Steel. There are two other environmental remediation projects which each had an accrued liability of between $1 million and $5 million . The total accrued liability for these projects at December 31, 2018 was $4 million . These projects have progressed through a significant portion of the design phase and material additional costs are not expected. The remaining environmental remediation projects have an accrued liability of less than $1 million each. The total accrued liability for these projects at December 31, 2018 was approximately $5 million . We do not foresee material additional liabilities for any of these sites. Post-Closure Costs – Accrued liabilities for post-closure site monitoring and other costs at various closed landfills totaled $22 million at December 31, 2018 and were based on known scopes of work. Administrative and Legal Costs – As of December 31, 2018 , U. S. Steel had an accrued liability of $10 million for administrative and legal costs related to environmental remediation projects. These accrued liabilities were based on projected administrative and legal costs for the next three years and do not change significantly from year to year. Capital Expenditures – For a number of years, U. S. Steel has made substantial capital expenditures to comply with various regulations, laws, and other requirements relating to the environment. In 2018 and 2017 , such capital expenditures totaled $125 million and $52 million , respectively. U. S. Steel anticipates making additional such expenditures in the future, which may be material; however, the exact amounts and timing of such expenditures are uncertain because of the continuing evolution of specific regulatory requirements. EU Environmental Requirements – Under the Emission Trading Scheme (ETS), USSK's final allocation of free allowances for the Phase III period, which covers the years 2013 through 2020 is 48 million allowances. We estimate a shortfall of approximately 15 million allowances for the Phase III period. Based on projected total production level during Phase III, we started to purchase allowances in the third quarter of 2017 to meet the annual compliance submission in the future. As of December 31, 2018 , we have purchased 11 million European Union Allowances (EUA) totaling €118 million (approximately $135 million ). However, due to a number of variables such as the future market value of allowances, future production levels and future emissions intensity levels, we cannot reliably estimate the full cost of complying with the ETS regulations at this time. The EU's Industry Emission Directive requires implementation of EU determined best available techniques (BAT) for Iron and Steel production to reduce environmental impacts as well as compliance with BAT associated emission levels. Our most recent broad estimate of future capital expenditures for projects that go beyond BAT requirements is €138 million (approximately $158 million ) over the 2017 to 2020 program period. These costs may be mitigated if USSK complies with certain financial covenants, which are assessed annually. USSK complied with these covenants as of December 31, 2018. If we are unable to meet these covenants in the future, USSK might be required to provide additional collateral (e.g. bank guarantee) to secure the full value of estimated expenditures. There could be increased operating costs associated with these projects, such as increased energy and maintenance costs. We are currently unable to reliably estimate what the increase in operating costs will be as many projects are still in the development stage. Due to other EU legislation, BAT for Large Combustion Plants (LCP), we were required to make changes to the boilers at our steam and power generation plant in order to comply with stricter air emission limits for large combustion plants. The requirements for LCP resulted in the construction of a new boiler and certain upgrades to our existing boilers. In January 2014, the operation of USSK's boilers was approved by the European Commission (EC) as part of Slovakia's Transitional National Plan (TNP) for bringing all boilers in Slovakia into compliance by no later than 2020. The TNP establishes emissions ceilings for each category of emissions (total suspended particulate, sulfur dioxide (SO 2 ), and nitrogen oxide (NOx)). The allowable amount of discharged emissions from existing boilers will decrease each year until mid-2020. These projects will result in a reduction in electricity, emissions, and operating, maintenance and waste disposal costs. The construction of the new boiler is complete with a total final installed cost of €128 million (approximately $147 million ). Environmental indemnifications – Throughout its history, U. S. Steel has sold numerous properties and businesses and many of these sales included indemnifications and cost sharing agreements related to the assets that were divested. These indemnifications and cost sharing agreements have included provisions related to the condition of the property, the approved use, certain representations and warranties, matters of title, and environmental matters. While most of these provisions have not specifically dealt with environmental issues, there have been transactions in which U. S. Steel indemnified the buyer for clean-up or remediation costs relating to the business sold or its then existing conditions or past practices related to non-compliance with environmental laws. Most of the recent indemnification and cost sharing agreements are of a limited nature, only applying to non-compliance with past and/or current laws. Some indemnifications and cost sharing agreements only run for a specified period of time after the transactions close and others run indefinitely. In addition, current owners or operators of property formerly owned or operated by U. S. Steel may have common law claims and cost recovery and contribution rights against U. S. Steel related to environmental matters. The amount of potential environmental liability associated with these transactions and properties is not estimable due to the nature and extent of the unknown conditions related to the properties divested and deconsolidated. Aside from the environmental liabilities already recorded as a result of these transactions due to specific environmental remediation activities and cases (included in the $187 million of accrued liabilities for remediation discussed above), there are no other known environmental liabilities related to these transactions. Guarantees – The maximum guarantees of the indebtedness and other obligations of unconsolidated entities of U. S. Steel totaled $4 million at December 31, 2018 . Other contingencies – Under certain operating lease agreements covering various equipment, U. S. Steel has the option to renew the lease or to purchase the equipment at the end of the lease term. If U. S. Steel does not exercise the purchase option by the end of the lease term, U. S. Steel guarantees a residual value of the equipment as determined at the lease inception date (totaling approximately $17 million at December 31, 2018 ). No liability has been recorded for these guarantees as the potential loss is not probable. Insurance – U . S. Steel maintains insurance for certain property damage, equipment, business interruption and general liability exposures; however, insurance is applicable only after certain deductibles and retainages. U. S. Steel is self-insured for certain other exposures including workers’ compensation (where permitted by law) and auto liability. Liabilities are recorded for workers’ compensation and personal injury obligations. Other costs resulting from losses under deductible or retainage amounts or not otherwise covered by insurance are charged against income upon occurrence. U. S. Steel uses surety bonds, trusts and letters of credit to provide whole or partial financial assurance for certain obligations such as workers’ compensation. The total amount of active surety bonds, trusts and letters of credit being used for financial assurance purposes was approximately $181 million as of December 31, 2018 , which reflects U. S. Steel’s maximum exposure under these financial guarantees, but not its total exposure for the underlying obligations. A significant portion of our trust arrangements and letters of credit are collateralized by our Fourth Amended and Restated Credit Agreement. The remaining trust arrangements and letters of credit are collateralized by restricted cash. Restricted cash, which is recorded in other current and noncurrent assets, totaled $40 million and $44 million at December 31, 2018 and December 31, 2017 respectively. Capital Commitments – At December 31, 2018 , U. S. Steel’s contractual commitments to acquire property, plant and equipment totaled $601 million . Contractual Purchase Commitments – U. S. Steel is obligated to make payments under contractual purchase commitments, including unconditional purchase obligations. Payments for contracts with remaining terms in excess of one year are summarized below (in millions): 2019 2020 2021 2022 2023 Later years Total $842 $484 $310 $310 $296 $582 $2,824 The majority of U. S. Steel’s unconditional purchase obligations relates to the supply of industrial gases, and certain energy and utility services with terms ranging from two to 15 years. Unconditional purchase obligations also include coke and steam purchase commitments related to a coke supply agreement with Gateway Energy & Coke Company LLC (Gateway) under which Gateway is obligated to supply a minimum volume of the expected targeted annual production of the heat recovery coke plant, and U. S. Steel is obligated to purchase the coke from Gateway at the contract price. As of December 31, 2018 , if U. S. Steel were to terminate the agreement, it may be obligated to pay in excess of $142 million . Total payments relating to unconditional purchase obligations were approximately $600 million in 2018 , $576 million in 2017 and $457 million in 2016 .

Common Stock Repurchase Program

Common Stock Repurchase Program and Common Stock Issuance	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Common Stock Repurchase Program and Common Stock Issuance	Common Stock Repurchase Program and Common Stock Issuance In November 2018, U. S. Steel announced a common stock repurchase program that allows for the repurchase of up to $300 million of its outstanding common stock from time to time in the open market or privately negotiated transactions over the next two years at the discretion of management. During 2018, U. S. Steel repurchased 2,760,112 shares of common stock for approximately $75 million under this program. Additionally, during January of 2019, U. S. Steel repurchased 1,313,982 shares of common stock for approximately $25 million under this program. In August 2016, the Company issued 21,735,000 shares of common stock, par value of $1.00 per share, at a price of $23.00 per share in an underwritten public offering. Third-party expenses related to the issuance of approximately $18 million were recorded as a decrease to additional paid-in capital, resulting in net proceeds of approximately $482 million .

2018 Labor Agreements

2018 Labor Agreements	12 Months Ended
	Dec. 31, 2018
Risks and Uncertainties [Abstract]
2018 Labor Agreements	2018 Labor Agreements Effective September 1, 2018, U. S. Steel and its U. S. Steel Seamless Tubular Operations, LLC and U. S. Steel Tubular Products, Inc. subsidiaries reached new labor agreements with the United Steelworkers (USW) covering approximately 14,000 employees at our flat-rolled, tubular, cokemaking and iron ore operations in the United States (2018 Labor Agreements). The 2018 Labor Agreements expire on September 1, 2022. The 2018 Labor Agreements include a signing bonus (which was paid in December of 2018) and annual wage increases of 4% , 3.5% , 3.5% and 3% effective September 1, 2018, 2019, 2020 and 2021, respectively. Additionally, the 2018 Labor Agreements provide for certain employee benefit modifications to our defined benefit pension plan (see Note 18) and increases to the contribution rate per hour to our multiemployer plan covering certain USW employees from $2.65 per hour to $3.15 , $3.35 , and $3.50 per hour effective January 1, 2019, 2020 and 2021, respectively. During the fourth quarter of 2018, U. S. Steel recorded a charge of approximately $81 million for the 2018 Labor Agreements signing bonus and related costs.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On February 4, 2019, U. S. Steel announced plans to restart the No. 1 Electric-Weld Pipe mill (No. 1 mill) at Lone Star Tubular Operations in Lone Star, Texas. The No. 1 mill was idled in 2016. The restart of the No. 1 mill is in response to the growing energy market and will enable U. S. Steel to provide full-body normalized electric-welded pipe in size ranges 7" to 16" outside diameter for customers across the U.S., including the very active Permian Basin. The restart process is expected to be complete in the third quarter of 2019, and restart costs are not expected to be material. On February 11, 2019, U. S. Steel announced plans to restart the delayed electric arc furnace (EAF) capital project located in Fairfield, Alabama. The restart of the project is in response to positive market conditions and support from the USW in the form of a new agreement. The investment to complete the EAF, which includes modernization of the existing rounds caster, is expected to be approximately $215 million . The EAF will have an annual capacity of approximately 1.6 million tons and is expected to commence startup in the second half of 2020.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts and Reserves	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts and Reserves	SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS AND RESERVES YEARS ENDED DECEMBER 31, 2018 , 2017 AND 2016 (Millions of Dollars) Additions Deductions Description Balance at Charged to Charged Charged to Charged Balance Year ended December 31, 2018: Reserves deducted in the balance sheet from the assets to which they apply: Allowance for doubtful accounts $ 28 $ 5 $ — $ — $ 4 $ 29 Investments and long-term receivables reserve 11 — — — 6 5 Deferred tax valuation allowance: Domestic 604 — — 393 — 211 Foreign 4 — — 1 — 3 Year ended December 31, 2017: Reserves deducted in the balance sheet from the assets to which they apply: Allowance for doubtful accounts $ 25 $ 2 $ 2 $ — $ 1 $ 28 Allowance for related party doubtful accounts 265 — — — 265 — Investments and long-term receivables reserve 10 — 1 — — 11 Long-term receivables from related parties reserve 1,627 — — — 1,627 — Deferred tax valuation allowance: Domestic 1,109 42 — 373 174 604 Foreign 4 — — — — 4 Year ended December 31, 2016: Reserves deducted in the balance sheet from the assets to which they apply: Allowance for doubtful accounts $ 28 $ — $ — $ — $ 3 $ 25 Allowance for related party doubtful accounts 254 — 11 — — 265 Investments and long-term receivables reserve 7 — 3 — — 10 Long-term receivables from related parties reserve 1,446 — 181 — — 1,627 Deferred tax valuation allowance: Domestic 804 174 131 — — 1,109 Foreign 4 — — — — 4

Nature of Business and Signif_2

Nature of Business and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Principles applied in consolidation	Principles applied in consolidation These financial statements include the accounts of U. S. Steel and its majority-owned subsidiaries. Additionally, variable interest entities for which U. S. Steel is the primary beneficiary are included in the Consolidated Financial Statements and their impacts are either partially or completely offset by noncontrolling interests. Intercompany accounts, transactions and profits have been eliminated in consolidation. Investments in entities over which U. S. Steel has significant influence are accounted for using the equity method of accounting and are carried at U. S. Steel’s share of net assets plus loans, advances and our share of earnings less distributions. Earnings or loss from investees includes U. S. Steel’s share of earnings or loss from equity method investments, which is generally recorded a month in arrears, except for significant and unusual items which are recorded in the period of occurrence.
Use of estimates	Use of estimates Generally accepted accounting principles require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at year-end and the reported amounts of revenues and expenses during the year. Significant items subject to such estimates and assumptions include the carrying value of property, plant and equipment; intangible assets; valuation allowances for receivables, inventories and deferred income tax assets and liabilities; environmental liabilities; liabilities for potential tax deficiencies; potential litigation claims and settlements; and assets and obligations related to employee benefits. Actual results could differ materially from the estimates and assumptions used.
Sales recognition	Sales recognition Sales are recognized when U. S. Steel's performance obligations are satisfied. Generally, U. S. Steel’s performance obligations are satisfied, control of our products is transferred, and revenue is recognized at a single point in time, when title transfers to our customer for product shipped or when services are provided. Revenues are recorded net of any sales incentives. Shipping and other transportation costs charged to customers are treated as fulfillment activities and are recorded in both revenue and cost of sales at the time control is transferred to the customer.
Inventories	Inventories Inventories are carried at the lower of cost or market. Fixed costs related to abnormal production capacity are expensed in the period incurred rather than capitalized into inventory. LIFO (last-in, first-out) is the predominant method of inventory costing for inventories in the United States and FIFO (first-in, first-out) is the predominant method in Europe. The LIFO method of inventory costing was used on 74 percent and 75 percent of consolidated inventories at December 31, 2018 and 2017 , respectively.
Derivative instruments	Derivative instruments From time to time, U. S. Steel may use fixed price forward physical purchase contracts to partially manage our exposure to price risk. Generally, forward physical purchase contracts qualify for the normal purchase normal sales exclusion in Accounting Standards Codification (ASC) 815, Derivatives and Hedging , and are not subject to mark-to-market accounting. U. S. Steel also uses derivatives such as commodity-based financial swaps and foreign currency exchange forward contracts to manage its exposure to purchase and sale price fluctuations and foreign currency exchange rate risk. U. S. Steel elects hedge accounting for some of its derivatives. Under hedge accounting, fluctuations in the value of the derivative are recognized in Accumulated Other Comprehensive Income (AOCI) until the associated underlying is recognized in earnings. When the associated underlying is recognized in earnings, the value of the derivative is reclassified to earnings from AOCI. We recognize fair value changes for derivatives where hedge accounting has not been elected immediately in earnings. See Note 16 for further details on U. S. Steel’s derivatives.
Property, plant and equipment	Property, plant and equipment Property, plant and equipment is carried at cost and is depreciated on a straight-line basis over the estimated useful lives of the assets. Depletion of mineral properties is based on rates which are expected to amortize cost over the estimated tonnage of minerals to be removed. When property, plant and equipment is sold or otherwise disposed of, any gains or losses are reflected in income. If a loss on disposal is expected, such losses are recognized when the assets are reclassified as assets held for sale or when impaired as part of an asset group’s impairment. U. S. Steel evaluates impairment of its property, plant and equipment whenever circumstances indicate that the carrying value may not be recoverable. We evaluate the impairment of long-lived assets at the asset group level. Our asset groups are Flat-Rolled, welded tubular, seamless tubular and U. S. Steel Europe (USSE). Asset impairments are recognized when the carrying value of an asset grouping exceeds its recoverable amount as determined by the asset group's aggregate projected undiscounted cash flows. During 2018 and 2017, there were no triggering events that required fixed assets to be evaluated for impairment. During 2016, the permanent shutdown of certain Lorain, Lone Star and Bellville (sold in 2018) tubular assets, was considered a triggering event for our welded and seamless tubular asset groups. U. S. Steel completed a quantitative analysis of its long-lived assets for these asset groups within the Tubular segment and determined that the remaining assets were not impaired. The welded tubular asset group had a carrying value of $410 million at December 31, 2016 and the recoverable amount exceeded this carrying value by approximately $93 million , or 23 percent . The seamless tubular asset group had a carrying value of $210 million at December 31, 2016 and the recoverable amount exceeded this carrying value by $220 million , or 106 percent . The key assumption used to estimate the recoverable amounts for both the welded and seamless tubular asset groups was the forecasted price of oil over the 11 -year average remaining useful lives of the assets within the asset groups. Management will continue to monitor market and economic conditions for triggering events that may warrant further review of long-lived assets.
Change in accounting estimate - capitalization and depreciation method	Change in Accounting Estimate - Capitalization and Depreciation Method During 2017, U. S. Steel completed a review of its accounting policy for property, plant and equipment depreciated on a group basis. As a result of this review, U. S. Steel changed its accounting method for property, plant and equipment from the group method of depreciation to the unitary method of depreciation, effective as of January 1, 2017. The Company believes the change from the group method to the unitary method of depreciation is preferable under U.S. GAAP as it results in a more precise estimate of depreciation expense. Additionally, the change to the unitary method of depreciation is consistent with the depreciation method applied by our competitors, and improves the comparability of our results to the results of our competitors. Our change in the method of depreciation was considered a change in accounting estimate effected by a change in accounting principle and has been applied prospectively. Due to the application of the unitary method of depreciation and resultant change in our capitalization policy, maintenance and outage spending that had previously been expensed as well as capital investments associated with our asset revitalization program are now capitalized if the useful life of the related asset is extended. When property, plant, and equipment are disposed of by sale, retirement, or abandonment, the gross value of the property, plant and equipment and corresponding accumulated depreciation are removed from the Company’s financial accounting records. Due to the application of the unitary method of depreciation, any gain or loss resulting from an asset disposal by sale is now immediately recognized as a gain or loss on the disposal of assets line in our consolidated statement of operations. Assets that are retired or abandoned are reflected as an immediate charge to depreciation expense for any remaining book value in our consolidated statement of operations. Gains (losses) on disposals of assets for the year ended December 31, 2017 and 2018 were immaterial. U. S. Steel's property, plant and equipment totaled $3,979 million at December 31, 2016. U. S. Steel allocated the existing net book value of group assets at the transition date to approximate a unitary depreciation methodology, and the fixed assets are being depreciated over their estimated remaining useful lives as follows: (In millions) Remaining Useful Life of Assets Net Book Value at December 31, 2016 Under 5 years $ 597 6-10 years 629 11-15 years 765 16-20 years 654 21-25 years 363 Over 25 years 479 Assets not subject to depreciation 492 Total $ 3,979
Environmental remediation	Environmental remediation Environmental expenditures are capitalized if the costs mitigate or prevent future contamination or if the costs improve existing assets’ environmental safety or efficiency. U. S. Steel provides for remediation costs and penalties when the responsibility to remediate is probable and the amount of associated costs is reasonably estimable. The timing of remediation accruals typically coincides with completion of studies defining the scope of work to be undertaken or when it is probable that a formal plan of action will be approved by the oversight agency. Remediation liabilities are accrued based on estimates of believed environmental exposure and are discounted if the amount and timing of the cash disbursements are readily determinable.
Asset retirement obligations	Asset retirement obligations Asset retirement obligations (AROs) are initially recorded at fair value and are capitalized as part of the cost of the related long-lived asset and depreciated in accordance with U. S. Steel’s depreciation policies for property, plant and equipment. The fair value of the obligation is determined as the discounted value of expected future cash flows. Accretion expense is recorded each month to increase this discounted obligation over time. Certain AROs related to disposal costs of the majority of assets at our integrated steel facilities are not recorded because they have an indeterminate settlement date. These AROs will be initially recognized in the period in which sufficient information exists to estimate their fair value. See Note 19 for further details on U. S. Steel's AROs.
Pensions and postemployment benefits	Pensions and other post-employment benefits U. S. Steel has defined contribution or multi-employer arrangements for pension benefits for more than three-quarters of its employees in the United States and defined benefit pension plans covering the remaining employees. For hires before January 1, 2016, U. S. Steel has defined benefit retiree health care and life insurance plans (Other Benefits) that cover its represented employees in North America upon their retirement. Government-sponsored programs into which U. S. Steel makes required contributions cover the majority of U. S. Steel’s European employees. For more details regarding pension and other post-employment benefits see Note 18 of the Consolidated Financial Statements. The pension and other benefits obligations and the related net periodic benefit costs are based on, among other things, assumptions of the discount rate, estimated return on plan assets, salary increases, the projected mortality of participants and the current level and future escalation of health care costs. Additionally, U. S. Steel recognizes an obligation to provide post-employment benefits for disability-related claims covering indemnity and medical payments for certain employees in North America. The obligation for these claims and the related periodic costs are measured using actuarial techniques and assumptions. Actuarial gains and losses occur when actual experience differs from any of the many assumptions used to value the benefit plans, or when assumptions change. For pension and other benefits, the Company recognizes into income on an annual basis any unrecognized actuarial net gains or losses that exceed 10 percent of the larger of projected benefit obligations or plan assets (the corridor). These unrecognized amounts in excess of the corridor are amortized over the plan participants' average life expectancy or average future service, depending on the demographics of the plan. Unrecognized actuarial net gains and losses for disability-related claims are immediately recognized into income.
Deferred taxes	Deferred taxes Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. The realization of deferred tax assets is assessed quarterly based on several interrelated factors. These factors include U. S. Steel’s expectation to generate sufficient future taxable income and the projected time period over which these deferred tax assets will be realized. U. S. Steel records a valuation allowance when necessary to reduce deferred tax assets to the amount that will more likely than not be realized. See Note 11 for further details of deferred taxes.
Reclassifications	Reclassifications and Adjustments Certain reclassifications of prior years' data have been made to conform to the current year presentation including the following: U. S. Steel reclassified certain prior year data as a result of the retrospective adoption on January 1, 2018 of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments and ASU 2017-07, Compensation - Retirement Benefits . See Note 3 for further details.

Nature of Business and Signif_3

Nature of Business and Significant Accounting Policies Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Change in Accounting Estimate - Capitalization and Depreciation Method	U. S. Steel allocated the existing net book value of group assets at the transition date to approximate a unitary depreciation methodology, and the fixed assets are being depreciated over their estimated remaining useful lives as follows: (In millions) Remaining Useful Life of Assets Net Book Value at December 31, 2016 Under 5 years $ 597 6-10 years 629 11-15 years 765 16-20 years 654 21-25 years 363 Over 25 years 479 Assets not subject to depreciation 492 Total $ 3,979

Recently Adopted Accounting S_2

Recently Adopted Accounting Standards (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of Changes Related to Net Periodic Benefit Cost	The effect of the retrospective presentation change related to the net periodic benefit cost of our defined benefit pension and other post-employment benefits (OPEB) plans on our consolidated statement of operations was as follows: Year Ended December 31, 2017 Statement of Operations (In millions) As Revised Previously Reported Effect of Change Higher/(Lower) Cost of Sales $ 10,858 $ 10,864 $ (6 ) Selling, general and administrative expenses 320 375 (55 ) Net periodic benefit cost (other than service cost) 61 — 61 Year Ended December 31, 2016 Statement of Operations (In millions) As Revised Previously Reported Effect of Change Higher/(Lower) Cost of Sales $ 9,608 $ 9,623 $ (15 ) Selling, general and administrative expenses 306 255 51 Net periodic benefit cost (other than service cost) (36 ) — (36 )

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Results of Segment Operations	The results of segment operations are as follows: (In millions) Customer Intersegment Net Earnings Earnings (Loss) before Interest and Income Taxes Depreciation, Capital 2018 Flat-Rolled $ 9,681 $ 231 $ 9,912 $ 54 $ 883 $ 367 $ 820 USSE 3,205 23 3,228 — 359 87 104 Tubular 1,231 5 1,236 7 (58 ) 47 45 Total reportable segments 14,117 259 14,376 61 1,184 501 969 Other Businesses 61 125 186 — 55 20 32 Reconciling Items and Eliminations — (384 ) (384 ) — (115 ) — — Total $ 14,178 $ — $ 14,178 $ 61 $ 1,124 $ 521 $ 1,001 2017 Flat-Rolled $ 8,297 $ 194 $ 8,491 $ 38 $ 375 $ 352 $ 388 USSE 2,949 25 2,974 — 327 76 83 Tubular 944 1 945 8 (99 ) 51 28 Total reportable segments 12,190 220 12,410 46 603 479 499 Other Businesses 60 119 179 (2 ) 44 22 6 Reconciling Items and Eliminations — (339 ) (339 ) — 22 — — Total $ 12,250 $ — $ 12,250 $ 44 $ 669 $ 501 $ 505 2016 Flat-Rolled $ 7,507 $ 25 $ 7,532 $ 106 $ 22 $ 349 $ 111 USSE 2,243 3 2,246 — 185 80 83 Tubular 449 2 451 6 (303 ) 68 88 Total reportable segments 10,199 30 10,229 112 (96 ) 497 282 Other Businesses 62 107 169 (2 ) 63 10 24 Reconciling Items and Eliminations — (137 ) (137 ) (12 ) (168 ) — — Total $ 10,261 $ — $ 10,261 $ 98 $ (201 ) $ 507 $ 306
Schedule of Assets by Segment	A summary of total assets by segment is as follows: December 31, (In millions) 2018 2017 Flat-Rolled (a) $ 6,977 $ 5,823 USSE (a) 5,607 5,423 Tubular 1,076 1,076 Total reportable segments $ 13,660 $ 12,322 Other Businesses $ 329 $ 344 Corporate, reconciling items, and eliminations (b) (3,007 ) (2,804 ) Total assets $ 10,982 $ 9,862 (a) Included in segment assets for each year presented is goodwill for Flat-Rolled and USSE of $3 million and $4 million , respectively. (b) The majority of Corporate, reconciling items, and eliminations total assets is comprised of cash and the elimination of intersegment amounts.
Schedule of Reconciling Items to EBIT	The detail of reconciling items to consolidated earnings (loss) before interest and income taxes is as follows: (In millions) 2018 2017 2016 Items not allocated to segments: United Steelworkers labor agreement signing bonus and related costs (Note 28) (81 ) — — Granite City Works restart and related costs (80 ) — — Loss on shutdown of certain tubular pipe mill assets (a) — (35 ) (126 ) Gain associated with U. S. Steel Canada Inc. (Note 5) — 72 — Restructuring and other charges (a) — — 2 Granite City Works temporary idling charges 8 (17 ) (18 ) Gain (loss) on equity investee transactions (Note 12) 38 2 (12 ) Impairment of intangible assets (Note 14) — — (14 ) Total reconciling items $ (115 ) $ 22 $ (168 ) (a) Included in Restructuring and other charges on the Consolidated Statements of Operations. See Note 25 to the Consolidated Financial Statements.
Net Sales, Property, Plant and Equipment and Equity Method Investments Based on Location of Operating Segment	Geographic Area: The information below summarizes external sales, property, plant and equipment and equity method investments based on the location of the operating segment to which they relate. (In millions) Year External Assets North America 2018 $ 10,973 $ 4,432 (a) 2017 9,301 3,831 (a) 2016 8,018 3,671 (a) Europe 2018 3,205 919 2017 2,949 906 2016 2,243 789 Other Foreign Countries 2018 — — 2017 — — 2016 — 18 Total 2018 14,178 5,351 2017 12,250 4,737 2016 $ 10,261 $ 4,478 (a) Assets with a book value of $4,432 million , $3,817 million and $3,670 million were located in the United States at December 31, 2018 , 2017 and 2016 , respectively.

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Sales by Product	The following table disaggregates our revenue by product for each of our reportable business segments for the years ended December 31, 2018 , 2017 and 2016 , respectively: Customer Sales by Product: (In millions) Year Ended December 31, 2018 Flat-Rolled USSE Tubular Other Businesses Total Semi-finished $ 156 $ 174 $ — $ — $ 330 Hot-rolled sheets 2,816 1,313 — — 4,129 Cold-rolled sheets 2,709 384 — — 3,093 Coated sheets 3,090 1,164 — — 4,254 Tubular products — 48 1,195 — 1,243 All Other (a) 910 122 36 61 1,129 Total $ 9,681 $ 3,205 $ 1,231 $ 61 $ 14,178 (In millions) Year Ended December 31, 2017 Flat-Rolled USSE Tubular Other Businesses Total Semi-finished $ 72 $ 232 $ — $ — $ 304 Hot-rolled sheets 2,045 1,210 — — 3,255 Cold-rolled sheets 2,355 328 — — 2,683 Coated sheets 2,902 1,038 — — 3,940 Tubular products — 39 909 — 948 All Other (a) 923 102 35 60 1,120 Total $ 8,297 $ 2,949 $ 944 $ 60 $ 12,250 (In millions) Year Ended December 31, 2016 Flat-Rolled USSE Tubular Other Businesses Total Semi-finished $ 6 $ 165 $ — $ — $ 171 Hot-rolled sheets 1,495 907 — — 2,402 Cold-rolled sheets 2,405 230 — — 2,635 Coated sheets 2,932 834 — — 3,766 Tubular products — 32 430 — 462 All Other (a) 669 75 19 62 825 Total $ 7,507 $ 2,243 $ 449 $ 62 $ 10,261 (a) Consists primarily of sales of raw materials and coke making by-products.

Net Interest and Other Financ_2

Net Interest and Other Financial Costs (Tables)	12 Months Ended
	Dec. 31, 2018
Other Income and Expenses [Abstract]
Net Interest and Other Financial Costs	(In millions) 2018 2017 2016 Interest income: Interest income $ (23 ) $ (17 ) $ (5 ) Interest expense and other financial costs: Interest incurred 175 229 234 Less interest capitalized 7 3 4 Total interest expense 168 226 230 Loss on debt extinguishment (a) 98 54 22 Net periodic benefit costs (other than service cost) (b) 69 61 (36 ) Foreign currency net (gain) loss (c) (19 ) 23 (14 ) Financial costs on: Amended Credit Agreement 5 6 6 USSK credit facilities 3 3 3 Other 3 2 — Amortization of discounts and deferred financing costs 8 10 9 Total other financial costs — 44 4 Net interest and other financial costs $ 312 $ 368 $ 215 (a) Represents a net pretax charge of a $98 million during 2018 related to the retirement of our 2020 Senior Notes and 2021 Senior Secured Notes, a net pretax charge of $54 million during 2017 related to the retirement of our 2018, 2021, and 2022 Senior Notes, partial redemption of our 2021 Senior Secured Notes, and redemption of the Lorain Recovery Zone Facility Bonds, and a net pretax charge of $22 million during 2016 related to the retirement of our 2017 Senior Notes, and partial redemption of our 2018, 2020 and 2021 Senior Notes. (b) Represents postretirement benefit expense as a result of the adoption of Accounting Standards Update 2017-07, Compensation - Retirement Benefits on January 1, 2018. See Note 3 to the Consolidated Financial Statements. (c) The functional currency for USSE is the euro. Foreign currency net (gain) loss is a result of transactions denominated in currencies other than the euro.

Earnings and Dividends Per Co_2

Earnings and Dividends Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Computations for Basic and Diluted Earnings Per Common Share from Continuing Operations	The computations for basic and diluted earnings (loss) per common share from continuing operations are as follows: (Dollars in millions, except per share amounts) 2018 2017 2016 Net earnings (loss) attributable to United States Steel Corporation stockholders $ 1,115 $ 387 $ (440 ) Weighted-average shares outstanding (in thousands): Basic 176,633 174,793 156,673 Effect of stock options, restricted stock units and performance awards 1,828 1,727 — Adjusted weighted-average shares outstanding, diluted 178,461 176,520 156,673 Basic earnings (loss) per common share $ 6.31 $ 2.21 $ (2.81 ) Diluted earnings (loss) per common share $ 6.25 $ 2.19 $ (2.81 )
Antidilutive Securities that were Not Included in Computations of Diluted Loss Per Common Share	The following table summarizes the securities that were antidilutive, and therefore, were not included in the computation of diluted earnings (loss) per common share: (In thousands) 2018 2017 2016 Securities granted under the 2005 Stock Incentive Plan $ 1,631 $ 1,579 $ 8,820

Cash, Cash Equivalents, and R_2

Cash, Cash Equivalents, and Restricted Cash (Tables)	12 Months Ended
	Dec. 31, 2018
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within U. S. Steel's Consolidated Balance Sheets that sum to the total of the same amounts shown in the Consolidated Statement of Cash Flows: December 31, (In millions) 2018 2017 2016 Cash and cash equivalents $ 1,000 $ 1,553 $ 1,515 Restricted cash in other current assets 3 6 — Restricted cash in other noncurrent assets 37 38 40 Total cash, cash equivalents and restricted cash $ 1,040 $ 1,597 $ 1,555
Schedule of Restrictions on Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within U. S. Steel's Consolidated Balance Sheets that sum to the total of the same amounts shown in the Consolidated Statement of Cash Flows: December 31, (In millions) 2018 2017 2016 Cash and cash equivalents $ 1,000 $ 1,553 $ 1,515 Restricted cash in other current assets 3 6 — Restricted cash in other noncurrent assets 37 38 40 Total cash, cash equivalents and restricted cash $ 1,040 $ 1,597 $ 1,555

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventories	(In millions) December 31, 2018 December 31, 2017 Raw materials $ 605 $ 527 Semi-finished products 1,021 796 Finished products 404 356 Supplies and sundry items 62 59 Total $ 2,092 $ 1,738

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Earnings (Loss)	Components of earnings (loss) (In millions) 2018 2017 2016 United States $ 434 $ 75 $ (588 ) Foreign 378 226 172 Earnings (loss) before income taxes $ 812 $ 301 $ (416 )
(Benefit) Provision for Income Taxes	Components of earnings (loss) (In millions) 2018 2017 2016 United States $ 434 $ 75 $ (588 ) Foreign 378 226 172 Earnings (loss) before income taxes $ 812 $ 301 $ (416 ) At the end of both 2018 and 2017, U. S. Steel does not have any undistributed foreign earnings and profits for which U.S. deferred taxes have not been provided. (Benefit) Provision for income taxes 2018 2017 2016 (In millions) Current Deferred Total Current Deferred Total Current Deferred Total Federal $ (40 ) $ (283 ) $ (323 ) $ (66 ) $ (81 ) $ (147 ) $ (18 ) $ — $ (18 ) State and local 2 (58 ) (56 ) (1 ) — (1 ) 1 — 1 Foreign 64 12 76 53 9 62 32 9 41 Total $ 26 $ (329 ) $ (303 ) $ (14 ) $ (72 ) $ (86 ) $ 15 $ 9 $ 24
Reconciliation of Federal Statutory Tax to Total Provisions	reconciliation of the federal statutory tax rate of 21 percent ( 35 percent in 2017 and 2016) to total provision follows: (In millions) 2018 2017 2016 Statutory rate applied to earnings (loss) before income taxes $ 171 $ 105 $ (146 ) Valuation allowance (412 ) 36 252 Excess percentage depletion (48 ) (68 ) (49 ) State and local income taxes after federal income tax effects 8 (28 ) (20 ) Effects of foreign operations 74 62 42 U.S. impact of foreign operations (21 ) (6 ) (6 ) Tax credits (71 ) (56 ) (39 ) Effect of tax reform — (81 ) — Alternative minimum tax credit refund — (48 ) (18 ) Other (4 ) (2 ) 8 Total (benefit) provision $ (303 ) $ (86 ) $ 24
Reconciliation of Unrecognized Tax Benefits	A tabular reconciliation of unrecognized tax benefits follows: (In millions) 2018 2017 2016 Unrecognized tax benefits, beginning of year $ 42 $ 72 $ 74 Increases – tax positions taken in prior years — 1 — Decreases – tax positions taken in prior years (2 ) (26 ) (4 ) Increases – current tax positions — — 3 Settlements — (4 ) — Lapse of statute of limitations (5 ) (1 ) (1 ) Unrecognized tax benefits, end of year $ 35 $ 42 $ 72
Deferred Tax Assets and Liabilities	Deferred tax assets and liabilities resulted from the following: December 31, (In millions) 2018 2017 Deferred tax assets: Federal tax loss carryforwards (expiring in 2035 through 2036) $ 220 $ 394 Federal capital loss carryforwards (expiring 2021) 33 36 State tax credit carryforwards (expiring in 2019 through 2027) 16 14 State tax loss carryforwards (expiring in 2019 through 2038) 137 155 Minimum tax credit carryforwards 38 76 General business credit carryforwards (expiring in 2027 through 2038) 85 86 Foreign tax loss and credit carryforwards (expiring in 2024 through 2028) 173 102 Employee benefits 337 266 Contingencies and accrued liabilities 62 70 Investments in subsidiaries and equity investees 59 33 Other temporary differences 26 1 Valuation allowance (214 ) (608 ) Total deferred tax assets 972 625 Deferred tax liabilities: Property, plant and equipment 468 516 Inventory 22 6 Receivables, payables and debt 33 14 Indefinite-lived intangible assets 18 18 Other temporary differences — 21 Total deferred tax liabilities 541 575 Net deferred tax asset $ 431 $ 50

Investments, Long-Term Receiv_2

Investments, Long-Term Receivables and Equity Investee Transactions (Tables)	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investments and Long-Term Receivables	Investments, Long-Term Receivables and Equity Investee Transactions December 31, (In millions) 2018 2017 Equity method investments $ 485 $ 457 Receivables due after one year, less allowance of $5 and $11 24 20 Other 4 3 Total $ 513 $ 480
Summarized Financial Information of Investees Accounted for by Equity Method of Accounting	Summarized financial information of all investees accounted for by the equity method of accounting is as follows (amounts represent 100% of investee financial information): (In millions) 2018 2017 2016 Income data – year ended December 31: (a) Net Sales $ 2,193 $ 2,485 $ 2,839 Operating income 157 132 345 Net earnings 134 109 323 Balance sheet date – December 31: Current Assets $ 642 $ 633 $ 771 Noncurrent Assets 853 710 989 Current liabilities 348 441 478 Noncurrent Liabilities 516 335 506 (a) Former equity affiliates, Swan Point Development Company, Inc., Tilden Mining Company and Apolo Tubulars S.A. were sold on February 6, 2017, September 29, 2017 and December 22, 2017, respectively. We exited Leeds Retail Center, LLC and sold Acero Prime, S.R.L. de CV on May 31, 2018, and October 23, 2018, respectively. The former equity affiliates are included in the income data through the month prior to the date of sale.
Investees Accounted for using Equity Method	Investees accounted for using the equity method include: Investee Country December 31, 2018 Interest Chrome Deposit Corporation United States 50 % Daniel Ross Bridge, LLC United States 50 % Double G Coatings Company, Inc. United States 50 % Feralloy Processing Company United States 49 % Hibbing Development Company United States 24.1 % Hibbing Taconite Company (a) United States 14.7 % Patriot Premium Threading Services, LLC United States 50 % PRO-TEC Coating Company, LLC United States 50 % Strategic Investment Fund Partners II (b) United States 5.2 % USS-POSCO Industries United States 50 % Worthington Specialty Processing United States 49 % (a) Hibbing Taconite Company (HTC) is an unincorporated joint venture that is owned, in part, by Hibbing Development Company (HDC), which is accounted for using the equity method. Through HDC we are able to influence the activities of HTC, and as such, its activities are accounted for using the equity method. (b) Strategic Investment Fund Partners II is a limited partnership and in accordance with ASC Topic 323, the financial activities are accounted for using the equity method.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	December 31, (In millions) Useful Lives 2018 2017 Land and depletable property — $ 207 $ 208 Buildings 35 years 1,098 1,109 Machinery and equipment Steel producing 2-30 years 12,784 12,014 Transportation 3-40 years 268 239 Other 5-30 years 123 122 Information technology 5-6 years 786 782 Assets under capital lease 5-15 years 36 36 Construction in process — 706 576 Total 16,008 15,086 Less accumulated depreciation and depletion 11,143 10,806 Net $ 4,865 $ 4,280

Intangible Assets (Tables)

Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortizable Intangible Assets	Intangible assets are being amortized on a straight-line basis over their estimated useful lives and are detailed below: As of December 31, 2018 As of December 31, 2017 (In millions) Useful Gross Accumulated Net Gross Accumulated Net Customer relationships 22 Years $ 132 $ 70 $ 62 $ 132 $ 64 $ 68 Patents 10-15 Years 22 7 15 22 5 17 Other 4-20 Years 14 8 6 15 8 7 Total amortizable intangible assets $ 168 $ 85 $ 83 $ 169 $ 77 $ 92

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total Stock-Based Compensation Awards Granted	The following table summarizes the total stock-based compensation awards granted during the years 2018 , 2017 and 2016 : Stock Options Restricted Stock Units TSR Performance Awards ROCE Performance Awards 2018 Grants — 824,195 79,190 247,510 2017 Grants 647,780 348,040 169,850 — 2016 Grants 1,333,210 1,120,332 308,130 —
Total Compensation Expense Recognized for Stock-Based Compensation Awards	The following table summarizes the total compensation expense recognized for stock-based compensation awards: (In millions, except per share amounts) Year Ended December 31, 2018 Year Ended December 31, 2017 Year Ended December 31, 2016 Stock-based compensation expense recognized: Cost of sales $ 11 $ 10 $ 9 Selling, general and administrative expenses 21 17 13 Decrease in net income 32 27 22 Decrease in basic earnings per share 0.14 0.15 0.14 Decrease in diluted earnings per share 0.13 0.15 0.14
Black-Scholes Assumptions	Compensation expense for stock options is recorded over the vesting period based on the fair value on the date of grant, as calculated by U. S. Steel using the Black-Scholes model and the assumptions listed below. Awards generally vest ratably over a three -year service period and have a term of ten years . Stock options are generally issued at the market price of the underlying stock on the date of the grant. Upon exercise of stock options, shares of U. S. Steel stock are issued from treasury stock or from authorized, but unissued common stock. There were no stock options granted in 2018 . Black-Scholes Assumptions (a) 2017 Grants 2016 Grants Grant date price per share of option award $ 36.94 $ 14.78 Exercise price per share of option award $ 36.94 $ 14.78 Expected annual dividends per share $ 0.20 $ 0.20 Expected life in years 5.0 5.0 Expected volatility 57 % 53 % Risk-free interest rate 2.0 % 1.5 % Average grant date fair value per share of unvested option awards as calculated from above $ 17.28 $ 6.24 (a) The assumptions represent a weighted-average for all grants during the year.
Status and Activity of Stock Options	The following table shows a summary of the status and activity of stock options for the year ended December 31, 2018 : Shares Weighted- Weighted- Aggregate Outstanding at January 1, 2018 4,612,940 $ 28.92 Granted — $ — Exercised (1,541,989 ) $ 22.65 Forfeited or expired (324,431 ) $ 72.15 Outstanding at December 31, 2018 2,746,520 $ 27.73 5.03 $ 2 Exercisable at December 31, 2018 2,174,000 $ 28.10 4.32 $ 1 Exercisable and expected to vest at December 31, 2018 2,640,308 $ 27.76 4.92 $ 2
Performance Awards Outstanding and their Fair Market Value on Respective Grant Date	The following table shows a summary of the performance awards outstanding as of December 31, 2018 , and their fair market value on the respective grant date: Performance Period Fair Value Minimum Target Maximum 2018 - 2020 $ 15 — 313,874 627,748 2017 - 2019 $ 4 — 105,479 210,958 2016 - 2018 $ 2 — 192,332 384,664
Status and Activity of Nonvested Stock Awards	The following table shows a summary of the status and activity of nonvested stock awards for the year ended December 31, 2018 : Restricted TSR Performance (a) ROCE Performance (a) Total Weighted- Nonvested at January 1, 2018 1,188,746 515,531 — 1,704,277 $ 21.08 Granted 824,195 79,190 247,510 1,150,895 41.65 Vested (431,661 ) (150,133 ) — (581,794 ) 24.20 Performance adjustment factor (b) — (52,557 ) — (52,557 ) 24.95 Forfeited or expired (85,008 ) (16,244 ) (11,612 ) (112,864 ) 28.99 Nonvested at December 31, 2018 1,496,272 375,787 235,898 2,107,957 $ 30.92 (a) The number of shares shown for the performance awards is based on the target number of share awards. (b) Consists of adjustments to vested performance awards to reflect actual performance. The adjustments were required since the original grants of the awards were at 100 percent of the targeted amounts and the awards vested at less than target.
Restricted Stock Units and Performance Awards Granted	The following table presents information on RSUs and performance awards granted: 2018 2017 2016 Number of awards granted 1,150,895 517,890 1,428,462 Weighted-average grant-date fair value per share $ 41.65 $ 37.68 $ 13.39

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions	The table below shows the outstanding swap quantities used to hedge forecasted purchases and sales as of December 31, 2018 and December 31, 2017 : Hedge Contracts Classification December 31, 2018 December 31, 2017 Natural gas (in mmbtus) Commodity purchase swaps 33,951,016 22,049,500 Tin (in metric tons) Commodity purchase swaps 585 80 Zinc (in metric tons) Commodity purchase swaps 3,471 4,179 Hot-rolled coils (in tons) Sales swaps 9,000 38,000 Iron ore pellets (in metric tons) Sales swaps — 40,000 Foreign currency (in millions of euros) Foreign exchange forwards € 286 € 234 Foreign currency (in millions of CAD) Foreign exchange forwards C$ 50 C$ —
Location and Amounts of Fair Values Related to Derivatives in Financial Statements	The following summarizes the fair value amounts included in our Consolidated Balance Sheets as of December 31, 2018 and December 31, 2017 : (In millions) Designated as Hedging Instruments Balance Sheet Location December 31, 2018 December 31, 2017 Sales swaps Accounts payable $ 1 $ — Commodity purchase swaps Accounts receivable 2 4 Commodity purchase swaps Accounts payable 17 2 Commodity purchase swaps Investments and long-term receivables — 1 Commodity purchase swaps Other long-term liabilities 1 1 Foreign exchange forwards Accounts payable 1 — Foreign exchange forwards Other long-term liabilities 1 — Not Designated as Hedging Instruments Sales swaps Accounts payable — 2 Commodity purchase swaps Accounts payable — 1 Foreign exchange forwards Accounts receivable 12 11
Schedule of Effect of Hedge Accounting on Accumulated Other Comprehensive Income	The table below summarizes the effect of hedge accounting on AOCI and amounts reclassified from AOCI into earnings for 2018 , 2017 , and 2016 : Gain (Loss) on Derivatives in AOCI Amount of Gain (Loss) Recognized in Income (In millions) 2018 2017 2016 Location of Reclassification from AOCI (a) 2018 2017 2016 Sales swaps (b) $ — $ — $ — Net sales $ (13 ) $ — $ — Commodity purchase swaps (15 ) 1 2 Cost of sales (c) (8 ) (2 ) 13 Foreign exchange forwards (2 ) — — Cost of sales — — — (a) The earnings impact of our hedging instruments substantially offsets the earnings impact of the related hedged items since ineffectiveness is less than $1 million . (b) U. S. Steel has elected hedge accounting for hot-rolled coil sales swaps prospectively on January 1, 2018. Iron ore pellet sales swaps were not classified as hedges. (c) Costs for commodity purchase swaps are recognized in cost of sales as products are sold.
Location and Amounts of Gains and Losses Related to Derivatives in Financial Instruments	The table below summarizes the impact of derivative activity where hedge accounting has not been elected on our Consolidated Statements of Operations for 2018 , 2017 and 2016 : Amount of Gain (Loss) Recognized in Income (In millions) Consolidated Statement of Operations Location 2018 2017 2016 Sales swaps (a) Net sales $ (1 ) $ 6 $ (3 ) Commodity purchase swaps (b) Cost of sales — 3 3 Foreign exchange forwards (c) Other financial costs 24 (23 ) 7 (a) U. S. Steel has elected hedge accounting for hot-rolled coil sales swaps prospectively on January 1, 2018. Iron ore pellet sales swaps were not classified as hedges. (b) The 2017 impacts were for de-designated zinc contracts for our domestic operations and the 2016 impacts were for zinc and tin contracts not elected for hedge accounting for our European operations.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt	December 31, (In millions) Interest Maturity 2018 2017 2037 Senior Notes 6.650 2037 $ 350 $ 350 2026 Senior Notes 6.250 2026 650 — 2025 Senior Notes 6.875 2025 750 750 2021 Senior Secured Notes 8.375 2021 — 780 2020 Senior Notes 7.375 2020 — 432 Environmental Revenue Bonds 5.750 - 6.875 2019 - 2042 400 400 Fairfield Caster Lease 2022 22 24 Other capital leases and all other obligations 2019 6 1 Fourth Amended and Restated Credit Agreement Variable 2023 — — USSK Credit Agreement Variable 2023 229 — USSK credit facilities Variable 2021 — — Total debt 2,407 2,737 Less unamortized discount and debt issuance costs 26 34 Less short-term debt and long-term debt due within one year 65 3 Long-term debt $ 2,316 $ 2,700
Debt Redemption	U. S. Steel may redeem the 2026 Senior Notes, in whole or in part, at our option at any time, or from time to time, on or after March 15, 2021 at the redemption price for such notes set forth below as a percentage of the principal amount, plus accrued and unpaid interest, if any, to, but excluding the redemption date, if redeemed during the twelve-month period beginning March 15 of the years indicated below: Year Redemption Price 2021 103.125 % 2022 101.563 % 2023 and thereafter 100.000 %
Aggregate Maturities of Debt	Debt Maturities – Aggregate maturities of debt are as follows (in millions): 2019 2020 2021 2022 2023 Later Total $ 65 $ 4 $ 4 $ 10 $ 229 $ 2,095 $ 2,407

Pensions and Other Benefits (Ta

Pensions and Other Benefits (Tables)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	U. S. Steel’s Pension plan and Other Benefits plan assets are classified as follows: Level 1 Level 2 Level 3 Short-term Investments Corporate Bonds - U.S. & Non U.S. Private Equities Equity Securities - U.S. & Non U.S. Government Bonds - U.S. & Non U.S. Real Estate Exchange-traded Funds Mortgage and asset-backed securities Mineral Interests Investment Trusts Timberlands
Details Relating to Pension Benefits and Other Benefits	Details relating to Pension Benefits and Other Benefits are below. Pension Benefits Other Benefits (In millions) 2018 2017 2018 2017 Change in benefit obligations Benefit obligations at January 1 $ 6,107 $ 6,214 $ 2,379 $ 2,432 Service cost 49 50 17 17 Interest cost 233 235 92 94 Plan amendments 26 — — — Actuarial (gains) losses (223 ) 214 (185 ) 8 Exchange rate loss (3 ) 4 — — Settlements, curtailments and termination benefits (18 ) (12 ) — — Benefits paid (545 ) (598 ) (182 ) (172 ) Benefit obligations at December 31 $ 5,626 $ 6,107 $ 2,121 $ 2,379 Change in plan assets Fair value of plan at January 1 $ 5,732 $ 5,482 $ 2,042 $ 1,984 Actual return on plan assets (228 ) 773 (49 ) 171 Employer contributions — 75 — — Benefits paid from plan assets (544 ) (598 ) (133 ) (113 ) Fair value of plan assets at December 31 $ 4,960 $ 5,732 $ 1,860 $ 2,042 Funded status of plans at December 31 (666 ) (375 ) (261 ) (337 )
Amounts Recognized in Accumulated Other Comprehensive Loss	Amounts recognized in accumulated other comprehensive loss: 2018 (In millions) 12/31/2017 Amortization Activity 12/31/2018 Pensions Prior Service Cost $ (8 ) $ — $ 26 $ 18 Actuarial Losses 2,238 (152 ) 356 2,442 Other Benefits Prior Service Cost (51 ) (29 ) — (80 ) Actuarial Losses 41 (4 ) (54 ) (17 ) Amount reclassified (In millions) (a) Details about AOCI components 2018 2017 2016 Amortization of pension and other benefit items Prior service costs (a) $ (29 ) $ (29 ) $ (37 ) Actuarial losses (a) (156 ) (151 ) (132 ) Settlements, termination and curtailment losses (a) (10 ) (7 ) (12 ) Total pensions and other benefits items (195 ) (187 ) (181 ) Derivative reclassifications to Consolidated Statements of Operations (19 ) (4 ) (18 ) Total before tax (214 ) (191 ) (199 ) Tax benefit (b) 52 — — Net of tax $ (162 ) $ (191 ) $ (199 ) (a) These AOCI components are included in the computation of net periodic benefit cost (see Note 18 for additional details). (b) Amounts in 2017 and 2016 do not reflect a tax benefit as a result of a full valuation allowance on our domestic deferred tax assets.
Pension and Other Benefits Recognized in Balance Sheet	As of December 31, 2018 and 2017 , the following amounts were recognized in the Consolidated Balance Sheet: Pension Benefits Other Benefits (In millions) 2018 2017 2018 2017 Current liabilities (2 ) (4 ) (52 ) (59 ) Noncurrent liabilities (664 ) (371 ) (209 ) (278 ) Accumulated other comprehensive loss (a) 2,460 2,230 (97 ) (10 ) Net amount recognized $ 1,794 $ 1,855 $ (358 ) $ (347 ) (a) Accumulated other comprehensive loss effects associated with accounting for pensions and other benefits in accordance with ASC Topic 715 at December 31, 2018 and December 31, 2017 , respectively, are reflected net of tax of $991 million and $958 million respectively, on the Consolidated Statements of Stockholders’ Equity.
Information for Pension Plans with Accumulated Benefit Obligation in Excess of Plan Assets	The Accumulated Benefit Obligation (ABO) for all defined benefit pension plans was $5,454 million and $5,937 million at December 31, 2018 and 2017 , respectively. December 31, (In millions) 2018 2017 Information for pension plans with an accumulated benefit obligation in excess of plan assets: Aggregate accumulated benefit obligations (ABO) $ (5,454 ) $ (5,937 ) Aggregate projected benefit obligations (PBO) (5,626 ) (6,107 ) Aggregate fair value of plan assets 4,960 5,732
Details of Net Periodic Benefit Costs Related to Pension and Other Benefits	Following are the details of net periodic benefit costs related to Pension and Other Benefits: Pension Benefits Other Benefits (In millions) 2018 2017 2016 2018 2017 2016 Components of net periodic benefit cost: Service cost $ 49 $ 50 $ 54 $ 17 $ 17 $ 20 Interest cost 233 235 258 92 94 98 Expected return on plan assets (361 ) (390 ) (422 ) (82 ) (65 ) (151 ) Amortization - prior service costs — — 11 29 29 26 - actuarial losses 152 148 129 4 3 3 Net periodic benefit cost (benefit), excluding below 73 43 30 60 78 (4 ) Multiemployer plans (a) 60 59 63 — — — Settlement, termination and curtailment losses/(gains) 10 7 13 — — (1 ) Net periodic benefit cost (benefit) $ 143 $ 109 $ 106 $ 60 $ 78 $ (5 ) (a) Primarily represents pension expense for the SPT covering USW employees hired from National Steel Corporation and new USW employees hired after May 21, 2003.
Amounts in Accumulated Other Comprehensive Income that are Expected to be Recognized as Components of Net Periodic Benefit Cost	The amounts in accumulated other comprehensive income that are expected to be recognized as components of net periodic benefit cost during 2019 are as follows: (In millions) Pension Benefits 2019 Other Benefits 2019 Amortization of actuarial loss $ 131 $ 3 Amortization of prior service cost 2 29 Total recognized from accumulated other comprehensive income $ 133 $ 32
Assumptions used to Determine Benefit Obligation and Net Periodic Benefit Cost	Weighted average assumptions used to determine the benefit obligation at December 31 and net periodic benefit cost for the year ended December 31 are detailed below. Pension Benefits Other Benefits 2018 2017 2018 2017 U.S. and Europe U.S. and Europe U.S. U.S. Actuarial assumptions used to determine benefit obligations at December 31: Discount rate 4.41 % 4.00 % 4.47 % 4.03 % Increase in compensation rate 2.60 % 2.60 % N/A N/A Pension Benefits 2018 2017 2016 U.S. and Europe U.S. and Europe U.S. and Europe Actuarial assumptions used to determine net periodic benefit cost for the year ended December 31: Discount rate 4.00 % 4.00 % 4.25 % Expected annual return on plan assets 6.85 % 7.25 % 7.50 % Increase in compensation rate 2.60 % 2.60 % 2.60 % Other Benefits 2018 2017 2016 U.S. U.S. U.S. Discount rate 4.03 % 4.00 % 4.25 % Expected annual return on plan assets 4.25 % 3.25 % 7.50 % Increase in compensation rate N/A 3.50 % 3.50 %
Assumed Health Care Cost Trend Rates	2018 2017 Assumed health care cost trend rates at December 31: U.S. U.S. Health care cost trend rate assumed for next year 7.00% 7.00% Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 5.00% 5.00% Year that the rate reaches the ultimate trend rate 2023 2022
Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates	A one-percentage-point change in the assumed return on plan assets, discount rate or health care cost trend rates would have the following effects: (In millions) 1-Percentage- 1-Percentage- Expected return on plan assets Incremental (decrease) increase in: Net periodic pension & other benefits costs for 2019 $ (69 ) $ 69 Discount rate Incremental (decrease) increase in: Net periodic pension & other benefits costs for 2019 $ (18 ) $ 8 Pension & other benefits liabilities at December 31, 2018 $ (650 ) $ 770 Health care cost escalation trend rates Incremental increase (decrease) in: Other post-employment benefit obligations $ 77 $ (66 ) Service and interest costs components for 2019 $ 4 $ (3 )
Pension and Other Benefits Plan Assets Carried at Fair Value	The following is a summary of U. S. Steel’s Pension plan assets carried at fair value at December 31, 2018 and 2017 : Fair Value Measurements at December 31, 2018 (in millions) Total Quoted Prices in Other Significant Observable Inputs Significant Asset Classes Short-term investments $ 7 $ 7 $ — $ — Equity Securities (a) 101 101 — — Corporate & Government Bonds (b) 2,143 — 2,143 — Mineral Interests 2 — — 2 Timberlands 294 — — 294 Private equities (c) 2 — — 2 Real Estate (d) 33 — — 33 All Other (e) 14 14 — — Total assets in the fair value hierarchy $ 2,596 $ 122 $ 2,143 $ 331 Investments measured at net asset value (f) 2,364 Investments at fair value $ 4,960 (a) Includes $95 million of U.S. equity securities and $6 million of Non U.S. equity securities. (b) Underlying investments include: Corporate Bonds – U.S. $ 933 Corporate Bonds - Non U.S. 149 Government Bonds – U.S. 858 Government Bonds - Non U.S. 67 Mortgage and asset-backed securities 136 Total $ 2,143 (c) Includes investments in CAI Partners and Company III LP, Clayton Dubilier Rice Fund VI and Epiris Club 2007. (d) Includes investments in the Avanti Funds and the Mariano Ranch properties. (e) Includes $32 million of cash, $57 million of investment sales, $21 million of accrued income, $(80) million of investment purchases and $(16) million of miscellaneous payables. (f) In accordance with ASC Topic 820, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy.	Fair Value Measurements at December 31, 2017 (in millions) Total Quoted Prices in Other Significant Observable Inputs (Level 2) Significant Asset Classes Short-term investments $ 155 $ 155 $ — $ — Equity Securities - U.S. (a) 260 260 — — Corporate & Government Bonds (b) 1,806 — 1,806 — Mineral Interests 3 — — 3 Timberlands 300 — — 300 Private equities (c) 4 — — 4 Real Estate (d) 33 — — 33 All Other (e) (39 ) (39 ) — — Total assets in the fair value hierarchy $ 2,522 $ 376 1,806 $ 340 Investments measured at net asset value (f) 3,210 Investments at fair value $ 5,732 (a) Includes U. S. Steel stock. (b) Underlying investments include: Corporate Bonds – U.S. $ 1,084 Government Bonds – U.S. 720 Agency Mortgages 2 Total $ 1,806 (c) Includes investments in CAI Partners and Company III LP, Clayton Dubilier Rice Fund VI, Epiris Club 2007 and FF&P Investor 8 ERISA LP. (d) Includes investments in the Avanti Funds and the Mariano Ranch properties. (e) Includes $157 million of investment sales, $19 million of accrued income, and $(197) million of investment purchases and $(18) million of miscellaneous payables. (f) In accordance with ASC Topic 820, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy.
Multiemployer Pension Plans	U. S. Steel’s participation in the SPT for the annual periods ended December 31, 2018 , 2017 and 2016 is outlined in the table below. Employer Pension Protection Act Zone (a) FIP/RP Status (b) U.S. Steel Surcharge (c) Expiration Date Pension Fund 2018 2017 2018 2017 2016 2018 2017 Steelworkers Pension Trust 23-6648508/499 Green Green No $ 60 $ 59 $ 63 No No September 1, 2022 (a) The zone status is based on information that U. S. Steel received from the plan and is certified by the plan’s actuary. Among other factors, plans in the green zone are at least 80 percent funded, while plans in the yellow zone are less than 80 percent funded and plans in the red zone are less than 65 percent funded. (b) Indicates if a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented. (c) Indicates whether there were charges to U. S. Steel from the plan.
Benefit Payments Expected to be Paid from Defined Benefit Plans	Estimated Future Benefit Payments – The following benefit payments, which reflect expected future service as appropriate, are expected to be paid from U. S. Steel’s defined benefit plans: (In millions) Pension Other 2019 $ 498 $ 164 2020 470 184 2021 453 186 2022 440 186 2023 426 185 Years 2024 - 2027 1,962 755
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Investments Based on Net Asset Value	The following table represents investments based on net asset value and the significant unobservable inputs and the ranges of values for those inputs: Net Asset Value at December 31, 2018 Unfunded Commitments Redemption Frequency Redemption Notice Period Private Equity Funds (a) $ 254 $ 68 Not redeemable NA Real Estate Funds (a) 236 93 Not redeemable NA Commingled Funds 1,874 NA NA NA Investments measured at net asset value $ 2,364 (a) The remaining lives of such investments range from approximately less than 1 year to up to 10 years.	The following table represents investments based on net asset value and the significant unobservable inputs and the ranges of values for those inputs: Net Asset Value at December 31, 2017 Unfunded Commitments Redemption Frequency Redemption Notice Period Private Equity Funds (a) $ 252 $ 91 Not redeemable N/A Real Estate Funds (a) 260 117 ** N/A Interest in Investment Partnerships (b) 729 N/A N/A N/A Commingled Funds 1,969 N/A N/A N/A Investments measured at net asset value $ 3,210 ** Not redeemable, except for JP Morgan Real Estate Income & Growth, which has a quarterly redemption provision. (a) The remaining lives of such investments range from approximately less than 1 year to up to 11 years. (b) Investment partnerships whose investment objectives are to achieve long-term capital appreciation by investing in global equity markets.
Changes in Fair Value of Pension and Other Benefits Plan Level 3 Assets	The following table sets forth a summary of changes in the fair value of U. S. Steel’s Pension plan Level 3 assets for the years ended December 31, 2018 and 2017 (in millions): (In millions) 2018 2017 Balance at beginning of period $ 340 $ 357 Transfers in and/or out of Level 3 — — Actual return on plan assets: Realized gain 11 2 Net unrealized loss (8 ) (16 ) Purchases, sales, issuances and settlements: Sales (12 ) (3 ) Balance at end of period $ 331 $ 340
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and Other Benefits Plan Assets Carried at Fair Value	The following is a summary of U. S. Steel’s Other Benefits plan assets carried at fair value at December 31, 2018 and 2017 . Fair Value Measurements at December 31, 2018 (in millions) Total Quoted Prices in Other Significant Observable Inputs (Level 2) Significant Asset Classes Short-term investments $ 42 $ 42 — $ — Equity Securities (a) 45 45 — — Corporate & Government Bonds (b) 1,631 — 1,631 — Timberlands 35 — — 35 All Other (c) 13 13 — — Total assets in the fair value hierarchy $ 1,766 $ 100 $ 1,631 $ 35 Investments measured at net asset value (d) 94 Investments at fair value $ 1,860 (a) Includes $27 million of U.S. equity securities and $18 million of Non U.S. equity securities. (b) Underlying investments include: Corporate Bonds – U.S. $ 1,052 Corporate Bonds - Non U.S. 271 Government Bonds – U.S. 270 Government Bonds - Non U.S. 8 Mortgage and asset-backed securities 30 Total $ 1,631 (c) Includes $16 million of accrued income and $(3) million of investment purchase payables. (d) In accordance with Subtopic 820-10, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy.	Fair Value Measurements at December 31, 2017 (in millions) Total Quoted Prices in Other Significant Observable Inputs (Level 2) Significant Asset Classes Short-term investments 54 54 — — Equity Securities - U.S. 29 29 — — Corporate Bonds - U.S. 1,455 — 1,455 — Government bonds - U.S. 323 — 323 — Timberlands 34 — — 34 Private equities (a) 1 — — 1 All Other (b) 39 39 — — Total assets in the fair value hierarchy $ 1,935 $ 122 1,778 $ 35 Investments measured at net asset value (c) 107 Investments at fair value $ 2,042 (a) Includes investment in Epiris Club 2007 (formerly Electra Partners Club 2007 LP) and FF&P Investor 8 ERISA LP. (b) Includes $23 million of investment sales, $17 million of accrued income and $(1) million of investment purchase payables. (c) In accordance with Subtopic 820-10, certain investments that were measured at net asset value per share (or its equivalent) have not been classified in the fair value hierarchy.
Investments Based on Net Asset Value	The following table represents investments based on net asset value and the significant unobservable inputs and the ranges of values for those inputs: Net Asset Value at December 31, 2018 Unfunded Commitments Redemption Frequency Redemption Notice Period Private Equity Funds (a) $ 61 $ 10 Not redeemable NA Real Estate Funds (a) 33 12 Not redeemable NA Investments measured at net asset value $ 94 (a) The remaining lives of such investments range from approximately less than 1 year up to 10 years.	The following table represents investments based on net asset value and the significant unobservable inputs and the ranges of values for those inputs: Net Asset Value at December 31, 2017 Unfunded Commitments Redemption Frequency Redemption Notice Period Private Equity Funds (a) $ 62 $ 15 Not redeemable N/A Real Estate Funds (a) 33 15 ** N/A Interest in Investment Partnerships (b) 12 N/A N/A N/A Investments measured at net asset value $ 107 ** Not redeemable, except for JP Morgan U.S. Real Estate Income & Growth, which has a quarterly redemption provision. (a) The remaining lives of such investments range from approximately less than 1 year to up to 11 years. (b) Investment partnerships whose investment objectives are to achieve long-term capital appreciation by investing in global equity markets.
Changes in Fair Value of Pension and Other Benefits Plan Level 3 Assets	The following table sets forth a summary of changes in the fair value of U. S. Steel’s Other Benefits plan Level 3 assets for the years ended December 31, 2018 and 2017 (in millions): (In millions) 2018 2017 Balance at beginning of period $ 35 $ 38 Transfers in and/or out of Level 3 — — Actual return on plan assets: Realized gain 1 — Net unrealized loss (1 ) (2 ) Purchases, sales, issuances and settlements: Sales — (1 ) Balance at end of period $ 35 $ 35

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Changes in Carrying Values of Asset Retirement Obligations	The following table reflects changes in the carrying values of AROs for the years ended December 31, 2018 and 2017 : December 31, (In millions) 2018 2017 Balance at beginning of year $ 69 $ 79 Obligations settled (12 ) (8 ) Change in estimate of obligations — (6 ) Foreign currency translation effects — 2 Accretion expense 3 2 Balance at end of period $ 60 $ 69

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities Not Carried at Fair Value	The following table summarizes U. S. Steel’s financial assets and liabilities that were not carried at fair value at December 31, 2018 and 2017 . December 31, 2018 December 31, 2017 (In millions) Fair Value Carrying Fair Value Carrying Financial liabilities: Long-term debt (a) $ 2,182 $ 2,353 $ 2,851 $ 2,678 (a) Excludes capital lease obligations.

Reclassifications from Accumu_2

Reclassifications from Accumulated Other Comprehensive Income (AOCI) (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	(In millions) (a) Pension and Other Benefit Items Foreign Currency Items Unrealized Gain (Loss) on Derivatives Total Balance at December 31, 2016 $ (1,771 ) $ 274 $ — $ (1,497 ) Other comprehensive income before reclassifications 640 189 5 834 Amounts reclassified from AOCI (b) (187 ) — (4 ) (191 ) Sale of ownership interest in Tilden Mining Company L.C. 9 — — 9 Net current-period other comprehensive income 462 189 1 652 Balance at December 31, 2017 $ (1,309 ) $ 463 $ 1 $ (845 ) Other comprehensive income (loss) before reclassifications 41 (60 ) — (19 ) Amounts reclassified from AOCI (b) (148 ) — (14 ) (162 ) Net current-period other comprehensive loss (107 ) (60 ) (14 ) (181 ) Balance at December 31, 2018 $ (1,416 ) $ 403 $ (13 ) $ (1,026 ) (a) Amounts in 2017 and 2016 do not reflect a tax benefit as a result of a full valuation allowance on our domestic deferred tax assets. (b) See table below for further details.
Amounts Recognized in Accumulated Other Comprehensive Loss	Amounts recognized in accumulated other comprehensive loss: 2018 (In millions) 12/31/2017 Amortization Activity 12/31/2018 Pensions Prior Service Cost $ (8 ) $ — $ 26 $ 18 Actuarial Losses 2,238 (152 ) 356 2,442 Other Benefits Prior Service Cost (51 ) (29 ) — (80 ) Actuarial Losses 41 (4 ) (54 ) (17 ) Amount reclassified (In millions) (a) Details about AOCI components 2018 2017 2016 Amortization of pension and other benefit items Prior service costs (a) $ (29 ) $ (29 ) $ (37 ) Actuarial losses (a) (156 ) (151 ) (132 ) Settlements, termination and curtailment losses (a) (10 ) (7 ) (12 ) Total pensions and other benefits items (195 ) (187 ) (181 ) Derivative reclassifications to Consolidated Statements of Operations (19 ) (4 ) (18 ) Total before tax (214 ) (191 ) (199 ) Tax benefit (b) 52 — — Net of tax $ (162 ) $ (191 ) $ (199 ) (a) These AOCI components are included in the computation of net periodic benefit cost (see Note 18 for additional details). (b) Amounts in 2017 and 2016 do not reflect a tax benefit as a result of a full valuation allowance on our domestic deferred tax assets.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Year Ended December 31, (In millions) 2018 2017 2016 Net cash used in operating activities included: Interest and other financial costs paid (net of amount capitalized) $ (207 ) $ (242 ) $ (193 ) Income taxes paid $ (39 ) $ (40 ) $ (6 ) Non-cash investing and financing activities: Change in accrued capital expenditures $ 135 $ 208 $ (110 ) U. S. Steel common stock issued for employee/non-employee director stock plans $ 21 $ 49 $ 32 U. S. Steel common stock issued for defined benefit pension plans $ — $ — $ 100

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Future Minimum Commitments for Capital Leases and Operating Leases	Future minimum commitments for capital leases (including sale-leasebacks accounted for as financings) and for operating leases having initial non-cancelable lease terms in excess of one year are as follows: (In millions) Capital Operating 2019 $ 5 $ 66 2020 5 55 2021 5 45 2022 11 37 2023 — 28 Later years — 72 Total minimum lease payments $ 26 $ 303 Less imputed interest costs 4 Present value of net minimum lease payments included in long-term debt (see Note 17) $ 22
Operating Lease Rental Expense	Operating lease rental expense: Year Ended December 31, (In millions) 2018 2017 2016 Minimum rentals $ 114 $ 114 $ 115 Contingent rentals 19 10 8 Net rental expense $ 133 $ 124 $ 123

Restructuring and Other Charg_2

Restructuring and Other Charges (Tables)	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Activity in Accrued Balances for Restructuring and Other Cost Reduction Programs	The activity in the accrued balances incurred in relation to restructuring and other cost reduction programs during the years ended December 31, 2018 and December 31, 2017 were as follows: (in millions) Employee Related Costs Exit Costs Non-cash Charges Total Balance at December 31, 2016 $ 14 $ 60 $ — $ 74 Additional charges 2 — 35 (a) 37 Cash payments/utilization (8 ) (24 ) (35 ) (67 ) Other adjustments and reclasses (4 ) (2 ) — (6 ) Balance at December 31, 2017 $ 4 $ 34 $ — $ 38 Cash payments/utilization (4 ) (17 ) — (21 ) Balance at December 31, 2018 $ — $ 17 $ — $ 17 (a) Charges are primarily related to the write down of assets associated with the permanent shutdown of the No. 6 Quench & Temper Mill at Lorain Tubular Operations.
Balance Sheet Location of Accrued Liabilities for Restructuring and Other Cost Reduction Programs	Accrued liabilities for restructuring and other cost reduction programs are included in the following balance sheet lines: (in millions) December 31, 2018 December 31, 2017 Accounts payable $ 11 $ 26 Payroll and benefits payable — 4 Deferred credits and other noncurrent liabilities 6 8 Total $ 17 $ 38

Contingencies and Commitments (

Contingencies and Commitments (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Asbestos Litigation Activity	The following table shows the number of asbestos claims in the current year and the prior two years: Period ended Opening Claims (a) New Closing December 31, 2016 3,315 225 250 3,340 December 31, 2017 3,340 275 250 3,315 December 31, 2018 3,315 1,285 290 2,320
Changes in Accrued Liabilities for Remediation Activities	Changes in accrued liabilities for remediation activities where U. S. Steel is identified as a named party are summarized in the following table: Year Ended December 31, (In millions) 2018 2017 Beginning of period $ 179 $ 179 Accruals for environmental remediation deemed probable and reasonably estimable 14 8 Obligations settled (6 ) (8 ) End of period $ 187 $ 179
Accrued Liabilities for Remediation Activities Included in Balance Sheet	Accrued liabilities for remediation activities are included in the following Consolidated Balance Sheet lines: (In millions) December 31, 2018 December 31, 2017 Accounts payable $ 37 $ 29 Deferred credits and other noncurrent liabilities 150 150 Total $ 187 $ 179
Payments for Contracts with Remaining Terms in Excess of One Year	Payments for contracts with remaining terms in excess of one year are summarized below (in millions): 2019 2020 2021 2022 2023 Later years Total $842 $484 $310 $310 $296 $582 $2,824

Nature of Business and Signif_4

Nature of Business and Significant Accounting Policies Change in Accounting Estimate - Capitalization and Depreciation Method (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net (Note 13)	$ 4,865	$ 4,280	$ 3,979
Under 5 years
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net (Note 13)			597
6-10 years
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net (Note 13)			629
11-15 years
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net (Note 13)			765
16-20 years
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net (Note 13)			654
21-25 years
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net (Note 13)			363
Over 25 years
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net (Note 13)			479
Assets not subject to depreciation
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net (Note 13)			$ 492

Nature of Business and Signif_5

Nature of Business and Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2016	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Percentage of LIFO (last in first out) inventory to total inventory	74.00%		75.00%
Carrying value of property, plant and equipment	$ 4,865	$ 3,979	$ 4,280
Portion of salaried employees that receive pension benefits through a defined contribution pension plan	three-quarters
Portion of represented employees covered by SPT	two-thirds
Pension corridor percentage	10.00%
Current liabilities	$ 3,197		2,773
Welded Tubular
Significant Accounting Policies [Line Items]
Carrying value of property, plant and equipment		$ 410
Estimated useful life of long-lived assets		11 years
Seamless Tubular
Significant Accounting Policies [Line Items]
Carrying value of property, plant and equipment		$ 210
Property, Plant and Equipment | Welded Tubular
Significant Accounting Policies [Line Items]
Amount carrying value exceeds recoverable value		$ 93
Percentage carrying value exceeds recoverable value		23.00%
Property, Plant and Equipment | Seamless Tubular
Significant Accounting Policies [Line Items]
Amount carrying value exceeds recoverable value		$ 220
Percentage carrying value exceeds recoverable value		106.00%
Restatement Adjustment
Significant Accounting Policies [Line Items]
Current liabilities			$ 52

New Accounting Standards (Detai

New Accounting Standards (Details) - Accounting Standards Update 2016-02 $ in Millions	Dec. 31, 2018USD ($)
Minimum
Significant Accounting Policies [Line Items]
Operating lease liability	$ 230
Maximum
Significant Accounting Policies [Line Items]
Operating lease liability	$ 250

Recently Adopted Accounting S_3

Recently Adopted Accounting Standards - Changes Related to Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of Sales	$ 12,305	$ 10,858	$ 9,608
Selling, general and administrative expenses	336	320	306
Cash removed from investing activities	963	386	315
Decrease in net cash provided by operating activities	(938)	(826)	(754)
Increase in repayment of long-term debt	$ 1,299	1,127	1,093
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of Sales		10,858	9,608
Selling, general and administrative expenses		320	306
Net periodic benefit cost (other than service cost)		61	(36)
Accounting Standards Update 2017-07 | Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of Sales		10,864	9,623
Selling, general and administrative expenses		375	255
Net periodic benefit cost (other than service cost)		0	0
Accounting Standards Update 2017-07 | Effect of Change Higher/(Lower)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of Sales		(6)	(15)
Selling, general and administrative expenses		(55)	51
Net periodic benefit cost (other than service cost)		61	(36)
Accounting Standards Update 2016-18 | Effect of Change Higher/(Lower)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash removed from investing activities		3	3
Decrease in net cash provided by operating activities		23	23
Accounting Standards Update 2016-15 | Effect of Change Higher/(Lower)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in repayment of long-term debt		$ 23	$ 23

Segment Information - Additiona

Segment Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018Segment
Segment Reporting [Abstract]
Number of reportable segments	3
Number of commercial entities	3

Segment Information - Results o

Segment Information - Results of Segment Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net sales	$ 14,178	$ 12,250	$ 10,261
Earnings (loss) from investees	61	44	98
Earnings (Loss) before Interest and Income Taxes	1,124	669	(201)
Depreciation, depletion & amortization	521	501	507
Capital expenditures	1,001	505	306
Flat-Rolled
Segment Reporting Information [Line Items]
Net sales	9,681	8,297	7,507
Earnings (loss) from investees	54	38	106
Earnings (Loss) before Interest and Income Taxes	883	375	22
Depreciation, depletion & amortization	367	352	349
Capital expenditures	820	388	111
USSE
Segment Reporting Information [Line Items]
Net sales	3,205	2,949	2,243
Earnings (loss) from investees	0	0	0
Earnings (Loss) before Interest and Income Taxes	359	327	185
Depreciation, depletion & amortization	87	76	80
Capital expenditures	104	83	83
Tubular
Segment Reporting Information [Line Items]
Net sales	1,231	944	449
Earnings (loss) from investees	7	8	6
Earnings (Loss) before Interest and Income Taxes	(58)	(99)	(303)
Depreciation, depletion & amortization	47	51	68
Capital expenditures	45	28	88
Total reportable segments
Segment Reporting Information [Line Items]
Earnings (loss) from investees	61	46	112
Earnings (Loss) before Interest and Income Taxes	1,184	603	(96)
Depreciation, depletion & amortization	501	479	497
Capital expenditures	969	499	282
Other Businesses
Segment Reporting Information [Line Items]
Net sales	61	60	62
Earnings (loss) from investees	0	(2)	(2)
Earnings (Loss) before Interest and Income Taxes	55	44	63
Depreciation, depletion & amortization	20	22	10
Capital expenditures	32	6	24
Reconciling Items and Eliminations
Segment Reporting Information [Line Items]
Net sales	(384)	(339)	(137)
Earnings (loss) from investees			(12)
Earnings (Loss) before Interest and Income Taxes	(115)	22	(168)
Customer Sales | Flat-Rolled
Segment Reporting Information [Line Items]
Net sales	9,681	8,297	7,507
Customer Sales | USSE
Segment Reporting Information [Line Items]
Net sales	3,205	2,949	2,243
Customer Sales | Tubular
Segment Reporting Information [Line Items]
Net sales	1,231	944	449
Customer Sales | Total reportable segments
Segment Reporting Information [Line Items]
Net sales	14,117	12,190	10,199
Customer Sales | Other Businesses
Segment Reporting Information [Line Items]
Net sales	61	60	62
Intersegment Sales
Segment Reporting Information [Line Items]
Net sales	0	0	0
Intersegment Sales | Flat-Rolled
Segment Reporting Information [Line Items]
Net sales	231	194	25
Intersegment Sales | USSE
Segment Reporting Information [Line Items]
Net sales	23	25	3
Intersegment Sales | Tubular
Segment Reporting Information [Line Items]
Net sales	5	1	2
Intersegment Sales | Total reportable segments
Segment Reporting Information [Line Items]
Net sales	259	220	30
Intersegment Sales | Other Businesses
Segment Reporting Information [Line Items]
Net sales	125	119	107
Net Sales
Segment Reporting Information [Line Items]
Net sales	14,178	12,250	10,261
Net Sales | Flat-Rolled
Segment Reporting Information [Line Items]
Net sales	9,912	8,491	7,532
Net Sales | USSE
Segment Reporting Information [Line Items]
Net sales	3,228	2,974	2,246
Net Sales | Tubular
Segment Reporting Information [Line Items]
Net sales	1,236	945	451
Net Sales | Total reportable segments
Segment Reporting Information [Line Items]
Net sales	14,376	12,410	10,229
Net Sales | Other Businesses
Segment Reporting Information [Line Items]
Net sales	186	179	169
Reconciling Items and Eliminations | Reconciling Items and Eliminations
Segment Reporting Information [Line Items]
Net sales	$ (384)	$ (339)	$ (137)

Segment Information - Schedule

Segment Information - Schedule of Assets by Segment (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 10,982	$ 9,862
Flat-Rolled
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,977	5,823
Goodwill	3	3
USSE
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	5,607	5,423
Goodwill	4	4
Tubular
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	1,076	1,076
Total reportable segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	13,660	12,322
Other Businesses
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	329	344
Corporate, reconciling items, and eliminations(b)
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (3,007)	$ (2,804)

Segment Information - Schedul_2

Segment Information - Schedule of Reconciling Items to EBIT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other items not allocated to segments:
Gain associated with U. S. Steel Canada Inc. (Note 5)	$ 0	$ (72)	$ 0
Restructuring and other charges	0	(31)	(122)
Impairment of intangible assets (Note 13)	0	0	(14)
Earnings (loss) before interest and income taxes	1,124	669	(201)
Reconciling Items and Eliminations
Other items not allocated to segments:
Gain associated with U. S. Steel Canada Inc. (Note 5)	0	(72)	0
Restructuring and other charges	0	0	2
Gain (loss) on equity investee transactions (Note11)	(38)	(2)	12
Impairment of intangible assets (Note 13)	0	0	(14)
Earnings (loss) before interest and income taxes	(115)	22	(168)
United Steelworkers Labor Agreement | Reconciling Items and Eliminations
Other items not allocated to segments:
Restructuring and other charges	(81)	0	0
Granite City | Reconciling Items and Eliminations
Other items not allocated to segments:
Restructuring and other charges	8	(17)	(18)
Restart Costs	(80)	0	0
Tubular | Reconciling Items and Eliminations
Other items not allocated to segments:
Restructuring and other charges	$ 0	$ (35)	$ (126)

Segment Information - Net Sales

Segment Information - Net Sales, Property, Plant and Equipment and Equity Method Investments Based on Location of Operating Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
External Sales	$ 14,178	$ 12,250	$ 10,261
Assets	5,351	4,737	4,478
North America
Segment Reporting Information [Line Items]
External Sales	10,973	9,301	8,018
Assets	4,432	3,831	3,671
Europe
Segment Reporting Information [Line Items]
External Sales	3,205	2,949	2,243
Assets	919	906	789
Other Foreign Countries
Segment Reporting Information [Line Items]
External Sales	0	0	0
Assets	0	0	18
U.S.
Segment Reporting Information [Line Items]
Assets	$ 4,432	$ 3,817	$ 3,670

USSC Retained Interest - Additi

USSC Retained Interest - Additional Information (Details) - U. S. Steel Canada Inc. $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)
Investments in and Advances to Affiliates [Line Items]
Proceeds in satisfaction of secured claims	$ 127
Gain on sale of retained interest in USSC	$ 72

Revenue - Additional Informatio

Revenue - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018Segment
Revenue from Contract with Customer [Abstract]
Number of reportable segments	3

Revenue - Disaggregation of Sal

Revenue - Disaggregation of Sales by Product (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Net sales	$ 14,178	$ 12,250	$ 10,261
Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	330	304	171
Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	4,129	3,255	2,402
Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	3,093	2,683	2,635
Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	4,254	3,940	3,766
Tubular products
Disaggregation of Revenue [Line Items]
Net sales	1,243	948	462
All Other (a)
Disaggregation of Revenue [Line Items]
Net sales	1,129	1,120	825
Flat-Rolled
Disaggregation of Revenue [Line Items]
Net sales	9,681	8,297	7,507
Flat-Rolled | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	156	72	6
Flat-Rolled | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	2,816	2,045	1,495
Flat-Rolled | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	2,709	2,355	2,405
Flat-Rolled | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	3,090	2,902	2,932
Flat-Rolled | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Flat-Rolled | All Other (a)
Disaggregation of Revenue [Line Items]
Net sales	910	923	669
USSE
Disaggregation of Revenue [Line Items]
Net sales	3,205	2,949	2,243
USSE | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	174	232	165
USSE | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	1,313	1,210	907
USSE | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	384	328	230
USSE | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	1,164	1,038	834
USSE | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	48	39	32
USSE | All Other (a)
Disaggregation of Revenue [Line Items]
Net sales	122	102	75
Tubular
Disaggregation of Revenue [Line Items]
Net sales	1,231	944	449
Tubular | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Tubular | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Tubular | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Tubular | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Tubular | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	1,195	909	430
Tubular | All Other (a)
Disaggregation of Revenue [Line Items]
Net sales	36	35	19
Other Businesses
Disaggregation of Revenue [Line Items]
Net sales	61	60	62
Other Businesses | Semi-finished
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other Businesses | Hot-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other Businesses | Cold-rolled sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other Businesses | Coated sheets
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other Businesses | Tubular products
Disaggregation of Revenue [Line Items]
Net sales	0	0	0
Other Businesses | All Other (a)
Disaggregation of Revenue [Line Items]
Net sales	$ 61	$ 60	$ 62

Net Interest and Other Financ_3

Net Interest and Other Financial Costs - Net Interest and Other Financial Costs (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income:
Interest income		$ (23)	$ (17)	$ (5)
Interest expense and other financial costs:
Interest incurred		175	229	234
Less interest capitalized		7	3	4
Total interest expense		168	226	230
Loss on debt extinguishment (a)		(98)	(54)	(22)
Net periodic benefit costs (other than service cost) (b)	[1]	69	61	(36)
Foreign currency net (gain) loss (c)		(19)	23	(14)
Financial costs on:
Amended Credit Agreement		5	6	6
USSK credit facilities		3	3	3
Other		3	2	0
Amortization of discounts and deferred financing costs		8	10	9
Total other financial costs		0	44	4
Net interest and other financial costs		$ 312	$ 368	$ 215
[1]	Represents postretirement benefit expense as a result of the adoption of Accounting Standards Update 2017-07, Compensation - Retirement Benefits on January 1, 2018 (see Note 3 for further details).

Earnings and Dividends Per Co_3

Earnings and Dividends Per Common Share - Computations for Basic and Diluted Income (Loss) Per Common Share from Continuing Operations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net earnings (loss) attributable to United States Steel Corporation stockholders	$ 1,115	$ 387	$ (440)
Weighted-average shares outstanding (in thousands):
Basic	176,633	174,793	156,673
Effect of stock options, restricted stock units and performance awards	1,828	1,727	0
Adjusted weighted-average shares outstanding, diluted	178,461	176,520	156,673
Basic earnings (loss) per common share	$ 6.31	$ 2.21	$ (2.81)
Diluted earnings (loss) per common share	$ 6.25	$ 2.19	$ (2.81)

Earnings and Dividends Per Co_4

Earnings and Dividends Per Common Share - Antidilutive Securities that were Not Included in Computation of Diluted Loss Per Common Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Securities granted under the 2005 Stock Incentive Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted loss per common share	1,631	1,579	8,820

Earnings and Dividends Per Co_5

Earnings and Dividends Per Common Share - Additional Information (Details) - $ / shares	3 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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Earnings Per Share [Abstract]
Quarterly dividends per common share	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05

Cash, Cash Equivalents, and R_3

Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 1,000	$ 1,553	$ 1,515
Restricted cash in other current assets	3	6	0
Restricted cash in other noncurrent assets	37	38	40
Total cash, cash equivalents and restricted cash	$ 1,040	$ 1,597	$ 1,555	$ 792

Inventories Inventory balances

Inventories Inventory balances (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 605	$ 527
Semi-finished products	1,021	796
Finished products	404	356
Supplies and sundry items	62	59
Total	$ 2,092	$ 1,738

Inventories - Additional Inform

Inventories - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Estimate in excess of current acquisition costs over stated inventory values	$ 1,038	$ 802
Decrease in income from operations as a result of liquidations of LIFO inventories	10	6	$ 77
Land held for residential or commercial development	$ 39	$ 42

Income Taxes - Components of Ea

Income Taxes - Components of Earnings (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Earnings (loss) before income taxes	$ 812	$ 301	$ (416)
U.S. and Europe
Income Taxes [Line Items]
Earnings (loss) before income taxes	434	75	(588)
Foreign
Income Taxes [Line Items]
Earnings (loss) before income taxes	$ 378	$ 226	$ 172

Income Taxes - (Benefit) Provis

Income Taxes - (Benefit) Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current (Benefit) Provision for Income Taxes
Current Federal income tax (benefit) provision	$ (40)	$ (66)	$ (18)
Current state and local Income tax (benefit) provision	2	(1)	1
Current foreign income tax (benefit) provision	64	53	32
Current income tax (benefit) provision	26	(14)	15
Deferred (Benefit) Provision for Income Taxes
Deferred Federal income tax (benefit) provision	(283)	(81)	0
Deferred state and local Income tax (benefit) provision	(58)	0	0
Deferred foreign income tax (benefit) provision	12	9	9
Deferred income tax (benefit) provision	(329)	(72)	9
(Benefit) Provision for Income Taxes, Total
Federal income tax (benefit) provision	(323)	(147)	(18)
State and local Income tax (benefit) provision	(56)	(1)	1
Foreign income tax (benefit) provision	76	62	41
Total (benefit) provision	$ (303)	$ (86)	$ 24

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Federal Statutory Tax to Total Provisions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory rate applied to earnings (loss) before income taxes	$ 171	$ 105	$ (146)
Valuation allowance	(412)	36	252
Excess percentage depletion	(48)	(68)	(49)
State and local income taxes after federal income tax effects	8	(28)	(20)
Effects of foreign operations	74	62	42
U.S. impact of foreign operations	(21)	(6)	(6)
Tax credits	(71)	(56)	(39)
Effect of tax reform	0	(81)	0
Alternative minimum tax credit refund	0	(48)	(18)
Other	(4)	(2)	8
Total (benefit) provision	$ (303)	$ (86)	$ 24

Income Taxes - Reconciliation_2

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 unrecognized tax benefits [Roll Forward]:
Unrecognized tax benefits, beginning of year	$ 42	$ 72	$ 74
Increases – tax positions taken in prior years	0	1	0
Decreases – tax positions taken in prior years	(2)	(26)	(4)
Increases – current tax positions	0	0	3
Settlements	0	(4)	0
Lapse of statute of limitations	(5)	(1)	(1)
Unrecognized tax benefits, end of year	$ 35	$ 42	$ 72

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets
Federal tax loss carryforwards (expiring in 2035 through 2036)	$ 220	$ 394
State tax credit carryforwards (expiring in 2019 through 2027)	16	14
Minimum tax credit carryforwards	38	76
General business credit carryforwards (expiring in 2027 through 2038)	85	86
Foreign tax loss and credit carryforwards (expiring in 2024 through 2028)	173	102
Employee benefits	337	266
Contingencies and accrued liabilities	62	70
Investments in subsidiaries and equity investees	59	33
Other temporary differences	26	1
Valuation allowance	214	608
Total deferred tax assets	972	625
Deferred Tax Liabilities
Property, plant and equipment	468	516
Inventory	22	6
Receivables, payables and debt	33	14
Indefinite-lived intangible assets	18	18
Other temporary differences	0	21
Total deferred tax liabilities	541	575
Net deferred tax asset	431	50
Federal
Deferred Tax Assets
Capital loss carryforwards	33	36
Valuation allowance	211	604
Deferred Tax Liabilities
Net deferred tax asset	445	53
State
Deferred Tax Assets
Capital loss carryforwards	$ 137	$ 155

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Statutory tax rate		21.00%
Tax benefit related to partial reversal of valuation allowance		$ 374
Tax benefit related to reversal of the valuation allowance related to current year activity		38
Tax benefit related to corporate rate reduction			$ 10
Tax benefit related to reversal of valuation allowance on AMT credits			71
AMT credit refund		0	48	$ 18
Net deferred tax asset		431	50
Valuation allowance on net deferred tax asset		214	608
Unrecognized tax benefits		35	42	$ 72	$ 74
Total amount of unrecognized tax benefits that, if recognized, would affect effective tax rate		2	6
Accrued liabilities, interest on unrecognized tax benefits		2	6
Scenario, Forecast
Income Taxes [Line Items]
Unrecognized tax benefits reasonably expected	$ 32
Domestic Country
Income Taxes [Line Items]
Net deferred tax asset		445	53
Valuation allowance on net deferred tax asset		211	604
Foreign
Income Taxes [Line Items]
Valuation allowance on net deferred tax asset		3	4
Deferred Tax Liabilities, Net		$ 14	$ 3

Investments, Long-Term Receiv_3

Investments, Long-Term Receivables and Equity Investee Transactions - Schedule of Investments and Long-Term Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity method investments	$ 485	$ 457
Receivables due after one year, less allowance of $5 and $11	24	20
Allowance for long-term receivables	5	11
Other	4	3
Total	$ 513	$ 480

Investments, Long-Term Receiv_4

Investments, Long-Term Receivables and Equity Investee Transactions - Summarized Financial Information of Investees Accounted for by Equity Method of Accounting (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income data:
Net Sales	$ 2,193	$ 2,485	$ 2,839
Operating income	157	132	345
Net earnings	134	109	323
Balance sheet data:
Current Assets	642	633	771
Noncurrent Assets	853	710	989
Current liabilities	348	441	478
Noncurrent Liabilities	$ 516	$ 335	$ 506

Investments, Long-Term Receiv_5

Investments, Long-Term Receivables and Equity Investee Transactions - Investees Accounted for using Equity Method (Details) - U.S.	Dec. 31, 2018
Chrome Deposit Corporation
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	50.00%
Daniel Ross Bridge, LLC
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	50.00%
Double G Coatings Company, Inc.
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	50.00%
Feralloy Processing Company
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	49.00%
Hibbing Development Company
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	24.10%
Hibbing Taconite Company(a)
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	14.70%
Patriot Premium Threading Services, LLC
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	50.00%
PRO-TEC Coating Company, LLC
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	50.00%
Strategic Investment Fund Partners II(b)
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	5.20%
USS-POSCO Industries
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	50.00%
Worthington Specialty Processing
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in equity investees	49.00%

Investments, Long-Term Receiv_6

Investments, Long-Term Receivables and Equity Investee Transactions - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Income from investees		$ 61	$ 44	$ 98
Dividends and partnership distributions received from equity investees		13	12	9
Equity method investments		485	457
Allowance for long-term receivables		5	11
Tubular
Schedule of Investments [Line Items]
Income from investees		7	$ 8	6
Write-down of investment	$ 12
Equity method investments	$ 18			$ 18
Leeds Retail Center, LLC
Schedule of Investments [Line Items]
Gain (loss) on sale of equity investments		18
Acero Prime, S.R.L. de CV
Schedule of Investments [Line Items]
Gain (loss) on sale of equity investments		$ 20
Ownership percentage			40.00%
Tilden Mining Company, L.C.
Schedule of Investments [Line Items]
Gain (loss) on sale of equity investments			$ 2
Ownership percentage			1500.00%
Apolo Tubulars, S.A.
Schedule of Investments [Line Items]
Ownership percentage			5000.00%

Property, Plant and Equipment -

Property, Plant and Equipment - Schedule of 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]
Land and depletable property	$ 207	$ 208
Buildings	1,098	1,109
Steel producing	12,784	12,014
Transportation	268	239
Other	123	122
Information technology	786	782
Assets under capital lease	36	36
Construction in process	706	576
Total	16,008	15,086
Less accumulated depreciation and depletion	11,143	10,806
Net	$ 4,865	$ 4,280	$ 3,979
Buildings
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	35 years
Machinery and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	2 years
Machinery and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	30 years
Transportation Equipment [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	3 years
Transportation Equipment [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	40 years
Other Machinery and Equipment [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	5 years
Other Machinery and Equipment [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	30 years
Information Technology | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	5 years
Information Technology | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	6 years
Assets Held under Capital Leases | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	5 years
Assets Held under Capital Leases | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life of long-lived assets	15 years

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Accumulated depreciation and depletion for assets acquired under capital leases (including sale-leasebacks accounted for as financings)	$ 20	$ 18

Intangible Assets - Amortizable

Intangible Assets - Amortizable Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 168	$ 169
Accumulated Amortization	85	77
Net Amount	83	92
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	132	132
Accumulated Amortization	70	64
Net Amount	62	68
Patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	22	22
Accumulated Amortization	7	5
Net Amount	15	17
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	14	15
Accumulated Amortization	8	8
Net Amount	$ 6	$ 7

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Indefinite-lived Intangible Assets [Line Items]
Impairment charge	$ 0	$ 0	$ 14
Carrying value of customer relationships	83	92
Amortization expense	8	9
Water Rights
Indefinite-lived Intangible Assets [Line Items]
Carrying amount of acquired water rights with indefinite lives	$ 75	75
Patents
Indefinite-lived Intangible Assets [Line Items]
Royalty rate			5.00%
Customer relationships
Indefinite-lived Intangible Assets [Line Items]
Useful Lives (in years)	22 years
Carrying value of customer relationships	$ 62	68
Other
Indefinite-lived Intangible Assets [Line Items]
Carrying value of customer relationships	6	7
Patents
Indefinite-lived Intangible Assets [Line Items]
Carrying value of customer relationships	$ 15	$ 17
Minimum | Other
Indefinite-lived Intangible Assets [Line Items]
Useful Lives (in years)	4 years
Minimum | Patents
Indefinite-lived Intangible Assets [Line Items]
Useful Lives (in years)	10 years
Maximum | Other
Indefinite-lived Intangible Assets [Line Items]
Useful Lives (in years)	20 years
Maximum | Patents
Indefinite-lived Intangible Assets [Line Items]
Useful Lives (in years)	15 years
Measurement Input, Discount Rate | Patents
Indefinite-lived Intangible Assets [Line Items]
Discount rate			17.00%

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans - Total Stock-Based Compensation Awards Granted (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Stock Options, Grants	0	647,780	1,333,210
Restricted Stock Units and Performance Awards, Grants	1,150,895
Restricted Stock Units
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Restricted Stock Units and Performance Awards, Grants	824,195	348,040	1,120,332
TSR Performance Awards
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Restricted Stock Units and Performance Awards, Grants	79,190	169,850	308,130
ROCE Performance Awards
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Restricted Stock Units and Performance Awards, Grants	247,510	0	0

Stock-Based Compensation Plan_3

Stock-Based Compensation Plans - Total Compensation Expense Recognized for Stock-Based Compensation Awards (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock-based compensation expense recognized:
Stock-based compensation expense recognized:	$ 32	$ 27	$ 22
Decrease in basic earnings per share	$ 0.14	$ 0.15	$ 0.14
Decrease in diluted earnings per share	$ 0.13	$ 0.15	$ 0.14
Cost of sales
Stock-based compensation expense recognized:
Stock-based compensation expense recognized:	$ 11	$ 10	$ 9
Selling, general and administrative expenses
Stock-based compensation expense recognized:
Stock-based compensation expense recognized:	$ 21	$ 17	$ 13

Stock-Based Compensation Plan_4

Stock-Based Compensation Plans - Black-Scholes Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Grant date price per share of option award		$ 36.94	$ 14.78
Exercise price per share of option award	$ 0	$ 36.94	$ 14.78
Expected life in years		5 years	5 years
Expected volatility		57.00%	53.00%
Risk-free interest rate		2.00%	1.50%
Average grant date fair value per share of unvested option awards as calculated from above		$ 17.28	$ 6.24
Measurement Input, Expected Dividend Rate
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected annual dividends per share		$ 0.20	$ 0.20

Stock-Based Compensation Plan_5

Stock-Based Compensation Plans - Status and Activity of Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares [Roll Forward]
Outstanding at beginning of period	4,612,940
Granted	0
Exercised	(1,541,989)
Forfeited or expired	(324,431)
Outstanding at end of period	2,746,520	4,612,940
Exercisable at end of period	2,174,000
Exercisable and expected to vest at end of period	2,640,308
Weighted- Average Exercise Price (per share)
Outstanding at beginning of period	$ 28.92
Granted	0	$ 36.94	$ 14.78
Exercised	22.65
Forfeited or expired	72.15
Outstanding at end of period	27.73	$ 28.92
Exercisable at end of period	28.10
Exercisable and expected to vest at end of a period	$ 27.76
Weighted- Average Remaining Contractual Term (in years)
Outstanding at end of period	5 years 10 days
Exercisable at end of period	4 years 3 months 25 days
Exercisable and expected to vest at end of period	4 years 11 months 1 day
Aggregate Intrinsic Value
Outstanding at end of period	$ 2
Exercisable at end of period	1
Exercisable and expected to vest at end of period	$ 2

Stock-Based Compensation Plan_6

Stock-Based Compensation Plans - Performance Awards Outstanding and their Fair Market Value on Respective Grant Date (Details) - TSR Awards $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)shares
2018 - 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value | $	$ 15
Minimum Shares	0
Target Shares	313,874
Maximum Shares	627,748
2017 - 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value | $	$ 4
Minimum Shares	0
Target Shares	105,479
Maximum Shares	210,958
2016 - 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value | $	$ 2
Minimum Shares	0
Target Shares	192,332
Maximum Shares	384,664

Stock-Based Compensation Plan_7

Stock-Based Compensation Plans - Status and Activity of Nonvested Stock Awards (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Nonvested Stock Awards [Roll Forward]
Nonvested, beginning of period	1,704,277
Granted	1,150,895
Vested	(581,794)
Performance adjustment factor (b)	(52,557)
Forfeited or expired	(112,864)
Nonvested, end of period	2,107,957	1,704,277
Weighted- Average Grant-Date Fair Value
Beginning of period	$ 21.08
Granted	41.65
Vested	24.20
Performance adjustment factor (b)	24.95
Forfeited or expired	28.99
End of period	$ 30.92	$ 21.08
Percentage of original grants of awards to targeted amounts	100.00%
Restricted Stock Units
Nonvested Stock Awards [Roll Forward]
Nonvested, beginning of period	1,188,746
Granted	824,195	348,040	1,120,332
Vested	(431,661)
Performance adjustment factor (b)	0
Forfeited or expired	(85,008)
Nonvested, end of period	1,496,272	1,188,746
TSR Performance Awards
Nonvested Stock Awards [Roll Forward]
Nonvested, beginning of period	515,531
Granted	79,190	169,850	308,130
Vested	(150,133)
Performance adjustment factor (b)	(52,557)
Forfeited or expired	(16,244)
Nonvested, end of period	375,787	515,531
ROCE Performance Awards
Nonvested Stock Awards [Roll Forward]
Nonvested, beginning of period	0
Granted	247,510
Vested	0
Performance adjustment factor (b)	0
Forfeited or expired	(11,612)
Nonvested, end of period	235,898	0

Stock-Based Compensation Plan_8

Stock-Based Compensation Plans - Restricted Stock Units and Performance Awards Granted (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted	1,150,895
Weighted-average grant-date fair value per share	$ 30.92	$ 21.08
Restricted Stock Units and Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted	1,150,895	517,890	1,428,462
Weighted-average grant-date fair value per share	$ 41.65	$ 37.68	$ 13.39

Stock-Based Compensation Plan_9

Stock-Based Compensation Plans - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 25, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to nonvested stocks	$ 23
Weighted average period for recognizing nonvested stock based compensation costs	16 months
Stock options exercised, total intrinsic value	$ 27	$ 11	$ 13
Receipts from exercise of stock options (Note 15)	35	20	35
Net benefit realized from exercise of options	303	86	(24)
Shares vested, fair value	$ 14	$ 11	$ 17
2005 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future grant	10,936,016
Reduction in number of shares available under Stock Plan for each share issued under Plan pursuant to award other than stock option	1.73
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation plans, vesting period	3 years	3 years	3 years
Share-based compensation plans, term	10 years	10 years	10 years
Net benefit realized from exercise of options	$ 3
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation plans, vesting period	3 years
TSR Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation plans, vesting period	3 years
TSR Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting of performance awards as percentage to target award	0.00%
TSR Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting of performance awards as percentage to target award	200.00%
ROCE Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation plans, vesting period	3 years
Vesting of performance awards as percentage to target award	100.00%
Vesting of performance awards as percentage to threshold award	50.00%
Vesting of performance awards as percentage to maximum award	200.00%
Performance period weighting year one	20.00%
Performance period weighting year two	30.00%
Performance period weighting year three	50.00%
Omnibus Incentive Compensation Plan 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares to be issued					7,200,000
Additional shares authorized				6,300,000

Derivative Instruments - Schedu

Derivative Instruments - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) € in Millions, $ in Millions	Dec. 31, 2018EUR (€)TMMBTU	Dec. 31, 2018CAD ($)TMMBTU	Dec. 31, 2017EUR (€)TMMBTU	Dec. 31, 2017CAD ($)TMMBTU
Foreign exchange forwards
Derivative [Line Items]
Notional amount of derivatives	€ 286	$ 50	€ 234	$ 0
Cash Flow Hedges | Natural Gas | Commodity purchase swaps
Derivative [Line Items]
Quantities of derivatives held | MMBTU	33,951,016	33,951,016	22,049,500	22,049,500
Cash Flow Hedges | Tin | Commodity purchase swaps
Derivative [Line Items]
Quantities of derivatives held	585	585	80	80
Cash Flow Hedges | Zinc | Commodity purchase swaps
Derivative [Line Items]
Quantities of derivatives held	3,471	3,471	4,179	4,179
Cash Flow Hedges | Hot-rolled Coil | Sales swaps
Derivative [Line Items]
Quantities of derivatives held	9,000	9,000	38,000	38,000
Cash Flow Hedges | Iron-ore Pellets | Sales swaps
Derivative [Line Items]
Quantities of derivatives held			40,000	40,000

Derivative Instruments - Locati

Derivative Instruments - Location and Amounts of Fair Values Related to Derivatives in Financial Statements (Details) - Cash Flow Hedges - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounts payable | Sales swaps
Derivative [Line Items]
Derivatives designated as hedging instruments, liabilities	$ 1	$ 0
Derivatives not designated as hedging instruments, liabilities	0	2
Accounts payable | Commodity purchase swaps
Derivative [Line Items]
Derivatives designated as hedging instruments, liabilities	17	2
Derivatives not designated as hedging instruments, liabilities	0	1
Accounts payable | Foreign exchange forwards
Derivative [Line Items]
Derivatives designated as hedging instruments, liabilities	1	0
Accounts receivable | Commodity purchase swaps
Derivative [Line Items]
Derivatives designated as hedging instruments, assets	2	4
Accounts receivable | Foreign exchange forwards
Derivative [Line Items]
Derivatives not designated as hedging instruments, assets	12	11
Investments and long-term receivables | Commodity purchase swaps
Derivative [Line Items]
Derivatives designated as hedging instruments, assets	0	1
Other long-term liabilities | Commodity purchase swaps
Derivative [Line Items]
Derivatives designated as hedging instruments, liabilities	1	1
Other long-term liabilities | Foreign exchange forwards
Derivative [Line Items]
Derivatives designated as hedging instruments, liabilities	$ 1	$ 0

Derivative Instruments - Sche_2

Derivative Instruments - Schedule of Effect of Hedge Accounting on Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Sales swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives in AOCI	$ 0	$ 0	$ 0
Sales swaps | Net sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(13)	0	0
Commodity purchase swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives in AOCI	(15)	1	2
Commodity purchase swaps | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(8)	(2)	13
Foreign exchange forwards
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives in AOCI	(2)	0	0
Foreign exchange forwards | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ 0	$ 0	$ 0

Derivative Instruments - Loca_2

Derivative Instruments - Location and Amounts of Gains or Losses Related to Derivatives in Financial Statements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Sales swaps | Net sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (1)	$ 6	$ (3)
Commodity purchase swaps | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	0	3	3
Foreign exchange forwards | Other financial costs
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ 24	$ (23)	$ 7

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Derivative [Line Items]
Ineffectiveness of hedging related items	$ 1
Cost of sales
Derivative [Line Items]
Current contract values of derivative instruments	16
Net sales
Derivative [Line Items]
Current contract values of derivative instruments	$ 1
Foreign exchange forwards | Maximum
Derivative [Line Items]
Term of derivative contract	12 months
Commodity purchase swaps | Maximum
Derivative [Line Items]
Term of derivative contract	24 months

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Apr. 12, 2018	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt	$ 2,407			$ 2,737
Less unamortized discount and debt issuance costs	26			34
Less short-term debt and long-term debt due within one year	65			3
Long-term debt	$ 2,316			2,700
2037 Senior Notes
Debt Instrument [Line Items]
Interest rates percentages	6.65%
Total debt	$ 350			350
2026 Senior Notes
Debt Instrument [Line Items]
Interest rates percentages	6.25%
Total debt	$ 650			0
2025 Senior Notes
Debt Instrument [Line Items]
Interest rates percentages	6.875%
Total debt	$ 750			750
2021 Senior Secured Notes
Debt Instrument [Line Items]
Interest rates percentages	8.375%		8.375%
Total debt	$ 0	$ 281		780
2020 Senior Notes
Debt Instrument [Line Items]
Interest rates percentages	7.375%
Total debt	$ 0			432
Environmental Revenue Bonds
Debt Instrument [Line Items]
Total debt	400			400
Fairfield Caster Lease
Debt Instrument [Line Items]
Total debt	22			24
Other capital leases and all other obligations
Debt Instrument [Line Items]
Total debt	6			1
Fourth Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Total debt	0			0
USSK Credit Agreement
Debt Instrument [Line Items]
Total debt	229			0
USSK credit facilities
Debt Instrument [Line Items]
Total debt	$ 0			$ 0
Minimum | Environmental Revenue Bonds
Debt Instrument [Line Items]
Interest rates percentages	5.75%
Maximum | Environmental Revenue Bonds
Debt Instrument [Line Items]
Interest rates percentages	6.88%

Debt - Schedule of Debt Redempt

Debt - Schedule of Debt Redemption (Details) - 2026 Senior Notes	12 Months Ended
	Dec. 31, 2018
Debt Instrument, Redemption [Line Items]
Redemption Price	106.25%
2,021
Debt Instrument, Redemption [Line Items]
Redemption Price	103.125%
2,022
Debt Instrument, Redemption [Line Items]
Redemption Price	101.563%
2023 and thereafter
Debt Instrument, Redemption [Line Items]
Redemption Price	100.00%

Debt - Aggregate Maturities of

Debt - Aggregate Maturities of Debt (Details) $ in Millions	Dec. 31, 2018USD ($)
Debt Disclosure [Abstract]
2,019	$ 65
2,020	4
2,021	4
2,022	10
2,023	229
Later Years	2,095
Total	$ 2,407

Debt - Additional Information (

Debt - Additional Information (Details)	Apr. 12, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2018EUR (€)	Sep. 26, 2018EUR (€)	Sep. 25, 2018EUR (€)	Feb. 26, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017EUR (€)
Debt Instrument [Line Items]
Debt, principal amount			$ 2,407,000,000					$ 2,737,000,000
2020 Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount of debt redeemed			$ 357,000,000
Stated interest rate			7.375%	7.375%
Debt redemption price			105.307%
Cost of redemption			$ 376,000,000
Redemption premiums			19,000,000
Debt, principal amount			0					432,000,000
2020 Senior Notes | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount of debt redeemed			$ 75,000,000
Stated interest rate			7.375%	7.375%
Debt redemption price			107.119%
Cost of redemption			$ 80,000,000
Redemption premiums			$ 5,000,000
2021 Senior Secured Notes
Debt Instrument [Line Items]
Aggregate principal amount of debt redeemed		$ 499,000,000
Stated interest rate		8.375%	8.375%	8.375%
Cost of redemption	$ 302,000,000	$ 538,000,000
Redemption premiums	21,000,000	$ 39,000,000
Debt, principal amount	$ 281,000,000		$ 0					780,000,000
USSK Credit Agreement
Debt Instrument [Line Items]
Debt, principal amount			229,000,000					0
Maximum borrowing capacity | €									€ 200,000,000
USSK Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity			527,000,000	€ 460,000,000	€ 460,000,000
Borrowings under credit facility			229,000,000	200,000,000				0
Available borrowing capacity			298,000,000	260,000,000
USSK credit facilities
Debt Instrument [Line Items]
Debt, principal amount			0					0
USSK credit facilities | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity			34,000,000					60,000,000
Borrowings under credit facility			0					0
Available borrowing capacity			32,000,000					57,000,000
Customs and other guarantees outstanding			2,000,000					$ 3,000,000
USSK €10 Million Unsecured Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity | €				10,000,000					10,000,000
USSK €20 Million Unsecured Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity | €				€ 20,000,000
Change in Control Debt Obligations | Maximum
Debt Instrument [Line Items]
Obligations under financing arrangements			1,979,000,000
Change In Control Fairfield Lease | Maximum
Debt Instrument [Line Items]
Obligations under financing arrangements			$ 22,000,000
2026 Senior Notes
Debt Instrument [Line Items]
Stated interest rate		6.25%
Debt redemption price			106.25%
Debt, principal amount		$ 650,000,000
Net proceeds from debt offering		640,000,000
Payments of debt issuance fees		$ 10,000,000
Percentage of debt my redeem			35.00%
Fourth Amended and Restated Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 1,500,000,000				$ 1,500,000,000
Borrowings under credit facility			$ 0
Length debt maturity could be extended if liquidity conditions are not met			91 days
Fourth Amended and Restated Credit Facility | Covenant Requirement
Debt Instrument [Line Items]
Fixed coverage charge ratio, minimum			1	1
Percentage of total debt			10.00%	10.00%
Credit agreement, upper range of outstanding debt			$ 150,000,000
USSK Prior Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity | €						€ 200,000,000
USSK Separate Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity | €				€ 20,000,000	€ 20,000,000	€ 40,000,000			€ 40,000,000

Pensions and Other Benefits - D

Pensions and Other Benefits - Details Relating to Pension Benefits and Other Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits
Change in benefit obligations [Roll Forward]
Benefit obligations, Beginning Balance	$ 6,107	$ 6,214
Service cost	49	50	$ 54
Interest cost	233	235	258
Plan amendments	26	0
Actuarial (gains) losses	(223)	214
Exchange rate loss	(3)	4
Settlements, curtailments and termination benefits	(18)	(12)
Benefits paid	545	598
Benefit obligations, Ending Balance	5,626	6,107	6,214
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan Beginning Balance	5,732	5,482
Actual return on plan assets	(228)	773
Employer contributions	0	75
Fair value of plan assets, Ending Balance	4,960	5,732	5,482
Funded status of plans, Ending Balance	(666)	(375)
Pension Benefits | Change in plan assets
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Benefits paid from plan assets	544	598
Other Benefits
Change in benefit obligations [Roll Forward]
Benefit obligations, Beginning Balance	2,379	2,432
Service cost	17	17	20
Interest cost	92	94	98
Plan amendments	0	0
Actuarial (gains) losses	(185)	8
Exchange rate loss	0	0
Settlements, curtailments and termination benefits	0	0
Benefits paid	182	172
Benefit obligations, Ending Balance	2,121	2,379	2,432
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan Beginning Balance	2,042	1,984
Actual return on plan assets	(49)	171
Employer contributions	0	0
Fair value of plan assets, Ending Balance	1,860	2,042	$ 1,984
Funded status of plans, Ending Balance	(261)	(337)
Other Benefits | Change in plan assets
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Benefits paid from plan assets	$ 133	$ 113

Pensions and Other Benefits - A

Pensions and Other Benefits - Amounts Recognized in Accumulated Other Comprehensive Loss (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Pension Benefits | Prior Service Cost
Accumulated Other Comprehensive Income [Roll Forward]
Defined Benefit Plan costs in Accumulated Other Comprehensive, beginning balance	$ (8)
Amortization	0
Activity	26
Defined Benefit Plan costs in Accumulated Other Comprehensive, ending balance	18
Pension Benefits | Actuarial Losses
Accumulated Other Comprehensive Income [Roll Forward]
Defined Benefit Plan costs in Accumulated Other Comprehensive, beginning balance	2,238
Amortization	(152)
Activity	356
Defined Benefit Plan costs in Accumulated Other Comprehensive, ending balance	2,442
Other Benefits | Prior Service Cost
Accumulated Other Comprehensive Income [Roll Forward]
Defined Benefit Plan costs in Accumulated Other Comprehensive, beginning balance	(51)
Amortization	(29)
Activity	0
Defined Benefit Plan costs in Accumulated Other Comprehensive, ending balance	(80)
Other Benefits | Actuarial Losses
Accumulated Other Comprehensive Income [Roll Forward]
Defined Benefit Plan costs in Accumulated Other Comprehensive, beginning balance	41
Amortization	(4)
Activity	(54)
Defined Benefit Plan costs in Accumulated Other Comprehensive, ending balance	$ (17)

Pensions and Other Benefits - P

Pensions and Other Benefits - Pension and Other Benefits Recognized in Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Pension and Other Postretirement Benefits Disclosure [Line Items]
Accumulated other comprehensive loss effects associated with accounting for pensions and other benefits in accordance with ASC Topic 715	$ 991	$ 958
Pension Benefits
Pension and Other Postretirement Benefits Disclosure [Line Items]
Current liabilities	(2)	(4)
Noncurrent liabilities	(664)	(371)
Accumulated other comprehensive loss (a)	2,460	2,230
Net amount recognized	1,794	1,855
Other Benefits
Pension and Other Postretirement Benefits Disclosure [Line Items]
Current liabilities	(52)	(59)
Noncurrent liabilities	(209)	(278)
Accumulated other comprehensive loss (a)	(97)	(10)
Net amount recognized	$ (358)	$ (347)

Pensions and Other Benefits - I

Pensions and Other Benefits - Information for Pension Plans with Accumulated Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Information for pension plans with an accumulated benefit obligation in excess of plan assets:
Aggregate accumulated benefit obligations (ABO)	$ (5,454)	$ (5,937)
Aggregate projected benefit obligations (PBO)	(5,626)	(6,107)
Aggregate fair value of plan assets	$ 4,960	$ 5,732

Pensions and Other Benefits -_2

Pensions and Other Benefits - Details of Net Periodic Benefit Costs Related to Pension and Other Benefits (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of net periodic benefit cost:
Net periodic benefit cost (benefit)	[1]	$ 69	$ 61	$ (36)
Pension Benefits
Components of net periodic benefit cost:
Service cost		49	50	54
Interest cost		233	235	258
Expected return on plan assets		(361)	(390)	(422)
Amortization - prior service costs		0	0	11
Amortization - actuarial losses		152	148	129
Net periodic benefit cost (benefit), excluding below		73	43	30
Multiemployer plans (a)		60	59	63
Settlement, termination and curtailment losses/(gains)		10	7	13
Net periodic benefit cost (benefit)		143	109	106
Other Benefits
Components of net periodic benefit cost:
Service cost		17	17	20
Interest cost		92	94	98
Expected return on plan assets		(82)	(65)	(151)
Amortization - prior service costs		29	29	26
Amortization - actuarial losses		4	3	3
Net periodic benefit cost (benefit), excluding below		60	78	(4)
Multiemployer plans (a)		0	0	0
Settlement, termination and curtailment losses/(gains)		0	0	(1)
Net periodic benefit cost (benefit)		$ 60	$ 78	$ (5)
[1]	Represents postretirement benefit expense as a result of the adoption of Accounting Standards Update 2017-07, Compensation - Retirement Benefits on January 1, 2018 (see Note 3 for further details).

Pensions and Other Benefits -_3

Pensions and Other Benefits - Amounts in Accumulated Other Comprehensive Income Expected to Be Recognized as Components of Net Periodic Benefit Cost (Details) $ in Millions	Dec. 31, 2018USD ($)
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amortization of actuarial loss	$ 131
Amortization of prior service cost	2
Total recognized from accumulated other comprehensive income	133
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amortization of actuarial loss	(3)
Amortization of prior service cost	29
Total recognized from accumulated other comprehensive income	$ 32

Pensions and Other Benefits -_4

Pensions and Other Benefits - Assumptions used to Determine Benefit Obligation and Net Periodic Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits
Actuarial assumptions used to determine net periodic benefit cost for the year ended December 31:
Expected annual return on plan assets	6.50%
Pension Benefits | U.S. and Europe
Actuarial assumptions used to determine benefit obligations at December 31:
Discount rate	4.41%	4.00%
Increase in compensation rate	2.60%	2.60%
Actuarial assumptions used to determine net periodic benefit cost for the year ended December 31:
Discount rate	4.00%	4.00%	4.25%
Expected annual return on plan assets	6.85%	7.25%	7.50%
Increase in compensation rate	2.60%	2.60%	2.60%
Other Benefits
Actuarial assumptions used to determine net periodic benefit cost for the year ended December 31:
Expected annual return on plan assets	4.25%
Other Benefits | U.S. and Europe
Actuarial assumptions used to determine benefit obligations at December 31:
Discount rate	4.47%	4.03%
Actuarial assumptions used to determine net periodic benefit cost for the year ended December 31:
Discount rate	4.03%	4.00%	4.25%
Expected annual return on plan assets	4.25%	3.25%	7.50%
Increase in compensation rate		3.50%	3.50%

Pensions and Other Benefits -_5

Pensions and Other Benefits - Assumed Health Care Cost Trend Rates (Details) - U.S.	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Assumed health care cost trend rates
Health care cost trend rate assumed for next year	7.00%	7.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2,023	2,022

Pensions and Other Benefits - E

Pensions and Other Benefits - Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Retirement Benefits [Abstract]
Effect of one-percentage-point increase on expected return on plan assets, incremental (decrease) increase in net periodic pension costs for 2018	$ (69)
Effect of one-percentage-point increase on discount rate, incremental (decrease) increase in net periodic pension & other benefits costs for 2018	(18)
Effect of one-percentage-point increase on discount rate, incremental (decrease) increase in pension & other benefits liabilities at December 31, 2017	(650)
Effect of one-percentage-point increase on health care cost escalation trend rates, incremental increase (decrease) in other postretirement benefit obligations	77
Effect of one-percentage-point increase on health care cost escalation trend rates, incremental increase (decrease) in service and interest costs components	4
Effect of one-percentage-point decrease on expected return on plan assets, incremental (decrease) increase in net periodic pension costs for 2018	69
Effect of one-percentage-point decrease on discount rate, incremental (decrease) increase in net periodic pension & other benefits costs for 2018	8
Effect of one-percentage-point decrease on discount rate, incremental (decrease) increase in pension & other benefits liabilities at December 31, 2017	770
Effect of one-percentage-point decrease on health care cost escalation trend rates, incremental increase (decrease) in other postretirement benefit obligations	(66)
Effect of one-percentage-point decrease on health care cost escalation trend rates, incremental increase (decrease) in service and interest costs components	$ (3)

Pensions and Other Benefits -_6

Pensions and Other Benefits - Pension Plan and Other Plan Assets Carried at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	$ 4,960	$ 5,732	$ 5,482
Investments measured in the fair value hierarchy	2,596	2,522
Investments measured at net asset value	2,364	3,210
Pension Benefits | Short-term Investments
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	7	155
Pension Benefits | Defined Benefit Plan, Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	101
Pension Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		1,806
Pension Benefits | Corporate & Government Bonds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	2,143
Pension Benefits | Mineral Interests
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	2	3
Pension Benefits | Timberlands
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	294	300
Pension Benefits | Private equities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	2	4
Pension Benefits | Real estate
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	33	33
Pension Benefits | Other securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	14	(39)
Pension Benefits | Exchange-Traded Funds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		260
Pension Benefits | Defined Benefit Plan, Equity Securities, US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	95
Pension Benefits | Defined Benefit Plan, Equity Securities, Non-US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	6
Other Benefits
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	1,860	2,042	$ 1,984
Investments measured in the fair value hierarchy	1,766	1,935
Investments measured at net asset value	94	107
Other Benefits | Short-term Investments
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	42
Other Benefits | Defined Benefit Plan, Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	45
Other Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		54
Other Benefits | Corporate & Government Bonds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	1,631
Other Benefits | Government bonds - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		1,455
Other Benefits | Timberlands
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	35	34
Other Benefits | Private equities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		1
Other Benefits | Other securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	13	39
Other Benefits | Debt Securities - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	1,631	29
Other Benefits | Agency Mortgages
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		323
Other Benefits | Defined Benefit Plan, Equity Securities, US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	27
Other Benefits | Defined Benefit Plan, Equity Securities, Non-US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	18
Quoted Prices in Active Markets (Level 1) | Pension Benefits
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	122	376
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Short-term Investments
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	7	155
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Defined Benefit Plan, Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	101
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Corporate & Government Bonds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Mineral Interests
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Timberlands
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Private equities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Real estate
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Other securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	14	(39)
Quoted Prices in Active Markets (Level 1) | Pension Benefits | Exchange-Traded Funds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		260
Quoted Prices in Active Markets (Level 1) | Other Benefits
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	100	122
Quoted Prices in Active Markets (Level 1) | Other Benefits | Short-term Investments
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	42
Quoted Prices in Active Markets (Level 1) | Other Benefits | Defined Benefit Plan, Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	45
Quoted Prices in Active Markets (Level 1) | Other Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		54
Quoted Prices in Active Markets (Level 1) | Other Benefits | Government bonds - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Quoted Prices in Active Markets (Level 1) | Other Benefits | Timberlands
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Quoted Prices in Active Markets (Level 1) | Other Benefits | Private equities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Quoted Prices in Active Markets (Level 1) | Other Benefits | Other securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	13	39
Quoted Prices in Active Markets (Level 1) | Other Benefits | Debt Securities - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	29
Quoted Prices in Active Markets (Level 1) | Other Benefits | Agency Mortgages
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Other Significant Observable Inputs (Level 2) | Pension Benefits
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	2,143	1,806
Other Significant Observable Inputs (Level 2) | Pension Benefits | Short-term Investments
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Other Significant Observable Inputs (Level 2) | Pension Benefits | Defined Benefit Plan, Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0
Other Significant Observable Inputs (Level 2) | Pension Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		1,806
Other Significant Observable Inputs (Level 2) | Pension Benefits | Corporate & Government Bonds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	2,143
Other Significant Observable Inputs (Level 2) | Pension Benefits | Mineral Interests
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Other Significant Observable Inputs (Level 2) | Pension Benefits | Timberlands
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Other Significant Observable Inputs (Level 2) | Pension Benefits | Private equities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Other Significant Observable Inputs (Level 2) | Pension Benefits | Real estate
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Other Significant Observable Inputs (Level 2) | Pension Benefits | Other securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Other Significant Observable Inputs (Level 2) | Pension Benefits | Exchange-Traded Funds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Other Significant Observable Inputs (Level 2) | Other Benefits
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	1,631	1,778
Other Significant Observable Inputs (Level 2) | Other Benefits | Short-term Investments
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0
Other Significant Observable Inputs (Level 2) | Other Benefits | Defined Benefit Plan, Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0
Other Significant Observable Inputs (Level 2) | Other Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Other Significant Observable Inputs (Level 2) | Other Benefits | Government bonds - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		1,455
Other Significant Observable Inputs (Level 2) | Other Benefits | Timberlands
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Other Significant Observable Inputs (Level 2) | Other Benefits | Private equities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Other Significant Observable Inputs (Level 2) | Other Benefits | Other securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Other Significant Observable Inputs (Level 2) | Other Benefits | Debt Securities - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	1,631	0
Other Significant Observable Inputs (Level 2) | Other Benefits | Agency Mortgages
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		323
Significant Unobservable Inputs (Level 3) | Pension Benefits
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	331	340
Significant Unobservable Inputs (Level 3) | Pension Benefits | Short-term Investments
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Significant Unobservable Inputs (Level 3) | Pension Benefits | Defined Benefit Plan, Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0
Significant Unobservable Inputs (Level 3) | Pension Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Significant Unobservable Inputs (Level 3) | Pension Benefits | Corporate & Government Bonds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0
Significant Unobservable Inputs (Level 3) | Pension Benefits | Mineral Interests
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	2	3
Significant Unobservable Inputs (Level 3) | Pension Benefits | Timberlands
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	294	300
Significant Unobservable Inputs (Level 3) | Pension Benefits | Private equities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	2	4
Significant Unobservable Inputs (Level 3) | Pension Benefits | Real estate
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	33	33
Significant Unobservable Inputs (Level 3) | Pension Benefits | Other securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Significant Unobservable Inputs (Level 3) | Pension Benefits | Exchange-Traded Funds
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Significant Unobservable Inputs (Level 3) | Other Benefits
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	35	35
Significant Unobservable Inputs (Level 3) | Other Benefits | Short-term Investments
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0
Significant Unobservable Inputs (Level 3) | Other Benefits | Defined Benefit Plan, Equity Securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0
Significant Unobservable Inputs (Level 3) | Other Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Significant Unobservable Inputs (Level 3) | Other Benefits | Government bonds - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Significant Unobservable Inputs (Level 3) | Other Benefits | Timberlands
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	35	34
Significant Unobservable Inputs (Level 3) | Other Benefits | Private equities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		1
Significant Unobservable Inputs (Level 3) | Other Benefits | Other securities
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Significant Unobservable Inputs (Level 3) | Other Benefits | Debt Securities - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	0	0
Significant Unobservable Inputs (Level 3) | Other Benefits | Agency Mortgages
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		0
Corporate Bond Securities | Pension Benefits | Debt Security, Corporate, US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	933
Corporate Bond Securities | Pension Benefits | Debt Security, Corporate, Non-US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	149
Corporate Bond Securities | Pension Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		1,084
Corporate Bond Securities | Other Benefits | Debt Security, Corporate, US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	1,052
Corporate Bond Securities | Other Benefits | Debt Security, Corporate, Non-US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	271
Government bonds - U.S. | Pension Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		720
Agency Mortgages | Pension Benefits | Equity Securities – U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		2
Corporate & Government Bonds | Pension Benefits | Debt Securities - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	858
Corporate & Government Bonds | Pension Benefits | Agency Mortgages
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	136
Corporate & Government Bonds | Pension Benefits | Debt Security, Government, Non-US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	67
Corporate & Government Bonds | Other Benefits | Debt Securities - U.S.
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	270
Corporate & Government Bonds | Other Benefits | Agency Mortgages
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	30
Corporate & Government Bonds | Other Benefits | Debt Security, Government, Non-US
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at net asset value	8
Other securities | Pension Benefits | Cash
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	32
Other securities | Pension Benefits | Investment sales
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	57	157
Other securities | Pension Benefits | Accrued income
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	21	19
Other securities | Pension Benefits | Investment purchases
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	(80)	(197)
Other securities | Pension Benefits | Miscellaneous Payables
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	(16)
Other securities | Pension Benefits | Investment purchase payables
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	(1)
Other securities | Pension Benefits | Miscellaneous payables
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		(18)
Other securities | Other Benefits | Investment sales
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value		23
Other securities | Other Benefits | Accrued income
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	16	$ 17
Other securities | Other Benefits | Investment purchase payables
Schedule of Pension and Other Postretirment Plan Assets by Fair Value [Line Items]
Investments measured at fair value	$ (3)

Pensions and Other Benefits - F

Pensions and Other Benefits - Fair Value, Investments, Entities that Calculate Net Asset Value per Share (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 4,960	$ 5,732	$ 5,482
Investments measured at net asset value	2,364	3,210
Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Defined Benefit Plan, Plan Assets, Amount	1,860	2,042	$ 1,984
Investments measured at net asset value	94	107
Equity Funds | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments measured at net asset value		1,969
Fixed Income Funds | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments measured at net asset value		729
Private Equity Funds | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded commitments	68	91
Investments measured at net asset value	254	252
Private Equity Funds | Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded commitments	10	15
Investments measured at net asset value	61	62
Real Estate Funds | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded commitments	93	117
Investments measured at net asset value	236	260
Real Estate Funds | Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Unfunded commitments	12	15
Investments measured at net asset value	33	33
Interest in Investment Partnerships | Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments measured at net asset value		12
Commingled Funds | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments measured at net asset value	1,874
Debt Securities - U.S. | Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Defined Benefit Plan, Plan Assets, Amount	$ 1,631	29
Exchange-Traded Funds | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Defined Benefit Plan, Plan Assets, Amount		260
Equity Securities – U.S. | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Defined Benefit Plan, Plan Assets, Amount		1,806
Equity Securities – U.S. | Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Defined Benefit Plan, Plan Assets, Amount		54
Equity Securities – U.S. | Government bonds - U.S. | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Defined Benefit Plan, Plan Assets, Amount		720
Agency Mortgages | Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Defined Benefit Plan, Plan Assets, Amount		$ 323
Minimum | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Remaining life of investments	1 year	1 year
Minimum | Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Remaining life of investments	1 year	1 year
Maximum | Pension Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Remaining life of investments	10 years	11 years
Maximum | Other Benefits
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Remaining life of investments	10 years	11 years

Pensions and Other Benefits - C

Pensions and Other Benefits - Changes in Fair Value of Pension Plan and Other Benefit Plan Level 3 Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Pension Plan Assets [Roll Forward]
Balance at beginning of period	$ 340	$ 357
Transfers in and/or out of Level 3	0	0
Actual return on plan assets:
Realized gain	11	2
Net unrealized loss	(8)	(16)
Purchases, sales, issuances and settlements:
Sales	(12)	(3)
Balance at end of period	331	340
Other Benefits
Pension Plan Assets [Roll Forward]
Balance at beginning of period	35	38
Transfers in and/or out of Level 3	0	0
Actual return on plan assets:
Realized gain	(1)	0
Net unrealized loss	(1)	(2)
Purchases, sales, issuances and settlements:
Sales	0	(1)
Balance at end of period	$ 35	$ 35

Pensions and Other Benefits - M

Pensions and Other Benefits - Multiemployer Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Steelworkers Pension Trust
Defined Benefit Plan Disclosure [Line Items]
Employer Identification Number/ Pension Plan Number	23-6648508/499
Pension Protection Act Zone Status	Green	Green
FIP/RP Status Pending/Implemented	No
U.S. Steel Contributions	$ 60	$ 59	$ 63
Surcharged Imposed	No	No
Expiration Date of Collective Bargaining Agreement	Sep. 1, 2022
Minimum | Steelworkers Pension Trust | Green Zone
Defined Benefit Plan Disclosure [Line Items]
Funded Percentage Under Pension Protection Act	80.00%
Maximum | Steelworkers Pension Trust | Yellow Zone
Defined Benefit Plan Disclosure [Line Items]
Funded Percentage Under Pension Protection Act	80.00%
Maximum | Steelworkers Pension Trust | Red Zone
Defined Benefit Plan Disclosure [Line Items]
Funded Percentage Under Pension Protection Act	65.00%

Pensions and Other Benefits - B

Pensions and Other Benefits - Benefit Payments Expected to be Paid from Defined Benefit Plans (Details) $ in Millions	Dec. 31, 2018USD ($)
Pension Benefits
Schedule of Pension and Other Postretirement Benefits Expected Benefit Payments [Line Items]
2,019	$ 498
2,020	470
2,021	453
2,022	440
2,023	426
Years 2024 - 2027	1,962
Other Benefits
Schedule of Pension and Other Postretirement Benefits Expected Benefit Payments [Line Items]
2,019	164
2,020	184
2,021	186
2,022	186
2,023	185
Years 2024 - 2027	$ 755

Pensions and Other Benefits -_7

Pensions and Other Benefits - Additional Information (Details)	Jan. 01, 2021USD ($)	Jan. 01, 2020USD ($)	Jan. 01, 2019USD ($)	Nov. 13, 2018USD ($)	Nov. 20, 2017USD ($)	Dec. 31, 2018USD ($)$ / shares$ / h	Dec. 31, 2017USD ($)$ / shares	Dec. 31, 2016USD ($)$ / shares	Dec. 31, 2007
Defined Benefit Plan Disclosure [Line Items]
Portion of represented employees covered by SPT						two-thirds
Collective bargaining agreement term				4 years
Increase to defined benefit plan pension liability due to 2018 labor agreements				$ 26,000,000
Defined benefit plans, accumulated benefit obligation						$ 5,454,000,000	$ 5,937,000,000
Portion of costs for retiree health benefits limited to a per capital dollar maximum						three quarters
U. S. Steel common stock issued for defined benefit pension plans						$ 0	$ 0	$ 100,000,000
Common stock, par value (usd per share) | $ / shares						$ 1	$ 1
Discount rate used for calculating benefit obligation, other postemployment benefit plans						4.36%	3.57%
Future projected benefit cost, other postretirement benefit plans						$ 14,000,000
Net periodic benefit cost, other postretirement benefit plans						$ 10,000,000	$ 22,000,000
Portion of employees included In multiemployer plan						three-quarters
Employees eligible savings account contribution amount								0.50
Subsequent Event
Defined Benefit Plan Disclosure [Line Items]
Employees eligible savings account contribution amount	$ 0.65	$ 0.60	$ 0.55
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plans, expected net periodic benefit cost						$ 158,000,000
Expected annual return on plan assets						6.50%
Employer contributions						$ 0	75,000,000
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plans, expected net periodic benefit cost						$ 57,000,000
Target allocation for plan assets						90.00%
Expected annual return on plan assets						4.25%
Employer contributions						$ 0	0
Steelworkers Pension Trust
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plans, expected net periodic benefit cost						$ 66,000,000
Contribution rate for multiemployer defined benefit plans | $ / h						2.65
Total amortization period of losses						29 years			15 years
U. S. Steel Retirement Plan Trust
Defined Benefit Plan Disclosure [Line Items]
Target allocation for plan assets						45.00%
Employer contributions					$ 75,000,000
U. S. Steel common stock issued for defined benefit pension plans								$ 3,763,643
Common stock, par value (usd per share) | $ / shares								$ 1
Price per common shares issued (in dollars per share) | $ / shares								$ 26.57
Payments for pension benefits								$ 100,000,000
Unfunded Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Payments for pension benefits						$ 20,000,000	13,000,000	26,000,000
Unfunded Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Payments for pension benefits						48,000,000	59,000,000	61,000,000
Defined Contribution Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan expense						23,000,000	22,000,000	23,000,000
Defined Contribution Pension Matching Contribution
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan expense						17,000,000	17,000,000	17,000,000
Supplemental Thrift Plan
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan expense						4,000,000	1,000,000	1,000,000
Canadian Hourly Employees Savings Match
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan expense						2,000,000	1,000,000	$ 1,000,000
Other Postemployment Benefit
Defined Benefit Plan Disclosure [Line Items]
Accrued employee benefits						$ 110,000,000	$ 116,000,000
Minimum | Steelworkers Pension Trust
Defined Benefit Plan Disclosure [Line Items]
Proportion of single plan contribution as to total combined contribution						5.00%

Asset Retirement Obligations -C

Asset Retirement Obligations -Changes in Carrying Values of Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligations [Roll Forward]
Balance at beginning of year	$ 69	$ 79
Obligations settled	(12)	(8)
Change in estimate of obligations	0	(6)
Foreign currency translation effects	0	2
Accretion expense	3	2
Balance at end of period	$ 60	$ 69

Fair Value of Financial Instr_3

Fair Value of Financial Instruments -Financial Assets and Liabilities Not Carried at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Financial liabilities:
Long-term debt (a)	$ 2,407
Fair Value
Financial liabilities:
Long-term debt (a)	2,182	$ 2,851
Carrying Amount
Financial liabilities:
Long-term debt (a)	$ 2,353	$ 2,678

Reclassifications from Accumu_3

Reclassifications from Accumulated Other Comprehensive Income (AOCI) - Schedule of Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period	$ (845)	$ (1,497)
Other comprehensive income before reclassifications	(19)	834
Amounts reclassified from AOCI (b)	(162)	(191)
Sale of ownership interest in Tilden Mining Company L.C.		9
Net current-period other comprehensive income	(181)	652
Balance, end of period	(1,026)	(845)
Pension and Other Benefit Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period	(1,309)	(1,771)
Other comprehensive income before reclassifications	41	640
Amounts reclassified from AOCI (b)	(148)	(187)
Sale of ownership interest in Tilden Mining Company L.C.		9
Net current-period other comprehensive income	(107)	462
Balance, end of period	(1,416)	(1,309)
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period	463	274
Other comprehensive income before reclassifications	(60)	189
Amounts reclassified from AOCI (b)	0	0
Sale of ownership interest in Tilden Mining Company L.C.		0
Net current-period other comprehensive income	(60)	189
Balance, end of period	403	463
Unrealized Gain (Loss) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period	1	0
Other comprehensive income before reclassifications	0	5
Amounts reclassified from AOCI (b)	(14)	(4)
Sale of ownership interest in Tilden Mining Company L.C.		0
Net current-period other comprehensive income	(14)	1
Balance, end of period	$ (13)	$ 1

Reclassifications from Accumu_4

Reclassifications from Accumulated Other Comprehensive Income (AOCI) - Detail of Amounts Reclassified From Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Earnings (loss) before income taxes	$ 812	$ 301	$ (416)
Tax benefit (b)	303	86	(24)
Net of tax	1,115	387	(440)
Pension and Other Benefit Items | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service costs (a)	(29)	(29)	(37)
Actuarial losses (a)	(156)	(151)	(132)
Settlements, termination and curtailment losses (a)	(10)	(7)	(12)
Total pensions and other benefits items	(195)	(187)	(181)
Derivative reclassifications to Consolidated Statements of Operations	(19)	(4)	(18)
Earnings (loss) before income taxes	(214)	(191)	(199)
Tax benefit (b)	52	0	0
Net of tax	$ (162)	$ (191)	$ (199)

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information -Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net cash used in operating activities included:
Interest and other financial costs paid (net of amount capitalized)	$ 207	$ 242	$ 193
Income taxes paid	39	40	6
Non-cash investing and financing activities:
Change in accrued capital expenditures	135	208	(110)
U. S. Steel common stock issued for employee/non-employee director stock plans	21	49	32
U. S. Steel common stock issued for defined benefit pension plans	$ 0	$ 0	$ 100

Transactions with Related Par_2

Transactions with Related Parties - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Related party sales and service transactions	$ 1,420	$ 1,204	$ 1,216
Other noncurrent assets, allowance	5	11
Accounts payable to related parties	81	74
Outside processing services
Related Party Transaction [Line Items]
Purchases from related parties	29	70	80
Taconite pellets
Related Party Transaction [Line Items]
Purchases from related parties	91	140	$ 177
PRO-TEC Coating Company, LLC
Related Party Transaction [Line Items]
Accounts payable to related parties	80	72
Other related parties
Related Party Transaction [Line Items]
Accounts payable to related parties	$ 1	$ 2

Leases - Future Minimum Commitm

Leases - Future Minimum Commitments for Capital Leases and Operating Leases (Details) $ in Millions	Dec. 31, 2018USD ($)
Capital Leases
Capital leases future minimum payment in 2019	$ 5
Capital leases future minimum payment in 2020	5
Capital leases future minimum payment in 2021	5
Capital leases future minimum payment in 2022	11
Capital leases future minimum payment in 2023	0
Capital leases future minimum payment, later years	0
Total minimum lease payments	26
Less imputed interest costs	4
Present value of net minimum lease payments included in long-term debt (see Note 17)	22
Operating Leases
Operating leases future minimum payment in 2019	66
Operating leases future minimum payment in 2020	55
Operating leases future minimum payment in 2021	45
Operating leases future minimum payment in 2022	37
Operating leases future minimum payment in 2023	28
Operating leases future minimum payment, later years	72
Total minimum lease payments	$ 303

Leases - Operating Lease Rental

Leases - Operating Lease Rental Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Leases [Abstract]
Minimum rentals	$ 114	$ 114	$ 115
Contingent rentals	19	10	8
Net rental expense	$ 133	$ 124	$ 123

Restructuring and Other Charg_3

Restructuring and Other Charges - Activity in Accrued Balances for Restructuring and Other Cost Reduction Programs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Balance at beginning of period	$ 38	$ 74
Additional charges		37
Cash payments/utilization	(21)	(67)
Other adjustments and reclasses		(6)	$ (26)
Balance at end of period	17	38	74
Employee Related Costs
Restructuring Reserve [Roll Forward]
Balance at beginning of period	4	14
Additional charges		2
Cash payments/utilization	(4)	(8)
Other adjustments and reclasses		(4)
Balance at end of period	0	4	14
Exit Costs
Restructuring Reserve [Roll Forward]
Balance at beginning of period	34	60
Additional charges		0
Cash payments/utilization	(17)	(24)
Other adjustments and reclasses		(2)
Balance at end of period	17	34	60
Non-cash Charges
Restructuring Reserve [Roll Forward]
Balance at beginning of period	0	0
Additional charges		35
Cash payments/utilization	0	(35)
Other adjustments and reclasses		0
Balance at end of period	$ 0	$ 0	$ 0

Restructuring and Other Charg_4

Restructuring and Other Charges - Balance Sheet Location of Accrued Liabilities for Restructuring and Other Cost Reduction Programs (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Total	$ 17	$ 38	$ 74
Accounts payable
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, current	11	26
Payroll and benefits payable
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, current	0	4
Deferred credits and other noncurrent liabilities
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, noncurrent	$ 6	$ 8

Restructuring and Other Charg_5

Restructuring and Other Charges -Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 0	$ 31	$ 122
Other adjustments and reclasses		(6)	(26)
Severance costs			24
Restructuring Charges
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		31	122
Employee Severance
Restructuring Cost and Reserve [Line Items]
Other adjustments and reclasses		(4)
Payments for restructuring	$ 21	32	79
Tubular
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		$ 37	$ 124

Contingencies and Commitments -

Contingencies and Commitments - Asbestos Litigation Activity (Details) - Asbestos Matters - Claim_Group	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loss Contingency Accrual [Roll Forward]
Opening Number of Claims	3,315	3,340	3,315
Claims Dismissed, Settled and Resolved (a)	1,285	275	225
New Claims	290	250	250
Closing Number of Claims	2,320	3,315	3,340

Contingencies and Commitments_2

Contingencies and Commitments - Changes in Accrued Liabilities for Remediation Activities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in Accrued Liabilities for Remediation Activities [Roll Forward]
Beginning of period	$ 179	$ 179
Accruals for environmental remediation deemed probable and reasonably estimable	14	8
Obligations settled	(6)	(8)
End of period	$ 187	$ 179

Contingencies and Commitments_3

Contingencies and Commitments - Accrued Liabilities for Remediation Activities Included in Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Line Items]
Accrued liabilities for remediation activities	$ 187	$ 179	$ 179
Accounts payable
Commitments and Contingencies Disclosure [Line Items]
Accrued liabilities for remediation activities	37	29
Deferred credits and other noncurrent liabilities
Commitments and Contingencies Disclosure [Line Items]
Accrued liabilities for remediation activities	$ 150	$ 150

Contingencies and Commitments_4

Contingencies and Commitments - Payments for Contracts with Remaining Terms in Excess of One Year (Details) $ in Millions	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,019	$ 842
2,020	484
2,021	310
2,022	310
2,023	296
Later years	582
Total	$ 2,824

Contingencies and Commitments_5

Contingencies and Commitments - Additional Information (Details) € in Millions, Allowances in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)	Dec. 31, 2018USD ($)ProjectPlaintiffFacilityClaim_GroupAllowances	Dec. 31, 2018EUR (€)PlaintiffAllowances	Dec. 31, 2017USD ($)Claim_Group	Dec. 31, 2016USD ($)Claim_Group	Dec. 31, 2015Claim_Group
Loss Contingencies [Line Items]
Number of cases dismissed		1,000	1,000
Accrued liabilities for remediation activities		$ 187,000,000		$ 179,000,000	$ 179,000,000
Accrued liabilities for post-closure site monitoring and other costs		22,000,000
Accrued liability for administrative and legal costs		$ 10,000,000
Number of years of projected administrative and legal costs included in accrual		3 years	3 years
Capital expenditures		$ 125,000,000		52,000,000
Final allocation for emissions allowances during NAP III period | Allowances		48	48
Emissions allowances purchased | Allowances		11
Cost of emissions allowances purchased		$ 135,000,000	€ 118
Estimated shortfall in emissions allowances during NAP III period | Allowances		15	15
Financial assurance guarantees, maximum		$ 4,000,000
Residual value of equipment		17,000,000
Residual value liability		0
Restricted cash		40,000,000		44,000,000
Contract commitments to acquire property, plant and equipment		601,000,000
Total payment under take-or-pay contracts		600,000,000		$ 576,000,000	$ 457,000,000
Gateway Energy and Coke Company, LLC
Loss Contingencies [Line Items]
Maximum default payment on termination of agreement		$ 142,000,000
Minimum
Loss Contingencies [Line Items]
Projected percentage remediation costs may exceed accrued liabilities		15.00%	15.00%
Estimated capital expenditures of complying with BAT over 2017 to 2020 period		$ 158,000,000	€ 138
Unconditional purchase obligation term		2 years	2 years
Maximum
Loss Contingencies [Line Items]
Projected percentage remediation costs may exceed accrued liabilities		25.00%	25.00%
Unconditional purchase obligation term		15 years	15 years
Asbestos Matters
Loss Contingencies [Line Items]
Active cases brought against U.S. Steel | Claim_Group		755		820
Number of claims pending in jurisdictions | Claim_Group		2,320		3,315	3,340	3,315
Number of plaintiffs involved | Plaintiff		1,540	1,540
Percentage of claims pending in jurisdictions		66.00%
Projects with Ongoing Study and Scope Development
Loss Contingencies [Line Items]
Environmental remediation projects | Facility		5
Accrued liabilities for remediation activities		$ 1,000,000
Projects with Ongoing Study and Scope Development | Minimum
Loss Contingencies [Line Items]
Environment exit costs, possible additional loss		25,000,000
Projects with Ongoing Study and Scope Development | Maximum
Loss Contingencies [Line Items]
Environment exit costs, possible additional loss		$ 40,000,000
Other Project With Defined Scope
Loss Contingencies [Line Items]
Environmental remediation projects | Project		4
Accrued liabilities for remediation activities		$ 144,000,000
Other Project With Defined Scope | Minimum
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		5,000,000
Gary Works, Project with Defined Scope
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		25,000,000
Geneva Project
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		62,000,000
Cherryvale Zinc Site
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		11,000,000
St Louis Estuary Project
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		$ 46,000,000
Environmental Remediation Other Projects
Loss Contingencies [Line Items]
Environmental remediation projects | Facility		2
Accrued liabilities for remediation activities		$ 4,000,000
Environmental Remediation Other Projects | Minimum
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		1,000,000
Environmental Remediation Other Projects | Maximum
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		5,000,000
Environmental Remediation Projects Less Than One Million
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		5,000,000
Environmental Remediation Projects Less Than One Million | Maximum
Loss Contingencies [Line Items]
Accrued liabilities for remediation activities		1,000,000
New boiler
Loss Contingencies [Line Items]
Estimated capital expenditures for boiler project		147,000,000	€ 128
Surety Bonds
Loss Contingencies [Line Items]
Financial assurance guarantees, maximum		$ 181,000,000
U. S. Steel Canada Inc.
Loss Contingencies [Line Items]
Proceeds in satisfaction of secured claims	$ 127,000,000

Common Stock Repurchase Progr_2

Common Stock Repurchase Program and Common Stock Issuance - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 15, 2016	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount			$ 300	$ 300
Class of Stock [Line Items]
Shares repurchased (in shares)			2,760,112
Value of shares repurchased			$ 75
Par value of common shares issued (in dollars per share)			$ 1	$ 1	$ 1
Proceeds from common shares issued				$ 0	$ 0	$ 482
Common stock
Class of Stock [Line Items]
Common stock, shares issued	21,735,000
Par value of common shares issued (in dollars per share)	$ 1
Price per common shares issued (in dollars per share)	$ 23
Third party expenses related to common shares issued	$ 18
Proceeds from common shares issued	$ 482
Subsequent Event
Class of Stock [Line Items]
Shares repurchased (in shares)		1,313,982
Value of shares repurchased		$ 25

2018 Labor Agreements (Details)

2018 Labor Agreements (Details) Employee in Thousands	Sep. 01, 2021	Jan. 01, 2021USD ($)	Sep. 01, 2020	Jan. 01, 2020USD ($)	Sep. 01, 2019	Jan. 01, 2019USD ($)	Sep. 01, 2018Employee	Dec. 31, 2018USD ($)	Dec. 31, 2018USD ($)
Risks and Uncertainties [Abstract]
Number of employees covered under collective bargaining agreement | Employee							14
Gross payments under labor agreements								$ 81,000,000
Concentration Risk [Line Items]
Wage adjustment percentage under labor agreements							4.00%
Wage adjustment amount per hour									$ 2.65
Scenario, Forecast
Concentration Risk [Line Items]
Wage adjustment percentage under labor agreements	3.00%		3.50%		3.50%
Wage adjustment amount per hour		$ 3.50		$ 3.35		$ 3.15

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event $ in Millions	Feb. 11, 2019USD ($)
Subsequent Event [Line Items]
Payments to fund investment in capital projects	$ 215
Annual capacity of tons produced under electric arc furnace capital project	1,600,000

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 28	$ 25	$ 28
Additions, Charged to Costs and Expenses	5	2	0
Additions, Charged to Other Accounts	0	2	0
Deductions, Charged to Costs and Expenses	0	0	0
Deductions, Charged to Other Accounts	4	1	3
Balance at End of Period	29	28	25
Allowance for related party doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	0	265	254
Additions, Charged to Costs and Expenses		0	0
Additions, Charged to Other Accounts		0	11
Deductions, Charged to Costs and Expenses		0	0
Deductions, Charged to Other Accounts		265	0
Balance at End of Period		0	265
Investments and long-term receivables reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	11	10	7
Additions, Charged to Costs and Expenses	0	0	0
Additions, Charged to Other Accounts	0	1	3
Deductions, Charged to Costs and Expenses	0	0	0
Deductions, Charged to Other Accounts	6	0	0
Balance at End of Period	5	11	10
Long-term receivables from related parties reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	0	1,627	1,446
Additions, Charged to Costs and Expenses		0	0
Additions, Charged to Other Accounts		0	181
Deductions, Charged to Costs and Expenses		0	0
Deductions, Charged to Other Accounts		1,627	0
Balance at End of Period		0	1,627
Domestic deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	604
Additions, Charged to Costs and Expenses	0
Additions, Charged to Other Accounts	0
Deductions, Charged to Costs and Expenses	393
Deductions, Charged to Other Accounts	0
Balance at End of Period	211	604
Foreign deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	4	4	4
Additions, Charged to Costs and Expenses	0	0	0
Additions, Charged to Other Accounts	0	0	0
Deductions, Charged to Costs and Expenses	1	0	0
Deductions, Charged to Other Accounts	0	0	0
Balance at End of Period	3	4	4
State deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 604	1,109	804
Additions, Charged to Costs and Expenses		42	174
Additions, Charged to Other Accounts		0	131
Deductions, Charged to Costs and Expenses		373	0
Deductions, Charged to Other Accounts		174	0
Balance at End of Period		$ 604	$ 1,109