United States Steel (X) 10-Q 29 Oct 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Oct. 23, 2014
Document and Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'X	'
Entity Registrant Name	'UNITED STATES STEEL CORP	'
Entity Central Index Key	'0001163302	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	145,484,622

Consolidated_Statement_Of_Oper

Consolidated Statement Of Operations (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net sales:	'	'	'	'
Net sales	$4,285	$3,856	$12,582	$12,292
Net sales to related parties (Note 19)	302	275	853	863
Total	4,587	4,131	13,435	13,155
Operating expenses (income):	'	'	'	'
Cost of sales (excludes items shown below)	3,848	3,749	11,983	12,105
Selling, general and administrative expenses	125	153	406	449
Depreciation, depletion and amortization	158	173	489	514
Income from investees	-50	-26	-103	-31
Impairment of goodwill (Note 5)	0	1,783	0	1,783
Restructuring and other charges (Note 20)	236	0	254	0
Loss on deconsolidation of U. S. Steel Canada and other charges (Note 4)	413	0	413	0
Net gain on disposal of assets (Note 21)	-2	0	-23	0
Other expense, net	0	1	0	6
Total	4,728	5,833	13,419	14,826
(Loss) income from operations	-141	-1,702	16	-1,671
Interest expense	57	61	178	204
Interest income	-2	0	-4	-2
Other financial costs	5	24	19	55
Net interest and other financial costs (Note 7)	60	85	193	257
Loss before income taxes and noncontrolling interests	-201	-1,787	-177	-1,928
Income tax provision (benefit) (Note 9)	6	4	-4	14
Net loss	-207	-1,791	-173	-1,942
Less: Net loss attributable to noncontrolling interests	0	0	0	0
Net loss	($207)	($1,791)	($173)	($1,942)
Earnings per share attributable to United States Steel Corporation shareholders:	'	'	'	'
Basic (in dollars per share)	($1.42)	($12.38)	($1.19)	($13.44)
Diluted (in dollars per share)	($1.42)	($12.38)	($1.19)	($13.44)

Consolidated_Statement_Of_Comp

Consolidated Statement Of Comprehensive Income (Loss) (USD $)	3 Months Ended			9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Condensed Statement of Income Captions [Line Items]	'		'	'		'
Net loss	($207)		($1,791)	($173)		($1,942)
Other comprehensive (loss) income, net of tax:	'		'	'		'
Changes in foreign currency translation adjustments	107		31	93		13
Changes in pension and other employee benefit accounts	53		59	175		197
Deconsolidation of U. S. Steel Canada	468	[1]	0	468	[1]	0
Total other comprehensive income, net of tax	628		90	736		210
Comprehensive income (loss) including noncontrolling interest	421		-1,701	563		-1,732
Comprehensive income attributable to noncontrolling interest	0		0	0		0
Comprehensive income (loss) attributable to United States Steel Corporation	421		-1,701	563		-1,732
Pension and other benefit adjustments	'		'	'		'
Other comprehensive (loss) income, net of tax:	'		'	'		'
Deconsolidation of U. S. Steel Canada	493		'	493		'
Currency translation adjustment	'		'	'		'
Other comprehensive (loss) income, net of tax:	'		'	'		'
Deconsolidation of U. S. Steel Canada	($25)		'	($25)		'
[1]	Consists of $493 million for Pension and other benefit adjustments and $(25) million for currency translation adjustment.

Consolidated_Balance_Sheet

Consolidated Balance Sheet (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$1,257	$604
Receivables, less allowance of $49 and $53	1,876	1,818
Receivables from related parties, less allowance of $117 and $0 (Note 19)	182	157
Inventories (Note 12)	2,199	2,688
Income tax receivable (Note 9)	14	185
Deferred income tax benefits (Note 9)	535	576
Other current assets	38	50
Total current assets	6,101	6,078
Property, plant and equipment	15,058	16,799
Less accumulated depreciation and depletion	10,488	10,877
Total property, plant and equipment, net	4,570	5,922
Investments and long-term receivables, less allowance of $9 and $10	586	621
Long-term receivables from related parties, less allowance of $1,317 and $0	400	0
Intangibles – net (Note 5)	205	271
Deferred income tax benefits (Note 9)	13	16
Other noncurrent assets	133	235
Total assets	12,008	13,143
Current liabilities:	'	'
Accounts payable and other accrued liabilities	1,941	1,681
Accounts payable to related parties (Note 19)	131	73
Bank checks outstanding	26	0
Payroll and benefits payable	925	974
Accrued taxes	118	140
Accrued interest	73	54
Short-term debt and current maturities of long-term debt (Note 13)	336	323
Total current liabilities	3,550	3,245
Long-term debt, less unamortized discount (Note 14)	3,162	3,616
Employee benefits	554	2,064
Deferred income tax liabilities (Note 9)	411	418
Deferred credits and other noncurrent liabilities	388	424
Total liabilities	8,065	9,767
Contingencies and commitments (Note 21)	'	'
Stockholders’ Equity (Note 17):	'	'
Common stock (150,925,911 shares issued) (Note 11)	151	151
Treasury stock, at cost (5,455,773 and 6,245,666 shares)	-410	-480
Additional paid-in capital	3,623	3,667
Retained earnings	1,594	1,789
Accumulated other comprehensive loss (Note 18)	-1,016	-1,752
Total stockholders’ equity	3,942	3,375
Noncontrolling interests	1	1
Total liabilities and stockholders’ equity	$12,008	$13,143

Consolidated_Balance_Sheet_Par

Consolidated Balance Sheet (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, except Share data, unless otherwise specified
Receivables, allowance	$49	$53
Investments and long-term receivables, allowance	9	10
Common stock, shares issued	150,925,911	150,925,911
Treasury stock, shares	5,455,773	6,245,666
Affiliated Entity [Member]	'	'
Receivables, allowance	117	0
Investments and long-term receivables, allowance	$0	$0

Consolidated_Statement_Of_Cash

Consolidated Statement Of Cash Flows (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating activities:	'	'
Net loss	($173)	($1,942)
Adjustments to reconcile to net cash provided by operating activities:	'	'
Depreciation, depletion and amortization	489	514
Impairment of goodwill (Note 5)	0	1,783
Restructuring and other charges (Note 20)	254	0
Loss on deconsolidation of U. S. Steel Canada and other charges (Note 4)	413	0
Provision for doubtful accounts	-4	2
Pensions and other postretirement benefits	-266	-143
Deferred income taxes	6	3
Net gain on disposal of assets (Note 21)	-23	0
Currency remeasurement loss	32	8
Distributions received, net of equity investees income	-96	-20
Changes in:	'	'
Current receivables	-312	137
Inventories	63	15
Current accounts payable and accrued expenses	586	-34
Income taxes receivable/payable	167	1
Bank checks outstanding	25	40
All other, net	78	61
Net cash provided by operating activities	1,247	421
Investing activities:	'	'
Capital expenditures	-282	-328
Acquisition of intangible assets (Note 5)	0	12
Disposal of assets	28	0
Change in restricted cash, net	23	39
Investments, net	-3	-8
Net cash used in investing activities	-234	-309
Financing activities:	'	'
Issuance of long-term debt, net of financing costs of $0 and $15	0	575
Repayment of long-term debt	-323	-542
Receipts from exercise of stock options	10	0
Dividends paid	-22	-22
Net cash (used in) provided by financing activities	-335	11
Effect of exchange rate changes on cash	-25	4
Net increase in cash and cash equivalents	653	127
Cash and cash equivalents at beginning of year	604	570
Cash and cash equivalents at end of period	$1,257	$697

Consolidated_Statement_Of_Cash1

Consolidated Statement Of Cash Flows (Parenthetical) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Statement of Cash Flows [Abstract]	'	'
Financing costs	$0	$15

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	United States Steel Corporation (U. S. Steel or the Company) produces and sells steel products, including flat-rolled and tubular products, in North America and Central Europe. Operations in North America also include iron ore and coke production facilities, railroad services and real estate operations. Operations in Europe also include coke production facilities.
	The year-end consolidated balance sheet data was derived from audited statements but does not include all disclosures required for complete financial statements by accounting principles generally accepted in the United States of America (U.S. GAAP). The other information in these financial statements is unaudited but, in the opinion of management, reflects all adjustments necessary for a fair statement of the results for the periods covered. All such adjustments are of a normal recurring nature unless disclosed otherwise. These financial statements, including notes, have been prepared in accordance with the applicable rules of the Securities and Exchange Commission and do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. Additional information is contained in the United States Steel Corporation Annual Report on Form 10-K for the year ended December 31, 2013, which should be read in conjunction with these financial statements.
	Revision of prior period financial statements - During the second quarter of 2014, the Company identified a prior period error related to the accounting for income taxes associated with the 2013 tax restructuring. The effect of the $27 million adjustment has been recorded in the second quarter of 2014 as a revision to retained earnings and long-term deferred tax liabilities on the Company’s consolidated balance sheet as of December 31, 2013. The effects of the revision to the Company’s 2013 financial statements in the 2014 Form 10-K will result in an additional tax benefit of $27 million to the previously reported income tax benefit in the consolidated statement of operations and a corresponding decrease to long-term deferred tax liabilities and an increase in retained earnings of $27 million to the previously reported amounts in the consolidated balance sheet. The Company concluded that the impact of this error was not material to the prior period.

New_Accounting_Standards

New Accounting Standards	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
New Accounting Standards	'
	New Accounting Standards
	On August 27, 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (ASU 2014-15). ASU 2014-15 explicitly requires management to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosures in certain circumstances. Currently, there is no guidance in U.S. GAAP about management's responsibility to evaluate whether there is substantial doubt about an entity's ability to continue as a going concern or to provide related footnote disclosures. ASU 2014-15 is effective for all entities for interim and annual periods beginning after December 15, 2016; early application is permitted. U. S. Steel does not expect any financial statement impact relating to the adoption of this ASU.
	On May 28, 2014, the FASB and the International Accounting Standards Board issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09). ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. ASU 2014-09 is effective for interim and annual periods beginning after December 15, 2016; early application is not permitted. U. S. Steel is evaluating the financial statement implications of adopting ASU 2014-09.
	On April 10, 2014, the FASB issued Accounting Standards Update No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of components of an Entity (ASU 2014-08). ASU 2014-08 amends the definition of a discontinued operation in ASC 205-20 and requires entities to provide additional disclosures about disposal transactions that do not meet the discontinued operations criteria. The revised guidance will change how entities identify and disclose information about disposal transactions under U.S. GAAP. ASU 2014-08 is effective for all disposals (or classifications as held for sale) of components of an entity that occur within annual periods beginning on or after December 15, 2014 and interim periods within those years. U. S. Steel is evaluating the financial statement implications of adopting ASU 2014-08.
	On July 18, 2013, the FASB issued Accounting Standards Update No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists (ASU 2013-11). ASU 2013-11 requires the netting of unrecognized tax benefits (UTBs) against a deferred tax asset for a loss or other carryforward that would apply in settlement of the uncertain tax positions. UTBs are required to be netted against all available same-jurisdiction loss or other tax carryforwards that would be utilized, rather than only against carryforwards that are created by the UTBs. ASU 2013-11 was effective for interim and annual periods beginning after December 15, 2013. U. S. Steel early adopted ASU 2013-11 in the second quarter of 2013 on a prospective basis. The adoption did not have a significant impact on U. S. Steel's consolidated financial statements.
	On March 4, 2013, the FASB issued Accounting Standards Update No. 2013-05, Parent’s Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries of Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity (ASU 2013-05). ASU 2013-05 applies to the release of the cumulative translation adjustment into net income when a parent either sells a part or all of its investment in a foreign entity or no longer holds a controlling financial interest in a subsidiary or group of assets that is a nonprofit activity or a business (other than a sale of in substance real estate or conveyance of oil and gas mineral rights) within a foreign entity. In addition, the amendments in ASU 2013-05 resolve the diversity in practice for the treatment of business combinations achieved in stages (sometimes also referred to as step acquisitions) involving a foreign entity. ASU 2013-05 was effective for interim and annual periods beginning after December 31, 2013. The adoption did not have a significant impact on U. S. Steel’s consolidated financial statements.
	On February 28, 2013, the FASB issued Accounting Standards Update No. 2013-04, Obligations Resulting from Joint and Several Liability Arrangements for which the Total Amount of the Obligation Is Fixed at the Reporting Date (ASU 2013-04). ASU 2013-04 requires companies to measure obligations resulting from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date, as the sum of the amount a company has agreed to pay on the basis of its arrangement among its co-obligors and any additional amount a company expects to pay on behalf of its co-obligors. ASU 2013-04 also requires a company to disclose the nature and amount of the obligation as well as other information about those obligations. ASU 2013-04 was effective for interim and annual periods beginning after December 31, 2013. The adoption did not have a significant impact on U. S. Steel’s consolidated financial statements.

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	U. S. Steel has three reportable segments: Flat-rolled Products (Flat-rolled), U. S. Steel Europe (USSE), and Tubular Products (Tubular). The results of several other operating segments that do not constitute reportable segments, which include railroad services and real estate operations, are combined and disclosed in the Other Businesses category.
	On September 16, 2014, U. S. Steel Canada Inc. (USSC), a wholly owned subsidiary of USS, applied for relief from its creditors pursuant to Canada’s Companies’ Creditors Arrangement Act (CCAA). As a result of USSC filing for protection under the CCAA (CCAA filing), U. S. Steel determined that USSC and its subsidiaries would be deconsolidated from U. S. Steel’s financial statements. We recorded a total non-cash charge of $413 million in the third quarter of 2014 related to the deconsolidation of USSC. See Note 4.
	The Flat-rolled segment information subsequent to September 16, 2014 does not include USSC. After the deconsolidation of USSC, transactions between U. S. Steel and USSC are considered related party transactions.
	The chief operating decision maker evaluates performance and determines resource allocations based on a number of factors, the primary measure being income (loss) from operations. Income (loss) from operations for reportable segments and Other Businesses does not include net interest and other financial costs (income), income taxes, postretirement benefit expenses (other than service cost and amortization of prior service cost for active employees) and certain other items that management believes are not indicative of future results. Information on segment assets is not disclosed, as it is not reviewed by the chief operating decision maker.
	The accounting principles applied at the operating segment level in determining income (loss) from operations are generally the same as those applied at the consolidated financial statement level. The transfer value for steel rounds from Flat-rolled to Tubular is based on cost. All other 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 for the three months ended September 30, 2014 and 2013 are:
	(In millions) Three Months Ended September 30, 2014	Customer			Intersegment			Net			Income			Income
		Sales			Sales			Sales			(loss)			(loss)
											from			from
											investees			operations
	Flat-rolled	$	3,125		$	319		$	3,444		$	47		$	347
	USSE	687			1			688			—			29
	Tubular	700			—			700			3			69
	Total reportable segments	4,512			320			4,832			50			445
	Other Businesses	75			33			108			—			34
	Reconciling Items and Eliminations	—			(353		)	(353		)	—			(620		)
	Total	$	4,587		$	—		$	4,587		$	50		$	(141	)
	Three Months Ended September 30, 2013
	Flat-rolled	$	2,731		$	324		$	3,055		$	28		$	82
	USSE	643			1			644			—			(32		)
	Tubular	731			2			733			(1		)	49
	Total reportable segments	4,105			327			4,432			27			99
	Other Businesses	26			32			58			(1		)	14
	Reconciling Items and Eliminations	—			(359		)	(359		)	—			(1,815		)
	Total	$	4,131		$	—		$	4,131		$	26		$	(1,702	)
	The results of segment operations for the nine months ended September 30, 2014 and 2013 are:
	(In millions) Nine Months Ended September 30, 2014	Customer			Intersegment			Net			Income			Income
		Sales			Sales			Sales			(loss)			(loss)
											from			from
											investees			operations
	Flat-rolled	$	9,089		$	947		$	10,036		$	98		$	462
	USSE	2,203			45			2,248			—			99
	Tubular	2,030			2			2,032			8			140
	Total reportable segments	13,322			994			14,316			106			701
	Other Businesses	113			101			214			(3		)	64
	Reconciling Items and Eliminations	—			(1,095		)	(1,095		)	—			(749		)
	Total	$	13,435		$	—		$	13,435		$	103		$	16
	Nine Months Ended September 30, 2013
	Flat-rolled	$	8,710		$	985		$	9,695		$	41		$	18
	USSE	2,204			3			2,207			—			16
	Tubular	2,126			4			2,130			(7		)	158
	Total reportable segments	13,040			992			14,032			34			192
	Other Businesses	115			101			216			(3		)	62
	Reconciling Items and Eliminations	—			(1,093		)	(1,093		)	—			(1,925		)
	Total	$	13,155		$	—		$	13,155		$	31		$	(1,671	)
	The following is a schedule of reconciling items to income (loss) from operations:
		Three Months Ended September 30,						Nine Months Ended September 30,
	(In millions)	2014			2013			2014			2013
	Items not allocated to segments:
	Postretirement benefit expense (a)	$	(26	)	$	(55	)	$	(90	)	$	(165	)
	Other items not allocated to segments:
	Loss on deconsolidation of U. S. Steel Canada and other charges (Note 4)	(413		)	—			(413		)	—
	Impairment of carbon alloy facilities (Note 20)	(199		)	—			(199		)	—
	Write-off of pre-engineering costs (Note 20)	(37		)	—			(37		)	—
	Gain on sale of real estate assets (b)	55			—			55			—
	Litigation reserves (Note 21)	—			—			(70		)	—
	Loss on assets held for sale (Note 20)	—			—			(14		)	—
	Curtailment gain (Note 6)	—			—			19			—
	Impairment of goodwill (Note 5)	—			(1,783		)	—			(1,783		)
	Supplier contract dispute settlement	—			23			—			23
	Total other items not allocated to segments	(594		)	(1,760		)	(659		)	(1,760		)
	Total reconciling items	$	(620	)	$	(1,815	)	$	(749	)	$	(1,925	)
(a) Consists of the net periodic benefit cost elements, other than service cost and amortization of prior service cost for active employees, associated with our pension, retiree health care and life insurance benefit plans.
(b) Gain on sale of surface rights and mineral royalty revenue streams in the state of Alabama.

U_S_Steel_Canada_Deconsolidati

U. S. Steel Canada Deconsolidation U. S. Steel Canada Deconsolidation (Notes)	9 Months Ended
	Sep. 30, 2014
Deconsolidation of Subsidiary [Abstract]	'
Deconsolidation of U.S. Steel Canada and other charges	'
	Deconsolidation of U. S. Steel Canada and other charges
	Restructuring and Creditor Protection
	U. S. Steel Canada Inc. (USSC), an indirect wholly owned subsidiary of U. S. Steel, with unanimous approval from its Board of Directors applied for relief from its creditors pursuant to CCAA on September 16, 2014. The CCAA filing was approved by the Ontario Superior Court of Justice (the Court) on September 16, 2014 and grants USSC creditor protection while it formulates a plan of restructuring. To assist USSC with its plan of restructuring, the Court confirmed the engagement by USSC of a chief restructuring officer, the appointment of a monitor and certain other financial advisors. As of the date of the CCAA filing, any proceedings pending against USSC, or currently underway affecting USSC’s business operations or property, have been stayed pending further order by the Court.
	As a result of the CCAA proceedings, U. S. Steel no longer has a controlling financial interest over USSC, as defined under ASC 810, Consolidation, and therefore has deconsolidated USSC’s financial position as of the end of the day on September 15, 2014. This has resulted in a pretax loss on deconsolidation and other charges of $413 million, which includes approximately $20 million of professional fees. The pretax loss on deconsolidation includes the derecognition of the carrying amounts of USSC's assets and liabilities and accumulated other comprehensive loss that were previously consolidated in U. S. Steel's consolidated balance sheet and the impact of recording the retained interest in USSC. Subsequent to the deconsolidation, U. S. Steel will account for USSC using the cost method of accounting, which has been reflected as zero in U. S. Steel’s consolidated balance sheet as of September 30, 2014, due to the negative equity associated with USSC’s underlying financial position.
	The following disclosure represents USSC’s assets, liabilities and accumulated other comprehensive loss which have been deconsolidated from U. S. Steel’s consolidated balance sheet as of the end of the day on September 15, 2014. The amounts presented are before the elimination of balances with U. S. Steel, presenting USSC as if on a stand-alone basis.
	(Dollars in millions)	15-Sep-14
	Assets
	Current assets:
	Cash and cash equivalents	$	80
	Receivables	291
	Inventories	373
	Other current assets	6
	Total current assets	750
	Property, plant and equipment, net	840
	Other noncurrent assets	126
	Total assets	$	1,716
	Liabilities
	Current liabilities:
	Accounts payable	$	435
	Other current liabilities	149
	Total current liabilities	584
	Long-term debt	126
	Long-term notes payable	1,733
	Employee benefits	948
	Other noncurrent liabilities	29
	Total liabilities	3,420
	Stockholders’ Equity
	Additional paid-in capital	2,268
	Retained earnings	(3,504		)
	Accumulated other comprehensive loss	(468		)
	Total stockholders’ equity	(1,704		)
	Noncontrolling interests	—
	Total liabilities and stockholders’ equity	$	1,716
	USSC’s results of operations have been removed from U. S. Steel’s consolidated statement of operations beginning September 16, 2014. Because USSC remains a wholly owned subsidiary of U. S. Steel, as of September 30, 2014, and does not meet the requirements of a discontinued operation, USSC’s results of operations continue to be included in our consolidated statement of operations through September 15, 2014. Our consolidated statements of operations include the following amounts for USSC’s results of operations. The amounts presented are before the elimination of transactions with U. S. Steel, presenting USSC as if on a stand-alone basis.
	(Dollars in millions)	Period from July 1, 2014 - September 15, 2014			Three months ended September 30, 2013			Period from January 1, 2014 - September 15, 2014			Nine months ended September 30, 2013
	Total net sales	$	447		$	282		$	1,508		$	960
	Total operating expenses	467			1,026			1,587			1,941
	Loss from continuing operations	(20		)	(744		)	(79		)	(981		)
	Net interest and other financial costs	37			39			121			142
	Loss before income taxes	(57		)	(783		)	(200		)	(1,123		)
	Income tax benefit	—			—			—			—
	Net loss	$	(57	)	$	(783	)	$	(200	)	$	(1,123	)
	Related Party Transactions
	Prior to the deconsolidation, U. S. Steel made loans to USSC for the purpose of funding its operations and had net trade accounts receivable in the ordinary course of business. The loans, the corresponding interest and the net trade accounts receivable were considered intercompany transactions and were eliminated in the consolidated U. S. Steel financial statements. As of the deconsolidation date, the loans, associated interest and net trade accounts receivable are now considered third party transactions and have been recognized in U. S. Steel's consolidated financial statements based upon the recoverability of their carrying amounts and whether or not the amounts are secured or unsecured. U. S. Steel has estimated a recovery rate based upon the fair value of the net assets of USSC available for distribution to its creditors in relation to the secured and unsecured creditor claims in the CCAA filing.
	Fair values of the Hamilton Works finishing operations, Hamilton Works coke operations and Lake Erie Works (the USSC Businesses) were used to determine the recoverability of the loans receivable, accrued interest receivable and the net trade accounts receivable using various valuation approaches depending on the type of assets being valued and the highest and best use of those assets. The Hamilton Works finishing operations were valued under a liquidation basis using replacement costs, market comparables, and other recoverability measures as it had negative cash flows on a discounted cash flow basis, while the remainder of the USSC Businesses were valued on a going concern basis.
	The going concern fair value for the Hamilton Works coke operations and Lake Erie Works was determined based upon an income approach using a discounted cash flow (DCF) analysis, discounted at an appropriate risk-adjusted rate.
	The amount and timing of future cash flows within the DCF analysis and the liquidation basis were based on the following inputs within the fair value framework prescribed by ASC Topic 820, Fair Value Measurements, in the table below.
	Level 2 Other Observable Inputs	Level 3 Other Unobservable Inputs
	Market Participant Weighted Average Cost of Capital (1)	Recent Operating Budgets
	Perpetual Growth Rate (2)	Long Range Strategic Plans
	Market Comparables	Estimated Shipments
	Replacement Cost	Projected Raw Material Costs
		Projected Margins
		Recoverability Measures
	(1) Ranged from 15.54% - 18.31%
	(2) Set at approximately 2%
	Actual results may differ from those assumed in U. S. Steel’s forecasts for the USSC Businesses.
	The total fair values associated with the underlying net assets of the USSC Businesses were then compared to the estimated outstanding creditor claims, both secured and unsecured, to determine the expected recoverability. This has resulted in a fair value of the retained interest in the intercompany loans, interest receivable and trade accounts receivable of $432 million, net of an allowance for doubtful accounts of $1,448 million, which has been reflected as a component of the loss on deconsolidation of USSC and other charges in the consolidated statement of operations.
	For further information regarding USSC’s related party transactions with U. S. Steel subsequent to the date of deconsolidation, see Transactions with Related Parties at Note 19.
	Debtor-in Possession Financing
	In conjunction with the CCAA filing, U. S. Steel agreed to provide a debtor-in-possession (DIP) credit facility to USSC, that was approved by the Court on October 8, 2014, and provides for borrowings under the facility of a maximum commitment of C$185 million (approximately $165 million). The DIP facility will be primarily used for USSC’s working capital needs as well as to provide support for any guarantees, letters of credit and other forms of credit support related to USSC’s operations and contains certain covenants governing the terms and provisions of the DIP facility.
	Borrowings under the DIP facility will bear interest at a rate of 5% annually on outstanding principal balances. Interest on the DIP will be due and payable on the first business day of the month. Upon an occurrence of default, the interest rate will be increased by 2%. USSC will pay U. S. Steel a lending fee of 2% of the maximum commitment which is payable from the initial DIP advance. If the DIP facility is repaid using funds advanced to USSC by a party other than U. S. Steel, prior to USSC emerging from CCAA protection, USSC will pay U. S. Steel an exit fee of approximately 3% of the maximum commitment.
	All outstanding amounts owed to U. S. Steel pursuant to the DIP facility will be due and payable by USSC on the earliest of the occurrence of any of the following: (i) December 31, 2015; (ii) the implementation of a plan of reorganization under the CCAA proceeding; (iii) conversion of the CCAA proceeding into a proceeding under the Bankruptcy and Insolvency Act (Canada); (iv) the completion of the sale of all or substantially all of the assets of USSC; or (v) an event of default.
Amounts borrowed by USSC under the DIP facility will have a priority claim over certain other secured and unsecured claims subsequent to USSC emerging from CCAA protection. As of September 30, 2014, there were no amounts drawn under the DIP facility.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill and Intangible Assets	'
	Goodwill and Intangible Assets
	Goodwill represents the excess of the cost over the fair value of acquired identifiable tangible and intangible assets and liabilities assumed from businesses acquired.
	Goodwill is tested for impairment at the reporting unit level annually in the third quarter and whenever events or circumstances indicate the carrying value may not be recoverable. The evaluation of goodwill impairment involves using either a qualitative or quantitative approach as outlined in ASC Topic 350, Intangibles - Goodwill and Other. U. S. Steel completed its annual goodwill impairment evaluation using the two-step quantitative analysis during the third quarter of 2013. We had two reporting units that included nearly all of our goodwill: our Flat-rolled reporting unit and our Texas Operations reporting unit, which is part of our Tubular operating segment. The results of the second step analysis showed the implied fair value of goodwill was zero for both of our reporting units and therefore, in 2013, U. S. Steel recorded a goodwill impairment charge of $969 million and $837 million for the Flat-rolled reporting unit and the Texas Operations reporting unit, respectively.
	As a result of this goodwill impairment charge, there is no goodwill remaining within the Flat-rolled and Tubular segments. Goodwill remaining on our consolidated balance sheet at September 30, 2014 is $4 million within the USSE reporting unit and is included as a component of other noncurrent assets.
	Amortizable intangible assets are being amortized on a straight-line basis over their estimated useful lives and are detailed below:
			As of September 30, 2014						As of December 31, 2013
	(In millions)	Useful	Gross		Accumulated		Net		Gross		Accumulated		Net
		Lives	Carrying		Amortization		Amount		Carrying		Amortization		Amount
			Amount						Amount
	Customer relationships (a)	22 Years	$	132	$	45	$	87	$	215	$	63	$	152
	Other	2-20 Years	23		13		10		23		12		11
	Total amortizable intangible assets		$	155	$	58	$	97	$	238	$	75	$	163
	(a) Amounts associated with USSC totaling $56 million were removed as of the end of the day on September 15, 2014.
	The carrying amount of acquired water rights with indefinite lives as of both September 30, 2014 and December 31, 2013 totaled $75 million. The water rights are tested for impairment annually in the third quarter. U. S. Steel performed a qualitative impairment evaluation of its water rights for 2014. The 2014 and prior year tests indicated the water rights were not impaired.
	During 2013, U. S. Steel acquired indefinite-lived intangible assets for $12 million and entered into an agreement to make future payments contingent upon certain factors. The aggregate purchase price was $36 million, and U. S. Steel allocated $33 million to indefinite-lived intangible assets, based upon their estimated fair value. The liability for contingent consideration will be reassessed each quarter. The maximum potential liability for contingent consideration is $53 million. As of September 30, 2014, U. S. Steel has recorded a liability of $24 million to reflect the estimated fair value of the contingent consideration. Contingent consideration was valued using a probability weighted discounted cash flow using both Level 2 inputs based on 2013 Standard and Poor’s Bond Guide as well as Level 3, significant other unobservable inputs, based on internal forecasts and the weighted average cost of capital derived from market data.
	Identifiable intangible assets with finite lives are reviewed for impairment whenever events or circumstances indicate that the carrying value may not be recoverable. During the third quarter of 2013, U. S. Steel completed a review of its identifiable intangible assets with finite lives and determined that the assets were not impaired. There were no such events or circumstances during the third quarter of 2014 that required a review for impairment.
	Amortization expense was $2 million in the three months ended September 30, 2014 and $3 million in the three months ended September 30, 2013 and $8 million in both the nine months ended September 30, 2014 and 2013. The estimated future amortization expense of identifiable intangible assets during the next five years is $2 million for the remaining portion of 2014 and $7 million each year from 2015 to 2018.

Pensions_and_Other_Benefits

Pensions and Other Benefits	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Pensions and Other Benefits	'
	Pensions and Other Benefits
	The following table reflects the components of net periodic benefit cost for the three months ended September 30, 2014 and 2013:
		Pension						Other
		Benefits						Benefits
	(In millions)	2014			2013			2014			2013
	Service cost	$	27		$	32		$	5		$	7
	Interest cost	103			100			33			35
	Expected return on plan assets	(147		)	(152		)	(37		)	(33		)
	Amortization of prior service cost	6			6			(4		)	(3		)
	Amortization of actuarial net loss	67			92			—			8
	Net periodic benefit cost, excluding below	56			78			(3		)	14
	Multiemployer plans	19			19			—			—
	Settlement, termination and curtailment losses	13			3			—			—
	Net periodic benefit cost	$	88		$	100		$	(3	)	$	14
	The following table reflects the components of net periodic benefit cost for the nine months ended September 30, 2014 and 2013:
		Pension						Other
		Benefits						Benefits
	(In millions)	2014			2013			2014			2013
	Service cost	$	81		$	96		$	17		$	21
	Interest cost	321			303			106			106
	Expected return on plan assets	(454		)	(459		)	(106		)	(98		)
	Amortization of prior service cost	17			18			(11		)	(10		)
	Amortization of actuarial net loss (gain)	208			275			(2		)	23
	Net periodic benefit cost, excluding below	173			233			4			42
	Multiemployer plans	56			55			—			—
	Settlement, termination and curtailment losses/(gains)	28			3			(19		)	—
	Net periodic benefit cost	$	257		$	291		$	(15	)	$	42
	Settlements and Curtailments
	Pension settlements have taken place in the non-qualified pension plan related to the retirement of several U. S. Steel executives that occurred throughout 2013. In accordance with Internal Revenue Code requirements, these executives were required to wait six months before receiving their non-qualified pension payments.
	A curtailment gain of $19 million was recognized in the nine months ended September 30, 2014 due to a change to the post retirement medical benefits for non-union, pre-Medicare retirees that will take effect after 2017.
	Employer Contributions
	During the first nine months of 2014, U. S. Steel made $47 million in required cash contributions to the USSC pension plans prior to the deconsolidation of USSC (see Note 4), cash payments of $56 million to the Steelworkers’ Pension Trust and $83 million of pension payments not funded by trusts.
	During the first nine months of 2014, cash payments of $180 million were made for other postretirement benefit payments not funded by trusts.
	Company contributions to defined contribution plans totaled $11 million in both the three months ended September 30, 2014 and 2013. Company contributions to defined contribution plans totaled $35 million and $33 million for the nine months ended September 30, 2014 and 2013, respectively.
	Pension Funding
	In November 2013, U. S. Steel's Board of Directors authorized voluntary contributions to U. S. Steel's trusts for pensions and other benefits of up to $300 million through the end of 2015. U. S. Steel made voluntary contributions to our main U.S. defined benefit plan of $140 million during the first nine months of 2014 and 2013.

Net_Interest_and_Other_Financi

Net Interest and Other Financial Costs	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Net Interest and Other Financial Costs	'
	Net Interest and Other Financial Costs
	Net interest and other financial costs includes interest expense (net of capitalized interest), interest income, financing costs, derivatives gains and losses and foreign currency remeasurement gains and losses. Foreign currency gains and losses are a result of foreign currency denominated assets and liabilities that require remeasurement. During the three months ended September 30, 2014 and 2013, net foreign currency remeasurement gains of less than $1 million and $3 million, respectively, were recorded in other financial costs. During the nine months ended September 30, 2014 and 2013, net foreign currency remeasurement losses of $1 million and $9 million, respectively, were recorded in other financial costs.
	For the three and nine months ended September 30, 2013, net interest and other financial costs also included a charge of $22 million related to a guarantee of an unconsolidated equity investment for which payment by U. S. Steel is probable (See Note 21). Also included in the nine months ended September 30, 2013 is a charge of $34 million related to repurchases of approximately $542 million aggregate principal amount of our 4.00% Senior Convertible Notes due May 15, 2014.
	See Note 13 for additional information on U. S. Steel’s use of derivatives to mitigate its foreign currency exchange rate exposure.

StockBased_Compensation_Plans

Stock-Based Compensation Plans	9 Months Ended
	Sep. 30, 2014
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 Plan), which is more fully described in Note 12 of the United States Steel Corporation 2013 Annual Report on Form 10-K. An aggregate of 21,250,000 shares of U. S. Steel common stock may be issued under the Plan. As of September 30, 2014, 4,930,655 shares were available for future grants.
	During the first quarter of 2014, the Committee added return on capital employed (ROCE) as a second performance measure for the 2014 Performance Awards as permitted under the terms of the Plan. Prior to 2014, performance awards were based solely on a total shareholder return (TSR) metric. ROCE awards granted will be measured on a weighted average basis of the Company’s consolidated worldwide income from operations, 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 at approximately 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 metric as outlined in the Plan and will be adjusted on a quarterly basis to reflect the probability of achieving the ROCE metric.
	Recent grants of stock-based compensation consist of stock options, restricted stock units, and TSR and ROCE performance awards. Stock options are generally issued at the market price of the underlying stock on the date of the grant. The 2013 executive grants, however, were issued at the greater of (1) the premium exercise price of $25 or (2) the market price on the grant date. Upon exercise of stock options, shares of U. S. Steel stock are issued from treasury stock. The following table is a general summary of the awards made under the Plan.
		2014 Grants						2013 Grants
	Grant Details	Shares(a)		Fair Value(b)				Shares(a)		Fair Value(b)
	Executive Stock Options	441,960		$	9.93			826,340		$	8.37
	Non-executive Stock Options	1,054,480		$	9.93			970,640		$	9.7
	Restricted Stock Units	724,510		$	24.29			1,033,210		$	18.58
	Performance Awards(c)
	TSR	282,770		$	22.09			271,960		$	21.26
	ROCE	262,800		$	23.76			—		$	—
	(a) The share amounts shown in this table do not reflect an adjustment for estimated forfeitures.
	(b) Represents the per share weighted-average for all grants during the year.
	(c) The number of performance awards shown represents the target value of the award.
	U. S. Steel recognized pretax stock-based compensation cost in the amount of $9 million in both the three month periods ended September 30, 2014 and 2013, and $26 million and $28 million in the first nine months of 2014 and 2013, respectively.
	As of September 30, 2014, total future compensation cost related to nonvested stock-based compensation arrangements was $46 million, and the weighted average period over which this cost is expected to be recognized is approximately 1.3 years.
	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. The stock options vest ratably over a three-year service period and have a term of ten years.
	Black-Scholes Assumptions(a)		2014 Grants			2013 Executive Grants			2013 Non-Executive Grants
	Grant date price per share of option award		$	24.29		$	18.48		$	18.64
	Exercise price per share of option award		$	24.29		$	25		$	18.64
	Expected annual dividends per share, at grant date		$	0.2		$	0.2		$	0.2
	Expected life in years		5			5			5
	Expected volatility		49		%	66		%	67		%
	Risk-free interest rate		1.621		%	1.315		%	1.049		%
	Grant date fair value per share of unvested option awards as calculated from above		$	9.93		$	8.37		$	9.7
	(a) The assumptions represent a weighted average of 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.
	Restricted stock units generally vest ratably over three years. The fair value of the restricted stock units is the market price of the underlying common stock on the date of the grant.
	TSR performance awards vest at the end of a three-year performance period as a function of U. S. Steel's total shareholder return compared to the total shareholder return of a group of peer companies over the three-year performance period. TSR performance awards can vest at between zero and 200 percent of the target award. The fair value of the TSR performance awards is calculated using a Monte-Carlo simulation.
	ROCE performance awards vest at the end of a three-year performance period contingent upon meeting the specified ROCE metric. ROCE performance awards can vest at between zero and 200 percent of the target award. The fair value of the ROCE performance awards is the average market price of the underlying common stock on the date of grant.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	Tax provision
	For the nine months ended September 30, 2014 and 2013, we recorded a tax benefit of $4 million on our pretax loss of $177 million and a tax provision of $14 million on our pretax loss of $1.9 billion, respectively. Included in the tax benefit in the first nine months of 2014 is a discrete benefit of $30 million related to the loss on deconsolidation of USSC and other charges as discussed in Note 4, as well as a discrete benefit related to the antitrust settlement discussed in Note 21. The tax provision reflects a benefit for percentage depletion in excess of cost depletion for iron ore that we produce and consume or sell. The tax provision does not reflect any tax benefit for pretax losses in Canada, prior to the deconsolidation on September 16, 2014, which is a jurisdiction where we had recorded a full valuation allowance on deferred tax assets.
	The tax benefit for the first nine months of 2014 is based on an estimated annual effective rate, which requires management to make its best estimate of annual pretax income or loss. During the year, management regularly updates forecasted annual pretax results for the various countries in which we operate based on changes in factors such as prices, shipments, product mix, plant operating performance and cost estimates. To the extent that actual 2014 pretax results for U.S. and foreign income or loss vary from estimates applied herein, the actual tax provision or benefit recognized in 2014 could be materially different from the forecasted amount used to estimate the tax provision for the nine months ended September 30, 2014.
	Income tax refunds
	During 2014, U. S. Steel has received $176 million representing the majority of its expected federal income tax refund related to the carryback of our 2013 net operating loss to prior years.
	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 gross unrecognized tax benefits was $114 million at September 30, 2014 and $127 million at December 31, 2013. The total amount of net unrecognized tax benefits that, if recognized, would affect the effective tax rate was $60 million as of September 30, 2014 and $69 million as of December 31, 2013.
	U. S. Steel records interest related to uncertain tax positions as a part of net interest and other financial costs in the consolidated statement of operations. Any penalties are recognized as part of selling, general and administrative expenses. As of both September 30, 2014 and December 31, 2013, U. S. Steel had accrued liabilities of $7 million for interest related to uncertain tax positions. U. S. Steel currently does not have a liability for tax penalties.
	Deferred taxes
	As of September 30, 2014, the net domestic deferred tax asset was $95 million compared to $115 million at December 31, 2013. A substantial amount of U. S. Steel’s domestic deferred tax assets relates to employee benefits that will become deductible for tax purposes over an extended period of time as cash contributions are made to employee benefit plans and retiree benefits are paid in the future. We continue to believe it is more likely than not that the net domestic deferred tax asset will be realized.
	As of September 30, 2014, the net foreign deferred tax asset was $42 million, net of established valuation allowances of $5 million. At December 31, 2013, the net foreign deferred tax asset was $59 million, net of established valuation allowances of $1,028 million. The net foreign deferred tax asset will fluctuate as the value of the U.S. dollar changes with respect to the euro. At December 31, 2013, a full valuation allowance was recorded for the net Canadian deferred tax asset primarily due to cumulative losses in Canada. The Canadian deferred tax asset and the related valuation allowance were deconsolidated from U. S. Steel's balance sheet as of the end of the day on September 15, 2014.

Significant_Equity_Investments

Significant Equity Investments	9 Months Ended
	Sep. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Significant Equity Investments	'
	Significant Equity Investments
	Summarized unaudited income statement information for our significant equity investments for the nine months ended September 30, 2014 and 2013 is reported below (amounts represent 100% of investee financial information):
	(In millions)	2014		2013
	Net sales	$	1,977	$	1,841
	Cost of sales	1,505		1,395
	Operating income	427		399
	Net income	412		382
	Net income attributable to significant equity investments	412		382
	U. S. Steel’s portion of the equity in net income of the significant equity investments above was $89 million and $50 million for the nine months ended September 30, 2014 and 2013, respectively, which is included in the income from investees line on the consolidated statement of operations.

Earnings_and_Dividends_Per_Com

Earnings and Dividends Per Common Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Earnings and Dividends Per Common Share	'
	Earnings and Dividends Per Common Share
	Earnings Per Share Attributable to United States Steel Corporation Shareholders
	Basic earnings per common share is based on the weighted average number of common shares outstanding during the period.
	Diluted earnings per common share assumes the exercise of stock options, the vesting of restricted stock units and performance awards and the conversion of convertible notes, provided in each case the effect is dilutive. The "if-converted" method was used to calculate the dilutive effect of the 2014 Senior Convertible Notes due May 2014 (2014 Senior Convertible Notes) and the dilutive effect of such securities was included in the calculation for the period prior to repurchase on May 15, 2014. The “treasury stock” method is used to calculate the dilutive effect of the Senior Convertible Notes due in 2019 (due to our current intent and policy, among other factors, to settle the principal amount of the 2019 Senior Convertible Notes in cash upon conversion).
	The computations for basic and diluted earnings per common share from continuing operations are as follows:
		Three Months Ended September 30,							Nine Months Ended September 30,
	(Dollars in millions, except per share amounts)	2014				2013			2014			2013
	Net loss attributable to United States Steel Corporation shareholders	$	(207	)		$	(1,791	)	$	(173	)	$	(1,942	)
	Plus income effect of assumed conversion-interest on convertible notes	—				—			—			—
	Net loss after assumed conversion	$	(207	)		$	(1,791	)	$	(173	)	$	(1,942	)
	Weighted-average shares outstanding (in thousands):
	Basic	145,348				144,727			144,999			144,523
	Effect of convertible notes	—				—			—			—
	Effect of stock options, restricted stock units and performance awards	—				—			—			—
	Adjusted weighted-average shares outstanding, diluted	145,348				144,727			144,999			144,523
	Basic earnings per common share	$	(1.42	)		$	(12.38	)	$	(1.19	)	$	(13.44	)
	Diluted earnings per common share	$	(1.42	)		$	(12.38	)	$	(1.19	)	$	(13.44	)
	The following table summarizes the securities that were antidilutive, and therefore, were not included in the computations of diluted earnings per common share:
		Three Months Ended September 30,						Nine Months Ended
								September 30,
	(In thousands)	2014			2013			2014		2013
	Securities granted under the 2005 Stock Incentive Plan	8,865			7,621			8,865		7,621
	Securities convertible under the Senior Convertible Notes (a)	3,477			10,058			6,523		15,351
	Total	12,342			17,679			15,388		22,972
	(a) On March 27, 2013, we repurchased approximately $542 million aggregate principal amount of our 2014 Senior Convertible Notes. If the repurchases had occurred on January 1, 2013, the antidilutive securities would be 10,058 for the nine months ended September 30, 2013. Additionally, on May 15, 2014, we redeemed the remaining amount due under the 2014 Senior Convertible Notes. If the redemption had occurred on January 1, 2014, the antidilutive securities would be zero for the nine months ended September 30, 2014.
	Dividends Paid Per Share
	The dividend for each of the first three quarters of 2014 and 2013 was five cents per common share.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories are carried at the lower of cost or market. The first-in, first-out method is the predominant method of inventory costing in Europe. The last-in, first-out (LIFO) method is the predominant method of inventory costing in the United States. At September 30, 2014 and December 31, 2013, the LIFO method accounted for 74 percent and 59 percent of total inventory values, respectively.
	(In millions)	September 30, 2014		December 31, 2013
	Raw materials	$	608	$	1,011
	Semi-finished products	994		1,023
	Finished products	518		558
	Supplies and sundry items	79		96
	Total	$	2,199	$	2,688
	Current acquisition costs were estimated to exceed the above inventory values by $1.0 billion at both September 30, 2014 and December 31, 2013. As a result of the liquidation of LIFO inventories, cost of sales decreased and income from operations increased by $8 million in the three months ended September 30, 2014 and by $1 million in the nine months ended September 30, 2014. Cost of sales increased and income from operations decreased by $3 million in both the three and nine months ended September 30, 2013 as a result of the liquidation of LIFO inventories.
	Inventory includes $69 million and $81 million of property held for residential or commercial development as of September 30, 2014 and December 31, 2013, respectively.

Derivative_Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Instruments	'
	Derivative Instruments
	U. S. Steel is exposed to foreign currency exchange rate risks as a result of our European operations and our Canadian operations (prior to the deconsolidation of USSC). USSE’s revenues are primarily in euros and costs are primarily in U.S. dollars and euros. USSC’s revenues and costs were denominated in both Canadian and U.S. dollars. In addition, foreign cash requirements have been, and in the future may be, funded by intercompany loans, creating intercompany monetary assets and liabilities in currencies other than the functional currency of the entities involved, which can affect income when remeasured at the end of each period.
	U. S. Steel uses euro forward sales contracts with maturities no longer than 12 months to exchange euros for U.S. dollars 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 euro forward sales contracts as hedges. Therefore, changes in their fair value are recognized immediately in the results of operations. The gains and losses recognized on the euro forward sales contracts may also partially offset the accounting remeasurement gains and losses recognized on intercompany loans.
	As of September 30, 2014, U. S. Steel held euro forward sales contracts with a total notional value of approximately $409 million. We mitigate the risk of concentration of counterparty credit risk by purchasing our forward sales contracts from several counterparties.
	Additionally, U. S. Steel uses fixed-price forward physical purchase contracts to partially manage our exposure to price risk related to the purchases of natural gas and certain nonferrous metals used in the production process. During 2014 and 2013, the forward physical purchase contracts for natural gas and nonferrous metals qualified for the normal purchases and normal sales exemption described in ASC Topic 815 and were not subject to mark-to-market accounting.
	The following summarizes the location and amounts of the fair values and gains or losses related to derivatives included in U. S. Steel’s consolidated financial statements as of September 30, 2014 and December 31, 2013 and for the three and nine months ended September 30, 2014 and 2013:
			Fair Value			Fair Value
	(In millions)	Balance Sheet	30-Sep-14			31-Dec-13
		Location
	Foreign exchange forward contracts	Accounts receivable	$	28		$	—
	Foreign exchange forward contracts	Accounts payable	$	—		$	11
		Statement of	Amount of Gain			Amount of Gain
		Operations	(Loss)			(Loss)
	(In millions)	Location	Three Months Ended September 30, 2014			Nine months ended September 30, 2014
	Foreign exchange forward contracts	Other financial	$	33		$	36
		costs
		Statement of	Amount of Gain			Amount of Gain
		Operations	(Loss)			(Loss)
	(In millions)	Location	Three Months Ended September 30, 2013			Nine Months Ended September 30, 2013
	Foreign exchange forward contracts	Other financial	$	(11	)	$	(7	)
		costs
	In accordance with the guidance found in ASC Topic 820 on fair value measurements and disclosures, the fair value of our euro forward sales contracts 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.

Debt

Debt	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt	'
	Debt
	(In millions)	Interest		Maturity	September 30, 2014		December 31, 2013
		Rates %
	2037 Senior Notes	6.65		2037	$	350	$	350
	2022 Senior Notes	7.5		2022	400		400
	2021 Senior Notes	6.875		2021	275		275
	2020 Senior Notes	7.375		2020	600		600
	2018 Senior Notes	7		2018	500		500
	2017 Senior Notes	6.05		2017	450		450
	2019 Senior Convertible Notes	2.75		2019	316		316
	2014 Senior Convertible Notes	4		2014	—		322
	USSC Province Note (C$150 million) (a)	1		2015	—		141
	Environmental Revenue Bonds	5.38 - 6.88		2015 - 2042	549		549
	Recovery Zone Facility Bonds	6.75		2040	70		70
	Fairfield Caster Lease			2022	34		35
	Other capital leases and all other obligations			2020	—		—
	Amended Credit Agreement	Variable		2016	—		—
	USSK Revolver	Variable		2016	—		—
	USSK credit facilities	Variable		2015 - 2016	—		—
	Total Debt				3,544		4,008
	Less Province Note fair value adjustment (a)				—		15
	Less unamortized discount				46		54
	Less short-term debt and long-term debt due within one year				336		323
	Long-term debt				$	3,162	$	3,616
	(a) As a result of USSC's CCAA filing, the USSC Province Note has been deconsolidated from U. S. Steel's consolidated balance sheet as of September 15, 2014. See Note 4 for additional details.
	To the extent not otherwise discussed below, information concerning the Senior Notes, the Senior Convertible Notes and other listed obligations can be found in Note 14 of the audited financial statements in the 2013 Annual Report on Form 10-K.
	In May 2014, U. S. Steel redeemed the remaining $322 million principal amount of our 2014 Senior Convertible Notes with cash. The aggregate price, including accrued and unpaid interest, for the 2014 Senior Convertible Notes was approximately $327 million.
	2019 Senior Convertible Notes Reclassification
	The CCAA filing on September 16, 2014 is an event of default under the terms of the Province Note loan agreement between USSC and the Province of Ontario. The failure of USSC to pay the Province Note would constitute an event of default under the indenture for the 2019 Senior Convertible Notes (2019 Notes) that enables the holders of the 2019 Notes to declare them immediately due and payable. It is U. S. Steel’s intent to settle the 2019 Notes in cash if the holders exercise their options to call the notes. In addition to the CCAA filing, the 2019 Notes have met certain conversion options based on the Company's stock price, which made the 2019 Notes eligible for immediate conversion by the holders at September 30, 2014. As a result of these events, the 2019 Notes have been reclassified from long-term to short-term in our consolidated balance sheet as of September 30, 2014.
	Amended Credit Agreement
	As of September 30, 2014, there were no amounts drawn on the Amended Credit Agreement and inventory values calculated in accordance with the Amended Credit Agreement supported the full $875 million of the facility. Under the Amended Credit Agreement, U. S. Steel must maintain a fixed charge coverage ratio (as further defined in the Amended Credit Agreement) of at least 1.00 to 1.00 for the most recent four consecutive quarters when availability under the Amended Credit Agreement is less than the greater of 10% of the total aggregate commitments and $87.5 million. Since availability was greater than $87.5 million, compliance with the fixed charge coverage ratio covenant was not applicable.
	On July 23, 2014, the Company amended its Amended Credit Agreement to designate USSC and each subsidiary of USSC formed under the laws of Canada or any province thereof as an excluded subsidiary and to waive any event of default that may occur as a result of the 2019 Notes being accelerated or caused to be accelerated as a result of specified actions of USSC.
	Receivables Purchase Agreement
	As of September 30, 2014, U. S. Steel has a Receivables Purchase Agreement (RPA) under which trade accounts receivable are sold, on a daily basis without recourse, to U. S. Steel Receivables, LLC (USSR), a wholly owned, bankruptcy-remote, special purpose entity used only for the securitization program. As U. S. Steel accesses this facility, USSR sells senior undivided interests in the receivables to a third-party and a third-party commercial paper conduit, while maintaining a subordinated undivided interest in a portion of the receivables. U. S. Steel has agreed to continue servicing the sold receivables at market rates.
	At both September 30, 2014 and December 31, 2013, eligible accounts receivable supported $625 million of availability under the RPA and there were no receivables sold to third-party conduits under this facility. The subordinated retained interest was $625 million at both September 30, 2014 and December 31, 2013. Availability under the RPA was $575 million at September 30, 2014, and $572 million at December 31, 2013, due to letters of credit outstanding of $50 million and $53 million, respectively.
	USSR pays the third parties a discount based on the third-parties’ borrowing costs plus incremental fees. We paid approximately $1 million for each of the three months ended September 30, 2014 and 2013, and approximately $3 million for each of the nine months ended September 30, 2014 and 2013, relating to fees on the RPA. These costs are included in other financial costs in the consolidated statement of operations.
	Generally, the facility provides that as payments are collected from the sold accounts receivables, USSR may elect to have the third-parties reinvest the proceeds in new eligible accounts receivable. As there was no activity under this facility during the nine months ended September 30, 2014 and 2013, there were no collections reinvested.
	The eligible accounts receivable and receivables sold to third party conduits are summarized below:
	(In millions)	September 30, 2014			December 31, 2013
	Balance of accounts receivable-net, eligible for sale to third-parties	$	1,166		$	988
	Accounts receivable sold to third-parties	—			—
	Balance included in Receivables on the balance sheet of U. S. Steel	$	1,166		$	988
	The net book value of U. S. Steel’s retained interest in the receivables represents the best estimate of the fair market value due to the short-term nature of the receivables. The retained interest in the receivables is recorded net of the allowance for bad debts, which historically have not been significant.
	The facility may be terminated on the occurrence and failure to cure certain events, including, among others, failure of USSR to maintain certain ratios related to the collectability of the receivables and failure to make payment under its material debt obligations, and may also be terminated upon a change of control. The facility expires in July 2016.
	On July 23, 2014, the RPA was amended to (a) modify a termination event so that if USSC and any of its subsidiaries organized in Canada failed to pay any principal of or premium or interest on any of its debt that is outstanding in a principal amount of at least $100 million, and (b) waive any termination event occurring as a result of the acceleration by the holders of the Company's 2019 Notes due to the acceleration of any debt of USSC or any of its subsidiaries but only if the notes are promptly paid in full.
	U. S. Steel Košice (USSK) credit facilities
	At September 30, 2014, USSK had no borrowings under its €200 million (approximately $252 million) unsecured revolving credit facility (the Credit Agreement). The Credit Agreement contains certain USSK financial covenants (as further defined in the Credit Agreement), including maximum Leverage, maximum Net Debt to Tangible Net Worth, and minimum Interest Cover ratios. The covenants are measured semi-annually for the period covering the last twelve calendar months. USSK may not draw on the Credit Agreement if it does not comply with any of the financial covenants until the next measurement date. The Credit Agreement expires in July 2016.
	At September 30, 2014, USSK had no borrowings under its €20 million and €10 million unsecured credit facilities (collectively approximately $38 million) and the availability was approximately $37 million due to approximately $1 million of customs and other guarantees outstanding.
	Change in control event
	If there is a change in control of U. S. Steel, the following may occur: (a) debt obligations totaling $2,891 million as of September 30, 2014 (including the Senior Notes and Senior Convertible Notes) may be declared immediately due and payable; (b) the Amended Credit Agreement, the RPA and USSK’s €200 million revolving credit agreement may be terminated and any amounts outstanding declared immediately due and payable; and (c) U. S. Steel may be required to either repurchase the leased Fairfield Works slab caster for $37 million or provide a letter of credit to secure the remaining obligation.

Asset_Retirement_Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2014
Asset Retirement Obligation Disclosure [Abstract]	'
Asset Retirement Obligations	'
	Asset Retirement Obligations
	U. S. Steel’s asset retirement obligations (AROs) primarily relate to mine and landfill closure and post-closure costs. The following table reflects changes in the carrying values of AROs:
	(In millions)	September 30, 2014			December 31, 2013
	Balance at beginning of year	$	59		$	33
	Additional obligations incurred	—			28
	Obligations settled(a)	(18		)	(7		)
	Foreign currency translation effects	(1		)	—
	Accretion expense	3			5
	Balance at end of period	$	43		$	59
	(a) Includes $16 million as a result of the deconsolidation of USSC as of the end of the day on September 15, 2014. See Note 4 for additional details.
	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_Instru

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2014
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, accrued interest and certain equity method investee guarantees included in the consolidated balance sheet approximate fair value due to their short-term nature. See Note 13 for disclosure of U. S. Steel’s derivative instruments, which are accounted for at fair value on a recurring basis. Additionally, see Note 4 for disclosure of short-term and long-term receivables from related parties which are accounted for at fair value.
	The following table summarizes U. S. Steel’s financial assets and liabilities that were not carried at fair value at September 30, 2014 and December 31, 2013.
		30-Sep-14				December 31, 2013
	(In millions)	Fair		Carrying		Fair		Carrying
		Value		Amount		Value		Amount
	Financial assets:
	Investments and long-term receivables (a)	$	45	$	45	$	63	$	63
	Financial liabilities:
	Debt (b)	$	3,957	$	3,464	$	4,198	$	3,904
	(a) Excludes equity method investments.
	(b) Excludes capital lease obligations.
	The following methods and assumptions were used to estimate the fair value of financial instruments included in the table above:
	Investments and long-term receivables: Fair value was based on Level 2 inputs which were discounted cash flows. U. S. Steel is subject to market risk and liquidity risk related to its investments.
	Long-term debt instruments: 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 21.

Statement_of_Changes_in_Stockh

Statement of Changes in Stockholders' Equity	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Statement of Changes in Stockholders' Equity	'
	Statement of Changes in Stockholders’ Equity
	The following table reflects the first nine months of 2014 and 2013 reconciliation of the carrying amount of total equity, equity attributable to U. S. Steel and equity attributable to noncontrolling interests:
	Nine Months Ended September 30, 2014 (In millions)	Total			Comprehensive			Retained			Accumulated			Common		Treasury			Paid-in			Non-
					Income (Loss)			Earnings			Other			Stock		Stock			Capital			Controlling
											Comprehensive											Interest
											(Loss) Income
	Balance at beginning of year	$	3,376					$	1,789		$	(1,752	)	$	151	$	(480	)	$	3,667		$	1
	Comprehensive income:
	Net loss	(173		)	(173		)	(173		)
	Other comprehensive income (loss), net of tax:
	Pension and other benefit adjustments	175			175						175
	Currency translation adjustment	93			93						93
	Deconsolidation of U. S. Steel	468			468						468
	Canada (a)
	Employee stock plans	26														70			(44		)
	Dividends paid on common stock	(22		)				(22		)
	Balance at September 30, 2014	$	3,943		$	563		$	1,594		$	(1,016	)	$	151	$	(410	)	$	3,623		$	1
	(a) Consists of $493 million for Pension and other benefit adjustments and $(25) million for currency translation adjustment.
	Nine Months Ended September 30, 2013 (In millions)	Total			Comprehensive			Retained			Accumulated			Common		Treasury			Paid-in			Non-
					Income (Loss)			Earnings			Other			Stock		Stock			Capital			Controlling
											Comprehensive											Interest
											(Loss) Income
	Balance at beginning of year	$	3,478					$	3,463		$	(3,268	)	$	151	$	(521	)	$	3,652		$	1
	Comprehensive income:
	Net loss	(1,942		)	(1,942		)	(1,942		)
	Other comprehensive income (loss), net of tax:
	Pension and other benefit adjustments	197			197						197
	Currency translation adjustment	13			13						13
	Issuance of conversion option in 2019 Senior Convertible Notes, net of tax	31																	31
	Employee stock plans	22														40			(18		)
	Dividends paid on common stock	(22		)				(22		)
	Other	(2		)				(2		)
	Balance at September 30, 2013	$	1,775		$	(1,732	)	$	1,497		$	(3,058	)	$	151	$	(481	)	$	3,665		$	1

Reclassifications_from_Accumul

Reclassifications from Accumulated Other Comprehensive Income (AOCI)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Reclassifications from Accumulated Other Comprehensive Income (AOCI)	'
	Reclassifications from Accumulated Other Comprehensive Income (AOCI)
	(In millions) (a)	Pension and				Foreign				Total
		Other Benefit				Currency
		Items				Items
	Balance at December 31, 2013	$	(2,127	)		$	375			$	(1,752	)
	Other comprehensive income (loss) before reclassifications	34				(69		)		(35		)
	Amounts reclassified from AOCI	141			(b)	162			(c)	303
	Deconsolidation of U. S. Steel Canada (c)	493				(25		)		468
	Net current-period other comprehensive income	668				68				736
	Balance at September 30, 2014	$	(1,459	)		$	443			$	(1,016	)
	(a)All amounts are net of tax. Amounts in parentheses indicate debits.
	(b)See table below for further details.
	(c)Included in Loss on deconsolidation of U. S. Steel Canada and other charges on the Consolidated Statement of Operations.
		Amount reclassified from AOCI
		Three Months Ended September 30,								Nine Months Ended September 30,
	Details about AOCI components	2014				2013				2014			2013
	(in millions) (a)
	Amortization of pension and other benefit items
	Prior service costs (b)	$	(2	)		$	(3	)		$	(6	)	$	(8	)
	Actuarial gains/(losses) (b)	(67		)		(100		)		(206		)	(298		)
	Settlement, termination and	(13		)		—				(9		)	—
	curtailment gains (b)
	Total before tax	(82		)		(103		)		(221		)	(306		)
	Tax benefit	25				29				80			96
	Net of tax	$	(57	)		$	(74	)		$	(141	)	$	(210	)
	(a)Amounts in parentheses indicate debits to income/loss.
	(b)These AOCI components are included in the computation of net periodic benefit cost (see Note 6 for additional details).

Transactions_with_Related_Part

Transactions with Related Parties	9 Months Ended
	Sep. 30, 2014
Related Party Transactions [Abstract]	'
Related Party Transactions	'
	Related Parties
	Net sales to related parties and receivables from related parties primarily reflect sales of steel products to equity investees and USSC after the CCAA filing on September 16, 2014. Generally, transactions are conducted under long-term market-based contractual arrangements. Related party sales and service transactions were $302 million and $275 million for the three months ended September 30, 2014 and 2013, respectively and $853 million and $863 million for the nine months ended September 30, 2014 and 2013, respectively.
	Purchases from related parties for outside processing services provided by equity investees and USSC after the CCAA filing on September 16, 2014 amounted to $30 million and $18 million for the three months ended September 30, 2014 and 2013, respectively and $60 million and $53 million for the nine months ended September 30, 2014 and 2013, respectively. Purchases of iron ore pellets from related parties amounted to $76 million and $63 million for the three months ended September 30, 2014 and 2013, respectively and $191 million and $180 million for the nine months ended September 30, 2014 and 2013, respectively.
	Accounts payable to related parties include balances due to PRO-TEC Coating Company (PRO-TEC) of $105 million and $70 million at September 30, 2014 and December 31, 2013, respectively for invoicing and receivables collection services provided by U. S. Steel. 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, including USSC after the CCAA filing on September 16, 2014, totaled $26 million and $3 million at September 30, 2014 and December 31, 2013, respectively.

Restructuring_and_Other_Charge

Restructuring and Other Charges	9 Months Ended
	Sep. 30, 2014
Restructuring and Related Activities [Abstract]	'
Restructuring and Other Charges	'
	Restructuring and Other Charges
	During the three months ended September 30, 2014, the Company recorded charges of $199 million and $37 million, which were reported in restructuring and other charges in the consolidated statement of operations, related to the impairment of carbon alloy facilities and the write-off of pre-engineering costs from the Keetac expansion, respectively, within our Flat-rolled segment. The Company also recorded severance related charges of $1 million during the three months ended September 30, 2014, which were reported in restructuring and other charges in the consolidated statement of operations, for additional headcount reductions related to our USSK operations. Cash payments were made related to severance and exit costs of $3 million. Favorable adjustments for changes in estimates on and the removal of restructuring reserves as a result of the deconsolidation of USSC were made for $6 million. There were no such items for the three months ended September 30, 2013.
	During the nine months ended September 30, 2014, the Company recorded severance related charges of $15 million, which were reported in restructuring and other charges in the consolidated statement of operations, for additional headcount reductions related to our Canadian operations, within our Flat-rolled segment; certain of our Tubular operations in Bellville, Texas and McKeesport, Pennsylvania, within our Tubular segment; and our USSK operations as well as headcount reductions principally at the Company’s corporate headquarters in conjunction with the Carnegie Way transformation efforts. The Company also recorded charges of $199 million and $37 million, related to the impairment of carbon alloy facilities and the write-off of pre-engineering costs from the Keetac expansion, respectively, within our Flat-rolled segment. Additionally, an asset impairment charge of $14 million was taken for certain of the Company's non-strategic assets that were designated as held for sale. Cash payments were made related to severance and exit costs of $8 million. Favorable adjustments for changes in estimates on and the removal of restructuring reserves as a result of the deconsolidation of USSC were made for $16 million. There were no such items for the nine months ended September 30, 2013.
	During the fourth quarter of 2013, the Company implemented certain headcount reductions and production facility closures related to our iron and steelmaking facilities at Hamilton Works in Canada, barge operations related to Warrior and Gulf Navigation (WGN) in Alabama and administrative headcount reductions at our Hamilton Works and Lake Erie Works also in Canada. We closed our iron and steelmaking facilities at Hamilton Works effective December 31, 2013.
	Charges for restructuring and ongoing cost reduction initiatives are recorded in the period the Company 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 include severance costs, accelerated depreciation, asset impairments and other closure costs.
	The activity in the accrued balances incurred in relation to restructuring and other cost reduction programs during the nine months ended September 30, 2014 were as follows:
		Severance				Exit			Asset
	(in millions)	Accrual				Costs			Impairments
	Balance at December 31, 2013	$	16			$	6		$	—
	Additional charges	15				—			250
	Cash payments/utilization	(8		)		(5		)	(250		)
	Other adjustments and re-classes	(16		)	(a)	(1		)	—
	Balance at September 30, 2014	$	7			$	—		$	—
	(a) Includes an adjustment to remove restructuring reserves of $4 million as a result of the deconsolidation of USSC on September 15, 2014.
	Accrued liabilities for restructuring and other cost reduction programs are included in the following balance sheet lines:
	(in millions)	September 30, 2014				December 31, 2013
	Accounts payable	$	—			$	6
	Payroll and benefits payable	6				8
	Employee benefits	1				8
	Total	$	7			$	22

Contingencies_and_Commitments

Contingencies and Commitments	9 Months Ended
	Sep. 30, 2014
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.
	Asbestos matters – As of September 30, 2014, U. S. Steel was a defendant in approximately 830 active cases involving approximately 3,460 plaintiffs. Many of these cases involve multiple defendants (typically from fifty to more than one hundred). About 2,630, or approximately 76 percent, of these plaintiff claims are currently pending in jurisdictions which permit filings with massive numbers of 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. During the nine months ended September 30, 2014, U. S. Steel paid approximately $5 million in settlements. These settlements and other dispositions resolved approximately 110 claims. New case filings in the first nine months of 2014 added approximately 250 claims. At December 31, 2013, U. S. Steel was a defendant in approximately 720 active cases involving approximately 3,320 plaintiffs. During 2013, U. S. Steel paid approximately $11 million in settlements. These settlements and other dispositions resolved approximately 250 claims. New case filings in the year ended December 31, 2013 added approximately 240 claims. Most claims filed in 2014 and 2013 involved individual or small groups of claimants as many jurisdictions no longer permit the filing of mass complaints.
	Historically, these claims against U. S. Steel fall into three major groups: (1) claims made by persons who allegedly were exposed to asbestos at U. S. Steel facilities (referred to as “premises claims”); (2) claims made by industrial workers allegedly exposed to products manufactured by U. S. Steel; and (3) claims made under certain federal and general maritime laws by employees of former operations of U. S. Steel. In general, the only insurance available to U. S. Steel with respect to asbestos claims is excess casualty insurance, which has multi-million dollar retentions. To date, U. S. Steel has received payments for a certain minority of asbestos claims.
	These asbestos cases allege a variety of respiratory and other diseases based on alleged exposure to asbestos. U. S. Steel is currently a defendant in cases in which a total of approximately 270 plaintiffs allege that they are suffering from mesothelioma. The potential for damages against defendants may be greater in cases where the plaintiffs can prove mesothelioma.
	In many cases in which claims have been asserted against U. S. Steel, the plaintiffs have been unable to establish any causal relationship to U. S. Steel or our products or premises; however, with the decline in mass plaintiff cases, the incidence of claimants actually alleging a claim against U. S. Steel is increasing. In addition, in many asbestos cases, the plaintiffs have been unable to demonstrate that they have suffered any identifiable injury or compensable loss at all; that any injuries that they have incurred did in fact result from alleged exposure to asbestos; or that such alleged exposure was in any way related to U. S. Steel or our products or premises.
	The amount U. S. Steel has accrued for pending asbestos claims is not material to U. S. Steel’s financial position. U. S. Steel does not accrue for unasserted asbestos claims because it is not possible to determine whether any loss is probable with respect to such claims or even to estimate the amount or range of any possible losses. The vast majority of pending claims against U. S. Steel allege so-called “premises” liability-based alleged exposure on U. S. Steel’s current or former premises. These claims are made by an indeterminable number of people such as truck drivers, railroad workers, salespersons, contractors and their employees, government inspectors, customers, visitors and even trespassers. In most cases, the claimant also was exposed to asbestos in non-U. S. Steel settings; the relative periods of exposure between U. S. Steel and non-U. S. Steel settings vary with each claimant; and the strength or weakness of the causal link between U. S. Steel exposure and any injury vary widely as do the nature and severity of the injury claimed.
	U. S. Steel is unable to estimate the ultimate outcome of asbestos-related lawsuits, claims and proceedings due to the unpredictable nature of personal injury litigation. Despite this uncertainty, management believes that the ultimate resolution of these matters will not have a material adverse effect on U. S. Steel’s financial condition, although the resolution of such matters could significantly impact results of operations for a particular quarter. Among the factors considered in reaching this conclusion are: (1) it has been many years since U. S. Steel employed maritime workers or manufactured or sold asbestos containing products, (2) most asbestos containing material was removed or remediated at U. S. Steel facilities many years ago, and (3) U. S. Steel’s history of trial outcomes, settlements and dismissals.
	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:
	(In millions)	Nine Months Ended September 30, 2014
	Beginning of period	$	233
	Accruals for environmental remediation deemed probable and reasonably estimable	4
	Obligations settled (a)	(19		)
	End of period	$	218
	(a) Includes approximately $2 million as a result of the deconsolidation of USSC on September 15, 2014. See Note 4 for details.
	Accrued liabilities for remediation activities are included in the following consolidated balance sheet lines:
	(In millions)		September 30, 2014			December 31, 2013
	Accounts payable		$	17		$	17
	Deferred credits and other noncurrent liabilities		201			216
	Total		$	218		$	233
	Expenses related to remediation are recorded in cost of sales and totaled $1 million for each of the three month periods ended September 30, 2014 and 2013; and $4 million and $5 million for the nine month periods ended September 30, 2014, and September 30, 2013, respectively. 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 possible that total remediation costs for active matters may exceed the accrued liabilities by as much as 10 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 are those projects which are still in the study and 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 cost estimates cannot be determined. Therefore, significant costs, in addition to the accrued liabilities for these projects, are reasonably possible.
	-2	Significant Projects with Defined Scope are those projects with significant accrued liabilities, a defined scope and little likelihood of material additional costs.
	-3	Other Projects are those projects with relatively small accrued liabilities for which we believe that, while additional costs are possible, they are not likely to be significant, and those projects for which we do not yet possess sufficient information to estimate potential costs to U. S. Steel.
	Projects with Ongoing Study and Scope Development – There are five environmental remediation projects where reasonably possible additional costs for completion are not currently estimable, but could be material. These projects are four Resource Conservation and Recovery Act (RCRA) programs (at Fairfield Works, Lorain Tubular, USS-POSCO Industries (UPI) and the Fairless Plant) and a voluntary remediation program at the former steelmaking plant at Joliet, Illinois. As of September 30, 2014, accrued liabilities for these projects totaled $2 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.
	Significant Projects with Defined Scope – As of September 30, 2014, there are four significant projects with defined scope greater than or equal to $5 million each, with a total accrued liability of $165 million. These projects are: Gary RCRA currently accrued at $43 million, the former Geneva facility currently accrued at $64 million, the former Duluth facility St. Louis River Estuary currently accrued at $51 million, and the Solid Waste Management Unit (SWMU) #4 at UPI currently accrued at $7 million.
	Other Projects – There are four 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 September 30, 2014 was $9 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 each had an accrued liability of less than $1 million. The total accrued liability for these projects at September 30, 2014 was $8 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 $28 million at September 30, 2014 and were based on known scopes of work.
	Administrative and Legal Costs – As of September 30, 2014, U. S. Steel had an accrued liability of $6 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 have not changed significantly from year to year.
	Capital Expenditures – For a number of years, U. S. Steel has made substantial capital expenditures to bring existing facilities into compliance with various laws relating to the environment. In the first nine months of 2014 and 2013, such capital expenditures totaled $50 million and $36 million, respectively. U. S. Steel anticipates making additional such expenditures in the future; however, the exact amounts and timing of such expenditures are uncertain because of the continuing evolution of specific regulatory requirements.
	CO2 Emissions – Current and potential regulation of greenhouse gas (GHG) emissions remains a significant issue for the steel industry, particularly for integrated steel producers such as U. S. Steel. The regulation of carbon dioxide (CO2) emissions has either become law or is being considered by legislative bodies of many nations, including countries where we have operating facilities. The European Union (EU) has established GHG regulations based upon national allocations and a cap and trade system. In the United States, the Environmental Protection Agency (EPA) has published rules for regulating GHG emissions for certain facilities and has implemented various reporting requirements as further described below. In 2010, GHG legislation was passed in the House of Representatives and introduced in the Senate. The federal courts are considering several suits that challenge the EPA’s authority to regulate GHG emissions under the Clean Air Act (CAA). We do not know what action, if any, may be taken by the current or future sessions of Congress.
	The European Commission (EC) has created an Emissions Trading System (ETS) and starting in 2013, the ETS began to employ centralized allocation, rather than national allocation plans, that are more stringent than the previous requirements. The ETS also includes a cap designed to achieve an overall reduction of GHGs for the ETS sectors of 21% in 2020 compared to 2005 emissions and auctioning as the basic principle for allocating emissions allowances, with some transitional free allocation provided on the basis of benchmarks for manufacturing industries under risk of transferring their production to other countries with lesser constraints on greenhouse gas emissions, or what is more commonly referred to as carbon leakage. Manufacturing of sinter, coke oven products, basic iron and steel, ferro-alloys and cast iron tubes have all been recognized as exposing companies to a significant risk of carbon leakage, but the ETS is still expected to lead to additional costs for steel companies in Europe. The EU has imposed limitations under the ETS for the 2013-2020 period (Phase III) that are more stringent than those in the 2008-2012 period (NAP II), reducing the number of free allowances granted to companies to cover their CO2 emissions.
	In September of 2013, the EC issued EU wide legislation further reducing the expected free allocation for Phase III by an average of approximately 12% for the Phase III period. USSK's final allocation for the Phase III period that was approved by the EC in January 2014 is approximately 48 million allowances. Based on 2013 emission intensity levels and projected future production levels and as a result of carryover allowances from the NAP II period, we do not currently anticipate the need to purchase credits until 2019, and we currently estimate a shortfall of 14 million allowances for the Phase III period. However, due to a number of variable factors such as the future market value of allowances, future production levels and future emission intensity levels, we cannot reliably estimate the full cost of complying with the ETS regulations at this time.
	U. S. Steel entered into transactions to sell and swap a portion of our emission allowances and recognized gains related to these transactions which are reflected in the net gain on disposal of assets line in the consolidated statements of operations. U. S. Steel recognized gains of $17 million during the nine months ended September 30, 2014. There were no such similar transactions for the nine months ended September 30, 2013.
	On May 13, 2010, the EPA published its final Greenhouse Gas Tailoring Rule establishing a mechanism for regulating GHG emissions from facilities through the CAA’s Prevention of Significant Deterioration (PSD) permitting process. U. S. Steel reported its emissions under these rules in accordance with the regulation and its deadlines. Since 2011, new projects that increase GHG emissions by more than 75,000 tons per year have new PSD requirements based on best available control technology (BACT), but only if the project also significantly increases emissions of at least one non-GHG pollutant. Only existing sources with Title V permits or new sources obtaining Title V permits for non-GHG pollutants will also be required to address GHG emissions. As of July 1, 2011, new sources not already subject to Title V requirements that emit over 100,000 tons per year, or modifications to existing permits that increase GHG emissions by more than 75,000 tons per year, are subject to PSD and Title V requirements. On November 17, 2010 the EPA issued its “PSD and Title V Permitting Guidance for Greenhouse Gases” and “Available and Emerging Technologies for Reducing Greenhouse Gas Emissions from the Iron and Steel Industry.” With this guidance, the EPA intends to help state and local air permitting authorities identify GHG reductions under the CAA. Additionally, the EPA revised the National Ambient Air Quality Standards (NAAQS) for nitrogen oxide, sulfur dioxide and lead in 2010 and is in the process of revising the NAAQS for 2.5 micron particulate matter, ozone and sulfur dioxides.
	It is not possible to estimate the timing or impact of these or other future government action on U. S. Steel, although it could be significant. Such impacts may include substantial capital expenditures, costs for emission allowances, restriction of production, and higher prices for coking coal, natural gas and electricity generated by carbon based systems.
	European Union (EU) Environmental Requirements – Slovakia is currently considering a law implementing an EU Waste Framework Directive that would more strictly regulate waste disposal and increase fees for waste disposed of in landfills including privately owned landfills. The intent of the waste directive is to encourage recycling, but because Slovakia has not adopted implementing legislation we cannot estimate the full financial impact of this prospective legislation at this time.
	The EU’s Industry Emission Directive will require implementation of EU determined best available techniques (BAT) to reduce environmental impacts as well as compliance with BAT associated emission levels. This directive includes operational requirements for air emissions, wastewater discharges, solid waste disposal and energy conservation, dictates certain operating practices and imposes stricter emission limits. Producers will be required to be in compliance with the iron and steel BAT by March 8, 2016, unless specific extensions are granted by the Slovak environmental authority. We are currently evaluating the costs of complying with BAT, but our most recent broad estimate of likely capital expenditures is $200 million to $250 million over the 2014 to 2016 period. We also believe there will be increased operating costs, such as increased energy and maintenance costs, but we are currently unable to reliably estimate them.
	We are currently investigating the possibility of obtaining EU grants to fund a portion of these capital expenditures. The EU has various programs under which funds are allocated to member states to implement broad public policies. These are being implemented in two campaigns, Operational Program 1 which covered the years 2007-2013 (OP1) and Operational Program 2 which will cover the years 2014-2020 (OP2). Each member state legislates its own framework for implementing the operational programs and administers its allocation of funds under the operational programs by offering these funds to government units and private entities for qualifying projects. USSK submitted two BAT projects under the last call of OP1. Both projects were approved for funding by the Ministry of Environment of the Slovak Republic in May 2014 in an amount not to exceed approximately €9 million (approximately $11 million). The actual amount of the grant funding received will be based on 35% of the identified eligible costs as defined in OP1 actually incurred on the projects.
	We plan to submit several additional BAT projects for EU grants as well. However, all future projects will be submitted under calls governed by OP2. The specific legislation governing OP2 has not yet been finalized by the Slovak Republic, so we are not able to accurately estimate at this time the amount of additional grant funding that we may receive, if any.
	Due to other EU legislation, we will be 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. In January of 2014, the operation of USSK's boilers was approved by the 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 parameters for determining the date by which specific boilers are required to reach compliance with the new air standards, which has been determined to be October 2017 for our boilers. This gives us the flexibility of delaying the completion of the project to upgrade our boilers to no later than that date, although we may choose to accelerate the implementation of this project in order to qualify for supplementary support payments as part of Slovakia’s renewable energy program. This project will result in a reduction in electricity, operating, maintenance and waste disposal costs once completed. The current projected cost to reconstruct one existing boiler and build one new boiler to achieve compliance is broadly estimated at $170 million.
	Environmental and other 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 sold. These indemnifications and cost sharing agreements have 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 non-compliance with past, current and future environmental laws related to existing conditions, and there can be questions as to the applicability of more general indemnification provisions to environmental matters. Most recent indemnifications 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 of property formerly owned by U. S. Steel may have common law claims and contribution rights against U. S. Steel for 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 sold. Aside from the environmental liabilities already recorded as a result of these transactions due to specific environmental remediation activities and cases (included in the $218 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 of unconsolidated entities of U. S. Steel totaled $29 million at September 30, 2014, which includes a $24 million current liability related to a guarantee of debt of an unconsolidated equity investment for which payment by U. S. Steel is probable. The $24 million is the maximum amount U. S. Steel would be obligated to pay as the guarantor and represents the fair value of the obligation at September 30, 2014. If any default related to the guaranteed indebtedness occurs, U. S. Steel has access to its interest in the assets of the investees to reduce its potential losses under the guarantees.
	Antitrust Class Actions – In a series of lawsuits filed in federal court in the Northern District of Illinois beginning September 12, 2008, individual direct or indirect buyers of steel products have asserted that eight steel manufacturers, including U. S. Steel, conspired in violation of antitrust laws to restrict the domestic production of raw steel and thereby to fix, raise, maintain or stabilize the price of steel products in the United States. The cases are filed as class actions and claim damages related to steel product purchases during the time period of April 1, 2005, to December 31, 2007. A Hearing on class certification was completed in April of 2014. On July 10, 2014, preliminary approval of U. S. Steel's $58 million settlement agreement was granted by the Court. By Order dated October 21, 2014, the Court entered final approval of the settlement agreement.
	EPA Region V Federal Lawsuit – On August 1, 2012, the EPA, joined by the States of Illinois, Indiana and Michigan, initiated an action in the Northern District of Indiana alleging various air regulatory violations at Gary Works, Granite City Works, and Great Lakes Works. The action also contends that Gary Works failed to obtain the proper pre-construction permit for a routine reline of its Blast Furnace No. 4 in 1990, and that the three facilities failed to meet certain operational, maintenance, opacity, and recordkeeping requirements. Statutory penalties and injunctive relief is requested. U. S. Steel believes that the claims asserted in the action are not justified and are without statutory foundation. The Court has since dismissed all claims related to the Blast Furnace No. 4 reline. Fact discovery on the remaining claims is being conducted in three phases with discovery regarding Granite City Works and Great Lakes Works now complete. U. S. Steel will continue to vigorously defend against these claims. At this time, the potential outcome on all asserted claims is not reasonably estimable.
	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 $13 million at September 30, 2014). 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 $165 million as of September 30, 2014, 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 RPA. 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 $57 million at September 30, 2014, of which less than $1 million was classified as current, and $81 million at December 31, 2013, of which less than $1 million was classified as current. Restricted cash at September 30, 2014 also includes $20 million to fund certain capital projects at Gary Works, our Clairton Plant and Granite City Works. The proceeds become unrestricted as capital expenditures for these projects are made.
	Capital Commitments – At September 30, 2014, U. S. Steel’s contractual commitments to acquire property, plant and equipment totaled $218 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):
	Remainder of 2014		2015		2016	2017		2018	Later	Total
									Years
	$336		$898		$667	$572		$326	$1,279	$4,078
	The majority of U. S. Steel’s unconditional purchase obligations relates to the supply of industrial gases, energy and utility services with terms ranging from two to 14 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 90 percent to 105 percent of the expected annual capacity of the heat recovery coke plant at our Granite City Works, and U. S. Steel is obligated to purchase the coke from Gateway at the contract price. As of September 30, 2014, a maximum default payment of approximately $239 million would apply if U. S. Steel terminates the agreement.
	Total payments relating to unconditional purchase obligations were $119 million and $115 million for the three months ended September 30, 2014 and 2013, respectively and $389 million and $410 million for the nine months ended September 30, 2014 and September 30, 2013, respectively.

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Results of Segment Operations	'
	The results of segment operations for the three months ended September 30, 2014 and 2013 are:
	(In millions) Three Months Ended September 30, 2014	Customer			Intersegment			Net			Income			Income
		Sales			Sales			Sales			(loss)			(loss)
											from			from
											investees			operations
	Flat-rolled	$	3,125		$	319		$	3,444		$	47		$	347
	USSE	687			1			688			—			29
	Tubular	700			—			700			3			69
	Total reportable segments	4,512			320			4,832			50			445
	Other Businesses	75			33			108			—			34
	Reconciling Items and Eliminations	—			(353		)	(353		)	—			(620		)
	Total	$	4,587		$	—		$	4,587		$	50		$	(141	)
	Three Months Ended September 30, 2013
	Flat-rolled	$	2,731		$	324		$	3,055		$	28		$	82
	USSE	643			1			644			—			(32		)
	Tubular	731			2			733			(1		)	49
	Total reportable segments	4,105			327			4,432			27			99
	Other Businesses	26			32			58			(1		)	14
	Reconciling Items and Eliminations	—			(359		)	(359		)	—			(1,815		)
	Total	$	4,131		$	—		$	4,131		$	26		$	(1,702	)
	The results of segment operations for the nine months ended September 30, 2014 and 2013 are:
	(In millions) Nine Months Ended September 30, 2014	Customer			Intersegment			Net			Income			Income
		Sales			Sales			Sales			(loss)			(loss)
											from			from
											investees			operations
	Flat-rolled	$	9,089		$	947		$	10,036		$	98		$	462
	USSE	2,203			45			2,248			—			99
	Tubular	2,030			2			2,032			8			140
	Total reportable segments	13,322			994			14,316			106			701
	Other Businesses	113			101			214			(3		)	64
	Reconciling Items and Eliminations	—			(1,095		)	(1,095		)	—			(749		)
	Total	$	13,435		$	—		$	13,435		$	103		$	16
	Nine Months Ended September 30, 2013
	Flat-rolled	$	8,710		$	985		$	9,695		$	41		$	18
	USSE	2,204			3			2,207			—			16
	Tubular	2,126			4			2,130			(7		)	158
	Total reportable segments	13,040			992			14,032			34			192
	Other Businesses	115			101			216			(3		)	62
	Reconciling Items and Eliminations	—			(1,093		)	(1,093		)	—			(1,925		)
	Total	$	13,155		$	—		$	13,155		$	31		$	(1,671	)
Schedule of reconciling items to income (loss) from operations	'
	The following is a schedule of reconciling items to income (loss) from operations:
		Three Months Ended September 30,						Nine Months Ended September 30,
	(In millions)	2014			2013			2014			2013
	Items not allocated to segments:
	Postretirement benefit expense (a)	$	(26	)	$	(55	)	$	(90	)	$	(165	)
	Other items not allocated to segments:
	Loss on deconsolidation of U. S. Steel Canada and other charges (Note 4)	(413		)	—			(413		)	—
	Impairment of carbon alloy facilities (Note 20)	(199		)	—			(199		)	—
	Write-off of pre-engineering costs (Note 20)	(37		)	—			(37		)	—
	Gain on sale of real estate assets (b)	55			—			55			—
	Litigation reserves (Note 21)	—			—			(70		)	—
	Loss on assets held for sale (Note 20)	—			—			(14		)	—
	Curtailment gain (Note 6)	—			—			19			—
	Impairment of goodwill (Note 5)	—			(1,783		)	—			(1,783		)
	Supplier contract dispute settlement	—			23			—			23
	Total other items not allocated to segments	(594		)	(1,760		)	(659		)	(1,760		)
	Total reconciling items	$	(620	)	$	(1,815	)	$	(749	)	$	(1,925	)
	(a) Consists of the net periodic benefit cost elements, other than service cost and amortization of prior service cost for active employees, associated with our pension, retiree health care and life insurance benefit plans.
	(b) Gain on sale of surface rights and mineral royalty revenue streams in the state of Alabama.

U_S_Steel_Canada_Deconsolidati1

U. S. Steel Canada Deconsolidation U. S. Steel Canada Deconsolidation (Tables)	9 Months Ended
	Sep. 30, 2014
Deconsolidation of Subsidiary [Abstract]	'
Assets, Liabilities, and Stockholder's Equity	'
	The following disclosure represents USSC’s assets, liabilities and accumulated other comprehensive loss which have been deconsolidated from U. S. Steel’s consolidated balance sheet as of the end of the day on September 15, 2014. The amounts presented are before the elimination of balances with U. S. Steel, presenting USSC as if on a stand-alone basis.
	(Dollars in millions)	15-Sep-14
	Assets
	Current assets:
	Cash and cash equivalents	$	80
	Receivables	291
	Inventories	373
	Other current assets	6
	Total current assets	750
	Property, plant and equipment, net	840
	Other noncurrent assets	126
	Total assets	$	1,716
	Liabilities
	Current liabilities:
	Accounts payable	$	435
	Other current liabilities	149
	Total current liabilities	584
	Long-term debt	126
	Long-term notes payable	1,733
	Employee benefits	948
	Other noncurrent liabilities	29
	Total liabilities	3,420
	Stockholders’ Equity
	Additional paid-in capital	2,268
	Retained earnings	(3,504		)
	Accumulated other comprehensive loss	(468		)
	Total stockholders’ equity	(1,704		)
	Noncontrolling interests	—
	Total liabilities and stockholders’ equity	$	1,716
Results of Operations	'
	Our consolidated statements of operations include the following amounts for USSC’s results of operations. The amounts presented are before the elimination of transactions with U. S. Steel, presenting USSC as if on a stand-alone basis.
	(Dollars in millions)	Period from July 1, 2014 - September 15, 2014			Three months ended September 30, 2013			Period from January 1, 2014 - September 15, 2014			Nine months ended September 30, 2013
	Total net sales	$	447		$	282		$	1,508		$	960
	Total operating expenses	467			1,026			1,587			1,941
	Loss from continuing operations	(20		)	(744		)	(79		)	(981		)
	Net interest and other financial costs	37			39			121			142
	Loss before income taxes	(57		)	(783		)	(200		)	(1,123		)
	Income tax benefit	—			—			—			—
	Net loss	$	(57	)	$	(783	)	$	(200	)	$	(1,123	)
Fair Value Inputs	'
	The amount and timing of future cash flows within the DCF analysis and the liquidation basis were based on the following inputs within the fair value framework prescribed by ASC Topic 820, Fair Value Measurements, in the table below.
	Level 2 Other Observable Inputs	Level 3 Other Unobservable Inputs
	Market Participant Weighted Average Cost of Capital (1)	Recent Operating Budgets
	Perpetual Growth Rate (2)	Long Range Strategic Plans
	Market Comparables	Estimated Shipments
	Replacement Cost	Projected Raw Material Costs
		Projected Margins
		Recoverability Measures
	(1) Ranged from 15.54% - 18.31%
	(2) Set at approximately 2%

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Amortizable Intangible Assets	'
	mortizable intangible assets are being amortized on a straight-line basis over their estimated useful lives and are detailed below:
			As of September 30, 2014						As of December 31, 2013
	(In millions)	Useful	Gross		Accumulated		Net		Gross		Accumulated		Net
		Lives	Carrying		Amortization		Amount		Carrying		Amortization		Amount
			Amount						Amount
	Customer relationships (a)	22 Years	$	132	$	45	$	87	$	215	$	63	$	152
	Other	2-20 Years	23		13		10		23		12		11
	Total amortizable intangible assets		$	155	$	58	$	97	$	238	$	75	$	163

Pensions_and_Other_Benefits_Ta

Pensions and Other Benefits (Tables)	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Net Periodic Benefit Cost	'
	The following table reflects the components of net periodic benefit cost for the three months ended September 30, 2014 and 2013:
		Pension						Other
		Benefits						Benefits
	(In millions)	2014			2013			2014			2013
	Service cost	$	27		$	32		$	5		$	7
	Interest cost	103			100			33			35
	Expected return on plan assets	(147		)	(152		)	(37		)	(33		)
	Amortization of prior service cost	6			6			(4		)	(3		)
	Amortization of actuarial net loss	67			92			—			8
	Net periodic benefit cost, excluding below	56			78			(3		)	14
	Multiemployer plans	19			19			—			—
	Settlement, termination and curtailment losses	13			3			—			—
	Net periodic benefit cost	$	88		$	100		$	(3	)	$	14
	The following table reflects the components of net periodic benefit cost for the nine months ended September 30, 2014 and 2013:
		Pension						Other
		Benefits						Benefits
	(In millions)	2014			2013			2014			2013
	Service cost	$	81		$	96		$	17		$	21
	Interest cost	321			303			106			106
	Expected return on plan assets	(454		)	(459		)	(106		)	(98		)
	Amortization of prior service cost	17			18			(11		)	(10		)
	Amortization of actuarial net loss (gain)	208			275			(2		)	23
	Net periodic benefit cost, excluding below	173			233			4			42
	Multiemployer plans	56			55			—			—
	Settlement, termination and curtailment losses/(gains)	28			3			(19		)	—
	Net periodic benefit cost	$	257		$	291		$	(15	)	$	42

StockBased_Compensation_Plans_

Stock-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Summary of Awards Made under Plans	'
	The following table is a general summary of the awards made under the Plan.
		2014 Grants						2013 Grants
	Grant Details	Shares(a)		Fair Value(b)				Shares(a)		Fair Value(b)
	Executive Stock Options	441,960		$	9.93			826,340		$	8.37
	Non-executive Stock Options	1,054,480		$	9.93			970,640		$	9.7
	Restricted Stock Units	724,510		$	24.29			1,033,210		$	18.58
	Performance Awards(c)
	TSR	282,770		$	22.09			271,960		$	21.26
	ROCE	262,800		$	23.76			—		$	—
	(a) The share amounts shown in this table do not reflect an adjustment for estimated forfeitures.
	(b) Represents the per share weighted-average for all grants during the year.
	(c) The number of performance awards shown represents the target value of the award.
	U
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. The stock options vest ratably over a three-year service period and have a term of ten years.
	Black-Scholes Assumptions(a)		2014 Grants			2013 Executive Grants			2013 Non-Executive Grants
	Grant date price per share of option award		$	24.29		$	18.48		$	18.64
	Exercise price per share of option award		$	24.29		$	25		$	18.64
	Expected annual dividends per share, at grant date		$	0.2		$	0.2		$	0.2
	Expected life in years		5			5			5
	Expected volatility		49		%	66		%	67		%
	Risk-free interest rate		1.621		%	1.315		%	1.049		%
	Grant date fair value per share of unvested option awards as calculated from above		$	9.93		$	8.37		$	9.7
	(a) The assumptions represent a weighted average of all grants during the year.

Significant_Equity_Investments1

Significant Equity Investments (Tables)	9 Months Ended
	Sep. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Summarized Unaudited Income Statement Information for Significant Equity Investments	'
	Summarized unaudited income statement information for our significant equity investments for the nine months ended September 30, 2014 and 2013 is reported below (amounts represent 100% of investee financial information):
	(In millions)	2014		2013
	Net sales	$	1,977	$	1,841
	Cost of sales	1,505		1,395
	Operating income	427		399
	Net income	412		382
	Net income attributable to significant equity investments	412		382

Earnings_and_Dividends_Per_Com1

Earnings and Dividends Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Computations for Basic and Diluted Income (Loss) Per Common Share from Continuing Operations	'
	The computations for basic and diluted earnings per common share from continuing operations are as follows:
		Three Months Ended September 30,							Nine Months Ended September 30,
	(Dollars in millions, except per share amounts)	2014				2013			2014			2013
	Net loss attributable to United States Steel Corporation shareholders	$	(207	)		$	(1,791	)	$	(173	)	$	(1,942	)
	Plus income effect of assumed conversion-interest on convertible notes	—				—			—			—
	Net loss after assumed conversion	$	(207	)		$	(1,791	)	$	(173	)	$	(1,942	)
	Weighted-average shares outstanding (in thousands):
	Basic	145,348				144,727			144,999			144,523
	Effect of convertible notes	—				—			—			—
	Effect of stock options, restricted stock units and performance awards	—				—			—			—
	Adjusted weighted-average shares outstanding, diluted	145,348				144,727			144,999			144,523
	Basic earnings per common share	$	(1.42	)		$	(12.38	)	$	(1.19	)	$	(13.44	)
	Diluted earnings per common share	$	(1.42	)		$	(12.38	)	$	(1.19	)	$	(13.44	)
Antidilutive Securities that were Not Included in Computations of Diluted Income (Loss) Per Common Share	'
	The following table summarizes the securities that were antidilutive, and therefore, were not included in the computations of diluted earnings per common share:
		Three Months Ended September 30,						Nine Months Ended
								September 30,
	(In thousands)	2014			2013			2014		2013
	Securities granted under the 2005 Stock Incentive Plan	8,865			7,621			8,865		7,621
	Securities convertible under the Senior Convertible Notes (a)	3,477			10,058			6,523		15,351
	Total	12,342			17,679			15,388		22,972
	(a) On March 27, 2013, we repurchased approximately $542 million aggregate principal amount of our 2014 Senior Convertible Notes. If the repurchases had occurred on January 1, 2013, the antidilutive securities would be 10,058 for the nine months ended September 30, 2013. Additionally, on May 15, 2014, we redeemed the remaining amount due under the 2014 Senior Convertible Notes. If the redemption had occurred on January 1, 2014, the antidilutive securities would be zero for the nine months ended September 30, 2014.

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	(In millions)	September 30, 2014		December 31, 2013
	Raw materials	$	608	$	1,011
	Semi-finished products	994		1,023
	Finished products	518		558
	Supplies and sundry items	79		96
	Total	$	2,199	$	2,688

Derivative_Instruments_Tables

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Location and Amounts of Fair Values Related to Derivatives in Financial Statements	'
			Fair Value			Fair Value
	(In millions)	Balance Sheet	30-Sep-14			31-Dec-13
		Location
	Foreign exchange forward contracts	Accounts receivable	$	28		$	—
	Foreign exchange forward contracts	Accounts payable	$	—		$	11
Location and Amounts of Gains or Losses Related to Derivatives in Financial Statements	'
		Statement of	Amount of Gain			Amount of Gain
		Operations	(Loss)			(Loss)
	(In millions)	Location	Three Months Ended September 30, 2014			Nine months ended September 30, 2014
	Foreign exchange forward contracts	Other financial	$	33		$	36
		costs
		Statement of	Amount of Gain			Amount of Gain
		Operations	(Loss)			(Loss)
	(In millions)	Location	Three Months Ended September 30, 2013			Nine Months Ended September 30, 2013
	Foreign exchange forward contracts	Other financial	$	(11	)	$	(7	)
		costs

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt	'
	(In millions)	Interest		Maturity	September 30, 2014		December 31, 2013
		Rates %
	2037 Senior Notes	6.65		2037	$	350	$	350
	2022 Senior Notes	7.5		2022	400		400
	2021 Senior Notes	6.875		2021	275		275
	2020 Senior Notes	7.375		2020	600		600
	2018 Senior Notes	7		2018	500		500
	2017 Senior Notes	6.05		2017	450		450
	2019 Senior Convertible Notes	2.75		2019	316		316
	2014 Senior Convertible Notes	4		2014	—		322
	USSC Province Note (C$150 million) (a)	1		2015	—		141
	Environmental Revenue Bonds	5.38 - 6.88		2015 - 2042	549		549
	Recovery Zone Facility Bonds	6.75		2040	70		70
	Fairfield Caster Lease			2022	34		35
	Other capital leases and all other obligations			2020	—		—
	Amended Credit Agreement	Variable		2016	—		—
	USSK Revolver	Variable		2016	—		—
	USSK credit facilities	Variable		2015 - 2016	—		—
	Total Debt				3,544		4,008
	Less Province Note fair value adjustment (a)				—		15
	Less unamortized discount				46		54
	Less short-term debt and long-term debt due within one year				336		323
	Long-term debt				$	3,162	$	3,616
Eligible Accounts Receivable and Receivables Sold to Third-Party Conduits	'
	The eligible accounts receivable and receivables sold to third party conduits are summarized below:
	(In millions)	September 30, 2014			December 31, 2013
	Balance of accounts receivable-net, eligible for sale to third-parties	$	1,166		$	988
	Accounts receivable sold to third-parties	—			—
	Balance included in Receivables on the balance sheet of U. S. Steel	$	1,166		$	988

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2014
Asset Retirement Obligation Disclosure [Abstract]	'
Changes in Carrying Values of Asset Retirement Obligations	'
	The following table reflects changes in the carrying values of AROs:
	(In millions)	September 30, 2014			December 31, 2013
	Balance at beginning of year	$	59		$	33
	Additional obligations incurred	—			28
	Obligations settled(a)	(18		)	(7		)
	Foreign currency translation effects	(1		)	—
	Accretion expense	3			5
	Balance at end of period	$	43		$	59
	(a) Includes $16 million as a result of the deconsolidation of USSC as of the end of the day on September 15, 2014. See Note 4 for additional details.

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
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 September 30, 2014 and December 31, 2013.
		30-Sep-14				December 31, 2013
	(In millions)	Fair		Carrying		Fair		Carrying
		Value		Amount		Value		Amount
	Financial assets:
	Investments and long-term receivables (a)	$	45	$	45	$	63	$	63
	Financial liabilities:
	Debt (b)	$	3,957	$	3,464	$	4,198	$	3,904
	(a) Excludes equity method investments.
	(b) Excludes capital lease obligations.

Statement_of_Changes_in_Stockh1

Statement of Changes in Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Consolidated Statement of Changes in Equity	'
	The following table reflects the first nine months of 2014 and 2013 reconciliation of the carrying amount of total equity, equity attributable to U. S. Steel and equity attributable to noncontrolling interests:
	Nine Months Ended September 30, 2014 (In millions)	Total			Comprehensive			Retained			Accumulated			Common		Treasury			Paid-in			Non-
					Income (Loss)			Earnings			Other			Stock		Stock			Capital			Controlling
											Comprehensive											Interest
											(Loss) Income
	Balance at beginning of year	$	3,376					$	1,789		$	(1,752	)	$	151	$	(480	)	$	3,667		$	1
	Comprehensive income:
	Net loss	(173		)	(173		)	(173		)
	Other comprehensive income (loss), net of tax:
	Pension and other benefit adjustments	175			175						175
	Currency translation adjustment	93			93						93
	Deconsolidation of U. S. Steel	468			468						468
	Canada (a)
	Employee stock plans	26														70			(44		)
	Dividends paid on common stock	(22		)				(22		)
	Balance at September 30, 2014	$	3,943		$	563		$	1,594		$	(1,016	)	$	151	$	(410	)	$	3,623		$	1
	(a) Consists of $493 million for Pension and other benefit adjustments and $(25) million for currency translation adjustment.
	Nine Months Ended September 30, 2013 (In millions)	Total			Comprehensive			Retained			Accumulated			Common		Treasury			Paid-in			Non-
					Income (Loss)			Earnings			Other			Stock		Stock			Capital			Controlling
											Comprehensive											Interest
											(Loss) Income
	Balance at beginning of year	$	3,478					$	3,463		$	(3,268	)	$	151	$	(521	)	$	3,652		$	1
	Comprehensive income:
	Net loss	(1,942		)	(1,942		)	(1,942		)
	Other comprehensive income (loss), net of tax:
	Pension and other benefit adjustments	197			197						197
	Currency translation adjustment	13			13						13
	Issuance of conversion option in 2019 Senior Convertible Notes, net of tax	31																	31
	Employee stock plans	22														40			(18		)
	Dividends paid on common stock	(22		)				(22		)
	Other	(2		)				(2		)
	Balance at September 30, 2013	$	1,775		$	(1,732	)	$	1,497		$	(3,058	)	$	151	$	(481	)	$	3,665		$	1

Reclassifications_from_Accumul1

Reclassifications from Accumulated Other Comprehensive Income (AOCI) (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Other Comprehensive Income Activity Net of Tax	'
	(In millions) (a)	Pension and				Foreign				Total
		Other Benefit				Currency
		Items				Items
	Balance at December 31, 2013	$	(2,127	)		$	375			$	(1,752	)
	Other comprehensive income (loss) before reclassifications	34				(69		)		(35		)
	Amounts reclassified from AOCI	141			(b)	162			(c)	303
	Deconsolidation of U. S. Steel Canada (c)	493				(25		)		468
	Net current-period other comprehensive income	668				68				736
	Balance at September 30, 2014	$	(1,459	)		$	443			$	(1,016	)
	(a)All amounts are net of tax. Amounts in parentheses indicate debits.
	(b)See table below for further details.
Defined Benefit Plan In other Comprehensive Income	'
		Amount reclassified from AOCI
		Three Months Ended September 30,								Nine Months Ended September 30,
	Details about AOCI components	2014				2013				2014			2013
	(in millions) (a)
	Amortization of pension and other benefit items
	Prior service costs (b)	$	(2	)		$	(3	)		$	(6	)	$	(8	)
	Actuarial gains/(losses) (b)	(67		)		(100		)		(206		)	(298		)
	Settlement, termination and	(13		)		—				(9		)	—
	curtailment gains (b)
	Total before tax	(82		)		(103		)		(221		)	(306		)
	Tax benefit	25				29				80			96
	Net of tax	$	(57	)		$	(74	)		$	(141	)	$	(210	)
	(a)Amounts in parentheses indicate debits to income/loss.
	(b)These AOCI components are included in the computation of net periodic benefit cost (see Note 6 for additional details).

Restructuring_and_Other_Charge1

Restructuring and Other Charges (Tables)	9 Months Ended
	Sep. 30, 2014
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 nine months ended September 30, 2014 were as follows:
		Severance				Exit			Asset
	(in millions)	Accrual				Costs			Impairments
	Balance at December 31, 2013	$	16			$	6		$	—
	Additional charges	15				—			250
	Cash payments/utilization	(8		)		(5		)	(250		)
	Other adjustments and re-classes	(16		)	(a)	(1		)	—
	Balance at September 30, 2014	$	7			$	—		$	—
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)	September 30, 2014				December 31, 2013
	Accounts payable	$	—			$	6
	Payroll and benefits payable	6				8
	Employee benefits	1				8
	Total	$	7			$	22

Contingencies_and_Commitments_

Contingencies and Commitments (Tables)	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
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:
	(In millions)	Nine Months Ended September 30, 2014
	Beginning of period	$	233
	Accruals for environmental remediation deemed probable and reasonably estimable	4
	Obligations settled (a)	(19		)
	End of period	$	218
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)		September 30, 2014			December 31, 2013
	Accounts payable		$	17		$	17
	Deferred credits and other noncurrent liabilities		201			216
	Total		$	218		$	233
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):
	Remainder of 2014		2015		2016	2017		2018	Later	Total
									Years
	$336		$898		$667	$572		$326	$1,279	$4,078

Basis_of_Presentation_Basis_of

Basis of Presentation Basis of Presentation - Additional Information (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014
Basis of Presentation [Abstract]	'
Prior Period Revision, Retained Earnings	$27
Prior Period Revision, Deferred Tax Benefits	$27

Segment_Information_Results_of

Segment Information - Results of Segment Operations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	$4,587	$4,131	$13,435	$13,155
Income (loss) from investees	50	26	103	31
Income (loss) from operations	-141	-1,702	16	-1,671
Flat-rolled	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	3,444	3,055	10,036	9,695
Income (loss) from investees	47	28	98	41
Income (loss) from operations	347	82	462	18
USSE	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	688	644	2,248	2,207
Income (loss) from investees	0	0	0	0
Income (loss) from operations	29	-32	99	16
Tubular	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	700	733	2,032	2,130
Income (loss) from investees	3	-1	8	-7
Income (loss) from operations	69	49	140	158
Total reportable segments	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	4,832	4,432	14,316	14,032
Income (loss) from investees	50	27	106	34
Income (loss) from operations	445	99	701	192
Other Businesses	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	108	58	214	216
Income (loss) from investees	0	-1	-3	-3
Income (loss) from operations	34	14	64	62
Reconciling Items and Eliminations	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	-353	-359	-1,095	-1,093
Income (loss) from investees	0	0	0	0
Income (loss) from operations	-620	-1,815	-749	-1,925
Revenues from External Customers	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	4,587	4,131	13,435	13,155
Revenues from External Customers | Flat-rolled	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	3,125	2,731	9,089	8,710
Revenues from External Customers | USSE	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	687	643	2,203	2,204
Revenues from External Customers | Tubular	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	700	731	2,030	2,126
Revenues from External Customers | Total reportable segments	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	4,512	4,105	13,322	13,040
Revenues from External Customers | Other Businesses	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	75	26	113	115
Revenues from External Customers | Reconciling Items and Eliminations	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	0	0	0	0
Intersegment Eliminations	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	0	0	0	0
Intersegment Eliminations | Flat-rolled	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	319	324	947	985
Intersegment Eliminations | USSE	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	1	1	45	3
Intersegment Eliminations | Tubular	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	0	2	2	4
Intersegment Eliminations | Total reportable segments	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	320	327	994	992
Intersegment Eliminations | Other Businesses	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	33	32	101	101
Intersegment Eliminations | Reconciling Items and Eliminations	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Customer Sales	($353)	($359)	($1,095)	($1,093)

Segment_Information_Schedule_o

Segment Information - Schedule of Reconciling Items to Income (Loss) from Operations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Other items not allocated to segments:	'	'	'	'
Loss on deconsolidation of U. S. Steel Canada and other charges (Note 4)	($413)	$0	($413)	$0
Curtailment gain (Note 6)	19	'	'	'
Impairment of goodwill (Note 5)	0	-1,783	0	-1,783
Total reconciling items	-141	-1,702	16	-1,671
Reconciling Items and Eliminations	'	'	'	'
Items not allocated to segments:	'	'	'	'
Postretirement benefit expense	-26	-55	-90	-165
Other items not allocated to segments:	'	'	'	'
Loss on deconsolidation of U. S. Steel Canada and other charges (Note 4)	-413	0	-413	0
Impairment of carbon alloy facilities (Note 20)	-199	-199	0	0
Write-off of pre-engineering costs (Note 20)	-37	0	-37	0
Gain on sale of real estate assets	55	55	0	0
Litigation reserves (Note 21)	0	0	-70	0
Loss on assets held for sale (Note 20)	0	0	-14	0
Curtailment gain (Note 6)	0	0	19	0
Impairment of goodwill (Note 5)	0	-1,783	0	-1,783
Supplier contract dispute settlement	0	23	0	23
Total other items not allocated to segments	-594	-1,760	-659	-1,760
Total reconciling items	($620)	($1,815)	($749)	($1,925)

Segment_Information_Additional

Segment Information - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
			Segment
Segment Reporting [Abstract]	'	'	'	'
Number of reportable segments	'	'	3	'
Non-cash charge on deconsolidation of USSC	$413	$0	$413	$0

U_S_Steel_Canada_Deconsolidati2

U. S. Steel Canada Deconsolidation U. S. Steel Canada Deconsolidation - Assets, Liabilities, and Stockholders' Equity (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 15, 2014
In Millions, unless otherwise specified					Us Steel Canada Inc
Noncontrolling Interest [Line Items]	'	'	'	'	'
Cash and cash equivalents	$1,257	$604	$697	$570	$80
Receivables	1,876	1,818	'	'	291
Inventories	2,199	2,688	'	'	373
Other current assets	38	50	'	'	6
Total current assets	6,101	6,078	'	'	750
Property, plant and equipment, net	4,570	5,922	'	'	840
Other noncurrent assets	133	235	'	'	126
Total assets	12,008	13,143	'	'	1,716
Accounts payable and other accrued liabilities	1,941	1,681	'	'	435
Other current liabilities	'	'	'	'	149
Total current liabilities	3,550	3,245	'	'	584
Long-term debt	3,162	3,616	'	'	126
Long-term notes payable	'	'	'	'	1,733
Employee benefits	554	2,064	'	'	948
Other noncurrent liabilities	388	424	'	'	29
Total liabilities	8,065	9,767	'	'	3,420
Additional paid-in capital	3,623	3,667	'	'	2,268
Retained earnings	1,594	1,789	'	'	-3,504
Accumulated other comprehensive loss	-1,016	-1,752	'	'	-468
Total stockholders’ equity	3,942	3,375	'	'	-1,704
Noncontrolling interests	1	1	'	'	0
Total liabilities and stockholders’ equity	$12,008	$13,143	'	'	$1,716

U_S_Steel_Canada_Deconsolidati3

U. S. Steel Canada Deconsolidation U. S. Steel Canada Deconsolidation - Results of Operations (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 15, 2014	Sep. 30, 2013	Sep. 15, 2014	Sep. 30, 2014	Sep. 30, 2013
					Us Steel Canada Inc	Us Steel Canada Inc	Us Steel Canada Inc	Us Steel Canada Inc	Us Steel Canada Inc
Noncontrolling Interest [Line Items]	'	'	'	'	'	'	'	'	'
Total net sales	$4,587	$4,131	$13,435	$13,155	$447	$282	$1,508	'	$960
Total operating expenses	'	'	'	'	467	1,026	1,587	'	1,941
(Loss) income from operations	-141	-1,702	16	-1,671	-20	-744	-79	'	-981
Net interest and other financial costs	60	85	193	257	37	39	121	'	142
Loss before income taxes and noncontrolling interests	-201	-1,787	-177	-1,928	-57	-783	-200	'	-1,123
Income tax benefit	6	4	-4	14	0	0	0	-30	0
Net loss	($207)	($1,791)	($173)	($1,942)	($57)	($783)	($200)	'	($1,123)

U_S_Steel_Canada_Deconsolidati4

U. S. Steel Canada Deconsolidation U. S. Steel Canada Deconsolidation - Additional Information (Details)	3 Months Ended		9 Months Ended		0 Months Ended	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 15, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014
	USD ($)	USD ($)	USD ($)	USD ($)	Us Steel Canada Inc	Us Steel Canada Inc	Us Steel Canada Inc	Minimum	Maximum
					USD ($)	USD ($)	CAD	Us Steel Canada Inc	Us Steel Canada Inc
Noncontrolling Interest [Line Items]	'	'	'	'	'	'	'	'	'
Non-cash charge on deconsolidation of USSC	$413,000,000	$0	$413,000,000	$0	$413,000,000	'	'	'	'
Professional Fees	'	'	'	'	20,000,000	'	'	'	'
U. S. Steel's interest in USSC under cost method of accounting	'	'	'	'	'	0	'	'	'
Fair Value Inputs, Discount Rate	'	'	'	'	'	'	'	15.54%	18.31%
Fair Value Inputs, Perpetual Growth Rate	'	'	'	'	'	2.00%	2.00%	'	'
Retained Interest in intercompany loans and other receivables	'	'	'	'	'	432,000,000	'	'	'
Allowance for Doubtful Accounts Receivable	'	'	'	'	'	1,448,000,000	'	'	'
Debtor-in-Possession Financing, Maximum Commitment	'	'	'	'	'	$165,000,000	185,000,000	'	'
Debtor-in-Possession Financing, Interest Rate on Borrowings Outstanding	'	'	'	'	'	5.00%	5.00%	'	'
Debtor-in-Possession Financings, Increase in Interest Rate upon Default	'	'	'	'	'	2.00%	2.00%	'	'
Debtor-in-Possession Financing, Fee on Unused Borrowings	'	'	'	'	'	2.00%	2.00%	'	'
Debtor-in-Possession Financings, Exit Fee Rate	'	'	'	'	'	3.00%	3.00%	'	'

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Amortizable Intangible Assets (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]	'	'
Gross Carrying Amount	$155	$238
Accumulated Amortization	58	75
Net Amount	97	163
Customer relationships	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Useful Lives	'22 years	'
Gross Carrying Amount	132	215
Accumulated Amortization	45	63
Net Amount	87	152
Other	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Gross Carrying Amount	23	23
Accumulated Amortization	13	12
Net Amount	10	11
Other | Minimum	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Useful Lives	'2 years	'
Other | Maximum	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Useful Lives	'20 years	'
Us Steel Canada Inc | Customer relationships	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Net Amount	$56	'

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
		Unit		Unit
Indefinite-lived Intangible Assets [Line Items]	'	'	'	'	'
Number of reporting units that have a significant amount of goodwill	'	2	'	2	'
Goodwill, Impairment Loss	$0	$1,783	$0	$1,783	'
Acquisition of intangible assets (Note 5)	'	'	0	12	12
Aggregate purchase price	'	'	'	'	36
Maximum potential liability for contingent consideration	'	'	'	'	53
Fair value of contingent consideration	24	'	24	'	'
Amortization expense	2	3	8	8	'
Expected amortization expense, remainder of current year	2	'	2	'	'
Expected amortization expense, for 2015	7	'	7	'	'
Expected amortization expense, for 2016	7	'	7	'	'
Expected amortization expense, for 2017	7	'	7	'	'
Expected amortization expense, for 2018	7	'	7	'	'
Use Rights [Member]	'	'	'	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'	'	'	'
Carrying amount of acquired water rights with indefinite lives	75	'	75	'	75
Developed Technology Rights [Member]	'	'	'	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'	'	'	'
Amount allocated to indefinite-lived intangible assets	'	'	'	'	33
Flat-rolled	'	'	'	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'	'	'	'
Goodwill, Impairment Loss	'	'	'	'	969
Goodwill (Note 4 )	'	0	'	0	'
Tubular	'	'	'	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'	'	'	'
Goodwill, Impairment Loss	'	'	'	'	837
Goodwill (Note 4 )	'	0	'	0	'
USSE	'	'	'	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'	'	'	'
Goodwill (Note 4 )	$4	'	$4	'	'

Pensions_and_Other_Benefits_Ne

Pensions and Other Benefits - Net Periodic Benefit Costs (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'
Service cost	$27	$32	$81	$96
Interest cost	103	100	321	303
Expected return on plan assets	-147	-152	-454	-459
Amortization of prior service cost	6	6	17	18
Amortization of actuarial net loss	67	92	208	275
Net periodic benefit cost, excluding below	56	78	173	233
Multiemployer plans	19	19	56	55
Settlement, termination and curtailment losses/(gains)	13	3	28	3
Net periodic benefit cost	88	100	257	291
Other Benefits	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'
Service cost	5	7	17	21
Interest cost	33	35	106	106
Expected return on plan assets	-37	-33	-106	-98
Amortization of prior service cost	-4	-3	-11	-10
Amortization of actuarial net loss	0	8	-2	23
Net periodic benefit cost, excluding below	-3	14	4	42
Multiemployer plans	0	0	0	0
Settlement, termination and curtailment losses/(gains)	0	0	-19	0
Net periodic benefit cost	($3)	$14	($15)	$42

Pensions_and_Other_Benefits_Ad

Pensions and Other Benefits - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Nov. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'	'
Curtailment gain (Note 6)	'	$19	'	'	'
Cash contribution by employer to defined contribution plans	'	11	11	35	33
Amount of contributions authorized by the board of directors	300	'	'	'	'
USSC Pension Plan	'	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'	'
Defined Benefit Plan, Contributions by Employer	'	'	'	47	'
Cash contribution by employer to pension plans	'	'	140	140	'
Steelworkers Pension Trust	'	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'	'
Defined Benefit Plan, Contributions by Employer	'	'	'	56	'
Other Pension Plans, Defined Benefit	'	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'	'
Defined Benefit Plan, Contributions by Employer	'	'	'	83	'
Unfunded Other Postretirement Benefit Plans	'	'	'	'	'
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]	'	'	'	'	'
Cash contribution by employer to pension plans	'	'	'	$180	'

Net_Interest_and_Other_Financi1

Net Interest and Other Financial Costs - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended					3 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014
				2014 Senior Convertible Notes	2014 Senior Convertible Notes	2014 Senior Convertible Notes	Maximum
Interest Expense [Line Items]	'	'	'	'	'	'	'
Net foreign currency remeasurement gains (losses)	$3	($1)	($9)	'	'	'	$1
Charge for guarantee in unconsolidated equity method investment	'	22,000,000	22,000,000	'	'	'	'
Gain (Loss) on Repurchase of Debt Instrument	'	'	'	34	'	'	'
Repayments of Long-term Debt	'	$323	$542	$542	'	'	'
Interest rate	'	'	'	'	4.00%	4.00%	'

StockBased_Compensation_Plans_1

Stock-Based Compensation Plans - Summary of Awards Made under Plans (Detail) (USD $)	6 Months Ended	9 Months Ended
	Jun. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Executive Stock Options	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Exercise price per share of option award	$25	'	$25
Shares - Stock Options	'	441,960	826,340
Grant date fair value per share of unvested option awards as calculated from above	'	$9.93	$8.37
Non-Executive Stock Options	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Exercise price per share of option award	'	'	$18.64
Shares - Stock Options	'	1,054,480	970,640
Grant date fair value per share of unvested option awards as calculated from above	'	$9.93	$9.70
Restricted Stock Units	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Shares - Other than Stock Options	'	724,510	1,033,210
Fair Value - Other than Stock Options	'	$24.29	$18.58
Total Shareholder Return (TSR) Performance Awards	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Shares - Other than Stock Options	'	282,770	271,960
Fair Value - Other than Stock Options	'	$22.09	$21.26
Return On Capital Employed (ROCE) Performance Awards	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Shares - Other than Stock Options	'	262,800	0
Fair Value - Other than Stock Options	'	$23.76	$0

StockBased_Compensation_Plans_2

Stock-Based Compensation Plans Stock-Based Compensation Plans - Black-Scholes Assumptions (Detail) (USD $)	6 Months Ended	9 Months Ended
	Jun. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Executive and Non-Executive Stock Options	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Grant date price per share of option award	'	$24.29	'
Exercise price per share of option award	'	$24.29	'
Expected annual dividends per share, at grant date	'	$0.20	'
Expected life in years	'	'5 years	'
Expected volatility	'	49.00%	'
Risk-free interest rate	'	1.62%	'
Grant date fair value per share of unvested option awards as calculated from above	'	$9.93	'
Executive Stock Options	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Grant date price per share of option award	'	'	$18.48
Exercise price per share of option award	$25	'	$25
Expected annual dividends per share, at grant date	'	'	$0.20
Expected life in years	'	'	'5 years
Expected volatility	'	'	66.00%
Risk-free interest rate	'	'	1.32%
Grant date fair value per share of unvested option awards as calculated from above	'	$9.93	$8.37
Non-Executive Stock Options	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Grant date price per share of option award	'	'	$18.64
Exercise price per share of option award	'	'	$18.64
Expected annual dividends per share, at grant date	'	'	$0.20
Expected life in years	'	'	'5 years
Expected volatility	'	'	67.00%
Risk-free interest rate	'	'	1.05%
Grant date fair value per share of unvested option awards as calculated from above	'	$9.93	$9.70

StockBased_Compensation_Plans_3

Stock-Based Compensation Plans - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Aggregate number of shares to be issued	21,250,000	'	21,250,000	'
Number of shares available for future grants	4,930,655	'	4,930,655	'
Stock-based compensation expense recognized	$9	$9	$26	$28
Unrecognized compensation costs related to non-vested stocks	$46	'	$46	'
Weighted average period for recognizing non-vested stock based compensation costs	'	'	'16 months	'
Stock Options	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Share-based compensation plans, award vesting period	'	'	'3 years	'
Share-based compensation plans, award term	'	'	'10 years	'
Restricted Stock Units	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Share-based compensation plans, award vesting period	'	'	'	'3 years
Total Shareholder Return (TSR) Performance Awards	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Share-based compensation plans, award vesting period	'	'	'3 years	'
Total Shareholder Return (TSR) Performance Awards | Minimum	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Vesting of performance awards as percentage to target award	'	'	0.00%	'
Total Shareholder Return (TSR) Performance Awards | Maximum	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Vesting of performance awards as percentage to target award	'	'	200.00%	'
Return On Capital Employed (ROCE) Performance Awards	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Performance Period Weighting Year 1	'	'	20.00%	'
Performance Period Weighting Year 2	'	'	30.00%	'
Performance Period Weighting Year 3	'	'	50.00%	'
Share-based compensation plans, award vesting period	'	'	'3 years	'
Return On Capital Employed (ROCE) Performance Awards | Minimum	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Vesting of performance awards as percentage to target award	'	'	0.00%	'
Return On Capital Employed (ROCE) Performance Awards | Threshold [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Vesting of performance awards as percentage to target award	'	'	50.00%	'
Return On Capital Employed (ROCE) Performance Awards | Target [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Vesting of performance awards as percentage to target award	'	'	100.00%	'
Return On Capital Employed (ROCE) Performance Awards | Maximum	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Vesting of performance awards as percentage to target award	'	'	200.00%	'

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 15, 2014

Sep. 30, 2013

Sep. 15, 2014

Sep. 30, 2014

Sep. 30, 2013

Domestic Country

Domestic Country

Foreign Country

Foreign Country

Us Steel Canada Inc

Us Steel Canada Inc

Us Steel Canada Inc

Us Steel Canada Inc

Us Steel Canada Inc

Income Taxes [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Income tax benefit

$6

$4

($4)

$14

'

'

'

'

'

$0

$0

$0

($30)

$0

(Loss) income before income taxes

201

1,787

177

1,928

'

'

'

'

'

57

783

200

'

1,123

Income Tax Refund Received

'

'

176

'

'

'

'

'

'

'

'

'

'

'

Unrecognized tax benefits

114

'

114

'

127

'

'

'

'

'

'

'

'

'

Total amount of unrecognized tax benefits that, if recognized, would affect effective tax rate

60

'

60

'

69

'

'

'

'

'

'

'

'

'

Accrued liabilities, interest on unrecognized tax benefits

7

'

7

'

'

'

'

'

'

'

'

'

'

'

Net deferred tax asset

'

'

'

'

'

95

115

42

59

'

'

'

'

'

Deferred tax asset, valuation allowance

'

'

'

'

'

'

'

$5

$1,028

'

'

'

'

'

Significant_Equity_Investments2

Significant Equity Investments - Summarized Unaudited Income Statement Information for Significant Equity Investments (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Equity Method Investments and Joint Ventures [Abstract]	'	'
Net sales	$1,977	$1,841
Cost of sales	1,505	1,395
Operating income	427	399
Net income	412	382
Net income attributable to significant equity investments	$412	$382

Significant_Equity_Investments3

Significant Equity Investments - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Income (loss) from investees	$50	$26	$103	$31
Significant Equity Investments [Member]	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Income (loss) from investees	'	'	$89	$50

Earnings_and_Dividends_Per_Com2

Earnings and Dividends Per Common Share - Computations for Basic and Diluted Income (Loss) Per Common Share from Continuing Operations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]	'	'	'	'
Net loss attributable to United States Steel Corporation shareholders	($207)	($1,791)	($173)	($1,942)
Plus income effect of assumed conversion-interest on convertible notes	0	0	0	0
Net loss after assumed conversion	($207)	($1,791)	($173)	($1,942)
Weighted-average shares outstanding:	'	'	'	'
Basic	145,348	144,727	144,999	144,523
Effect of convertible notes	0	0	0	0
Effect of stock options, restricted stock units and performance awards	0	0	0	0
Adjusted weighted-average shares outstanding, diluted	145,348	144,727	144,999	144,523
Basic earnings per common share	($1.42)	($12.38)	($1.19)	($13.44)
Diluted earnings per common share	($1.42)	($12.38)	($1.19)	($13.44)

Earnings_and_Dividends_Per_Com3

Earnings and Dividends Per Common Share - Antidilutive Securities that were Not Included in Computations of Diluted Income (Loss) Per Common Share (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Antidilutive Securities	12,342,000	17,679,000	15,388,000	22,972,000
Securities granted under the 2005 Stock Incentive Plan	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Antidilutive Securities	8,865,000	7,621,000	8,865,000	7,621,000
Securities convertible under the Senior Convertible Notes	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Antidilutive Securities	3,477,000	10,058,000	6,523,000	15,351,000

Earnings_and_Dividends_Per_Com4

Earnings and Dividends Per Common Share - Antidilutive Securities that were Not Included in Computations of Diluted Income (Loss) Per Common Share (Parenthetical) (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended		0 Months Ended	9 Months Ended
In Millions, except Share data, unless otherwise specified	31-May-14	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Mar. 27, 2013	Sep. 30, 2014	Sep. 30, 2013
						2014 Senior Convertible Notes	2014 Senior Convertible Notes	2014 Senior Convertible Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'	'	'	'	'
Repurchased face amount of senior notes	$322	'	'	'	'	$542	'	'
Antidilutive Securities	'	12,342,000	17,679,000	15,388,000	22,972,000	'	0	10,058,000

Earnings_and_Dividends_Per_Com5

Earnings and Dividends Per Common Share - Additional Information (Detail) (USD $)	3 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'	'	'	'	'
Quarterly dividend per common share	$0.05	$0.05	$0.05	$0.05	$0.05	$0.05

Inventories_Detail

Inventories (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Raw materials	$608	$1,011
Semi-finished products	994	1,023
Finished products	518	558
Supplies and sundry items	79	96
Total	$2,199	$2,688

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Inventory Disclosure [Abstract]	'	'	'	'	'
Percent of Last-in, First-out (LIFO) inventory to total inventory values	74.00%	'	74.00%	'	59.00%
Estimate in excess of current acquisition costs over stated inventory values	$1,000,000,000	'	$1,000,000,000	'	'
Cost of sales increase/reduction, liquidations of LIFO inventories	8,000,000	3,000,000	1,000,000	3,000,000	'
Land held for residential or commercial development	$69,000,000	'	$69,000,000	'	$81,000,000

Derivative_Instruments_Locatio

Derivative Instruments - Location and Amounts of Fair Values Related to Derivatives in Financial Statements (Detail) (Foreign exchange forward contracts, USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Accounts receivable	'	'
Derivative [Line Items]	'	'
Foreign exchange forward contracts, fair value, gross asset	$28	$0
Accounts payable	'	'
Derivative [Line Items]	'	'
Foreign exchange forward contracts, fair value, gross liability	$0	$11

Derivative_Instruments_Locatio1

Derivative Instruments - Location and Amounts of Gains or Losses Related to Derivatives in Financial Statements (Detail) (Foreign Exchange Forward Contracts, Other financial costs, USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Foreign Exchange Forward Contracts | Other financial costs	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Amount of Gain (Loss)	$33	($11)	$36	($7)

Derivative_Instruments_Additio

Derivative Instruments - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Derivative [Line Items]	'	'
Euro forward sales contracts notional value	409	'
Maximum	'	'
Derivative [Line Items]	'	'
Derivative, Term of Contract	'12 months	'12 months

Debt_Schedule_of_Debt_Detail

Debt - Schedule of Debt (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Debt and capital lease obligation	$3,544	$4,008
Less Province Note fair value adjustment (a)	0	15
Less unamortized discount	46	54
Less short-term debt and long-term debt due within one year	336	323
Long-term debt	3,162	3,616
2037 Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Interest rate	6.65%	'
Debt instrument, maturity date	'2037	'
Debt and capital lease obligation	350	350
2022 Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Interest rate	7.50%	'
Debt instrument, maturity date	'2022	'
Debt and capital lease obligation	400	400
2021 Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Interest rate	6.88%	'
Debt instrument, maturity date	'2021	'
Debt and capital lease obligation	275	275
2020 Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Interest rate	7.38%	'
Debt instrument, maturity date	'2020	'
Debt and capital lease obligation	600	600
2018 Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Interest rate	7.00%	'
Debt instrument, maturity date	'2018	'
Debt and capital lease obligation	500	500
2017 Senior Notes	'	'
Debt Instrument [Line Items]	'	'
Interest rate	6.05%	'
Debt instrument, maturity date	'2017	'
Debt and capital lease obligation	450	450
2019 Senior Convertible Notes	'	'
Debt Instrument [Line Items]	'	'
Interest rate	2.75%	'
Debt instrument, maturity date	'2019	'
Debt and capital lease obligation	316	316
2014 Senior Convertible Notes	'	'
Debt Instrument [Line Items]	'	'
Interest rate	4.00%	4.00%
Debt instrument, maturity date	'2014	'
Debt and capital lease obligation	0	322
USSC Province Note (C$150 million) (a)	'	'
Debt Instrument [Line Items]	'	'
Interest rate	1.00%	'
Debt instrument, maturity date	'2015	'
Debt and capital lease obligation	0	141
Environmental Revenue Bonds	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	5.38%	'
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	6.88%	'
Debt and capital lease obligation	549	549
Environmental Revenue Bonds | Minimum	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, maturity date	'2015	'
Environmental Revenue Bonds | Maximum	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, maturity date	'2042	'
Recovery Zone Facility Bonds	'	'
Debt Instrument [Line Items]	'	'
Interest rate	6.75%	'
Debt instrument, maturity date	'2040	'
Debt and capital lease obligation	70	70
Fairfield Caster Lease	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, maturity date	'2022	'
Debt and capital lease obligation	34	35
Other capital leases and all other obligations	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, maturity date	'2020	'
Debt and capital lease obligation	0	0
Amended Credit Agreement	'	'
Debt Instrument [Line Items]	'	'
Interest rate description	'Variable	'
Debt instrument, maturity date	'2016	'
Debt and capital lease obligation	0	0
USSK Revolver	'	'
Debt Instrument [Line Items]	'	'
Interest rate description	'Variable	'
Debt instrument, maturity date	'2016	'
Debt and capital lease obligation	0	0
USSK credit facilities	'	'
Debt Instrument [Line Items]	'	'
Interest rate description	'Variable	'
Debt and capital lease obligation	$0	$0
USSK credit facilities | Minimum	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, maturity date	'2015	'
USSK credit facilities | Maximum	'	'
Debt Instrument [Line Items]	'	'
Debt instrument, maturity date	'2016	'

Debt_Eligible_Accounts_Receiva

Debt - Eligible Accounts Receivable and Receivables Sold to Third Party Conduits (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Debt Disclosure [Abstract]	'	'
Balance of accounts receivable-net, eligible for sale to third-parties	$1,166	$988
Accounts receivable sold to third-parties	0	0
Balance included in Receivables on the balance sheet of U. S. Steel	$1,166	$988

Debt_Additional_Information_De

Debt - Additional Information (Detail)

1 Months Ended

3 Months Ended

9 Months Ended

31-May-14

15-May-14

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

USD ($)

USD ($)

2019 Senior Convertible Notes

Amended Credit Agreement

Amended Credit Agreement

Receivable Purchase Agreement

Receivable Purchase Agreement

Receivable Purchase Agreement

Receivable Purchase Agreement

Receivable Purchase Agreement

USSK Revolver

USSK Revolver

USSK credit facilities

USSK credit facilities

Us Steel Kosice Ten Million Credit Facility

Change in control event

Fairfield Slab Caster

Minimum

USD ($)

Covenant Requirement

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

EUR (€)

USD ($)

EUR (€)

EUR (€)

USD ($)

USD ($)

Receivable Purchase Agreement

USD ($)

USD ($)

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Repayments of Debt

$322,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Repurchase Amount

'

327,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest rate

'

'

2.75%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Event of Default, Exclude Indebtedness of Subsidiary

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100,000,000

Amounts drawn on credit facility

'

'

'

0

'

'

'

'

'

'

0

'

0

'

'

'

'

'

Maximum borrowing capacity on credit facility

'

'

'

875,000,000

'

'

'

'

'

'

252,000,000

200,000,000

38,000,000

20,000,000

10,000,000

'

'

'

Fixed charge coverage ratio

'

'

'

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of total aggregate commitments, upper range under financial covenant

'

'

'

'

10.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Credit Agreement, upper range of outstanding debt

'

'

'

'

87,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Receivables Purchase Agreement, maximum amount of receivable eligible for sale

'

'

'

'

'

625,000,000

'

625,000,000

'

625,000,000

'

'

'

'

'

'

'

'

Receivables sold under receivables purchase agreement

'

'

'

'

'

0

'

0

'

0

'

'

'

'

'

'

'

'

Receivables Purchase Agreement Subordinated Retained Interest

'

'

'

'

'

625,000,000

'

625,000,000

'

625,000,000

'

'

'

'

'

'

'

'

Receivables Purchase Agreement Availability at Period End

'

'

'

'

'

575,000,000

'

575,000,000

'

572,000,000

'

'

'

'

'

'

'

'

Receivables Purchase Agreement Borrowing Capacity Decrease Due To Letters Of Credit Outstanding

'

'

'

'

'

50,000,000

'

50,000,000

'

53,000,000

'

'

'

'

'

'

'

'

Payments For Fees Related To Receivable Purchase Agreement

'

'

'

'

'

1,000,000

1,000,000

3,000,000

3,000,000

'

'

'

'

'

'

'

'

'

Amount reinvested from collection of eligible accounts receivable

'

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

'

Available borrowing capacity

'

'

'

'

'

'

'

'

'

'

'

'

37,000,000

'

'

'

'

'

Customs and other guarantees outstanding

'

'

'

'

'

'

'

'

'

'

'

'

1,000,000

'

'

'

'

'

Loss Contingency, Range of Possible Loss, Maximum

'

'

'

'

'

'

'

'

'

'

$200,000,000

'

'

'

'

$2,891,000,000

$37,000,000

'

Asset_Retirement_Obligations_C

Asset Retirement Obligations - Changes in Carrying Values of Asset Retirement Obligations (Detail) (USD $)	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Deconsolidation of USSC [Line Items]	'	'
Asset Retirement Obligation, Liabilities Settled	$18	$7
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]	'	'
Balance at beginning of year	59	33
Additional obligations incurred	0	28
Obligations settled(a)	-18	-7
Asset Retirement Obligation, Foreign Currency Translation	-1	0
Accretion expense	3	5
Balance at end of period	43	59
Us Steel Canada Inc	'	'
Deconsolidation of USSC [Line Items]	'	'
Asset Retirement Obligation, Liabilities Settled	16	'
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]	'	'
Obligations settled(a)	($16)	'

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments - Financial Assets and Liabilities Not Carried at Fair Value (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Financial assets:	'	'
Investments and long-term receivables	$586	$621
Fair Value	'	'
Financial assets:	'	'
Investments and long-term receivables	45	63
Financial liabilities:	'	'
Debt	3,957	4,198
Carrying Amount	'	'
Financial assets:	'	'
Investments and long-term receivables	45	63
Financial liabilities:	'	'
Debt	$3,464	$3,904

Statement_of_Changes_in_Stockh2

Statement of Changes in Stockholders' Equity (Detail) (USD $)

3 Months Ended

9 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Comprehensive Income (Loss)

Comprehensive Income (Loss)

Retained Earnings

Retained Earnings

Accumulated Other Comprehensive (Loss) Income

Accumulated Other Comprehensive (Loss) Income

Common Stock

Common Stock

Common Stock

Common Stock

Treasury Stock

Treasury Stock

Paid-in Capital

Paid-in Capital

Non- Controlling Interest

Non- Controlling Interest

Non- Controlling Interest

Pension and other benefit adjustments

Pension and other benefit adjustments

Currency translation adjustment

Currency translation adjustment

Increase (Decrease) in Stockholders' Equity [Roll Forward]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Beginning balance

'

'

$3,376

$3,478

'

'

$1,789

$3,463

($1,752)

($3,268)

$151

$151

$151

$151

($480)

($521)

$3,667

$3,652

$1

$1

$1

'

'

'

'

Comprehensive income:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net loss

-207

-1,791

-173

-1,942

-173

-1,942

-173

-1,942

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other comprehensive (loss) income, net of tax:

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Pension and other benefit adjustments

53

59

175

197

175

197

'

'

175

197

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Currency translation adjustment

107

31

93

13

93

13

'

'

93

13

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Issuance of conversion option in 2019 Senior Convertible Notes, net of tax

'

'

'

31

'

'

'

'

'

'

'

'

'

'

'

'

'

31

'

'

'

'

'

'

'

Deconsolidation of U. S. Steel Canada

468

[1]

0

468

[1]

0

468

'

'

'

468

'

'

'

'

'

'

'

'

'

'

'

'

493

493

-25

-25

Employee stock plans

'

'

26

22

'

'

'

'

'

'

'

'

'

'

70

40

-44

-18

'

'

'

'

'

'

'

Dividends paid on common stock

'

'

-22

-22

'

'

-22

-22

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Other

'

'

'

-2

'

'

'

-2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ending balance

$3,943

$1,775

$3,943

$1,775

$563

($1,732)

$1,594

$1,497

($1,016)

($3,058)

$151

$151

$151

$151

($410)

($481)

$3,623

$3,665

$1

$1

$1

'

'

'

'

[1]

Consists of $493 million for Pension and other benefit adjustments and $(25) million for currency translation adjustment.

Reclassifications_from_Accumul2

Reclassifications from Accumulated Other Comprehensive Income (AOCI) - Other Comprehensive Income Activity Net of Tax (Detail) (USD $)	3 Months Ended			9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Accumulated Other Comprehensive Income [Roll Forward]	'		'	'		'
Beginning Balance	'		'	($1,752)		'
Other comprehensive income (loss) before reclassifications	'		'	-35		'
Amounts reclassified from AOCI	'		'	303		'
Deconsolidation of U. S. Steel Canada	468	[1]	0	468	[1]	0
Total other comprehensive income, net of tax	628		90	736		210
Ending Balance	-1,016		'	-1,016		'
Pension and Other Benefit Items	'		'	'		'
Accumulated Other Comprehensive Income [Roll Forward]	'		'	'		'
Beginning Balance	'		'	-2,127		'
Other comprehensive income (loss) before reclassifications	'		'	34		'
Amounts reclassified from AOCI	'		'	141		'
Deconsolidation of U. S. Steel Canada	'		'	493		'
Total other comprehensive income, net of tax	'		'	668		'
Ending Balance	-1,459		'	-1,459		'
Foreign Currency Items	'		'	'		'
Accumulated Other Comprehensive Income [Roll Forward]	'		'	'		'
Beginning Balance	'		'	375		'
Other comprehensive income (loss) before reclassifications	'		'	-69		'
Amounts reclassified from AOCI	'		'	162		'
Deconsolidation of U. S. Steel Canada	'		'	-25		'
Total other comprehensive income, net of tax	'		'	68		'
Ending Balance	$443		'	$443		'
[1]	Consists of $493 million for Pension and other benefit adjustments and $(25) million for currency translation adjustment.

Reclassifications_from_Accumul3

Reclassifications from Accumulated Other Comprehensive Income (AOCI) - Defined Benefit Plan In Other Comprehensive Income (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Amortization of pension and other benefit items	'	'	'	'
Loss before income taxes and noncontrolling interests	($201)	($1,787)	($177)	($1,928)
Tax benefit	-6	-4	4	-14
Net loss	-207	-1,791	-173	-1,942
Pension and Other Benefit Items | Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'	'
Amortization of pension and other benefit items	'	'	'	'
Prior service costs	-2	-3	-6	-8
Actuarial gains/(losses)	-67	-100	-206	-298
Settlement, termination and curtailment gains	-13	0	-9	0
Loss before income taxes and noncontrolling interests	-82	-103	-221	-306
Tax benefit	25	29	80	96
Net loss	($57)	($74)	($141)	($210)

Transactions_with_Related_Part1

Transactions with Related Parties - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Related Party Transaction [Line Items]	'	'	'	'	'
Net sales to related parties	$302	$275	$853	$863	'
Accounts payable to related parties	131	'	131	'	73
Outside processing services	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Purchases from related parties	30	18	60	53	'
Taconite pellets	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Purchases from related parties	76	63	191	180	'
PRO-TEC Coating Company	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Accounts payable to related parties	105	'	105	'	70
Other equity investees	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Accounts payable to related parties	$26	'	$26	'	$3

Restructuring_and_Other_Charge2

Restructuring and Other Charges Activity in Accrued Balances for Restructuring and Other Cost Reduction Programs (Details) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014
Restructuring Reserve [Roll Forward]	'	'
Balance at beginning of period	'	$22
Other adjustments and re-classes	6	16
Balance at end of period	7	7
Severance Accrual	'	'
Restructuring Reserve [Roll Forward]	'	'
Balance at beginning of period	'	16
Additional charges	'	15
Cash payments/utilization	'	-8
Other adjustments and re-classes	'	-16
Balance at end of period	7	7
Exit Costs	'	'
Restructuring Reserve [Roll Forward]	'	'
Balance at beginning of period	'	6
Additional charges	'	0
Cash payments/utilization	'	-5
Other adjustments and re-classes	'	-1
Balance at end of period	0	0
Asset Impairments	'	'
Restructuring Reserve [Roll Forward]	'	'
Balance at beginning of period	'	0
Additional charges	'	250
Cash payments/utilization	'	-250
Other adjustments and re-classes	'	0
Balance at end of period	0	0
Us Steel Canada Inc | Severance Accrual	'	'
Restructuring Reserve [Roll Forward]	'	'
Other adjustments and re-classes	'	$4

Balance_Sheet_Location_of_Accr

Balance Sheet Location of Accrued Liabilities for Restructuring and Other Cost Reduction Programs (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Restructuring Cost and Reserve [Line Items]	'	'
Total	$7	$22
Accounts payable	'	'
Restructuring Cost and Reserve [Line Items]	'	'
Restructuring reserve, current	0	6
Payroll and benefits payable	'	'
Restructuring Cost and Reserve [Line Items]	'	'
Restructuring reserve, current	6	8
Employee benefits	'	'
Restructuring Cost and Reserve [Line Items]	'	'
Restructuring reserve, noncurrent	$1	$8

Restructuring_and_Other_Charge3

Restructuring and Other Charges Restructuring and Other Charges - Additional Information (Details) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014
Restructuring Cost and Reserve [Line Items]	'	'
Adjustments to restructuring reserves	$6	$16
Cash payments related to restructuring	3	8
Restructuring Charges [Member]	'	'
Restructuring Cost and Reserve [Line Items]	'	'
Impairment of carbon alloy facilities (Note 20)	199	199
Write-off of pre-engineering costs	37	'
Restructuring charges	'	37
Impairment of Long-Lived Assets to be Disposed of	'	14
Severance Costs	$1	$15

Contingencies_and_Commitments_1

Contingencies and Commitments - Changes in Accrued Liabilities for Remediation Activities (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Change in Accrued Liabilities for Remediation Activities [Roll Forward]	'
Beginning of period	$233
Accruals for environmental remediation deemed probable and reasonably estimable	4
Obligations settled	-19
End of period	218
Us Steel Canada Inc	'
Change in Accrued Liabilities for Remediation Activities [Roll Forward]	'
Obligations settled	($2)

Contingencies_and_Commitments_2

Contingencies and Commitments - Accrued Liabilities for Remediation Activities Included in Balance Sheet (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Loss Contingencies [Line Items]	'	'
Total	$218	$233
Accounts payable	'	'
Loss Contingencies [Line Items]	'	'
Total	17	17
Deferred credits and other noncurrent liabilities	'	'
Loss Contingencies [Line Items]	'	'
Total	$201	$216

Contingencies_and_Commitments_3

Contingencies and Commitments - Payments for Contracts with Remaining Terms in Excess of One Year (Detail) (USD $)	Sep. 30, 2014
In Millions, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]	'
Remainder of 2014	$336
2015	898
2016	667
2017	572
2018	326
Later Years	1,279
Total	$4,078

Contingencies_and_Commitments_4

Contingencies and Commitments - Additional Information (Detail)

0 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

Aug. 02, 2012

Jan. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Facility

Allowances

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Minimum

Minimum

Maximum

Maximum

Maximum

Asbestos Matters

Asbestos Matters

Asbestos Matters

Asbestos Matters

Asbestos Matters

Projects with Ongoing Study and Scope Development

Projects with Ongoing Study and Scope Development

Projects with Ongoing Study and Scope Development

Projects with Ongoing Study and Scope Development

Projects with Ongoing Study and Scope Development

Gary Works, Project with Defined Scope

Geneva Project

St Louis Estuary Project

Solid Waste Management Unit at USS Posco Industries, Project with Defined Scope

Projects with Defined Scope Greater Than or Equal to $5 Million

Projects with Defined Scope Greater Than or Equal to $5 Million

Environmental Remediation Other Projects

Environmental Remediation Other Projects

Environmental Remediation Other Projects

Environmental Remediation Projects Less Than One Million

Environmental Remediation Projects Less Than One Million

Antitrust Class Actions

Surety Bonds

Restricted Cash To Fund Certain Capital Projects

boiler

campaigns

boiler

USD ($)

Gateway Energy and Coke Company, LLC

USD ($)

EUR (€)

Gateway Energy and Coke Company, LLC

USD ($)

USD ($)

Minimum

Maximum

Allege Suffering from Mesothelioma

USD ($)

Resource Conservation and Recovery Act (RCRA) Programs

Voluntary Remediation Program [Member]

Minimum

Maximum

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Minimum

USD ($)

Minimum

Maximum

USD ($)

Maximum

USD ($)

USD ($)

USD ($)

Micron

Project

LegalMatter

LegalMatter

Defendant

Defendant

Plaintiff

Project

Project

Project

USD ($)

USD ($)

Project

USD ($)

Project

USD ($)

USD ($)

USD ($)

Defendant

T

phase

Plaintiff

Plaintiff

non_GHG_pollutant

Micron

Claim_Group

T

non_GHG_pollutant

Loss Contingencies [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Active cases brought against U.S. Steel

'

'

'

'

'

'

'

'

'

'

'

'

830

720

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of plaintiffs involved

'

'

'

'

'

'

'

'

'

'

'

'

3,460

3,320

'

'

270

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of defendants involved

'

'

'

'

'

'

'

'

'

'

'

'

'

'

50

100

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

8

'

'

Litigation Settlement, Amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$58,000,000

'

'

Number of claims pending in jurisdictions

'

'

'

'

'

'

'

'

'

'

'

'

2,630

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of claims pending in jurisdictions

'

'

'

'

'

'

'

'

'

'

'

'

76.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payment in settlement of claims

'

'

'

'

'

'

'

'

'

'

'

'

5,000,000

11,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cases resolved upon payment

'

'

'

'

'

'

'

'

'

'

'

'

110

250

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of cases added and resulted in claims

'

'

'

'

'

'

'

'

'

'

'

'

250

240

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Projected percentage remediation costs may exceed accrued liabilities

'

'

'

'

'

'

'

10.00%

'

25.00%

25.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of major groups

'

'

'

'

'

'

'

'

'

'

'

'

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Expenses related to remediation included in cost of sales

'

'

1,000,000

1,000,000

4,000,000

5,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Environmental remediation projects

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5

4

1

'

'

'

'

'

'

4

'

4

'

'

'

'

'

'

'

Accrued liabilities for remediation activities

'

'

218,000,000

'

218,000,000

'

233,000,000

'

'

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

43,000,000

64,000,000

51,000,000

7,000,000

165,000,000

5,000,000

9,000,000

1,000,000

5,000,000

8,000,000

1,000,000

'

'

'

Environment exit costs, possible additional loss

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25,000,000

40,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accrued liabilities for post-closure site monitoring and other costs

'

'

28,000,000

'

28,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accrued liability for administrative and legal costs

'

'

6,000,000

'

6,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of years of projected administrative and legal costs included in accrual

'

'

'

'

'3 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Capital expenditures

'

'

'

'

50,000,000

36,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Overall Goal for Reduction in Emissions, Percent

'

'

21.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percent reduction in free allocation of emissions

'

'

12.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Final Allocation for Emissions Allowances

'

48,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated Shortfall in Emissions Allowances

'

14,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gain (Loss) on Disposition of Other Assets

'

'

'

'

17,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Minimum annual increment in GHG emission due to modifications to existing permits subject to Title V and PSD requirement if only project significantly increases emissions of at least one non-GHG pollutant

'

'

75,000

'

75,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Threshold for Subject To Title V And Prevention of Significant Deterioration Requirement, Project Significantly Increases Emissions, Number of Non-GHG Pollutant

'

'

1

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Minimum annual emission of new sources subject to PSD and Title V requirement

'

'

100,000

'

100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

NAAQS micron particulate matter in revision process

'

'

2.5

'

2.5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated capital expenditures of complying with BAT over 2014 to 2016 period

'

'

'

'

'

'

'

200,000,000

'

250,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

loss contingency, campaigns, number

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss Contingency, Project, Number

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss Contingency, Capital Expenditure Grant

'

'

'

'

'

'

'

'

'

11,000,000

9,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Capital Expenditure Grant, Percent of Total

'

'

'

'

35.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Boilers to be Reconstructed for Environmental Compliance

'

'

'

'

'

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of New Boilers to be Built for Environmental Compliance

'

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Estimated Capital Expenditures For Project, Boiler

'

'

170,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Financial assurance guarantees, maximum

'

'

29,000,000

'

29,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

165,000,000

'

Guarantor Obligations, Current Carrying Value

'

'

24,000,000

'

24,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of facilities that failed to meet certain environmental requirements

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Loss Contingency, Fact Discovery, Number of Phases

'

'

'

'

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Residual value of equipment

'

'

13,000,000

'

13,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restricted cash

'

'

57,000,000

'

57,000,000

'

81,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20,000,000

Restricted cash current

'

'

1,000,000

'

1,000,000

'

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Contract commitments to acquire property, plant and equipment

'

'

218,000,000

'

218,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unconditional purchase obligation term

'

'

'

'

'

'

'

'2 years

'

'14 years

'14 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of purchase obligation

'

'

'

'

'

'

'

'

90.00%

'

'

105.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum default payment on termination of agreement

'

'

239,000,000

'

239,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unrecorded Unconditional Purchase Obligation, Purchases

'

'

$119,000,000

$115,000,000

$389,000,000

$410,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'