Steel Dynamics (STLD) 10-Q 11 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document and Entity Information
Entity Registrant Name	STEEL DYNAMICS INC
Entity Central Index Key	1022671
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		241,804,284
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets
Cash and equivalents	$160,982	$361,363
Accounts receivable, net	741,309	859,835
Accounts receivable related parties	28,432	42,990
Inventories	1,453,242	1,618,419
Deferred income taxes	33,414	35,503
Other current assets	34,846	55,655
Total current assets	2,452,225	2,973,765
Property, plant and equipment, net	3,085,587	3,123,906
Restricted cash	19,242	19,312
Intangible assets, net	364,620	370,669
Goodwill	743,528	745,158
Other assets	70,636	78,217
Total assets	6,735,838	7,311,027
Current liabilities
Accounts payable	367,267	489,791
Accounts payable-related parties	9,695	21,265
Income taxes payable	5,116	6,086
Accrued payroll and benefits	66,427	128,968
Accrued interest	51,800	50,405
Accrued expenses	87,302	107,607
Current maturities of long-term debt	30,727	46,460
Total current liabilities	618,334	850,582
Long-term debt
Senior term loan	234,375	237,500
Senior notes	2,350,000	2,700,000
Other long-term debt	39,069	40,206
Total long-term debt	2,623,444	2,977,706
Deferred income taxes	555,031	542,033
Other liabilities	15,936	18,839
Commitments and contingencies
Redeemable noncontrolling interests	126,340	126,340
Equity
Common stock voting, $.0025 par value; 900,000,000 shares authorized; 261,539,685 and 261,420,126 shares issued; and 241,688,172 and 241,449,423 shares outstanding, as of March 31, 2015 and December 31, 2014, respectively	635	635
Treasury stock, at cost; 19,851,513 and 19,970,703 shares, as of March 31, 2015 and December 31, 2014, respectively	-396,517	-398,898
Additional paid-in capital	1,088,605	1,083,435
Retained earnings	2,225,354	2,227,843
Total Steel Dynamics, Inc. equity	2,918,077	2,913,015
Noncontrolling interests	-121,324	-117,488
Total equity	2,796,753	2,795,527
Total liabilities and equity	$6,735,838	$7,311,027

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
CONSOLIDATED BALANCE SHEETS
Common stock voting, par value (in dollars per share)	$0.00	$0.00
Common stock voting, shares authorized (in shares)	900,000,000	900,000,000
Common stock voting, shares issued (in shares)	261,539,685	261,420,126
Common stock voting, shares outstanding (in shares)	241,688,172	241,449,423
Treasury stock, shares (in shares)	19,851,513	19,970,703

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net sales
Unrelated parties	$2,003,973	$1,765,881
Related parties	43,462	64,201
Total net sales	2,047,435	1,830,082
Costs of goods sold	1,860,393	1,666,778
Gross profit	187,042	163,304
Selling, general and administrative expenses	76,350	70,042
Profit sharing	4,598	5,395
Amortization of intangible assets	6,323	6,935
Operating income	99,771	80,932
Interest expense, net of capitalized interest	43,087	30,569
Other (income) expense, net	16,192	-631
Income before income taxes	40,492	50,994
Income taxes	13,538	17,296
Net income	26,954	33,698
Net loss attributable to noncontrolling interests	3,807	4,881
Net income attributable to Steel Dynamics, Inc.	$30,761	$38,579
Basic earnings per share attributable to Steel Dynamics, Inc. stockholders (in dollars per share)	$0.13	$0.17
Weighted average common shares outstanding (in shares)	241,535	223,011
Diluted earnings per share attributable to Steel Dynamics, Inc. stockholders, including the effect of assumed conversions when dilutive (in dollars per share)	$0.13	$0.17
Weighted average common shares and share equivalents outstanding (in shares)	242,867	241,394
Dividends declared per share (in dollars per share)	$0.14	$0.12

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating activities:
Net income	$26,954	$33,698
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	72,822	57,568
Equity-based compensation	8,543	5,768
Deferred income taxes	16,717	-4,091
(Gain) loss on disposal of assets	4,985	2,641
Changes in certain assets and liabilities:
Accounts receivable	133,084	-88,950
Inventories	164,999	-17,354
Other assets	4,508	7,359
Accounts payable	-127,053	5,041
Income taxes receivable/payable	16,265	19,393
Accrued expenses and liabilities	-87,117	-48,320
Net cash provided by (used in) operating activities	234,707	-27,247
Investing activities:
Purchases of property, plant and equipment	-33,351	-24,841
Other investing activities	1,663	28,884
Net cash provided by (used in) investing activities	-31,688	4,043
Financing activities:
Issuance of current and long-term debt	50,093	43,453
Repayments of current and long-term debt	-427,451	-56,246
Proceeds from exercise of stock options, including related tax effect	1,753	2,905
Contributions from noncontrolling investors, net	-29	5,370
Dividends paid	-27,766	-24,515
Net cash used in financing activities	-403,400	-29,033
Decrease in cash and equivalents	-200,381	-52,237
Cash and equivalents at beginning of period	361,363	395,156
Cash and equivalents at end of period	160,982	342,919
Supplemental disclosure information:
Cash paid for interest	40,094	39,663
Cash paid (received) for federal and state income taxes, net	($18,539)	$2,143

Description_of_the_Business_an

Description of the Business and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Description of the Business and Significant Accounting Policies
Description of the Business and Significant Accounting Policies
	Note 1.  Description of the Business and Significant Accounting Policies
	Description of the Business
	Steel Dynamics, Inc. (SDI), together with its subsidiaries (the company), is a domestic manufacturer of steel products and metals recycler. The company has three reporting segments: steel operations, metals recycling and ferrous resources operations, and steel fabrication operations.
	Steel Operations.  Steel operations include the company’s Butler Flat Roll Division, Columbus Flat Roll Division (acquired September 16, 2014), The Techs galvanizing lines, Structural and Rail Division, Engineered Bar Products Division, Roanoke Bar Division, and Steel of West Virginia. These operations consist of electric arc furnace steel mills, producing steel from ferrous scrap, utilizing continuous casting, automated rolling mills, and eight downstream finishing facilities. Steel operations accounted for 68% and 61% of the company’s consolidated external net sales during the three-month periods ended March 31, 2015 and 2014, respectively.
	Metals Recycling and Ferrous Resources Operations. Metals recycling and ferrous resources operations primarily include OmniSource Corporation (OmniSource), the company’s metals recycling and processing locations, ferrous scrap procurement, and our two ironmaking initiatives: Iron Dynamics (IDI), a liquid pig iron production facility; and our Minnesota ironmaking operations, an iron nugget production facility and operations to supply the nugget facility with its primary raw material, iron concentrate. Metals recycling and ferrous resources operations accounted for 23% and 32% of the company’s consolidated external net sales during the three-month periods ended March 31, 2015, and 2014, respectively.
	Steel Fabrication Operations.  Steel fabrication operations include the company’s six New Millennium Building Systems’ joist and deck plants located throughout the United States and Northern Mexico. Revenues from these plants are generated from the fabrication of trusses, girders, steel joists and steel decking used within the non-residential construction industry. Steel fabrication operations accounted for approximately 8% and 6% of the company’s consolidated external net sales during the three-month periods ended March 31, 2015, and 2014, respectively.
	Significant Accounting Policies
	Principles of Consolidation.  The consolidated financial statements include the accounts of SDI, together with its wholly and majority-owned or controlled subsidiaries, after elimination of significant intercompany accounts and transactions. Noncontrolling interests represent the noncontrolling owner’s proportionate share in the equity, income, or losses of the company’s majority-owned or controlled consolidated subsidiaries.
	Use of Estimates.  These financial statements are prepared in conformity with accounting principles generally accepted in the United States, and accordingly, include amounts that require management to make estimates and assumptions that affect the amounts reported in the financial statements and in the notes thereto. Significant items subject to such estimates and assumptions include the carrying value of property, plant and equipment, intangible assets, and goodwill; valuation allowances for trade receivables, inventories and deferred income tax assets; unrecognized tax benefits; potential environmental liabilities; and litigation claims and settlements. Actual results may differ from these estimates and assumptions.
	In the opinion of management, these financial statements reflect all normal recurring adjustments necessary for a fair presentation of the interim period results. These financial statements and notes should be read in conjunction with the audited financial statements and notes thereto included in the company’s Annual Report on Form 10-K for the year ended December 31, 2014.
	Goodwill.  The company’s goodwill is allocated to the following reporting units at March 31, 2015, and December 31, 2014, (in thousands):
		March 31,		December 31,
		2015		2014
	OmniSource — Metals Recycling/Ferrous Resources Segment	$	455,097	$	456,727
	The Techs — Steel Segment	142,783		142,783
	Butler Flat Roll Division, Structural and Rail Division, and Engineered Bar Division — Metals Recycling/Ferrous Resources Segment	95,000		95,000
	Roanoke Bar Division — Steel Segment	29,041		29,041
	Columbus Flat Roll Division — Steel Segment	19,682		19,682
	New Millennium Building Systems — Fabrication Segment	1,925		1,925
		$	743,528	$	745,158
	OmniSource goodwill decreased $1.6 million from December 31, 2014 to March 31, 2015, in recognition of the 2015 tax benefit related to the amortization of the component of OmniSource tax-deductible goodwill in excess of book goodwill.
	Recently Issued Accounting Standards.
	In May 2014, the FASB issued guidance codified in ASC 606, Revenue Recognition — Revenue from Contracts with Customers, which amends the guidance in former ASC 605, Revenue Recognition.  The core principle of ASC 606 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Because the guidance in ASC 606 is principles-based, it can be applied to all contracts with customers regardless of industry-specific or transaction-specific fact patterns. Additionally, ASC 606 requires additional disclosures to help users of financial statements better understand the nature, amount, timing, and potential uncertainty of revenue that is recognized. This guidance is effective for annual and interim periods ending after December 15, 2016. The company is currently evaluating the impact of the provisions of ASC 606.
	In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements — Going Concern (Subtopic 205-40: Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern), effective for annual and interim periods ending after December 15, 2016. ASU 2014-15 requires management to evaluate whether there are conditions or events, considered in aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. There are required disclosures if principal conditions or events are identified that raised substantial doubt about the entity’s ability to continue as a going concern (before consideration of management’s plans), as well as management’s evaluation of the significance of those conditions or events in relation to the entity’s ability to meet its obligations, and management’s plans that alleviated substantial doubt about the entity’s ability to continue as a going concern. This ASU is not expected to have any impact on our overall results of operations, financial position or cash flows.
	In April 2015, the FASB issued ASU 2015-03, Interest — Imputation of Interest (Subtopic 835-30) — Simplifying the Presentation of Debt Issuance Costs, which requires debt issuance costs to be presented as a deduction from the corresponding debt liability, rather than as a separate asset, which is the current accounting method of the company. Implementation of this new guidance is required by the company in the first quarter of 2016, but can be early adopted. Upon adoption, the company must apply the new guidance retrospectively to all prior periods presented in the financial statements. The company is currently evaluating when and the manner in which to adopt the presentation and disclosure requirements of the new guidance. This ASU is not expected to have any impact on our overall results of operations, equity or cash flows as previously reported.

Acquisition

Acquisition	3 Months Ended
	Mar. 31, 2015
Acquisition
Acquisition	Note 2.  Acquisition
	The company completed its acquisition of 100% of Severstal Columbus, LLC (Columbus) on September 16, 2014, for a purchase price of $1.625 billion, with additional working capital adjustments of $44.4 million. The acquisition was funded through the issuance of $1.2 billion in Senior Notes, borrowings under the company’s senior secured credit facility, and available cash. The company purchased Columbus to significantly expand and diversify its steel operating base with the addition of 3.4 million tons of hot roll steel production capacity. The product offerings are diversified with respect to width, gauge, and strength when compared to the capabilities of our Butler Flat Roll Division. Located in northeast Mississippi, Columbus is one of the newest and most technologically advanced sheet steel electric arc furnace mills in North America. Additionally, Columbus is advantageously located to serve the growing markets in the southern U.S. and Mexico, providing the company with geographic diversification and growth opportunities.
	Unaudited Pro Forma Information.  Columbus’ operating results have been reflected in the company’s financial statements since the effective date of the acquisition, September 16, 2014, in the steel operations reporting segment. The following unaudited pro forma information is presented below for comparison purposes as if the Columbus acquisition was completed as of January 1, 2013, (in thousands):
		Three Months Ended
		March 31, 2014
	Net sales	$	2,358,273
	Net income attributable to Steel Dynamics, Inc.	63,065
	The information presented is for information purposes only and is not necessarily indicative of the actual results that would have occurred had the acquisition been consummated at January 1, 2013, nor is it necessarily indicative of future operating results of the combined companies under the ownership and management of the company. The pro forma results reflect the pre-acquisition operations of Columbus for the three-month period ended March 31, 2014.

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share
Earnings Per Share	Note 3.  Earnings Per Share
	Basic earnings per share is based on the weighted average shares of common stock outstanding during the period. Diluted earnings per share assumes the weighted average dilutive effect of common share equivalents outstanding during the period applied to the company’s basic earnings per share. Common share equivalents represent potentially dilutive stock options, restricted stock units, deferred stock units, and dilutive shares related to the company’s convertible subordinated debt; and are excluded from the computation in periods in which they have an anti-dilutive effect. There were no anti-dilutive options at March 31, 2015, and 2014.
	The following table presents a reconciliation of the numerators and the denominators of the company’s basic and diluted earnings per share computations for the three months ended March 31, 2015 and 2014 (in thousands, except per share data):
		2015					2014
		Net Income		Shares	Per Share		Net Income		Shares	Per Share
		(Numerator)		(Denominator)	Amount		(Numerator)		(Denominator)	Amount
	Basic earnings per share	$	30,761	241,535	$	0.13	$	38,579	223,011	$	0.17
	Dilutive common share equivalents	—		1,332			—		1,608
	5.125% Convertible Senior Notes, net of tax	—		—			2,358		16,775
	Diluted earnings per share	$	30,761	242,867	$	0.13	$	40,937	241,394	$	0.17

Inventories

Inventories	3 Months Ended
	Mar. 31, 2015
Inventories
Inventories	Note 4.  Inventories
	Inventories are stated at lower of cost or market. Cost is determined using a weighted average cost method for scrap, and on a first-in, first-out, basis for other inventory. Inventory consisted of the following (in thousands):
		March 31,		December 31,
		2015		2014
	Raw materials	$	677,346	$	764,883
	Supplies	381,695		374,599
	Work in progress	100,408		128,882
	Finished goods	293,793		350,055
		$	1,453,242	$	1,618,419

Debt

Debt	3 Months Ended
	Mar. 31, 2015
Long-Term Debt
Long-Term Debt	Note 5.  Debt
	On March 16, 2015, the company called and repaid all $350.0 million of its outstanding 75/8% Senior Notes due 2020 (the “Notes”) at a redemption price of 103.813% of the principal amount of the Notes, plus accrued interest and unpaid interest to, but not including, the date of redemption. Associated premiums and the write off of deferred financing costs of approximately $16.7 million were recorded in other expense in conjunction with the redemption.

Changes_in_Equity

Changes in Equity	3 Months Ended
	Mar. 31, 2015
Shareholders' Equity
Shareholders' Equity
	Note 6.  Changes in Equity
	The following table provides a reconciliation of the beginning and ending carrying amounts of total equity, equity attributable to stockholders of Steel Dynamics, Inc. and equity and redeemable amounts attributable to the noncontrolling interests (in thousands):
		Stockholders of Steel Dynamics, Inc.
		Common		Additional		Retained			Treasury			Noncontrolling			Total			Redeemable
				Paid-In														Noncontrolling
		Stock		Capital		Earnings			Stock			Interests			Equity			Interests
	Balances at January 1, 2015	$	635	$	1,083,435	$	2,227,843		$	(398,898	)	$	(117,488	)	$	2,795,527		$	126,340
	Proceeds from the exercise of stock options, including related tax effect	—		1,752		—			—			—			1,752			—
	Dividends declared	—		—		(33,232		)	—			—			(33,232		)	—
	Distributions to noncontrolling investors	—		—		—			—			(29		)	(29		)	—
	Equity-based compensation	—		3,418		(18		)	2,381			—			5,781			—
	Comprehensive and net income (loss)	—		—		30,761			—			(3,807		)	26,954			—
	Balances at March 31, 2015	$	635	$	1,088,605	$	2,225,354		$	(396,517	)	$	(121,324	)	$	2,796,753		$	126,340

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2015
Derivative Financial Instruments
Derivative Financial Instruments	Note 7.  Derivative Financial Instruments
	The company is exposed to certain risks relating to its ongoing business operations. The company utilizes derivative instruments to mitigate interest rate risk, foreign currency exchange rate risk, and commodity margin risk. The company routinely enters into forward exchange traded futures and option contracts to manage the price risk associated with nonferrous metals inventory as well as purchases and sales of nonferrous metals (specifically aluminum, copper, nickel and silver).  The company offsets fair value amounts recognized for derivative instruments executed with the same counterparty under master netting agreements.
	Commodity Futures Contracts.  If the company is “long” on futures contracts, it means the company has more futures contracts purchased than futures contracts sold for the underlying commodity. If the company is “short” on a futures contract, it means the company has more futures contracts sold than futures contracts purchased for the underlying commodity. The following summarizes the company’s futures contract commitments as of March 31, 2015 (MT represents metric tons and Lbs represents pounds):
	Commodity Futures	Long/Short	Total
	Aluminum	Long	3,825		MT
	Aluminum	Short	4,175		MT
	Copper	Long	6,267		MT
	Copper	Short	16,561		MT
	Silver	Short	343		Lbs
	The following summarizes the location and amounts of the fair values reported on the company’s balance sheets as of March 31, 2015, and December 31, 2014, and gains and losses related to derivatives included in the company’s statement of income for the three-month periods ended March 31, 2015, and 2014 (in thousands):
		Asset Derivatives						Liability Derivatives
			Fair Value					Fair Value
		Balance sheet location	March 31, 2015			December 31,		March 31, 2015			December 31,
						2014					2014
	Derivative instruments designated as fair value hedges -
	Commodity futures	Other current assets	$	688		$	3,180	$	2,734		$	913
	Derivative instruments not designated as hedges -
	Commodity futures	Other current assets	1,216			2,132		1,762			626
	Total derivative instruments		$	1,904		$	5,312	$	4,496		$	1,539
	The fair value of the above derivative instruments along with required margin deposit amounts with the same counterparty under master netting arrangements, which totaled $7.7 million at March 31, 2015, and $7.6 million at December 31, 2014, are reflected in other current assets in the consolidated balance sheet.
		Location of gain	Amount of gain (loss)					Hedged items		Location of gain		Amount of gain (loss)
		(loss) recognized	recognized in income on							(loss) recognized		recognized in income on
			derivatives for the three									related hedged items for
			months ended									the three months ended
		in income on	March 31,			March 31,		in fair value hedge		in income on		March 31,		March 31,
		derivatives	2015			2014		relationships		derivatives		2015		2014
	Derivatives in fair value hedging relationships -
	Commodity futures	Costs of goods sold	$	(4,313	)	$	1,617	Firm commitments		Costs of goods sold		$	494	$	984
								Inventory		Costs of goods sold		2,656		(2,488		)
												$	3,150	$	(1,504	)
	Derivatives not designated as hedging instruments -
	Commodity futures	Costs of goods sold	$	6,996		$	7,956
	Derivatives accounted for as fair value hedges had ineffectiveness resulting in gains of $107,000 and $296,000 during the three-month periods ended March 31, 2015, and 2014, respectively; and losses excluded from hedge effectiveness testing of $1.3 million and $183,000 that increased costs of goods sold during the three-month periods ended March 31, 2015, and 2014, respectively.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Measurements
Fair Value Measurements	Note 8.  Fair Value Measurements
	FASB accounting standards provide a comprehensive framework for measuring fair value and sets forth a definition of fair value and establishes a hierarchy prioritizing the inputs to valuation techniques, giving the highest priority to quoted prices in active markets for identical assets and liabilities and the lowest priority to unobservable value inputs.  Levels within the hierarchy are defined as follows:
	        Level 1—Unadjusted quoted prices for identical assets and liabilities in active markets;
		·		Level 2—Quoted prices for similar assets and liabilities in active markets (other than those included in Level 1) which are observable for the asset or liability, either directly or indirectly; and
		·		Level 3—Valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.
	The following table sets forth financial assets and liabilities measured at fair value on a recurring basis in the consolidated balance sheet and the respective levels to which the fair value measurements are classified within the fair value hierarchy as of March 31, 2015, and December 31, 2014 (in thousands):
			Total		Quoted Prices in		Significant		Significant
					Active Markets		Other		Unobservable
					for Identical		Observable		Inputs
					Assets		Inputs		(Level 3)
					(Level 1)		(Level 2)
	March 31, 2015
	Commodity futures — financial assets		$	1,904	$	—	$	1,904	$	—
	Commodity futures — financial liabilities		4,496		—		4,496		—
	December 31, 2014
	Commodity futures — financial assets		$	5,312	$	—	$	5,312	$	—
	Commodity futures — financial liabilities		1,539		—		1,539		—
	The carrying amounts of financial instruments including cash and equivalents approximate fair value. The fair values of commodity futures contracts are estimated by the use of quoted market prices, estimates obtained from brokers, and other appropriate valuation techniques based on references available. The fair value of long-term debt, including current maturities, as determined by quoted market prices (Level 2), was approximately $2.7 billion and $3.1 billion (with a corresponding carrying amount in the consolidated balance sheets of $2.7 billion and $3.0 billion) at March 31, 2015, and December 31, 2014, respectively.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies
Commitments and Contingencies	Note 9.  Commitments and Contingencies
	The company is involved in various routine litigation matters, including administrative proceedings, regulatory proceedings, governmental investigations, environmental matters, and commercial and construction contract disputes, none of which are expected to have a material impact on our financial condition, results of operations, or liquidity.
	The company is involved, along with other steel manufacturing companies, in several class action antitrust complaints filed in federal court in Chicago, Illinois, which allege a conspiracy to fix, raise, maintain and stabilize the price at which steel products were sold in the United States during a period between 2005 and 2007, by artificially restricting the supply of such steel products. One of the complaints were brought on behalf of a purported class consisting of all direct purchasers of steel products.  A second complaint was brought on behalf of a purported class consisting of all indirect purchasers of steel products within the same time period.  An additional complaint was brought in December 2010, on behalf of indirect purchasers of steel products in Tennessee and has been consolidated with the original complaints.  All complaints seek treble damages and costs, including reasonable attorney fees, pre- and post-judgment interest and injunctive relief.  Plaintiffs filed a Motion for Class Certification in May 2012, and on February 28, 2013, Defendants filed their Joint Memorandum in Opposition to Plaintiffs’ Motion for Class Certification. A hearing on class certification was held on March 5 — 7 and April 11, 2014, and the matter remains under advisement. It’s unclear when the court will issue its ruling.
	Due to the uncertain nature of litigation, the company cannot presently determine the ultimate outcome of this litigation. However, we have determined, based on the information available at this time, that there is not presently a “reasonable possibility” (as that term is defined in ASC 450-20-20), that the outcome of these legal proceedings would have a material impact on our financial condition, results of operations, or liquidity.  Although not presently necessary or appropriate to make a dollar estimate of exposure to loss, if any, in connection with the above matter, we may in the future determine that a loss accrual is necessary. Although we may make loss accruals, if and as warranted, any amounts that we may accrue from time to time could vary significantly from the amounts we actually pay, due to inherent uncertainties and the inherent shortcomings of the estimation process, the uncertainties involved in litigation and other factors. Additionally, an adverse result could have a material effect on our financial condition, results of operations and liquidity.

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2015
Segment Information
Segment Information	Note 10.  Segment Information
	The company has three reportable segments: steel operations, metals recycling and ferrous resources operations, and steel fabrication operations.  Columbus is reported in the steel operations reporting segment from its September 16, 2014, acquisition date. The segment operations are described in Note 1 to the financial statements. Revenues included in the category “Other” are from subsidiary operations that are below the quantitative thresholds required for reportable segments and primarily consist of further processing, slitting, and sale of certain steel products, and the resale of certain secondary and excess steel products.  In addition, “Other” also includes certain unallocated corporate accounts, such as the company’s senior secured credit facility, senior notes, convertible senior notes, certain other investments and certain profit sharing expenses.
	The company’s operations are primarily organized and managed by operating segment. Operating segment performance and resource allocations are primarily based on operating results before income taxes. The accounting policies of the reportable segments are consistent with those described in Note 1 to the financial statements. Intra-segment sales and any related profits are eliminated in consolidation. Refer to the company’s Annual Report on Form 10-K for the year ended December 31, 2014, for more information related to the company’s segment reporting. The company’s segment results for the three months ended March 31, 2015, and 2014, are as follows (in thousands):
	For the three months ended				Metals Recycling /			Steel Fabrication
	March 31, 2015	Steel Operations			Ferrous Resources			Operations		Other			Eliminations			Consolidated
	Net Sales
	External	$	1,313,426		$	427,411		$	161,024	$	22,114		$	—		$	1,923,975
	External Non-U.S.	71,993			51,303			—		164			—			123,460
	Other segments	48,903			227,078			4		6,689			(282,674		)	—
		1,434,322			705,792			161,028		28,967			(282,674		)	2,047,435
	Operating income (loss)	111,540			(17,066		)	21,361		(19,920		)(1)	3,856		-2	99,771
	Income (loss) before income taxes	85,906			(24,670		)	19,594		(44,194		)	3,856			40,492
	Depreciation and amortization	48,614			20,838			2,230		1,190			(50		)	72,822
	Capital expenditures	14,686			17,658			1,037		(30		)	—			33,351
	As of March 31, 2015
	Assets	4,130,841			2,022,821			289,814		481,726		-3	(189,364		)(4)	6,735,838
	Liabilities	617,868			521,404			46,328		2,810,613		-5	(183,468		)(6)	3,812,745
	Footnotes related to the three months ended March 31, 2015 segment results (in millions):
	(1) Corporate SG&A	$	(9.4	)
	Company-wide equity-based compensation	(5.9		)
	Profit sharing	(3.5		)
	Other, net	(1.1		)
		$	(19.9	)
	(2) Gross profit increase from intra-company sales	$	3.9
	(3) Cash and equivalents	$	136.5
	Accounts receivable	11.0
	Inventories	12.8
	Deferred income taxes	33.4
	Property, plant and equipment, net	67.9
	Debt issuance costs	37.0
	Intra-company debt	146.6
	Other	36.5
		$	481.7
	(4) Elimination of intra-company receivables	$	(37.6	)
	Elimination of intra-company debt	(146.6		)
	Other	(5.2		)
		$	(189.4	)
	(5) Accounts payable	$	52.5
	Income taxes payable	5.2
	Accrued interest	51.6
	Accrued profit sharing	3.5
	Debt	2,600.1
	Deferred income taxes	77.5
	Other	20.2
		$	2,810.6
	(6) Elimination of intra-company payables	$	(38.0	)
	Elimination of intra-company debt	(146.6		)
	Other	1.1
		$	(183.5	)
	For the three months ended				Metals Recycling /			Steel Fabrication
	March 31, 2014	Steel Operations			Ferrous Resources			Operations		Other			Eliminations			Consolidated
	Net Sales
	External	$	1,061,079		$	517,957		$	115,861	$	20,621		$	—		$	1,715,518
	External Non-U.S.	56,519			57,817			—		228			—			114,564
	Other segments	43,732			343,928			—		6,673			(394,333		)	—
		1,161,330			919,702			115,861		27,522			(394,333		)	1,830,082
	Operating income (loss)	105,643			(15,519		)	3,126		(16,545		)(1)	4,227		-2	80,932
	Income (loss) before income taxes	91,998			(22,696		)	1,652		(24,187		)	4,227			50,994
	Depreciation and amortization	27,377			26,621			2,222		1,399			(51		)	57,568
	Capital expenditures	18,606			5,779			311		145			—			24,841
	As of March 31, 2014
	Assets	2,731,246			2,537,892			263,688		609,206		-3	(228,175		)(4)	5,913,857
	Liabilities	576,643			613,611			17,022		2,290,332		-5	(218,081		)(6)	3,279,527
	Footnotes related to the three months ended March 31, 2014 segment results (in millions):
(1) Corporate SG&A	$	(8.3	)
Company-wide equity-based compensation	(4.6		)
Profit sharing	(4.7		)
Other, net	1.1
	$	(16.5	)
(2) Gross profit increase from intra-company sales	$	4.2
(3) Cash and equivalents	$	285.6
Accounts receivable	12.3
Inventories	13.5
Deferred income taxes	17.8
Property, plant and equipment, net	71.6
Debt issuance costs	24.4
Intra-company debt	153.8
Other	30.2
	$	609.2
(4) Elimination of intra-company receivables	$	(65.1	)
Elimination of intra-company debt	(153.8		)
Other	(9.3		)
	$	(228.2	)
(5) Accounts payable	$	44.1
Income taxes payable	23.5
Accrued interest	21.7
Accrued profit sharing	4.8
Debt	2,031.4
Deferred income taxes	138.0
Other	26.8
	$	2,290.3
(6) Elimination of intra-company payables	$	(65.5	)
Elimination of intra-company debt	(153.8		)
Other	1.2
	$	(218.1	)

Condensed_Consolidating_Inform

Condensed Consolidating Information	3 Months Ended
	Mar. 31, 2015
Condensed Consolidating Information
Condensed Consolidating Information
	Note 11.  Condensed Consolidating Information
	Certain 100%-owned subsidiaries of SDI have fully and unconditionally guaranteed all of the indebtedness relating to the issuance of the company’s senior unsecured notes due 2019, 2021, 2022, 2023 and 2024. Following are the company’s condensed consolidating financial statements, including the guarantors, which present the financial position, results of operations, and cash flows of (i) SDI (in each case, reflecting investments in its consolidated subsidiaries under the equity method of accounting), (ii) the guarantor subsidiaries of SDI, which includes Columbus since acquired on September 16, 2014, (iii) the non-guarantor subsidiaries of SDI, and (iv) the eliminations necessary to arrive at the information on a consolidated basis. The following statements should be read in conjunction with the accompanying consolidated financial statements and the company’s Annual Report on Form 10-K for the year ended December 31, 2014.
	Condensed Consolidating Balance Sheets (in thousands)
								Combined			Consolidating			Total
	As of March 31, 2015	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Cash and equivalents	$	130,541		$	17,058		$	13,383		$	—		$	160,982
	Accounts receivable, net	258,508			1,129,116			24,017			(641,900		)	769,741
	Inventories	611,529			759,470			82,347			(104		)	1,453,242
	Other current assets	72,189			9,213			5,243			(18,385		)	68,260
	Total current assets	1,072,767			1,914,857			124,990			(660,389		)	2,452,225
	Property, plant and equipment, net	989,601			1,796,992			301,158			(2,164		)	3,085,587
	Intangible assets, net	—			364,620			—			—			364,620
	Goodwill	—			743,528			—			—			743,528
	Other assets, including investments in subs	3,745,496			23,871			6,524			(3,686,013		)	89,878
	Total assets	$	5,807,864		$	4,843,868		$	432,672		$	(4,348,566	)	$	6,735,838
	Accounts payable	$	117,240		$	262,723		$	89,959		$	(92,960	)	$	376,962
	Accrued expenses	133,295			149,157			7,649			(79,456		)	210,645
	Current maturities of long-term debt	13,085			795			57,997			(41,150		)	30,727
	Total current liabilities	263,620			412,675			155,605			(213,566		)	618,334
	Long-term debt	2,589,085			224			167,621			(133,486		)	2,623,444
	Other liabilities	37,082			1,655,611			31,706			(1,153,432		)	570,967
	Redeemable noncontrolling interests	—			—			126,340			—			126,340
	Common stock	635			1,727,860			18,121			(1,745,981		)	635
	Treasury stock	(396,517		)	—			—			—			(396,517		)
	Additional paid-in-capital	1,088,605			117,737			635,335			(753,072		)	1,088,605
	Retained earnings (deficit)	2,225,354			929,761			(580,732		)	(349,029		)	2,225,354
	Total Steel Dynamics, Inc. equity	2,918,077			2,775,358			72,724			(2,848,082		)	2,918,077
	Noncontrolling interests	—			—			(121,324		)	—			(121,324		)
	Total equity	2,918,077			2,775,358			(48,600		)	(2,848,082		)	2,796,753
	Total liabilities and equity	$	5,807,864		$	4,843,868		$	432,672		$	(4,348,566	)	$	6,735,838
	Condensed Consolidating Balance Sheets (in thousands)
								Combined			Consolidating			Total
	As of December 31, 2014	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Cash and equivalents	$	265,313		$	81,690		$	14,360		$	—		$	361,363
	Accounts receivable, net	321,493			1,176,849			44,696			(640,213		)	902,825
	Inventories	662,970			862,796			94,916			(2,263		)	1,618,419
	Other current assets	94,634			8,416			6,577			(18,469		)	91,158
	Total current assets	1,344,410			2,129,751			160,549			(660,945		)	2,973,765
	Property, plant and equipment, net	1,002,407			1,826,208			297,505			(2,214		)	3,123,906
	Intangible assets, net	—			370,669			—			—			370,669
	Goodwill	—			745,158			—			—			745,158
	Other assets, including investments in subs	3,900,691			24,810			6,635			(3,834,607		)	97,529
	Total assets	$	6,247,508		$	5,096,596		$	464,689		$	(4,497,766	)	$	7,311,027
	Accounts payable	$	151,517		$	371,037		$	98,886		$	(110,384	)	$	511,056
	Accrued expenses	191,433			166,101			11,695			(76,163		)	293,066
	Current maturities of long-term debt	13,073			777			73,767			(41,157		)	46,460
	Total current liabilities	356,023			537,915			184,348			(227,704		)	850,582
	Long-term debt	2,942,360			624			158,665			(123,943		)	2,977,706
	Other liabilities	36,110			1,807,989			28,719			(1,311,946		)	560,872
	Redeemable noncontrolling interests	—			—			126,340			—			126,340
	Common stock	635			1,727,859			18,121			(1,745,980		)	635
	Treasury stock	(398,898		)	—			—			—			(398,898		)
	Additional paid-in-capital	1,083,435			117,737			635,156			(752,893		)	1,083,435
	Retained earnings (deficit)	2,227,843			904,472			(569,172		)	(335,300		)	2,227,843
	Total Steel Dynamics, Inc. equity	2,913,015			2,750,068			84,105			(2,834,173		)	2,913,015
	Noncontrolling interests	—			—			(117,488		)	—			(117,488		)
	Total equity	2,913,015			2,750,068			(33,383		)	(2,834,173		)	2,795,527
	Total liabilities and equity	$	6,247,508		$	5,096,596		$	464,689		$	(4,497,766	)	$	7,311,027
	Condensed Consolidating Statements of Operations (in thousands)
	For the three months ended,							Combined			Consolidating			Total
	March 31, 2015	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Net sales	$	798,718		$	2,191,009		$	104,573		$	(1,046,865	)	$	2,047,435
	Costs of goods sold	693,575			2,072,125			118,781			(1,024,088		)	1,860,393
Gross profit (loss)	105,143			118,884			(14,208		)	(22,777		)	187,042
Selling, general and administrative	30,743			58,033			3,365			(4,870		)	87,271
Operating income (loss)	74,400			60,851			(17,573		)	(17,907		)	99,771
Interest expense, net of capitalized interest	20,537			21,840			1,734			(1,024		)	43,087
Other (income) expense, net	15,652			688			(1,172		)	1,024			16,192
Income (loss) before income taxes and equity in net loss of subsidiaries	38,211			38,323			(18,135		)	(17,907		)	40,492
Income taxes (benefit)	6,941			13,034			(1,116		)	(5,321		)	13,538
	31,270			25,289			(17,019		)	(12,586		)	26,954
Equity in net loss of subsidiaries	(509		)	—			—			509			—
Net loss attributable to noncontrolling interests	—			—			3,807			—			3,807
Net income (loss) attributable to Steel Dynamics, Inc.	$	30,761		$	25,289		$	(13,212	)	$	(12,077	)	$	30,761
For the three months ended,							Combined			Consolidating			Total
March 31, 2014	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
Net sales	$	863,563		$	2,112,389		$	105,849		$	(1,251,719	)	$	1,830,082
Costs of goods sold	761,395			2,015,576			123,573			(1,233,766		)	1,666,778
Gross profit (loss)	102,168			96,813			(17,724		)	(17,953		)	163,304
Selling, general and administrative	28,834			54,289			3,408			(4,159		)	82,372
Operating income (loss)	73,334			42,524			(21,132		)	(13,794		)	80,932
Interest expense, net of capitalized interest	19,361			10,561			1,880			(1,233		)	30,569
Other (income) expense, net	(976		)	395			(1,284		)	1,234			(631		)
Income (loss) before income taxes and equity in net income of subsidiaries	54,949			31,568			(21,728		)	(13,795		)	50,994
Income taxes (benefit)	9,925			10,942			696			(4,267		)	17,296
	45,024			20,626			(22,424		)	(9,528		)	33,698
Equity in net loss of subsidiaries	(6,445		)	—			—			6,445			—
Net loss attributable to noncontrolling interests	—			—			4,881			—			4,881
Net income (loss) attributable to Steel Dynamics, Inc.	$	38,579		$	20,626		$	(17,543	)	$	(3,083	)	$	38,579
Condensed Consolidating Statements of Cash Flows (in thousands)
For the three months ended,							Combined			Consolidating			Total
March 31, 2015	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
Net cash provided by operating activities	$	102,678		$	114,451		$	9,456		$	8,122		$	234,707
Net cash used in investing activities	(18,547		)	(12,949		)	(9,727		)	9,535			(31,688		)
Net cash used in financing activities	(218,903		)	(166,134		)	(706		)	(17,657		)	(403,400		)
Decrease in cash and equivalents	(134,772		)	(64,632		)	(977		)	—			(200,381		)
Cash and equivalents at beginning of period	265,313			81,690			14,360			—			361,363
Cash and equivalents at end of period	$	130,541		$	17,058		$	13,383		$	—		$	160,982
For the three months ended,							Combined			Consolidating			Total
March 31, 2014	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
Net cash provided by (used in) operating activities	$	9,027		$	(17,195	)	$	(14,149	)	$	(4,930	)	$	(27,247	)
Net cash provided by (used in) investing activities	(12,430		)	(3,997		)	(1,625		)	22,095			4,043
Net cash provided by (used in) financing activities	(36,087		)	8,115			16,104			(17,165		)	(29,033		)
Increase (decrease) in cash and equivalents	(39,490		)	(13,077		)	330			—			(52,237		)
Cash and equivalents at beginning of period	320,866			61,148			13,142			—			395,156
Cash and equivalents at end of period	$	281,376		$	48,071		$	13,472		$	—		$	342,919

Description_of_the_Business_an1

Description of the Business and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Description of the Business and Significant Accounting Policies
Principles of Consolidation	Principles of Consolidation.  The consolidated financial statements include the accounts of SDI, together with its wholly and majority-owned or controlled subsidiaries, after elimination of significant intercompany accounts and transactions. Noncontrolling interests represent the noncontrolling owner’s proportionate share in the equity, income, or losses of the company’s majority-owned or controlled consolidated subsidiaries.
Use of Estimates
	Use of Estimates.  These financial statements are prepared in conformity with accounting principles generally accepted in the United States, and accordingly, include amounts that require management to make estimates and assumptions that affect the amounts reported in the financial statements and in the notes thereto. Significant items subject to such estimates and assumptions include the carrying value of property, plant and equipment, intangible assets, and goodwill; valuation allowances for trade receivables, inventories and deferred income tax assets; unrecognized tax benefits; potential environmental liabilities; and litigation claims and settlements. Actual results may differ from these estimates and assumptions.
	In the opinion of management, these financial statements reflect all normal recurring adjustments necessary for a fair presentation of the interim period results. These financial statements and notes should be read in conjunction with the audited financial statements and notes thereto included in the company’s Annual Report on Form 10-K for the year ended December 31, 2014.
Goodwill	Goodwill.  The company’s goodwill is allocated to the following reporting units at March 31, 2015, and December 31, 2014, (in thousands):
		March 31,		December 31,
		2015		2014
	OmniSource — Metals Recycling/Ferrous Resources Segment	$	455,097	$	456,727
	The Techs — Steel Segment	142,783		142,783
	Butler Flat Roll Division, Structural and Rail Division, and Engineered Bar Division — Metals Recycling/Ferrous Resources Segment	95,000		95,000
	Roanoke Bar Division — Steel Segment	29,041		29,041
	Columbus Flat Roll Division — Steel Segment	19,682		19,682
	New Millennium Building Systems — Fabrication Segment	1,925		1,925
		$	743,528	$	745,158
	OmniSource goodwill decreased $1.6 million from December 31, 2014 to March 31, 2015, in recognition of the 2015 tax benefit related to the amortization of the component of OmniSource tax-deductible goodwill in excess of book goodwill.
Recently Issued Accounting Standards
	Recently Issued Accounting Standards.
	In May 2014, the FASB issued guidance codified in ASC 606, Revenue Recognition — Revenue from Contracts with Customers, which amends the guidance in former ASC 605, Revenue Recognition.  The core principle of ASC 606 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Because the guidance in ASC 606 is principles-based, it can be applied to all contracts with customers regardless of industry-specific or transaction-specific fact patterns. Additionally, ASC 606 requires additional disclosures to help users of financial statements better understand the nature, amount, timing, and potential uncertainty of revenue that is recognized. This guidance is effective for annual and interim periods ending after December 15, 2016. The company is currently evaluating the impact of the provisions of ASC 606.
	In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements — Going Concern (Subtopic 205-40: Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern), effective for annual and interim periods ending after December 15, 2016. ASU 2014-15 requires management to evaluate whether there are conditions or events, considered in aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. There are required disclosures if principal conditions or events are identified that raised substantial doubt about the entity’s ability to continue as a going concern (before consideration of management’s plans), as well as management’s evaluation of the significance of those conditions or events in relation to the entity’s ability to meet its obligations, and management’s plans that alleviated substantial doubt about the entity’s ability to continue as a going concern. This ASU is not expected to have any impact on our overall results of operations, financial position or cash flows.
	In April 2015, the FASB issued ASU 2015-03, Interest — Imputation of Interest (Subtopic 835-30) — Simplifying the Presentation of Debt Issuance Costs, which requires debt issuance costs to be presented as a deduction from the corresponding debt liability, rather than as a separate asset, which is the current accounting method of the company. Implementation of this new guidance is required by the company in the first quarter of 2016, but can be early adopted. Upon adoption, the company must apply the new guidance retrospectively to all prior periods presented in the financial statements. The company is currently evaluating when and the manner in which to adopt the presentation and disclosure requirements of the new guidance. This ASU is not expected to have any impact on our overall results of operations, equity or cash flows as previously reported.

Description_of_the_Business_an2

Description of the Business and Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2015
Description of the Business and Significant Accounting Policies
Schedule of allocation of goodwill to reporting units	Goodwill.  The company’s goodwill is allocated to the following reporting units at March 31, 2015, and December 31, 2014, (in thousands):
		March 31,		December 31,
		2015		2014
	OmniSource — Metals Recycling/Ferrous Resources Segment	$	455,097	$	456,727
	The Techs — Steel Segment	142,783		142,783
	Butler Flat Roll Division, Structural and Rail Division, and Engineered Bar Division — Metals Recycling/Ferrous Resources Segment	95,000		95,000
	Roanoke Bar Division — Steel Segment	29,041		29,041
	Columbus Flat Roll Division — Steel Segment	19,682		19,682
	New Millennium Building Systems — Fabrication Segment	1,925		1,925
		$	743,528	$	745,158

Acquisition_Tables

Acquisition (Tables)	3 Months Ended
	Mar. 31, 2015
Acquisition
Schedule of unaudited pro forma information	The following unaudited pro forma information is presented below for comparison purposes as if the Columbus acquisition was completed as of January 1, 2013, (in thousands):
		Three Months Ended
		March 31, 2014
	Net sales	$	2,358,273
	Net income attributable to Steel Dynamics, Inc.	63,065

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share
Schedule of reconciliation of the numerators and denominators used in calculating basic and diluted earnings per share	The following table presents a reconciliation of the numerators and the denominators of the company’s basic and diluted earnings per share computations for the three months ended March 31, 2015 and 2014 (in thousands, except per share data):
		2015					2014
		Net Income		Shares	Per Share		Net Income		Shares	Per Share
		(Numerator)		(Denominator)	Amount		(Numerator)		(Denominator)	Amount
	Basic earnings per share	$	30,761	241,535	$	0.13	$	38,579	223,011	$	0.17
	Dilutive common share equivalents	—		1,332			—		1,608
	5.125% Convertible Senior Notes, net of tax	—		—			2,358		16,775
	Diluted earnings per share	$	30,761	242,867	$	0.13	$	40,937	241,394	$	0.17

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2015
Inventories
Schedule of inventories	Inventory consisted of the following (in thousands):
		March 31,		December 31,
		2015		2014
	Raw materials	$	677,346	$	764,883
	Supplies	381,695		374,599
	Work in progress	100,408		128,882
	Finished goods	293,793		350,055
		$	1,453,242	$	1,618,419

Changes_in_Equity_Tables

Changes in Equity (Tables)	3 Months Ended
	Mar. 31, 2015
Shareholders' Equity
Schedule of stockholders' equity	The following table provides a reconciliation of the beginning and ending carrying amounts of total equity, equity attributable to stockholders of Steel Dynamics, Inc. and equity and redeemable amounts attributable to the noncontrolling interests (in thousands):
		Stockholders of Steel Dynamics, Inc.
		Common		Additional		Retained			Treasury			Noncontrolling			Total			Redeemable
				Paid-In														Noncontrolling
		Stock		Capital		Earnings			Stock			Interests			Equity			Interests
	Balances at January 1, 2015	$	635	$	1,083,435	$	2,227,843		$	(398,898	)	$	(117,488	)	$	2,795,527		$	126,340
	Proceeds from the exercise of stock options, including related tax effect	—		1,752		—			—			—			1,752			—
	Dividends declared	—		—		(33,232		)	—			—			(33,232		)	—
	Distributions to noncontrolling investors	—		—		—			—			(29		)	(29		)	—
	Equity-based compensation	—		3,418		(18		)	2,381			—			5,781			—
	Comprehensive and net income (loss)	—		—		30,761			—			(3,807		)	26,954			—
	Balances at March 31, 2015	$	635	$	1,088,605	$	2,225,354		$	(396,517	)	$	(121,324	)	$	2,796,753		$	126,340

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Financial Instruments
Commodity option and futures contract commitments for non monetary notional amount	The following summarizes the company’s futures contract commitments as of March 31, 2015 (MT represents metric tons and Lbs represents pounds):
	Commodity Futures	Long/Short	Total
	Aluminum	Long	3,825		MT
	Aluminum	Short	4,175		MT
	Copper	Long	6,267		MT
	Copper	Short	16,561		MT
	Silver	Short	343		Lbs
Summary of the location and amounts of the fair values and gains or losses related to derivatives included in the entity's financial statements	The following summarizes the location and amounts of the fair values reported on the company’s balance sheets as of March 31, 2015, and December 31, 2014, and gains and losses related to derivatives included in the company’s statement of income for the three-month periods ended March 31, 2015, and 2014 (in thousands):
		Asset Derivatives						Liability Derivatives
			Fair Value					Fair Value
		Balance sheet location	March 31, 2015			December 31,		March 31, 2015			December 31,
						2014					2014
	Derivative instruments designated as fair value hedges -
	Commodity futures	Other current assets	$	688		$	3,180	$	2,734		$	913
	Derivative instruments not designated as hedges -
	Commodity futures	Other current assets	1,216			2,132		1,762			626
	Total derivative instruments		$	1,904		$	5,312	$	4,496		$	1,539
		Location of gain	Amount of gain (loss)					Hedged items		Location of gain		Amount of gain (loss)
		(loss) recognized	recognized in income on							(loss) recognized		recognized in income on
			derivatives for the three									related hedged items for
			months ended									the three months ended
		in income on	March 31,			March 31,		in fair value hedge		in income on		March 31,		March 31,
		derivatives	2015			2014		relationships		derivatives		2015		2014
	Derivatives in fair value hedging relationships -
	Commodity futures	Costs of goods sold	$	(4,313	)	$	1,617	Firm commitments		Costs of goods sold		$	494	$	984
								Inventory		Costs of goods sold		2,656		(2,488		)
												$	3,150	$	(1,504	)
	Derivatives not designated as hedging instruments -
	Commodity futures	Costs of goods sold	$	6,996		$	7,956

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Measurements
Schedule of assets and liabilities measured at fair value on a recurring basis	The following table sets forth financial assets and liabilities measured at fair value on a recurring basis in the consolidated balance sheet and the respective levels to which the fair value measurements are classified within the fair value hierarchy as of March 31, 2015, and December 31, 2014 (in thousands):
		Total		Quoted Prices in		Significant		Significant
				Active Markets		Other		Unobservable
				for Identical		Observable		Inputs
				Assets		Inputs		(Level 3)
				(Level 1)		(Level 2)
	March 31, 2015
	Commodity futures — financial assets	$	1,904	$	—	$	1,904	$	—
	Commodity futures — financial liabilities	4,496		—		4,496		—
	December 31, 2014
	Commodity futures — financial assets	$	5,312	$	—	$	5,312	$	—
	Commodity futures — financial liabilities	1,539		—		1,539		—

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Information
Schedule of operating segment results
	The company’s segment results for the three months ended March 31, 2015, and 2014, are as follows (in thousands):
	For the three months ended				Metals Recycling /			Steel Fabrication
	March 31, 2015	Steel Operations			Ferrous Resources			Operations		Other			Eliminations			Consolidated
	Net Sales
	External	$	1,313,426		$	427,411		$	161,024	$	22,114		$	—		$	1,923,975
	External Non-U.S.	71,993			51,303			—		164			—			123,460
	Other segments	48,903			227,078			4		6,689			(282,674		)	—
		1,434,322			705,792			161,028		28,967			(282,674		)	2,047,435
	Operating income (loss)	111,540			(17,066		)	21,361		(19,920		)(1)	3,856		-2	99,771
	Income (loss) before income taxes	85,906			(24,670		)	19,594		(44,194		)	3,856			40,492
	Depreciation and amortization	48,614			20,838			2,230		1,190			(50		)	72,822
	Capital expenditures	14,686			17,658			1,037		(30		)	—			33,351
	As of March 31, 2015
	Assets	4,130,841			2,022,821			289,814		481,726		-3	(189,364		)(4)	6,735,838
	Liabilities	617,868			521,404			46,328		2,810,613		-5	(183,468		)(6)	3,812,745
	Footnotes related to the three months ended March 31, 2015 segment results (in millions):
	(1) Corporate SG&A	$	(9.4	)
	Company-wide equity-based compensation	(5.9		)
	Profit sharing	(3.5		)
	Other, net	(1.1		)
		$	(19.9	)
	(2) Gross profit increase from intra-company sales	$	3.9
	(3) Cash and equivalents	$	136.5
	Accounts receivable	11.0
	Inventories	12.8
	Deferred income taxes	33.4
	Property, plant and equipment, net	67.9
	Debt issuance costs	37.0
	Intra-company debt	146.6
	Other	36.5
		$	481.7
	(4) Elimination of intra-company receivables	$	(37.6	)
	Elimination of intra-company debt	(146.6		)
	Other	(5.2		)
		$	(189.4	)
	(5) Accounts payable	$	52.5
	Income taxes payable	5.2
	Accrued interest	51.6
	Accrued profit sharing	3.5
	Debt	2,600.1
	Deferred income taxes	77.5
	Other	20.2
		$	2,810.6
	(6) Elimination of intra-company payables	$	(38.0	)
	Elimination of intra-company debt	(146.6		)
	Other	1.1
		$	(183.5	)
	For the three months ended				Metals Recycling /			Steel Fabrication
	March 31, 2014	Steel Operations			Ferrous Resources			Operations		Other			Eliminations			Consolidated
	Net Sales
	External	$	1,061,079		$	517,957		$	115,861	$	20,621		$	—		$	1,715,518
	External Non-U.S.	56,519			57,817			—		228			—			114,564
	Other segments	43,732			343,928			—		6,673			(394,333		)	—
		1,161,330			919,702			115,861		27,522			(394,333		)	1,830,082
	Operating income (loss)	105,643			(15,519		)	3,126		(16,545		)(1)	4,227		-2	80,932
	Income (loss) before income taxes	91,998			(22,696		)	1,652		(24,187		)	4,227			50,994
	Depreciation and amortization	27,377			26,621			2,222		1,399			(51		)	57,568
	Capital expenditures	18,606			5,779			311		145			—			24,841
	As of March 31, 2014
	Assets	2,731,246			2,537,892			263,688		609,206		-3	(228,175		)(4)	5,913,857
	Liabilities	576,643			613,611			17,022		2,290,332		-5	(218,081		)(6)	3,279,527
	Footnotes related to the three months ended March 31, 2014 segment results (in millions):
	(1) Corporate SG&A	$	(8.3	)
Company-wide equity-based compensation	(4.6		)
Profit sharing	(4.7		)
Other, net	1.1
	$	(16.5	)
(2) Gross profit increase from intra-company sales	$	4.2
(3) Cash and equivalents	$	285.6
Accounts receivable	12.3
Inventories	13.5
Deferred income taxes	17.8
Property, plant and equipment, net	71.6
Debt issuance costs	24.4
Intra-company debt	153.8
Other	30.2
	$	609.2
(4) Elimination of intra-company receivables	$	(65.1	)
Elimination of intra-company debt	(153.8		)
Other	(9.3		)
	$	(228.2	)
(5) Accounts payable	$	44.1
Income taxes payable	23.5
Accrued interest	21.7
Accrued profit sharing	4.8
Debt	2,031.4
Deferred income taxes	138.0
Other	26.8
	$	2,290.3
(6) Elimination of intra-company payables	$	(65.5	)
Elimination of intra-company debt	(153.8		)
Other	1.2
	$	(218.1	)

Condensed_Consolidating_Inform1

Condensed Consolidating Information (Tables)	3 Months Ended
	Mar. 31, 2015
Condensed Consolidating Information
Schedule of Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets (in thousands)
								Combined			Consolidating			Total
	As of March 31, 2015	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Cash and equivalents	$	130,541		$	17,058		$	13,383		$	—		$	160,982
	Accounts receivable, net	258,508			1,129,116			24,017			(641,900		)	769,741
	Inventories	611,529			759,470			82,347			(104		)	1,453,242
	Other current assets	72,189			9,213			5,243			(18,385		)	68,260
	Total current assets	1,072,767			1,914,857			124,990			(660,389		)	2,452,225
	Property, plant and equipment, net	989,601			1,796,992			301,158			(2,164		)	3,085,587
	Intangible assets, net	—			364,620			—			—			364,620
	Goodwill	—			743,528			—			—			743,528
	Other assets, including investments in subs	3,745,496			23,871			6,524			(3,686,013		)	89,878
	Total assets	$	5,807,864		$	4,843,868		$	432,672		$	(4,348,566	)	$	6,735,838
	Accounts payable	$	117,240		$	262,723		$	89,959		$	(92,960	)	$	376,962
	Accrued expenses	133,295			149,157			7,649			(79,456		)	210,645
	Current maturities of long-term debt	13,085			795			57,997			(41,150		)	30,727
	Total current liabilities	263,620			412,675			155,605			(213,566		)	618,334
	Long-term debt	2,589,085			224			167,621			(133,486		)	2,623,444
	Other liabilities	37,082			1,655,611			31,706			(1,153,432		)	570,967
	Redeemable noncontrolling interests	—			—			126,340			—			126,340
	Common stock	635			1,727,860			18,121			(1,745,981		)	635
	Treasury stock	(396,517		)	—			—			—			(396,517		)
	Additional paid-in-capital	1,088,605			117,737			635,335			(753,072		)	1,088,605
	Retained earnings (deficit)	2,225,354			929,761			(580,732		)	(349,029		)	2,225,354
	Total Steel Dynamics, Inc. equity	2,918,077			2,775,358			72,724			(2,848,082		)	2,918,077
	Noncontrolling interests	—			—			(121,324		)	—			(121,324		)
	Total equity	2,918,077			2,775,358			(48,600		)	(2,848,082		)	2,796,753
	Total liabilities and equity	$	5,807,864		$	4,843,868		$	432,672		$	(4,348,566	)	$	6,735,838
	Condensed Consolidating Balance Sheets (in thousands)
								Combined			Consolidating			Total
	As of December 31, 2014	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Cash and equivalents	$	265,313		$	81,690		$	14,360		$	—		$	361,363
	Accounts receivable, net	321,493			1,176,849			44,696			(640,213		)	902,825
	Inventories	662,970			862,796			94,916			(2,263		)	1,618,419
	Other current assets	94,634			8,416			6,577			(18,469		)	91,158
	Total current assets	1,344,410			2,129,751			160,549			(660,945		)	2,973,765
	Property, plant and equipment, net	1,002,407			1,826,208			297,505			(2,214		)	3,123,906
	Intangible assets, net	—			370,669			—			—			370,669
	Goodwill	—			745,158			—			—			745,158
	Other assets, including investments in subs	3,900,691			24,810			6,635			(3,834,607		)	97,529
	Total assets	$	6,247,508		$	5,096,596		$	464,689		$	(4,497,766	)	$	7,311,027
	Accounts payable	$	151,517		$	371,037		$	98,886		$	(110,384	)	$	511,056
	Accrued expenses	191,433			166,101			11,695			(76,163		)	293,066
	Current maturities of long-term debt	13,073			777			73,767			(41,157		)	46,460
	Total current liabilities	356,023			537,915			184,348			(227,704		)	850,582
	Long-term debt	2,942,360			624			158,665			(123,943		)	2,977,706
	Other liabilities	36,110			1,807,989			28,719			(1,311,946		)	560,872
	Redeemable noncontrolling interests	—			—			126,340			—			126,340
	Common stock	635			1,727,859			18,121			(1,745,980		)	635
	Treasury stock	(398,898		)	—			—			—			(398,898		)
	Additional paid-in-capital	1,083,435			117,737			635,156			(752,893		)	1,083,435
	Retained earnings (deficit)	2,227,843			904,472			(569,172		)	(335,300		)	2,227,843
	Total Steel Dynamics, Inc. equity	2,913,015			2,750,068			84,105			(2,834,173		)	2,913,015
	Noncontrolling interests	—			—			(117,488		)	—			(117,488		)
	Total equity	2,913,015			2,750,068			(33,383		)	(2,834,173		)	2,795,527
	Total liabilities and equity	$	6,247,508		$	5,096,596		$	464,689		$	(4,497,766	)	$	7,311,027
Schedule of Condensed Consolidating Statements of Operations	Condensed Consolidating Statements of Operations (in thousands)
	For the three months ended,							Combined			Consolidating			Total
	March 31, 2015	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Net sales	$	798,718		$	2,191,009		$	104,573		$	(1,046,865	)	$	2,047,435
	Costs of goods sold	693,575			2,072,125			118,781			(1,024,088		)	1,860,393
	Gross profit (loss)	105,143			118,884			(14,208		)	(22,777		)	187,042
	Selling, general and administrative	30,743			58,033			3,365			(4,870		)	87,271
	Operating income (loss)	74,400			60,851			(17,573		)	(17,907		)	99,771
	Interest expense, net of capitalized interest	20,537			21,840			1,734			(1,024		)	43,087
	Other (income) expense, net	15,652			688			(1,172		)	1,024			16,192
	Income (loss) before income taxes and equity in net loss of subsidiaries	38,211			38,323			(18,135		)	(17,907		)	40,492
	Income taxes (benefit)	6,941			13,034			(1,116		)	(5,321		)	13,538
		31,270			25,289			(17,019		)	(12,586		)	26,954
	Equity in net loss of subsidiaries	(509		)	—			—			509			—
	Net loss attributable to noncontrolling interests	—			—			3,807			—			3,807
	Net income (loss) attributable to Steel Dynamics, Inc.	$	30,761		$	25,289		$	(13,212	)	$	(12,077	)	$	30,761
	For the three months ended,							Combined			Consolidating			Total
	March 31, 2014	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Net sales	$	863,563		$	2,112,389		$	105,849		$	(1,251,719	)	$	1,830,082
	Costs of goods sold	761,395			2,015,576			123,573			(1,233,766		)	1,666,778
	Gross profit (loss)	102,168			96,813			(17,724		)	(17,953		)	163,304
	Selling, general and administrative	28,834			54,289			3,408			(4,159		)	82,372
	Operating income (loss)	73,334			42,524			(21,132		)	(13,794		)	80,932
	Interest expense, net of capitalized interest	19,361			10,561			1,880			(1,233		)	30,569
	Other (income) expense, net	(976		)	395			(1,284		)	1,234			(631		)
	Income (loss) before income taxes and equity in net income of subsidiaries	54,949			31,568			(21,728		)	(13,795		)	50,994
	Income taxes (benefit)	9,925			10,942			696			(4,267		)	17,296
		45,024			20,626			(22,424		)	(9,528		)	33,698
	Equity in net loss of subsidiaries	(6,445		)	—			—			6,445			—
	Net loss attributable to noncontrolling interests	—			—			4,881			—			4,881
	Net income (loss) attributable to Steel Dynamics, Inc.	$	38,579		$	20,626		$	(17,543	)	$	(3,083	)	$	38,579
Schedule of Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows (in thousands)
	For the three months ended,							Combined			Consolidating			Total
	March 31, 2015	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Net cash provided by operating activities	$	102,678		$	114,451		$	9,456		$	8,122		$	234,707
	Net cash used in investing activities	(18,547		)	(12,949		)	(9,727		)	9,535			(31,688		)
	Net cash used in financing activities	(218,903		)	(166,134		)	(706		)	(17,657		)	(403,400		)
	Decrease in cash and equivalents	(134,772		)	(64,632		)	(977		)	—			(200,381		)
	Cash and equivalents at beginning of period	265,313			81,690			14,360			—			361,363
	Cash and equivalents at end of period	$	130,541		$	17,058		$	13,383		$	—		$	160,982
	For the three months ended,							Combined			Consolidating			Total
	March 31, 2014	Parent			Guarantors			Non-Guarantors			Adjustments			Consolidated
	Net cash provided by (used in) operating activities	$	9,027		$	(17,195	)	$	(14,149	)	$	(4,930	)	$	(27,247	)
	Net cash provided by (used in) investing activities	(12,430		)	(3,997		)	(1,625		)	22,095			4,043
	Net cash provided by (used in) financing activities	(36,087		)	8,115			16,104			(17,165		)	(29,033		)
	Increase (decrease) in cash and equivalents	(39,490		)	(13,077		)	330			—			(52,237		)
	Cash and equivalents at beginning of period	320,866			61,148			13,142			—			395,156
	Cash and equivalents at end of period	$	281,376		$	48,071		$	13,472		$	—		$	342,919

Description_of_the_Business_an3

Description of the Business and Significant Accounting Policies (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
	facility
Description of the Business and Significant Accounting Policies
Number of reporting segments	3
Steel Operations
Segment Reporting Information
Percentage of external net sales	68.00%	61.00%
Number of downstream finishing facilities	8
Metals Recycling/Ferrous Resources
Segment Reporting Information
Percentage of external net sales	23.00%	32.00%
Number of ironmaking initiatives	2
Steel Fabrication Operations
Segment Reporting Information
Percentage of external net sales	8.00%	6.00%
Number of New Millennium Building Systems' joist and deck plants	6

Description_of_the_Business_an4

Description of the Business and Significant Accounting Policies (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Goodwill
Goodwill	$743,528,000	$745,158,000
Omni Source
Goodwill
Goodwill decrease due to tax benefit related to the amortization of the component	1,600,000
Metals Recycling/Ferrous Resources | Omni Source
Goodwill
Goodwill	455,097,000	456,727,000
Metals Recycling/Ferrous Resources | Butler Flat Roll Division, Structural and Rail Division, and Engineered Bar Division
Goodwill
Goodwill	95,000,000	95,000,000
Steel Operations | The Techs Operations
Goodwill
Goodwill	142,783,000	142,783,000
Steel Operations | Roanoke Bar Division
Goodwill
Goodwill	29,041,000	29,041,000
Steel Operations | Columbus Flat Roll Division
Goodwill
Goodwill	19,682,000	19,682,000
Steel Fabrication Operations | New Millennium Building Systems
Goodwill
Goodwill	$1,925,000	$1,925,000

Acquisition_Details

Acquisition (Details) (Severstal Columbus LLC, USD $)	0 Months Ended	3 Months Ended
	Sep. 16, 2014	Mar. 31, 2014	Sep. 16, 2014
	MT
Business Acquisition Information
Business acquisition percentage	100.00%		100.00%
Purchase price	$1,625,000,000
Working capital adjustments	44,400,000
Additional production capacity due to acquisition (in million tons)	3.4
Unaudited pro forma results
Net sales		2,358,273,000
Net Income attributable to Steel Dynamics, Inc.		63,065,000
Senior Notes
Business Acquisition Information
Issuance of Senior Notes	$1,200,000,000		1,200,000,000

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net Income (Numerator)
Basic earnings per share - net income (in dollars)	$30,761	$38,579
5.125% convertible senior notes, net of tax (in dollars)		2,358
Diluted earnings per share - net income (in dollars)	$30,761	$40,937
Weighted average common shares outstanding (in shares)
Weighted average common shares outstanding (in shares)	241,535,000	223,011,000
Dilutive common share equivalents (in shares)	1,332,000	1,608,000
5.125% convertible senior notes, net of tax (in shares)		16,775,000
Weighted average common shares outstanding - diluted (in shares)	242,867,000	241,394,000
Per Share Amount
Basic (in dollars per share)	$0.13	$0.17
Diluted (in dollars per share)	$0.13	$0.17
Options
Antidilutive securities excluded from computation of earnings per share amount
Antidilutive securities excluded from computation of earnings per share amount (in shares)	0	0

Inventories_Details

Inventories (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Inventories
Raw materials	$677,346	$764,883
Supplies	381,695	374,599
Work in progress	100,408	128,882
Finished goods	293,793	350,055
Total inventories	$1,453,242	$1,618,419

Debt_Details

Debt (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 16, 2015
Long Term Debt
Repayments of debt	$427,451,000	$56,246,000
Senior Notes
Long Term Debt
Repayments of debt			350,000,000
Stated interest rate (as a percent)			7.63%
Redemption price of debt instrument (as a percent)			103.81%
Associated premiums and related expenses recorded			$16,700,000

Changes_in_Equity_Details

Changes in Equity (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Increase (Decrease) in Equity
Balances	$2,795,527
Proceeds from exercise of stock options, including related tax effect	1,752
Dividends declared	-33,232
Distributions to noncontrolling investors	-29
Equity-based compensation	5,781
Comprehensive income (loss)	26,954
Net income (loss)	26,954	33,698
Balances	2,796,753
Common Stock
Increase (Decrease) in Equity
Balances			635
Balances	635		635
Additional Paid-in Capital
Increase (Decrease) in Equity
Balances	1,083,435
Proceeds from exercise of stock options, including related tax effect	1,752
Equity-based compensation	3,418
Balances	1,088,605
Retained Earnings
Increase (Decrease) in Equity
Balances	2,227,843
Dividends declared	-33,232
Equity-based compensation	-18
Comprehensive income (loss)	30,761
Net income (loss)	30,761
Balances	2,225,354
Treasury Stock
Increase (Decrease) in Equity
Balances	-398,898
Equity-based compensation	2,381
Balances	-396,517
Noncontrolling Interests
Increase (Decrease) in Equity
Balances	-117,488
Distributions to noncontrolling investors	-29
Comprehensive income (loss)	-3,807
Net income (loss)	-3,807
Balances	-121,324
Redeemable Noncontrolling Interest
Increase (Decrease) in Equity
Balances			126,340
Balances	$126,340		$126,340

Derivative_Financial_Instrumen2

Derivative Financial Instruments (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Designated as hedging instrument
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on related hedged items	$3,150,000	($1,504,000)
Futures | Aluminum | Long
Commodity contract commitments
Commodity contract (in MT/Lbs)	3,825
Futures | Aluminum | Short
Commodity contract commitments
Commodity contract (in MT/Lbs)	4,175
Futures | Copper | Long
Commodity contract commitments
Commodity contract (in MT/Lbs)	6,267
Futures | Copper | Short
Commodity contract commitments
Commodity contract (in MT/Lbs)	16,561
Futures | Silver | Short
Commodity contract commitments
Commodity contract (in MT/Lbs)	343
Commodity contract | Futures
Fair values of derivative instruments, balance sheet
Commodity futures, asset derivatives (in dollars)	1,904,000		5,312,000
Commodity futures, liability derivatives (in dollars)	4,496,000		1,539,000
Commodity contract | Futures | Other current assets
Fair values of derivative instruments, balance sheet
Fair value of derivatives including required margin deposits	7,700,000		7,600,000
Commodity contract | Futures | Designated as hedging instrument
Gains or losses on derivative instruments, statement of income
Ineffectiveness - amount of gain recognized in income on related hedged items	107,000	296,000
Loss excluded from hedge effectiveness testing	1,300,000	183,000
Commodity contract | Futures | Designated as hedging instrument | Cost of goods sold
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on derivatives	-4,313,000	1,617,000
Commodity contract | Futures | Designated as hedging instrument | Other current assets
Fair values of derivative instruments, balance sheet
Commodity futures, asset derivatives (in dollars)	688,000		3,180,000
Commodity futures, liability derivatives (in dollars)	2,734,000		913,000
Commodity contract | Futures | Not designated as hedging instrument | Cost of goods sold
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on derivatives	6,996,000	7,956,000
Commodity contract | Futures | Not designated as hedging instrument | Other current assets
Fair values of derivative instruments, balance sheet
Commodity futures, asset derivatives (in dollars)	1,216,000		2,132,000
Commodity futures, liability derivatives (in dollars)	1,762,000		626,000
Firm commitments | Designated as hedging instrument | Cost of goods sold
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on related hedged items	494,000	984,000
Inventory | Designated as hedging instrument | Cost of goods sold
Gains or losses on derivative instruments, statement of income
Amount of gain (loss) recognized in income on related hedged items	$2,656,000	($2,488,000)

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Assets and liabilities subject to fair value measurements
Outstanding Balance	$2,700,000,000	$3,000,000,000
Commodity contract | Futures
Assets and liabilities subject to fair value measurements
Commodity futures - financial assets	1,904,000	5,312,000
Commodity futures - financial liabilities	4,496,000	1,539,000
Recurring | Level 2
Assets and liabilities subject to fair value measurements
Fair value of long-term debt, including current maturities	2,700,000,000	3,100,000,000
Recurring | Level 2 | Commodity contract | Futures
Assets and liabilities subject to fair value measurements
Commodity futures - financial assets	1,904,000	5,312,000
Commodity futures - financial liabilities	4,496,000	1,539,000
Recurring | Total | Commodity contract | Futures
Assets and liabilities subject to fair value measurements
Commodity futures - financial assets	1,904,000	5,312,000
Commodity futures - financial liabilities	$4,496,000	$1,539,000

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	segment
Segment Information
Number of reporting segments	3
Segment Reporting Information
Total net sales	$2,047,435	$1,830,082
Operating income (loss)	99,771	80,932
Income (loss) before income taxes	40,492	50,994
Depreciation and amortization	72,822	57,568
Capital expenditures	33,351	24,841
Assets	6,735,838	5,913,857	7,311,027
Liabilities	3,812,745	3,279,527
U.S.
Segment Reporting Information
Total net sales	1,923,975	1,715,518
Non-U.S.
Segment Reporting Information
Total net sales	123,460	114,564
Steel Operations
Segment Reporting Information
Capital expenditures	14,686	18,606
Metals Recycling/Ferrous Resources
Segment Reporting Information
Capital expenditures	17,658	5,779
Steel Fabrication Operations
Segment Reporting Information
Capital expenditures	1,037	311
Other.
Segment Reporting Information
Capital expenditures	-30	145
Operating Segment
Segment Reporting Information
Total net sales	2,047,435	1,830,082
Operating Segment | Steel Operations
Segment Reporting Information
Total net sales	1,434,322	1,161,330
Operating income (loss)	111,540	105,643
Income (loss) before income taxes	85,906	91,998
Depreciation and amortization	48,614	27,377
Assets	4,130,841	2,731,246
Liabilities	617,868	576,643
Operating Segment | Steel Operations | Other segments
Segment Reporting Information
Total net sales	48,903	43,732
Operating Segment | Steel Operations | U.S.
Segment Reporting Information
Total net sales	1,313,426	1,061,079
Operating Segment | Steel Operations | Non-U.S.
Segment Reporting Information
Total net sales	71,993	56,519
Operating Segment | Metals Recycling/Ferrous Resources
Segment Reporting Information
Total net sales	705,792	919,702
Operating income (loss)	-17,066	-15,519
Income (loss) before income taxes	-24,670	-22,696
Depreciation and amortization	20,838	26,621
Assets	2,022,821	2,537,892
Liabilities	521,404	613,611
Operating Segment | Metals Recycling/Ferrous Resources | Other segments
Segment Reporting Information
Total net sales	227,078	343,928
Operating Segment | Metals Recycling/Ferrous Resources | U.S.
Segment Reporting Information
Total net sales	427,411	517,957
Operating Segment | Metals Recycling/Ferrous Resources | Non-U.S.
Segment Reporting Information
Total net sales	51,303	57,817
Operating Segment | Steel Fabrication Operations
Segment Reporting Information
Total net sales	161,028	115,861
Operating income (loss)	21,361	3,126
Income (loss) before income taxes	19,594	1,652
Depreciation and amortization	2,230	2,222
Assets	289,814	263,688
Liabilities	46,328	17,022
Operating Segment | Steel Fabrication Operations | Other segments
Segment Reporting Information
Total net sales	4
Operating Segment | Steel Fabrication Operations | U.S.
Segment Reporting Information
Total net sales	161,024	115,861
Operating Segment | Other.
Segment Reporting Information
Total net sales	28,967	27,522
Operating income (loss)	-19,920	-16,545
Income (loss) before income taxes	-44,194	-24,187
Depreciation and amortization	1,190	1,399
Assets	481,726	609,206
Liabilities	2,810,613	2,290,332
Operating Segment | Other. | Other segments
Segment Reporting Information
Total net sales	6,689	6,673
Operating Segment | Other. | U.S.
Segment Reporting Information
Total net sales	22,114	20,621
Operating Segment | Other. | Non-U.S.
Segment Reporting Information
Total net sales	164	228
Eliminations
Segment Reporting Information
Total net sales	-282,674	-394,333
Operating income (loss)	3,856	4,227
Income (loss) before income taxes	3,856	4,227
Depreciation and amortization	-50	-51
Assets	-189,364	-228,175
Liabilities	-183,468	-218,081
Eliminations | Other segments
Segment Reporting Information
Total net sales	($282,674)	($394,333)

Segment_Information_Details_2

Segment Information (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Operating income (loss)
Corporate SG & A	($76,350,000)	($70,042,000)
Profit sharing	-4,598,000	-5,395,000
Operating income	99,771,000	80,932,000
Assets
Cash and equivalents	160,982,000	342,919,000	361,363,000	395,156,000
Accounts receivable	741,309,000		859,835,000
Inventories	1,453,242,000		1,618,419,000
Deferred income taxes	33,414,000		35,503,000
Property, plant and equipment, net	3,085,587,000		3,123,906,000
Other	89,878,000		97,529,000
Total assets	6,735,838,000	5,913,857,000	7,311,027,000
Liabilities
Accounts payable	376,962,000		511,056,000
Income taxes payable	5,116,000		6,086,000
Accrued interest	51,800,000		50,405,000
Debt	2,700,000,000		3,000,000,000
Deferred income taxes	555,031,000		542,033,000
Liabilities	3,812,745,000	3,279,527,000
Operating Segment | Other.
Operating income (loss)
Corporate SG & A	-9,400,000	-8,300,000
Company-wide equity- based compensation	-5,900,000	-4,600,000
Profit sharing	-3,500,000	-4,700,000
Other, net	-1,100,000	1,100,000
Operating income	-19,920,000	-16,545,000
Assets
Cash and equivalents	136,500,000	285,600,000
Accounts receivable	11,000,000	12,300,000
Inventories	12,800,000	13,500,000
Deferred income taxes	33,400,000	17,800,000
Property, plant and equipment, net	67,900,000	71,600,000
Debt issuance costs, net	37,000,000	24,400,000
Intra-company debt	146,600,000	153,800,000
Other	36,500,000	30,200,000
Total assets	481,726,000	609,206,000
Liabilities
Accounts payable	52,500,000	44,100,000
Income taxes payable	5,200,000	23,500,000
Accrued interest	51,600,000	21,700,000
Accrued profit sharing	3,500,000	4,800,000
Debt	2,600,100,000	2,031,400,000
Deferred income taxes	77,500,000	138,000,000
Other	20,200,000	26,800,000
Liabilities	$2,810,613,000	$2,290,332,000

Segment_Information_Details_3

Segment Information (Details 3) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Operating income (loss)
Gross profit increase from intra-company sales	$187,042,000	$163,304,000
Assets elimination
Elimination of intra-company receivables	769,741,000		902,825,000
Other	89,878,000		97,529,000
Total assets	6,735,838,000	5,913,857,000	7,311,027,000
Liabilities elimination
Elimination of intra-company payables	376,962,000		511,056,000
Liabilities	3,812,745,000	3,279,527,000
Eliminations
Operating income (loss)
Gross profit increase from intra-company sales	3,900,000	4,200,000
Assets elimination
Elimination of intra-company receivables	-37,600,000	-65,100,000
Elimination of intra-company debt	-146,600,000	-153,800,000
Other	-5,200,000	-9,300,000
Total assets	-189,364,000	-228,175,000
Liabilities elimination
Elimination of intra-company payables	-38,000,000	-65,500,000
Elimination of intra-company debt	-146,600,000	-153,800,000
Other	1,100,000	1,200,000
Liabilities	($183,468,000)	($218,081,000)

Condensed_Consolidating_Inform2

Condensed Consolidating Information (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Condensed Consolidating Balance Sheets
Ownership interest in subsidiaries (as a percent)	100.00%
Cash and equivalents	$160,982	$361,363	$342,919	$395,156
Accounts receivable, net	769,741	902,825
Inventories	1,453,242	1,618,419
Other current assets	68,260	91,158
Total current assets	2,452,225	2,973,765
Property, plant and equipment, net	3,085,587	3,123,906
Intangible assets, net	364,620	370,669
Goodwill	743,528	745,158
Other assets, including investments in subs	89,878	97,529
Total assets	6,735,838	7,311,027	5,913,857
Accounts payable	376,962	511,056
Accrued expenses	210,645	293,066
Current maturities of long-term debt	30,727	46,460
Total current liabilities	618,334	850,582
Long-term debt	2,623,444	2,977,706
Other liabilities	570,967	560,872
Redeemable noncontrolling interests	126,340	126,340
Common stock	635	635
Treasury stock	-396,517	-398,898
Additional paid-in capital	1,088,605	1,083,435
Retained earnings (deficit)	2,225,354	2,227,843
Total Steel Dynamics, Inc. equity	2,918,077	2,913,015
Noncontrolling interests	-121,324	-117,488
Total equity	2,796,753	2,795,527
Total liabilities and equity	6,735,838	7,311,027
Reportable legal entity | Parent
Condensed Consolidating Balance Sheets
Cash and equivalents	130,541	265,313	281,376	320,866
Accounts receivable, net	258,508	321,493
Inventories	611,529	662,970
Other current assets	72,189	94,634
Total current assets	1,072,767	1,344,410
Property, plant and equipment, net	989,601	1,002,407
Other assets, including investments in subs	3,745,496	3,900,691
Total assets	5,807,864	6,247,508
Accounts payable	117,240	151,517
Accrued expenses	133,295	191,433
Current maturities of long-term debt	13,085	13,073
Total current liabilities	263,620	356,023
Long-term debt	2,589,085	2,942,360
Other liabilities	37,082	36,110
Common stock	635	635
Treasury stock	-396,517	-398,898
Additional paid-in capital	1,088,605	1,083,435
Retained earnings (deficit)	2,225,354	2,227,843
Total Steel Dynamics, Inc. equity	2,918,077	2,913,015
Total equity	2,918,077	2,913,015
Total liabilities and equity	5,807,864	6,247,508
Reportable legal entity | Guarantors
Condensed Consolidating Balance Sheets
Cash and equivalents	17,058	81,690	48,071	61,148
Accounts receivable, net	1,129,116	1,176,849
Inventories	759,470	862,796
Other current assets	9,213	8,416
Total current assets	1,914,857	2,129,751
Property, plant and equipment, net	1,796,992	1,826,208
Intangible assets, net	364,620	370,669
Goodwill	743,528	745,158
Other assets, including investments in subs	23,871	24,810
Total assets	4,843,868	5,096,596
Accounts payable	262,723	371,037
Accrued expenses	149,157	166,101
Current maturities of long-term debt	795	777
Total current liabilities	412,675	537,915
Long-term debt	224	624
Other liabilities	1,655,611	1,807,989
Common stock	1,727,860	1,727,859
Additional paid-in capital	117,737	117,737
Retained earnings (deficit)	929,761	904,472
Total Steel Dynamics, Inc. equity	2,775,358	2,750,068
Total equity	2,775,358	2,750,068
Total liabilities and equity	4,843,868	5,096,596
Reportable legal entity | Combined Non-Guarantors
Condensed Consolidating Balance Sheets
Cash and equivalents	13,383	14,360	13,472	13,142
Accounts receivable, net	24,017	44,696
Inventories	82,347	94,916
Other current assets	5,243	6,577
Total current assets	124,990	160,549
Property, plant and equipment, net	301,158	297,505
Other assets, including investments in subs	6,524	6,635
Total assets	432,672	464,689
Accounts payable	89,959	98,886
Accrued expenses	7,649	11,695
Current maturities of long-term debt	57,997	73,767
Total current liabilities	155,605	184,348
Long-term debt	167,621	158,665
Other liabilities	31,706	28,719
Redeemable noncontrolling interests	126,340	126,340
Common stock	18,121	18,121
Additional paid-in capital	635,335	635,156
Retained earnings (deficit)	-580,732	-569,172
Total Steel Dynamics, Inc. equity	72,724	84,105
Noncontrolling interests	-121,324	-117,488
Total equity	-48,600	-33,383
Total liabilities and equity	432,672	464,689
Consolidating Adjustments
Condensed Consolidating Balance Sheets
Accounts receivable, net	-641,900	-640,213
Inventories	-104	-2,263
Other current assets	-18,385	-18,469
Total current assets	-660,389	-660,945
Property, plant and equipment, net	-2,164	-2,214
Other assets, including investments in subs	-3,686,013	-3,834,607
Total assets	-4,348,566	-4,497,766
Accounts payable	-92,960	-110,384
Accrued expenses	-79,456	-76,163
Current maturities of long-term debt	-41,150	-41,157
Total current liabilities	-213,566	-227,704
Long-term debt	-133,486	-123,943
Other liabilities	-1,153,432	-1,311,946
Common stock	-1,745,981	-1,745,980
Additional paid-in capital	-753,072	-752,893
Retained earnings (deficit)	-349,029	-335,300
Total Steel Dynamics, Inc. equity	-2,848,082	-2,834,173
Total equity	-2,848,082	-2,834,173
Total liabilities and equity	($4,348,566)	($4,497,766)

Condensed_Consolidating_Inform3

Condensed Consolidating Information (Details 2) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Condensed Consolidating Statements of Operations
Net sales	$2,047,435	$1,830,082
Costs of goods sold	1,860,393	1,666,778
Gross profit	187,042	163,304
Selling, general and administrative	87,271	82,372
Operating income	99,771	80,932
Interest expense, net of capitalized interest	43,087	30,569
Other (income) expense, net	16,192	-631
Income before income taxes	40,492	50,994
Income taxes (benefit)	13,538	17,296
Net income	26,954	33,698
Net loss attributable to noncontrolling interests	3,807	4,881
Net income attributable to Steel Dynamics, Inc.	30,761	38,579
Reportable legal entity | Parent
Condensed Consolidating Statements of Operations
Net sales	798,718	863,563
Costs of goods sold	693,575	761,395
Gross profit	105,143	102,168
Selling, general and administrative	30,743	28,834
Operating income	74,400	73,334
Interest expense, net of capitalized interest	20,537	19,361
Other (income) expense, net	15,652	-976
Income before income taxes	38,211	54,949
Income taxes (benefit)	6,941	9,925
Net income	31,270	45,024
Equity in net loss of subsidiaries	-509	-6,445
Net income attributable to Steel Dynamics, Inc.	30,761	38,579
Reportable legal entity | Guarantors
Condensed Consolidating Statements of Operations
Net sales	2,191,009	2,112,389
Costs of goods sold	2,072,125	2,015,576
Gross profit	118,884	96,813
Selling, general and administrative	58,033	54,289
Operating income	60,851	42,524
Interest expense, net of capitalized interest	21,840	10,561
Other (income) expense, net	688	395
Income before income taxes	38,323	31,568
Income taxes (benefit)	13,034	10,942
Net income	25,289	20,626
Net income attributable to Steel Dynamics, Inc.	25,289	20,626
Reportable legal entity | Combined Non-Guarantors
Condensed Consolidating Statements of Operations
Net sales	104,573	105,849
Costs of goods sold	118,781	123,573
Gross profit	-14,208	-17,724
Selling, general and administrative	3,365	3,408
Operating income	-17,573	-21,132
Interest expense, net of capitalized interest	1,734	1,880
Other (income) expense, net	-1,172	-1,284
Income before income taxes	-18,135	-21,728
Income taxes (benefit)	-1,116	696
Net income	-17,019	-22,424
Net loss attributable to noncontrolling interests	3,807	4,881
Net income attributable to Steel Dynamics, Inc.	-13,212	-17,543
Consolidating Adjustments
Condensed Consolidating Statements of Operations
Net sales	-1,046,865	-1,251,719
Costs of goods sold	-1,024,088	-1,233,766
Gross profit	-22,777	-17,953
Selling, general and administrative	-4,870	-4,159
Operating income	-17,907	-13,794
Interest expense, net of capitalized interest	-1,024	-1,233
Other (income) expense, net	1,024	1,234
Income before income taxes	-17,907	-13,795
Income taxes (benefit)	-5,321	-4,267
Net income	-12,586	-9,528
Equity in net loss of subsidiaries	509	6,445
Net income attributable to Steel Dynamics, Inc.	($12,077)	($3,083)

Condensed_Consolidating_Inform4

Condensed Consolidating Information (Details 3) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities	$234,707	($27,247)
Net cash provided by (used in) investing activities	-31,688	4,043
Net cash provided by (used in) financing activities	-403,400	-29,033
Decrease in cash and equivalents	-200,381	-52,237
Cash and equivalents at beginning of period	361,363	395,156
Cash and equivalents at end of period	160,982	342,919
Reportable legal entity | Parent
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities	100,828	9,027
Net cash provided by (used in) investing activities	-18,547	-12,430
Net cash provided by (used in) financing activities	-217,053	-36,087
Decrease in cash and equivalents	-134,772	-39,490
Cash and equivalents at beginning of period	265,313	320,866
Cash and equivalents at end of period	130,541	281,376
Reportable legal entity | Guarantors
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities	114,451	-17,195
Net cash provided by (used in) investing activities	-12,949	-3,997
Net cash provided by (used in) financing activities	-166,134	8,115
Decrease in cash and equivalents	-64,632	-13,077
Cash and equivalents at beginning of period	81,690	61,148
Cash and equivalents at end of period	17,058	48,071
Reportable legal entity | Combined Non-Guarantors
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities	9,456	-14,149
Net cash provided by (used in) investing activities	-9,727	-1,625
Net cash provided by (used in) financing activities	-706	16,104
Decrease in cash and equivalents	-977	330
Cash and equivalents at beginning of period	14,360	13,142
Cash and equivalents at end of period	13,383	13,472
Consolidating Adjustments
Condensed Consolidating Statements of Cash Flows
Net cash provided by (used in) operating activities	9,972	-4,930
Net cash provided by (used in) investing activities	9,535	22,095
Net cash provided by (used in) financing activities	($19,507)	($17,165)