Nucor (NUE) 10-Q 8 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2017shares
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	NUE
Entity Registrant Name	NUCOR CORP
Entity Central Index Key	73,309
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	317,916,674

Condensed Consolidated Statemen

Condensed Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Income Statement [Abstract]
Net sales	$ 5,170,117	$ 4,290,236	$ 15,160,065	$ 12,251,584
Costs, expenses and other:
Cost of products sold	4,591,153	3,608,000	13,111,226	10,669,103
Marketing, administrative and other expenses	172,792	169,223	519,429	440,679
Equity in earnings of unconsolidated affiliates	(7,743)	(14,168)	(29,801)	(30,232)
Interest expense, net	43,310	43,009	131,495	128,415
Costs, expenses and other, total	4,799,512	3,806,064	13,732,349	11,207,965
Earnings before income taxes and noncontrolling interests	370,605	484,172	1,427,716	1,043,619
Provision for income taxes	104,500	152,807	442,239	318,388
Net earnings	266,105	331,365	985,477	725,231
Earnings attributable to noncontrolling interests	11,255	25,918	50,680	88,599
Net earnings attributable to Nucor stockholders	$ 254,850	$ 305,447	$ 934,797	$ 636,632
Net earnings per share:
Basic	$ 0.79	$ 0.95	$ 2.91	$ 1.99
Diluted	$ 0.79	$ 0.95	$ 2.90	$ 1.99
Average shares outstanding:
Basic	320,096	319,737	320,253	319,444
Diluted	320,763	320,028	321,045	319,632
Dividends declared per share	$ 0.3775	$ 0.3750	$ 1.1325	$ 1.1250

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Statement Of Comprehensive Income [Abstract]
Net earnings	$ 266,105	$ 331,365	$ 985,477	$ 725,231
Other comprehensive income (loss):
Net unrealized income (loss) on hedging derivatives, net of income taxes of $300 and ($300) for the third quarter of 2017 and 2016, respectively, and ($700) and $600 for the first nine months of 2017 and 2016, respectively	405	(600)	(1,301)	912
Reclassification adjustment for loss on settlement of hedging derivatives included in net income, net of income taxes of $0 and $1,200 for the third quarter of 2017 and 2016, respectively, and $300 and $4,800 for the first nine months of 2017 and 2016, respectively	195	2,000	851	8,288
Foreign currency translation gain (loss), net of income taxes of $0 for the third quarter of 2017 and 2016, and $0 for the first nine months of 2017 and 2016	74,479	(8,606)	100,437	53,578
Net current-period other comprehensive income (loss)	75,079	(7,206)	99,987	62,778
Comprehensive income	341,184	324,159	1,085,464	788,009
Comprehensive income attributable to noncontrolling interests	(11,255)	(25,918)	(50,680)	(88,599)
Comprehensive income attributable to Nucor stockholders	$ 329,929	$ 298,241	$ 1,034,784	$ 699,410

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Statement Of Comprehensive Income [Abstract]
Net unrealized income (loss) on hedging derivatives, tax	$ 300	$ (300)	$ (700)	$ 600
Reclassification adjustment for loss on settlement of hedging derivatives included in net income, tax effect	0	1,200	300	4,800
Foreign currency translation gain (loss) tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 1,575,944	$ 2,045,961
Short-term investments	50,000	150,000
Accounts receivable, net	2,113,890	1,631,676
Inventories, net	3,522,199	2,479,958
Other current assets	238,614	198,798
Total current assets	7,500,647	6,506,393
Property, plant and equipment, net	5,095,880	5,078,650
Goodwill	2,208,246	2,052,728
Other intangible assets, net	940,305	866,835
Other assets	758,756	718,912
Total assets	16,503,834	15,223,518
Current liabilities:
Short-term debt	50,370	17,959
Long-term debt due within one year	1,100,000	600,000
Accounts payable	1,312,817	838,109
Salaries, wages and related accruals	499,177	428,829
Accrued expenses and other current liabilities	593,102	505,069
Total current liabilities	3,555,466	2,389,966
Long-term debt due after one year	3,241,488	3,739,141
Deferred credits and other liabilities	861,066	839,703
Total liabilities	7,658,020	6,968,810
Nucor stockholders' equity:
Common stock	151,943	151,734
Additional paid-in capital	2,013,158	1,974,672
Retained earnings	8,201,667	7,630,916
Accumulated other comprehensive loss, net of income taxes	(217,856)	(317,843)
Treasury stock	(1,643,527)	(1,559,614)
Total Nucor stockholders' equity	8,505,385	7,879,865
Noncontrolling interests	340,429	374,843
Total equity	8,845,814	8,254,708
Total liabilities and equity	$ 16,503,834	$ 15,223,518

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016
Operating activities:
Net earnings	$ 985,477	$ 725,231
Adjustments:
Depreciation	474,822	459,109
Amortization	68,394	54,066
Stock-based compensation	51,227	44,210
Deferred income taxes	(38,335)	86,821
Distributions from affiliates	48,037	38,474
Equity in earnings of unconsolidated affiliates	(29,801)	(30,232)
Changes in assets and liabilities (exclusive of acquisitions and dispositions):
Accounts receivable	(406,582)	(328,000)
Inventories	(957,029)	(289,257)
Accounts payable	451,774	216,218
Federal income taxes	(30,859)	28,915
Salaries, wages and related accruals	70,231	103,324
Other operating activities	75,137	73,211
Cash provided by operating activities	762,493	1,182,090
Investing activities:
Capital expenditures	(292,312)	(327,436)
Investment in and advances to affiliates	(19,000)	(48,167)
Disposition of plant and equipment	19,420	14,883
Acquisitions (net of cash acquired)	(543,153)	(48,105)
Purchases of investments	(50,000)	(650,000)
Proceeds from the sale of investments	150,000	100,000
Other investing activities	(1,455)	13,350
Cash used in investing activities	(736,500)	(945,475)
Financing activities:
Net change in short-term debt	32,409	(21,520)
Issuance of common stock	9,492	5,727
Payment of tax withholdings on certain stock-based compensation	(13,960)	(10,410)
Excess tax benefits from stock-based compensation		1,507
Distributions to noncontrolling interests	(85,094)	(86,808)
Cash dividends	(364,302)	(360,675)
Acquisition of treasury stock	(90,305)	(5,173)
Other financing activities	(1,703)	(5,212)
Cash used in financing activities	(513,463)	(482,564)
Effect of exchange rate changes on cash	17,453	11,187
Decrease in cash and cash equivalents	(470,017)	(234,762)
Cash and cash equivalents-beginning of year	2,045,961	1,939,469
Cash and cash equivalents-end of nine months	1,575,944	1,704,707
Non-cash investing activity:
Change in accrued plant and equipment purchases and assets acquired by capital lease arrangements	$ 42,810	$ 140,347

Basis of Interim Presentation

Basis of Interim Presentation	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Interim Presentation	1. BASIS OF INTERIM PRESENTATION: The information included in this Item 1 reflects all adjustments which are, in the opinion of management, necessary to a fair statement of the results for the interim periods presented and are of a normal and recurring nature unless otherwise noted. The information furnished has not been audited; however, the December 31, 2016 condensed consolidated balance sheet data was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America. The unaudited condensed consolidated financial statements in this Item 1 should be read in conjunction with the audited consolidated financial statements and the notes thereto included in Nucor’s Annual Report on Form 10-K Recently Adopted Accounting Pronouncements – In the first quarter of 2017, Nucor adopted new accounting guidance that amends the accounting for employee share-based payment transactions. The new guidance requires income statement recognition of all tax effects, including all excess tax benefits and tax deficiencies, resulting from the settlement of share-based awards in the reporting period in which they occur. The new guidance also requires that all tax-related In January 2017, new guidance was issued regarding the simplification of the test for goodwill impairment. The new guidance eliminates Step 2 from the goodwill impairment test and will require an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2019, with early adoption permitted. The Company early adopted this new guidance in the first quarter of 2017. The adoption of this new guidance did not have a material impact on the Company’s consolidated financial statements. In August 2017, new guidance was issued regarding improvements to accounting and reporting for hedging activities to better reflect the economic results of an entity’s risk management activities. The new guidance reduces limitations on hedge designation and updates measurement guidance for qualifying hedging relationships. The new guidance also simplifies financial statement reporting for qualifying hedging relationships and aligns the recognition and presentation of the effects of the hedging instrument and hedged item within the financial statements. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2018, with early adoption permitted. The Company early adopted this new guidance in the third quarter of 2017. The adoption of this new guidance did not have a material impact on the Company’s consolidated financial statements. Recently Issued Accounting Pronouncements – In May 2014, new accounting guidance was issued that will supersede nearly all existing accounting guidance related to revenue recognition. The new guidance provides that an entity recognizes revenue when it transfers 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. The new guidance also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. The Financial Accounting Standards Board has also issued a number of updates to this new accounting guidance. The Company will adopt the new revenue recognition guidance effective January 1, 2018. Using the modified retrospective approach, the Company will recognize the cumulative effect of the adoption, if any, as an adjustment to the opening balance of retained earnings. The Company does not expect the adoption of this new guidance to have a material effect on the Company’s consolidated financial statements. In January 2016, new accounting guidance was issued regarding the recognition and measurement of financial assets and financial liabilities. Changes to the current accounting guidance primarily affect the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, the Financial Accounting Standards Board clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale In February 2016, new accounting guidance was issued regarding the accounting for leases. The new guidance requires all lessees to recognize on the balance sheet right to use assets and lease liabilities for the rights and obligations created by lease arrangements with terms greater than 12 months. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2018. The Company is evaluating the impact that the adoption of this new guidance will have on its consolidated financial statements, but it expects that assets and liabilities will increase on the consolidated balance sheet. In August 2016, new accounting guidance was issued regarding the presentation and classification of certain cash receipts and cash payments in the statement of cash flows. The new guidance addresses specific cash flow presentation issues in order to reduce diversity in existing practice. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2017. The Company is evaluating the impact that the adoption of this new guidance will have on its consolidated financial statements. In October 2016, new accounting guidance was issued regarding intra-entity transfers of assets other than inventory. The new guidance requires that an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2017. The Company is evaluating the impact that the adoption of this new guidance will have on its consolidated financial statements. Prior Year Change in Accounting Principle – In the fourth quarter of 2016, the Company changed its accounting method for valuing its inventories held by the parent company and Nucor-Yamato Steel Company to the first-in, first-out last-in, first-out The effects of the change in accounting principle from LIFO to FIFO have been retrospectively applied to all periods presented. As a result of the retrospective application of the change in accounting principle, certain financial statement line items in the Company’s condensed consolidated statements of earnings for the three- and nine-month periods ended October 1, 2016 and condensed consolidated statement of cash flows (no impact on total cash provided by operating activities) for the nine-month period ended October 1, 2016 were adjusted as follows: (in thousands, except per share data) As Originally Reported Effect of Change As Currently Reported Condensed Consolidated Statement of Earnings for the Three Months (13 Weeks) Ended October 1, 2016: Cost of products sold $ 3,665,900 $ (57,900 ) $ 3,608,000 Provision for income taxes 131,788 21,019 152,807 Net earnings 294,484 36,881 331,365 Earnings attributable to noncontrolling interests 24,448 1,470 25,918 Net earnings attributable to Nucor stockholders 270,036 35,411 305,447 Net earnings per share: Basic $ 0.84 $ 0.11 $ 0.95 Diluted $ 0.84 $ 0.11 $ 0.95 (in thousands, except per share data) As Originally Reported Effect of Change As Currently Reported Condensed Consolidated Statement of Earnings for the Nine Months (39 Weeks) Ended October 1, 2016: Cost of products sold $ 10,774,040 $ (104,937 ) $ 10,669,103 Provision for income taxes 281,401 36,987 318,388 Net earnings 657,281 67,950 725,231 Earnings attributable to noncontrolling interests 82,719 5,880 88,599 Net earnings attributable to Nucor stockholders 574,562 62,070 636,632 Net earnings per share: Basic $ 1.79 $ 0.20 $ 1.99 Diluted $ 1.79 $ 0.20 $ 1.99 (in thousands) Condensed Consolidated Statement of Cash Flows for the Nine Months (39 Weeks) Ended October 1, 2016: Net earnings $ 657,281 $ 67,950 $ 725,231 Changes in inventories (184,320 ) (104,937 ) (289,257 ) Changes in deferred income taxes 49,834 36,987 86,821

Acquisitions and Dispositions

Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Acquisitions and Dispositions	2. ACQUISITIONS AND DISPOSITIONS: On January 20, 2017, Nucor used cash on hand to acquire Republic Conduit (Republic) for a purchase price of $331.6 million. Republic produces steel electrical conduit primarily used to protect and route electrical wiring in various nonresidential structures such as hospitals, office buildings and stadiums. With its two facilities located in Kentucky and Georgia, Republic’s annual shipment volume has averaged 146,000 tons during the past two years. This acquisition not only further expands Nucor’s product portfolio to include steel electrical conduit but the Company also believes it will be an important, value-added channel to market for Nucor’s sheet mills. Republic’s financial results are included as part of the steel mills segment (see Note 16). We have allocated the purchase price for Republic to its individual assets acquired and liabilities assumed. While the purchase price allocation is substantially complete, it is still preliminary and subject to change. The following table summarizes the fair values of the assets acquired and liabilities assumed of Republic as of the date of acquisition (in thousands): Cash $ 206 Accounts receivable 39,177 Inventory 33,561 Other current assets 1,101 Property, plant and equipment 67,412 Goodwill 115,562 Other intangible assets 89,200 Other assets 3,118 Total assets acquired 349,337 Current liabilities 17,743 Total liabilities assumed 17,743 Net assets acquired $ 331,594 The following table summarizes the purchase price allocation to the identifiable intangible assets of Republic as of the date of acquisition (in thousands, except years): Weighted - Customer relationships $ 80,800 12 years Trademarks and trade names 8,400 13 years $ 89,200 The goodwill of approximately $115.6 million is calculated as the excess of the purchase price over the fair values of the assets acquired and liabilities assumed and has been allocated to the steel mills segment (see Note 5). Goodwill recognized for tax purposes was $118.6 million, all of which is deductible for such purposes. Other acquisitions, exclusive of purchase price adjustments of acquisitions made and net of cash acquired, totaled $212.7 million in the first nine months of 2017 ($48.1 million in the first nine months of 2016). Included in the 2017 amount is the January 9, 2017 acquisition of Southland Tube (Southland) and the September 1, 2017 acquisition of St. Louis Cold Drawn, Inc. (St. Louis Cold Drawn). Nucor used cash on hand to acquire Southland and St. Louis Cold Drawn for purchase prices of approximately $130 million and $60 million, respectively. Southland is a manufacturer of hollow structural section tubing, which is primarily used in nonresidential construction markets. Southland had shipments of approximately 240,000 tons in 2016 and has one manufacturing facility in Birmingham, Alabama. St. Louis Cold Drawn is a manufacturer of cold drawn rounds, hexagons, squares, and special sections that mainly serves the U.S. and Mexican automotive and industrial markets. St. Louis Cold Drawn has two manufacturing locations, one in St. Louis, Missouri and the other in Monterrey, Mexico, that have a combined annual capacity of 200,000 tons.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2017
Inventory Disclosure [Abstract]
Inventories	3. INVENTORIES: Inventories consisted of approximately 43% raw materials and supplies and 57% finished and semi-finished products at September 30, 2017 (37% and 63%, respectively, at December 31, 2016). Nucor’s manufacturing process consists of a continuous, vertically integrated process from which products are sold to customers at various stages throughout the process. Since most steel products can be classified as either finished or semi-finished products, these two categories of inventory are combined. Use of the lower of cost or market methodology reduced inventories by $1.9 million at September 30, 2017 ($2.2 million at December 31, 2016).

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	4. PROPERTY, PLANT AND EQUIPMENT: Property, plant and equipment is recorded net of accumulated depreciation of $8.61 billion at September 30, 2017 ($8.16 billion at December 31, 2016). Given the natural gas pricing environment, Nucor performed an impairment assessment of its proved producing natural gas well assets in December 2016. One of the main assumptions that most significantly affects the undiscounted cash flows determination is management’s estimate of future natural gas prices. The pricing used in this impairment assessment was developed by management based on projected natural gas market supply and demand dynamics, in conjunction with a review of projections by numerous sources of market data. This analysis was performed on each of Nucor’s three groups of wells, with each group defined by common geographic location. Each of Nucor’s three groups of wells passed the impairment test. One of the groups of wells had estimated undiscounted cash flows that were noticeably closer to its carrying value, which was $80.8 million as of December 31, 2016, than the other groups of wells. The carrying value of that group of wells was $74.0 million at September 30, 2017. The carrying value of the other groups of wells was $183.9 million as of September 30, 2017. Changes in the natural gas industry or a prolonged low price environment beyond what had already been assumed in the analysis could cause management to revise the natural gas price assumptions, which could possibly result in an impairment of some or all of the groups of proved well assets.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	5. GOODWILL AND OTHER INTANGIBLE ASSETS: The change in the net carrying amount of goodwill for the nine months ended September 30, 2017, by segment is as follows (in thousands): Steel Mills Steel Products Raw Materials Total Balance at December 31, 2016 $ 620,156 $ 702,995 $ 729,577 $ 2,052,728 Acquisitions 125,328 7,157 — 132,485 Translation — 23,033 — 23,033 Balance at September 30, 2017 $ 745,484 $ 733,185 $ 729,577 $ 2,208,246 Nucor completed its most recent annual goodwill impairment testing during the fourth quarter of 2016 and concluded that there was no impairment of goodwill for any of its reporting units. There have been no triggering events requiring an interim assessment for impairment since the most recent annual impairment testing date. Intangible assets with estimated useful lives of five to 22 years are amortized on a straight-line or accelerated basis and were comprised of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Gross Accumulated Gross Accumulated Customer relationships $ 1,422,569 $ 622,440 $ 1,295,803 $ 566,884 Trademarks and trade names 176,950 74,551 161,851 66,494 Other 62,807 25,030 62,807 20,248 $ 1,662,326 $ 722,021 $ 1,520,461 $ 653,626 Intangible asset amortization expense in the third quarter of 2017 and 2016 was $23.0 million and $18.5 million, respectively, and was $68.4 million and $54.1 million in the first nine months of 2017 and 2016, respectively. Annual amortization expense is estimated to be $91.2 million in 2017; $89.6 million in 2018; $86.7 million in 2019; $84.4 million in 2020; and $83.1 million in 2021.

Equity Investments

Equity Investments	9 Months Ended
	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity Investments	6. EQUITY INVESTMENTS: The carrying value of our equity investments in domestic and foreign companies was $695.2 million at September 30, 2017 ($663.4 million at December 31, 2016) and is recorded in other assets in the condensed consolidated balance sheets. NUMIT Nucor has a 50% economic and voting interest in NuMit LLC (NuMit). NuMit owns 100% of the equity interest in Steel Technologies LLC, an operator of 25 sheet processing facilities located throughout the United States, Canada and Mexico. Nucor accounts for the investment in NuMit (on a one-month DUFERDOFIN NUCOR Nucor owns a 50% economic and voting interest in Duferdofin Nucor S.r.l. (Duferdofin Nucor), an Italian steel manufacturer, and accounts for the investment (on a one-month Nucor’s investment in Duferdofin Nucor at September 30, 2017 was $280.8 million ($256.6 million at December 31, 2016). Nucor’s 50% share of the total net assets of Duferdofin Nucor was $112.6 million at September 30, 2017, resulting in a basis difference of $168.2 million due to the step-up step-up As of September 30, 2017, Nucor had outstanding notes receivable of €35.0 million ($41.3 million) from Duferdofin Nucor (€35.0 million, or $36.9 million, as of December 31, 2016). The notes receivable bear interest at 0.83% and reset annually on September 30 to the 12-month Euro Interbank Offered Rate (Euribor) plus 1% per year. The principal amounts are due on January 31, 2019. As of September 30, 2017 and December 31, 2016, the notes receivable were classified in other assets in the condensed consolidated balance sheets. Nucor has issued a guarantee, the fair value of which is immaterial, for its ownership percentage (50%) of Duferdofin Nucor’s borrowings under Facility A of a Structured Trade Finance Facilities Agreement (Facility A). The maximum amount Duferdofin Nucor could have borrowed under Facility A was €122.5 million ($144.6 million) as of September 30, 2017. As of September 30, 2017, there was €122.5 million ($144.6 million) outstanding under that facility (€107.0 million, or $112.7 million, as of December 31, 2016). Facility A was amended in 2015 to extend the maturity date to October 12, 2018. If Duferdofin Nucor fails to pay when due any amounts for which it is obligated under Facility A, Nucor could be required to pay 50% of such amounts pursuant to and in accordance with the terms of its guarantee. Any indebtedness of Duferdofin Nucor to Nucor is effectively subordinated to the indebtedness of Duferdofin Nucor under Facility A. Nucor has not recorded any liability associated with this guarantee. ALL EQUITY INVESTMENTS Nucor reviews its equity investments for impairment if and when circumstances indicate that a decline in value below their carrying amounts may have occurred. Nucor last assessed its equity investment in Duferdofin Nucor for impairment in 2015 due to the protracted challenging steel market conditions caused by excess global overcapacity, which increased in 2015, and the difficult economic environment in Europe. After completing its assessment, the Company determined that the carrying amount exceeded its estimated fair value and incurred a partial impairment of its investment. While the operating performance of Duferdofin Nucor showed meaningful improvement in 2016 and the first nine months of 2017, steel market conditions in Europe have continued to be challenging. Therefore, it is reasonably possible that material deviation of future performance from the estimates used in our most recent valuation could result in further impairment of our investment in Duferdofin Nucor. We will continue to monitor for potential triggering events that could affect the carrying value of our investment in Duferdofin Nucor as a result of future market conditions and any changes in our business strategy.

Current Liabilities

Current Liabilities	9 Months Ended
	Sep. 30, 2017
Payables and Accruals [Abstract]
Current Liabilities	7. CURRENT LIABILITIES: Book overdrafts, included in accounts payable in the condensed consolidated balance sheets, were $125.3 million at September 30, 2017 ($61.3 million at December 31, 2016). Dividends payable, included in accrued expenses and other current liabilities in the condensed consolidated balance sheets, were $121.0 million at September 30, 2017 ($121.3 million at December 31, 2016).

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	8. FAIR VALUE MEASUREMENTS: The following table summarizes information regarding Nucor’s financial assets and financial liabilities that are measured at fair value as of September 30, 2017 and December 31, 2016 (in thousands). Nucor does not have any non-financial non-financial Fair Value Measurements at Reporting Date Using Description Carrying Quoted Prices Significant Significant As of September 30, 2017 Assets: Cash equivalents $ 1,143,259 $ 1,143,259 $ — $ — Short-term investments 50,000 50,000 — — Commodity contracts 400 — 400 — Total assets $ 1,193,659 $ 1,193,259 $ 400 $ — Liabilities: Commodity and foreign exchange contracts $ (2,318 ) $ — $ (2,318 ) $ — As of December 31, 2016 Assets: Cash equivalents $ 1,609,523 $ 1,609,523 $ — $ — Short-term investments 150,000 150,000 — — Commodity and foreign exchange contracts 2,029 — 2,029 — Total assets $ 1,761,552 $ 1,759,523 $ 2,029 $ — Liabilities: Commodity contracts $ (605 ) $ — $ (605 ) $ — Fair value measurements for Nucor’s cash equivalents and short-term investments are classified under Level 1 because such measurements are based on quoted market prices in active markets for identical assets. Our short-term investments are held in similar short-term investment instruments as described in Note 4 to the audited consolidated financial statements included in Nucor’s Annual Report on Form 10-K The fair value of short-term and long-term debt, including current maturities, was approximately $4.75 billion at September 30, 2017 ($4.70 billion at December 31, 2016). The debt fair value estimates are classified under Level 2 because such estimates are based on readily available market prices of our debt at September 30, 2017 and December 31, 2016, or similar debt with the same maturities, ratings and interest rates.

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Contingencies	9. CONTINGENCIES: Nucor is subject to environmental laws and regulations established by federal, state and local authorities and, accordingly, makes provision for the estimated costs of compliance. Of the undiscounted total of $18.7 million of accrued environmental costs at September 30, 2017 ($21.9 million at December 31, 2016), $6.3 million was classified in accrued expenses and other current liabilities ($9.5 million at December 31, 2016) and $12.4 million was classified in deferred credits and other liabilities ($12.4 million at December 31, 2016). Inherent uncertainties exist in these estimates primarily due to unknown conditions, evolving remediation technology and changing governmental regulations and legal standards. We are from time to time a party to various lawsuits, claims and other legal proceedings that arise in the ordinary course of business. With respect to all such lawsuits, claims and proceedings, we record reserves when it is probable a liability has been incurred and the amount of loss can be reasonably estimated. We do not believe that any of these proceedings, individually or in the aggregate, would be expected to have a material adverse effect on our results of operations, financial position or cash flows. Nucor maintains liability insurance for certain risks that is subject to certain self-insurance limits.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	10. STOCK-BASED COMPENSATION: Stock Options – Stock options may be granted to Nucor’s key employees, officers and non-employee A summary of activity under Nucor’s stock option plans for the first nine months of 2017 is as follows (in thousands, except years and per share amounts): Shares Weighted - Weighted - Aggregate Number of shares under stock options: Outstanding at beginning of year 3,591 $ 45.32 Granted 698 $ 59.07 Exercised (144 ) $ 37.54 $ 3,618 Canceled — — Outstanding at September 30, 2017 4,145 $ 47.90 7.1 years $ 35,842 Stock options exercisable at September 30, 2017 1,848 $ 43.37 5.2 years $ 23,415 Stock options granted to employees who are eligible for retirement on the date of grant are expensed immediately since these awards vest upon retirement from the Company. Retirement, for purposes of vesting in these stock options, means termination of employment after satisfying age and years of service requirements. Similarly, stock options granted to employees who will become retirement-eligible prior to the end of the vesting term are expensed over the period through which the employee will become retirement-eligible. Compensation expense for stock options granted to employees who will not become retirement-eligible prior to the end of the vesting term is recognized on a straight-line basis over the vesting period. Compensation expense for stock options was $0.4 million and $0.3 million in the third quarter of 2017 and 2016, respectively, and $7.9 million and $7.6 million in the first nine months of 2017 and 2016, respectively. As of September 30, 2017, unrecognized compensation expense related to stock options was $2.5 million, which is expected to be recognized over a weighted-average period of 2.2 years. Restricted Stock Units – Nucor annually grants restricted stock units (RSUs) to key employees, officers and non-employee non-employee non-employee RSUs granted to employees who are eligible for retirement on the date of grant are expensed immediately, and RSUs granted to employees who will become retirement-eligible prior to the end of the vesting term are expensed over the period through which the employee will become retirement-eligible since these awards vest upon retirement from the Company. Compensation expense for RSUs granted to employees who will not become retirement-eligible prior to the end of the vesting term is recognized on a straight-line basis over the vesting period. Cash dividend equivalents are paid to holders of RSUs each quarter. Dividend equivalents paid on RSUs expected to vest are recognized as a reduction in retained earnings. The fair value of an RSU is determined based on the closing stock price of Nucor’s common stock on the date of the grant A summary of Nucor’s RSU activity for the first nine months of 2017 is as follows (shares in thousands): Shares Grant Date Restricted stock units: Unvested at beginning of year 1,040 $ 48.47 Granted 721 $ 59.07 Vested (634 ) $ 53.21 Canceled (13 ) $ 50.21 Unvested at September 30, 2017 1,114 $ 52.61 Shares reserved for future grants (stock options and RSUs) 7,268 Compensation expense for RSUs was $6.1 million and $5.7 million in the third quarter of 2017 and 2016, respectively, and $32.2 million and $28.9 million in the first nine months of 2017 and 2016, respectively. As of September 30, 2017, unrecognized compensation expense related to unvested RSUs was $40.4 million, which is expected to be recognized over a weighted-average period of 2.3 years. Restricted Stock Awards – Nucor’s Senior Officers Long-Term Incentive Plan (LTIP) and Senior Officers Annual Incentive Plan (AIP) authorize the award of shares of common stock to officers subject to certain conditions and restrictions. The LTIP provides for the award of shares of restricted common stock at the end of each LTIP performance measurement period at no cost to officers if certain financial performance goals are met during the period. One-third The AIP provides for the payment of annual cash incentive awards. An AIP participant may elect, however, to defer payment of up to one-half A summary of Nucor’s restricted stock activity under the AIP and the LTIP for the first nine months of 2017 is as follows (shares in thousands): Shares Grant Date Restricted stock awards and units: Unvested at beginning of year 67 $ 45.77 Granted 172 $ 60.62 Vested (144 ) $ 51.69 Canceled — — Unvested at September 30, 2017 95 $ 54.45 Shares reserved for future grants 683 Compensation expense for common stock and common stock units awarded under the AIP and the LTIP is recorded over the performance measurement and vesting periods based on the anticipated number and market value of shares of common stock and common stock units to be awarded. Compensation expense for anticipated awards based upon Nucor’s financial performance, exclusive of amounts payable in cash, was $3.6 million and $0.7 million in the third quarter of 2017 and 2016, respectively, and $11.1 million and $7.7 million in the first nine months of 2017 and 2016, respectively. As of September 30, 2017, unrecognized compensation expense related to unvested restricted stock awards was $1.3 million, which is expected to be recognized over a weighted-average period of 1.9 years.

Employee Benefit Plan

Employee Benefit Plan	9 Months Ended
	Sep. 30, 2017
Retirement Benefits [Abstract]
Employee Benefit Plan	11. EMPLOYEE BENEFIT PLAN: Nucor makes contributions to a Profit Sharing and Retirement Savings Plan for qualified employees based on the profitability of the Company. Nucor’s expense for these benefits totaled $35.7 million and $38.5 million in the third quarter of 2017 and 2016, respectively, and was $138.2 million and $86.3 million in the first nine months of 2017 and 2016, respectively. The related liability for these benefits is included in salaries, wages and related accruals in the condensed consolidated balance sheets.

Interest Expense (Income)

Interest Expense (Income)	9 Months Ended
	Sep. 30, 2017
Interest Revenue (Expense), Net [Abstract]
Interest Expense (Income)	12. INTEREST EXPENSE (INCOME): The components of net interest expense for the third quarter and first nine months of 2017 and 2016 are as follows (in thousands): Three Months (13 Weeks) Ended Nine Months (39 Weeks) Ended Sept. 30, 2017 Oct. 1, 2016 Sept. 30, 2017 Oct. 1, 2016 Interest expense $ 47,621 $ 46,519 $ 141,486 $ 137,370 Interest income (4,311 ) (3,510 ) (9,991 ) (8,955 ) Interest expense, net $ 43,310 $ 43,009 $ 131,495 $ 128,415

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	13. INCOME TAXES: The effective tax rate for the third quarter of 2017 was 28.2% compared to 31.6% for the third quarter of 2016. The decrease in the effective tax rate for the third quarter of 2017 as compared to the third quarter of 2016 was primarily due to a net tax benefit totaling $13.2 million related to a return to provision change in estimate and state tax credits included during the third quarter of 2017. Nucor has concluded U.S. federal income tax matters for years through 2013. The tax years 2014 through 2016 remain open to examination by the Internal Revenue Service. The Canada Revenue Agency has substantially concluded its examination of the 2012 Canadian returns for Harris Steel Group Inc. and certain related affiliates and is now examining the 2013 Canadian returns. The tax years 2010 through 2016 remain open to examination by other major taxing jurisdictions to which Nucor is subject (primarily Canada and other state and local jurisdictions). Non-current Non-current

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	14. STOCKHOLDERS’ EQUITY: The following tables reflect the changes in stockholders’ equity attributable to both Nucor and the noncontrolling interests of Nucor’s joint ventures, primarily Nucor-Yamato Steel Company, of which Nucor owns 51%, for the nine months ended September 30, 2017 and October 1, 2016 (in thousands): Attributable to Attributable to Total Stockholders’ equity at December 31, 2016 $ 7,879,865 $ 374,843 $ 8,254,708 Total comprehensive income 1,034,784 50,680 1,085,464 Stock options 13,300 — 13,300 Issuance of stock under award plans, net of forfeitures 30,787 — 30,787 Amortization of unearned compensation 1,000 — 1,000 Treasury stock acquired (90,305 ) — (90,305 ) Dividends declared (364,046 ) — (364,046 ) Distributions to noncontrolling interests — (85,094 ) (85,094 ) Stockholders’ equity at September 30, 2017 $ 8,505,385 $ 340,429 $ 8,845,814 Attributable to Attributable to Total Stockholders’ equity at December 31, 2015 $ 7,477,816 $ 372,061 $ 7,849,877 Total comprehensive income 699,410 88,599 788,009 Stock options 13,229 — 13,229 Issuance of stock under award plans, net of forfeitures 25,929 — 25,929 Amortization of unearned compensation 600 — 600 Treasury stock acquired (5,173 ) — (5,173 ) Dividends declared (360,955 ) — (360,955 ) Distributions to noncontrolling interests — (86,808 ) (86,808 ) Other (602 ) (1,776 ) (2,378 ) Stockholders’ equity at October 1, 2016 $ 7,850,254 $ 372,076 $ 8,222,330 In September 2015, the Company announced that the Board of Directors had approved a stock repurchase program under which the Company is authorized to repurchase up to $900 million of the Company’s common stock. This $900 million share repurchase program has no stated expiration and replaced any previously authorized repurchase programs. As of September 30, 2017, the Company had approximately $738.0 million remaining available under the program. The Company expects any share repurchases to be made through purchases from time to time in the open market at prevailing market prices, through private transactions or block trades. The timing and amount of any repurchases will depend on market conditions, share price, applicable legal requirements and other factors.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	15. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS): The following tables reflect the changes in accumulated other comprehensive income (loss) by component for the three- and nine-month periods ended September 30, 2017 and October 1, 2016 (in thousands): Three-Month (13 Week) Period Ended September 30, 2017 Gains and Losses on Foreign Currency Adjustment to Early Total Accumulated other comprehensive loss at July 1, 2017 $ (300 ) $ (300,212 ) $ 7,577 $ (292,935 ) Other comprehensive income (loss) before reclassifications 405 74,479 — 74,884 Amounts reclassified from accumulated other comprehensive income (loss) into earnings (1) 195 — — 195 Net current-period other comprehensive income (loss) 600 74,479 — 75,079 Accumulated other comprehensive loss at September 30, 2017 $ 300 $ (225,733 ) $ 7,577 $ (217,856 ) Nine-Month (39 Week) Period Ended September 30, 2017 Gains and Losses on Foreign Currency Adjustment to Early Total Accumulated other comprehensive loss at December 31, 2016 $ 750 $ (326,170 ) $ 7,577 $ (317,843 ) Other comprehensive income (loss) before reclassifications (1,301 ) 100,437 — 99,136 Amounts reclassified from accumulated other comprehensive income (loss) into earnings (1) 851 — — 851 Net current-period other comprehensive income (loss) (450 ) 100,437 — 99,987 Accumulated other comprehensive loss at September 30, 2017 $ 300 $ (225,733 ) $ 7,577 $ (217,856 ) (1) Includes $195 and $851 of accumulated other comprehensive income reclassifications into cost of products sold for net losses on commodity contracts in the third quarter and first nine months of 2017, respectively. The tax impacts of those reclassifications were $0 and $300, respectively. Three-Month (13 Week) Period Ended October 1, 2016 Gains and Losses on Foreign Currency Adjustment to Early Total Accumulated other comprehensive loss at July 2, 2016 $ (3,900 ) $ (289,481 ) $ 12,003 $ (281,378 ) Other comprehensive income (loss) before reclassifications (600 ) (8,606 ) — (9,206 ) Amounts reclassified from accumulated other comprehensive income (loss) into earnings (2) 2,000 — — 2,000 Net current-period other comprehensive income (loss) 1,400 (8,606 ) — (7,206 ) Accumulated other comprehensive loss at October 1, 2016 $ (2,500 ) $ (298,087 ) $ 12,003 $ (288,584 ) Nine-Month (39 Week) Period Ended October 1, 2016 Gains and Losses on Foreign Currency Adjustment to Early Total Accumulated other comprehensive loss at December 31, 2015 $ (11,700 ) $ (351,665 ) $ 12,003 $ (351,362 ) Other comprehensive income (loss) before reclassifications 912 53,578 — 54,490 Amounts reclassified from accumulated other comprehensive income (loss) into earnings (2) 8,288 — — 8,288 Net current-period other comprehensive income (loss) 9,200 53,578 — 62,778 Accumulated other comprehensive loss at October 1, 2016 $ (2,500 ) $ (298,087 ) $ 12,003 $ (288,584 ) (2) Includes $2,000 and $8,288 of accumulated other comprehensive income reclassifications into cost of products sold for net losses on commodity contracts in the third quarter and first nine months of 2016, respectively. The tax impacts of those reclassifications were $1,200 and $4,800, respectively.

Segments

Segments	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segments	16. SEGMENTS: Nucor reports its results in the following segments: steel mills, steel products and raw materials. The steel mills segment includes carbon and alloy steel in sheet, bars, structural and plate; steel foundation distributors; tubular products businesses; steel trading businesses; rebar distribution businesses; and Nucor’s equity method investments in Duferdofin Nucor and NuMit. The steel products segment includes steel joists and joist girders, steel deck, fabricated concrete reinforcing steel, cold finished steel, steel fasteners, metal building systems, steel grating and wire and wire mesh. The raw materials segment includes The David J. Joseph Company and its affiliates, primarily a scrap broker and processor; Nu-Iron Net interest expense, other income, profit sharing expense and stock-based compensation are shown under Corporate/eliminations. Corporate assets primarily include cash and cash equivalents, short-term investments, allowances to eliminate intercompany profit in inventory, deferred income tax assets, federal and state income taxes receivable and investments in and advances to affiliates. The balance of earnings (loss) before income taxes and noncontrolling interests as of and for the periods ended October 1, 2016 was adjusted due to the change in accounting principle from LIFO to FIFO for certain inventories (see Note 1). Nucor’s results by segment for the third quarter and first nine months of 2017 and 2016 were as follows (in thousands): Three Months (13 Weeks) Ended Nine Months (39 Weeks) Ended Sept. 30, 2017 Oct. 1, 2016 Sept. 30, 2017 Oct. 1, 2016 Net sales to external customers: Steel mills $ 3,639,488 $ 2,960,642 $ 10,982,636 $ 8,611,553 Steel products 1,089,519 1,011,602 2,919,992 2,763,335 Raw materials 441,110 317,992 1,257,437 876,696 $ 5,170,117 $ 4,290,236 $ 15,160,065 $ 12,251,584 Intercompany sales: Steel mills $ 767,268 $ 567,854 $ 2,189,123 $ 1,592,512 Steel products 28,537 31,117 80,652 80,277 Raw materials 2,333,840 1,774,538 6,971,831 4,717,370 Corporate/eliminations (3,129,645 ) (2,373,509 ) (9,241,606 ) (6,390,159 ) $ — $ — $ — $ — Earnings (loss) before income taxes and noncontrolling interests: Steel mills $ 432,718 $ 591,799 $ 1,734,245 $ 1,402,898 Steel products 59,225 72,578 131,956 197,891 Raw materials 9,957 14,313 102,575 (76,240 ) Corporate/eliminations (131,295 ) (194,518 ) (541,060 ) (480,930 ) $ 370,605 $ 484,172 $ 1,427,716 $ 1,043,619 Sept. 30, 2017 Dec. 31, 2016 Segment assets: Steel mills $ 9,272,209 $ 8,084,773 Steel products 2,893,703 2,544,344 Raw materials 3,462,340 3,235,237 Corporate/eliminations 875,582 1,359,164 $ 16,503,834 $ 15,223,518

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings Per Share	17. EARNINGS PER SHARE: The computations of basic and diluted net earnings per share for the third quarter and first nine months of 2017 and 2016 are as follows (in thousands, except per share amounts): Three Months (13 Weeks) Ended Nine Months (39 Weeks) Ended Sept. 30, 2017 Oct. 1, 2016 Sept. 30, 2017 Oct. 1, 2016 Basic net earnings per share: Basic net earnings $ 254,850 $ 305,447 $ 934,797 $ 636,632 Earnings allocated to participating securities (900 ) (1,034 ) (3,239 ) (2,115 ) Net earnings available to common stockholders $ 253,950 $ 304,413 $ 931,558 $ 634,517 Average shares outstanding 320,096 319,737 320,253 319,444 Basic net earnings per share $ 0.79 $ 0.95 $ 2.91 $ 1.99 Diluted net earnings per share: Diluted net earnings $ 254,850 $ 305,447 $ 934,797 $ 636,632 Earnings allocated to participating securities (899 ) (1,034 ) (3,233 ) (2,116 ) Net earnings available to common stockholders $ 253,951 $ 304,413 $ 931,564 $ 634,516 Diluted average shares outstanding: Basic shares outstanding 320,096 319,737 320,253 319,444 Dilutive effect of stock options and other 667 291 792 188 320,763 320,028 321,045 319,632 Diluted net earnings per share $ 0.79 $ 0.95 $ 2.90 $ 1.99 The following stock options were excluded from the computation of diluted net earnings per share for the third quarter and first nine months of 2017 and 2016 because their effect would have been anti-dilutive (in thousands, except per share amounts): Three Months (13 Weeks) Ended Nine Months (39 Weeks) Ended Sept. 30, 2017 Oct. 1, 2016 Sept. 30, 2017 Oct. 1, 2016 Anti-dilutive stock options: Weighted-average shares 698 — 309 1,254 Weighted-average exercise price $ 59.07 $ — $ 59.07 $ 47.04

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	18. SUBSEQUENT EVENTS: We evaluate events occurring after the date of our accompanying consolidated balance sheets for potential recognition or disclosure in our financial statements. Subsequent to September 30, 2017, we changed our estimate of potential liabilities related to certain legal matters that existed as of September 30, 2017. As a result of this change in estimate, we recorded a $0.05 per diluted share expense related to these legal matters. The expense is included in marketing, administrative and other expenses on the condensed consolidated statements of earnings for the three month and nine month periods ended September 30, 2017. The accrual related to this expense is included in accrued expenses and other current liabilities on the condensed consolidated balance sheets as of September 30, 2017. The developments that led to this change in estimate occurred after the Company issued a news release announcing the preliminary financial results for the third quarter and first nine months of 2017, which release was included as an exhibit to the Current Report on Form 8-K furnished with the Securities and Exchange Commission on October 19, 2017.

Basis of Interim Presentation (

Basis of Interim Presentation (Policies)	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements – In the first quarter of 2017, Nucor adopted new accounting guidance that amends the accounting for employee share-based payment transactions. The new guidance requires income statement recognition of all tax effects, including all excess tax benefits and tax deficiencies, resulting from the settlement of share-based awards in the reporting period in which they occur. The new guidance also requires that all tax-related In January 2017, new guidance was issued regarding the simplification of the test for goodwill impairment. The new guidance eliminates Step 2 from the goodwill impairment test and will require an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2019, with early adoption permitted. The Company early adopted this new guidance in the first quarter of 2017. The adoption of this new guidance did not have a material impact on the Company’s consolidated financial statements. In August 2017, new guidance was issued regarding improvements to accounting and reporting for hedging activities to better reflect the economic results of an entity’s risk management activities. The new guidance reduces limitations on hedge designation and updates measurement guidance for qualifying hedging relationships. The new guidance also simplifies financial statement reporting for qualifying hedging relationships and aligns the recognition and presentation of the effects of the hedging instrument and hedged item within the financial statements. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2018, with early adoption permitted. The Company early adopted this new guidance in the third quarter of 2017. The adoption of this new guidance did not have a material impact on the Company’s consolidated financial statements.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements – In May 2014, new accounting guidance was issued that will supersede nearly all existing accounting guidance related to revenue recognition. The new guidance provides that an entity recognizes revenue when it transfers 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. The new guidance also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments, and assets recognized from costs incurred to obtain or fulfill a contract. The Financial Accounting Standards Board has also issued a number of updates to this new accounting guidance. The Company will adopt the new revenue recognition guidance effective January 1, 2018. Using the modified retrospective approach, the Company will recognize the cumulative effect of the adoption, if any, as an adjustment to the opening balance of retained earnings. The Company does not expect the adoption of this new guidance to have a material effect on the Company’s consolidated financial statements. In January 2016, new accounting guidance was issued regarding the recognition and measurement of financial assets and financial liabilities. Changes to the current accounting guidance primarily affect the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. In addition, the Financial Accounting Standards Board clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale In February 2016, new accounting guidance was issued regarding the accounting for leases. The new guidance requires all lessees to recognize on the balance sheet right to use assets and lease liabilities for the rights and obligations created by lease arrangements with terms greater than 12 months. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2018. The Company is evaluating the impact that the adoption of this new guidance will have on its consolidated financial statements, but it expects that assets and liabilities will increase on the consolidated balance sheet. In August 2016, new accounting guidance was issued regarding the presentation and classification of certain cash receipts and cash payments in the statement of cash flows. The new guidance addresses specific cash flow presentation issues in order to reduce diversity in existing practice. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2017. The Company is evaluating the impact that the adoption of this new guidance will have on its consolidated financial statements. In October 2016, new accounting guidance was issued regarding intra-entity transfers of assets other than inventory. The new guidance requires that an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance is effective for the Company for annual and interim reporting periods beginning after December 15, 2017. The Company is evaluating the impact that the adoption of this new guidance will have on its consolidated financial statements.
Prior Year Change in Accounting Principle	Prior Year Change in Accounting Principle – In the fourth quarter of 2016, the Company changed its accounting method for valuing its inventories held by the parent company and Nucor-Yamato Steel Company to the first-in, first-out last-in, first-out

Basis of Interim Presentation26

Basis of Interim Presentation (Tables)	9 Months Ended
	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Adjustments to Condensed Consolidated Financial Statements and Effect of Change in Accounting Principle from LIFO to FIFO on Net Earnings	As a result of the retrospective application of the change in accounting principle, certain financial statement line items in the Company’s condensed consolidated statements of earnings for the three- and nine-month periods ended October 1, 2016 and condensed consolidated statement of cash flows (no impact on total cash provided by operating activities) for the nine-month period ended October 1, 2016 were adjusted as follows: (in thousands, except per share data) As Originally Reported Effect of Change As Currently Reported Condensed Consolidated Statement of Earnings for the Three Months (13 Weeks) Ended October 1, 2016: Cost of products sold $ 3,665,900 $ (57,900 ) $ 3,608,000 Provision for income taxes 131,788 21,019 152,807 Net earnings 294,484 36,881 331,365 Earnings attributable to noncontrolling interests 24,448 1,470 25,918 Net earnings attributable to Nucor stockholders 270,036 35,411 305,447 Net earnings per share: Basic $ 0.84 $ 0.11 $ 0.95 Diluted $ 0.84 $ 0.11 $ 0.95 (in thousands, except per share data) As Originally Reported Effect of Change As Currently Reported Condensed Consolidated Statement of Earnings for the Nine Months (39 Weeks) Ended October 1, 2016: Cost of products sold $ 10,774,040 $ (104,937 ) $ 10,669,103 Provision for income taxes 281,401 36,987 318,388 Net earnings 657,281 67,950 725,231 Earnings attributable to noncontrolling interests 82,719 5,880 88,599 Net earnings attributable to Nucor stockholders 574,562 62,070 636,632 Net earnings per share: Basic $ 1.79 $ 0.20 $ 1.99 Diluted $ 1.79 $ 0.20 $ 1.99 (in thousands) Condensed Consolidated Statement of Cash Flows for the Nine Months (39 Weeks) Ended October 1, 2016: Net earnings $ 657,281 $ 67,950 $ 725,231 Changes in inventories (184,320 ) (104,937 ) (289,257 ) Changes in deferred income taxes 49,834 36,987 86,821

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables) - Republic [Member]	9 Months Ended
	Sep. 30, 2017
Fair Values of Assets Acquired and Liabilities Assumed	The following table summarizes the fair values of the assets acquired and liabilities assumed of Republic as of the date of acquisition (in thousands): Cash $ 206 Accounts receivable 39,177 Inventory 33,561 Other current assets 1,101 Property, plant and equipment 67,412 Goodwill 115,562 Other intangible assets 89,200 Other assets 3,118 Total assets acquired 349,337 Current liabilities 17,743 Total liabilities assumed 17,743 Net assets acquired $ 331,594
Purchase Price Allocation of Identifiable Intangible Assets	The following table summarizes the purchase price allocation to the identifiable intangible assets of Republic as of the date of acquisition (in thousands, except years): Weighted - Customer relationships $ 80,800 12 years Trademarks and trade names 8,400 13 years $ 89,200

Goodwill and Other Intangible28

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Change in Net Carrying Amount of Goodwill by Segment	The change in the net carrying amount of goodwill for the nine months ended September 30, 2017, by segment is as follows (in thousands): Steel Mills Steel Products Raw Materials Total Balance at December 31, 2016 $ 620,156 $ 702,995 $ 729,577 $ 2,052,728 Acquisitions 125,328 7,157 — 132,485 Translation — 23,033 — 23,033 Balance at September 30, 2017 $ 745,484 $ 733,185 $ 729,577 $ 2,208,246
Schedule of Intangible Assets	Intangible assets with estimated useful lives of five to 22 years are amortized on a straight-line or accelerated basis and were comprised of the following as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Gross Accumulated Gross Accumulated Customer relationships $ 1,422,569 $ 622,440 $ 1,295,803 $ 566,884 Trademarks and trade names 176,950 74,551 161,851 66,494 Other 62,807 25,030 62,807 20,248 $ 1,662,326 $ 722,021 $ 1,520,461 $ 653,626

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities Measured at Fair Value	The following table summarizes information regarding Nucor’s financial assets and financial liabilities that are measured at fair value as of September 30, 2017 and December 31, 2016 (in thousands). Nucor does not have any non-financial non-financial Fair Value Measurements at Reporting Date Using Description Carrying Quoted Prices Significant Significant As of September 30, 2017 Assets: Cash equivalents $ 1,143,259 $ 1,143,259 $ — $ — Short-term investments 50,000 50,000 — — Commodity contracts 400 — 400 — Total assets $ 1,193,659 $ 1,193,259 $ 400 $ — Liabilities: Commodity and foreign exchange contracts $ (2,318 ) $ — $ (2,318 ) $ — As of December 31, 2016 Assets: Cash equivalents $ 1,609,523 $ 1,609,523 $ — $ — Short-term investments 150,000 150,000 — — Commodity and foreign exchange contracts 2,029 — 2,029 — Total assets $ 1,761,552 $ 1,759,523 $ 2,029 $ — Liabilities: Commodity contracts $ (605 ) $ — $ (605 ) $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Plans Activity	A summary of activity under Nucor’s stock option plans for the first nine months of 2017 is as follows (in thousands, except years and per share amounts): Shares Weighted - Weighted - Aggregate Number of shares under stock options: Outstanding at beginning of year 3,591 $ 45.32 Granted 698 $ 59.07 Exercised (144 ) $ 37.54 $ 3,618 Canceled — — Outstanding at September 30, 2017 4,145 $ 47.90 7.1 years $ 35,842 Stock options exercisable at September 30, 2017 1,848 $ 43.37 5.2 years $ 23,415
Summary of Nucor's RSU Activity	A summary of Nucor’s RSU activity for the first nine months of 2017 is as follows (shares in thousands): Shares Grant Date Restricted stock units: Unvested at beginning of year 1,040 $ 48.47 Granted 721 $ 59.07 Vested (634 ) $ 53.21 Canceled (13 ) $ 50.21 Unvested at September 30, 2017 1,114 $ 52.61 Shares reserved for future grants (stock options and RSUs) 7,268
Summary of Nucor's Restricted Stock Activity under AIP and LTIP	A summary of Nucor’s restricted stock activity under the AIP and the LTIP for the first nine months of 2017 is as follows (shares in thousands): Shares Grant Date Restricted stock awards and units: Unvested at beginning of year 67 $ 45.77 Granted 172 $ 60.62 Vested (144 ) $ 51.69 Canceled — — Unvested at September 30, 2017 95 $ 54.45 Shares reserved for future grants 683

Interest Expense (Income) (Tabl

Interest Expense (Income) (Tables)	9 Months Ended
	Sep. 30, 2017
Interest Revenue (Expense), Net [Abstract]
Schedule of Components of Net Interest Expense	The components of net interest expense for the third quarter and first nine months of 2017 and 2016 are as follows (in thousands): Three Months (13 Weeks) Ended Nine Months (39 Weeks) Ended Sept. 30, 2017 Oct. 1, 2016 Sept. 30, 2017 Oct. 1, 2016 Interest expense $ 47,621 $ 46,519 $ 141,486 $ 137,370 Interest income (4,311 ) (3,510 ) (9,991 ) (8,955 ) Interest expense, net $ 43,310 $ 43,009 $ 131,495 $ 128,415

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Schedule of Changes in Stockholders' Equity	The following tables reflect the changes in stockholders’ equity attributable to both Nucor and the noncontrolling interests of Nucor’s joint ventures, primarily Nucor-Yamato Steel Company, of which Nucor owns 51%, for the nine months ended September 30, 2017 and October 1, 2016 (in thousands): Attributable to Attributable to Total Stockholders’ equity at December 31, 2016 $ 7,879,865 $ 374,843 $ 8,254,708 Total comprehensive income 1,034,784 50,680 1,085,464 Stock options 13,300 — 13,300 Issuance of stock under award plans, net of forfeitures 30,787 — 30,787 Amortization of unearned compensation 1,000 — 1,000 Treasury stock acquired (90,305 ) — (90,305 ) Dividends declared (364,046 ) — (364,046 ) Distributions to noncontrolling interests — (85,094 ) (85,094 ) Stockholders’ equity at September 30, 2017 $ 8,505,385 $ 340,429 $ 8,845,814 Attributable to Attributable to Total Stockholders’ equity at December 31, 2015 $ 7,477,816 $ 372,061 $ 7,849,877 Total comprehensive income 699,410 88,599 788,009 Stock options 13,229 — 13,229 Issuance of stock under award plans, net of forfeitures 25,929 — 25,929 Amortization of unearned compensation 600 — 600 Treasury stock acquired (5,173 ) — (5,173 ) Dividends declared (360,955 ) — (360,955 ) Distributions to noncontrolling interests — (86,808 ) (86,808 ) Other (602 ) (1,776 ) (2,378 ) Stockholders’ equity at October 1, 2016 $ 7,850,254 $ 372,076 $ 8,222,330

Accumulated Other Comprehensi33

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Components of Accumulated Other Comprehensive Income (Loss)	The following tables reflect the changes in accumulated other comprehensive income (loss) by component for the three- and nine-month periods ended September 30, 2017 and October 1, 2016 (in thousands): Three-Month (13 Week) Period Ended September 30, 2017 Gains and Losses on Foreign Currency Adjustment to Early Total Accumulated other comprehensive loss at July 1, 2017 $ (300 ) $ (300,212 ) $ 7,577 $ (292,935 ) Other comprehensive income (loss) before reclassifications 405 74,479 — 74,884 Amounts reclassified from accumulated other comprehensive income (loss) into earnings (1) 195 — — 195 Net current-period other comprehensive income (loss) 600 74,479 — 75,079 Accumulated other comprehensive loss at September 30, 2017 $ 300 $ (225,733 ) $ 7,577 $ (217,856 ) Nine-Month (39 Week) Period Ended September 30, 2017 Gains and Losses on Foreign Currency Adjustment to Early Total Accumulated other comprehensive loss at December 31, 2016 $ 750 $ (326,170 ) $ 7,577 $ (317,843 ) Other comprehensive income (loss) before reclassifications (1,301 ) 100,437 — 99,136 Amounts reclassified from accumulated other comprehensive income (loss) into earnings (1) 851 — — 851 Net current-period other comprehensive income (loss) (450 ) 100,437 — 99,987 Accumulated other comprehensive loss at September 30, 2017 $ 300 $ (225,733 ) $ 7,577 $ (217,856 ) (1) Includes $195 and $851 of accumulated other comprehensive income reclassifications into cost of products sold for net losses on commodity contracts in the third quarter and first nine months of 2017, respectively. The tax impacts of those reclassifications were $0 and $300, respectively. Three-Month (13 Week) Period Ended October 1, 2016 Gains and Losses on Foreign Currency Adjustment to Early Total Accumulated other comprehensive loss at July 2, 2016 $ (3,900 ) $ (289,481 ) $ 12,003 $ (281,378 ) Other comprehensive income (loss) before reclassifications (600 ) (8,606 ) — (9,206 ) Amounts reclassified from accumulated other comprehensive income (loss) into earnings (2) 2,000 — — 2,000 Net current-period other comprehensive income (loss) 1,400 (8,606 ) — (7,206 ) Accumulated other comprehensive loss at October 1, 2016 $ (2,500 ) $ (298,087 ) $ 12,003 $ (288,584 ) Nine-Month (39 Week) Period Ended October 1, 2016 Gains and Losses on Foreign Currency Adjustment to Early Total Accumulated other comprehensive loss at December 31, 2015 $ (11,700 ) $ (351,665 ) $ 12,003 $ (351,362 ) Other comprehensive income (loss) before reclassifications 912 53,578 — 54,490 Amounts reclassified from accumulated other comprehensive income (loss) into earnings (2) 8,288 — — 8,288 Net current-period other comprehensive income (loss) 9,200 53,578 — 62,778 Accumulated other comprehensive loss at October 1, 2016 $ (2,500 ) $ (298,087 ) $ 12,003 $ (288,584 ) (2) Includes $2,000 and $8,288 of accumulated other comprehensive income reclassifications into cost of products sold for net losses on commodity contracts in the third quarter and first nine months of 2016, respectively. The tax impacts of those reclassifications were $1,200 and $4,800, respectively.

Segments (Tables)

Segments (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segments	Nucor’s results by segment for the third quarter and first nine months of 2017 and 2016 were as follows (in thousands): Three Months (13 Weeks) Ended Nine Months (39 Weeks) Ended Sept. 30, 2017 Oct. 1, 2016 Sept. 30, 2017 Oct. 1, 2016 Net sales to external customers: Steel mills $ 3,639,488 $ 2,960,642 $ 10,982,636 $ 8,611,553 Steel products 1,089,519 1,011,602 2,919,992 2,763,335 Raw materials 441,110 317,992 1,257,437 876,696 $ 5,170,117 $ 4,290,236 $ 15,160,065 $ 12,251,584 Intercompany sales: Steel mills $ 767,268 $ 567,854 $ 2,189,123 $ 1,592,512 Steel products 28,537 31,117 80,652 80,277 Raw materials 2,333,840 1,774,538 6,971,831 4,717,370 Corporate/eliminations (3,129,645 ) (2,373,509 ) (9,241,606 ) (6,390,159 ) $ — $ — $ — $ — Earnings (loss) before income taxes and noncontrolling interests: Steel mills $ 432,718 $ 591,799 $ 1,734,245 $ 1,402,898 Steel products 59,225 72,578 131,956 197,891 Raw materials 9,957 14,313 102,575 (76,240 ) Corporate/eliminations (131,295 ) (194,518 ) (541,060 ) (480,930 ) $ 370,605 $ 484,172 $ 1,427,716 $ 1,043,619 Sept. 30, 2017 Dec. 31, 2016 Segment assets: Steel mills $ 9,272,209 $ 8,084,773 Steel products 2,893,703 2,544,344 Raw materials 3,462,340 3,235,237 Corporate/eliminations 875,582 1,359,164 $ 16,503,834 $ 15,223,518

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Computations of Basic and Diluted Net Earnings Per Share	The computations of basic and diluted net earnings per share for the third quarter and first nine months of 2017 and 2016 are as follows (in thousands, except per share amounts): Three Months (13 Weeks) Ended Nine Months (39 Weeks) Ended Sept. 30, 2017 Oct. 1, 2016 Sept. 30, 2017 Oct. 1, 2016 Basic net earnings per share: Basic net earnings $ 254,850 $ 305,447 $ 934,797 $ 636,632 Earnings allocated to participating securities (900 ) (1,034 ) (3,239 ) (2,115 ) Net earnings available to common stockholders $ 253,950 $ 304,413 $ 931,558 $ 634,517 Average shares outstanding 320,096 319,737 320,253 319,444 Basic net earnings per share $ 0.79 $ 0.95 $ 2.91 $ 1.99 Diluted net earnings per share: Diluted net earnings $ 254,850 $ 305,447 $ 934,797 $ 636,632 Earnings allocated to participating securities (899 ) (1,034 ) (3,233 ) (2,116 ) Net earnings available to common stockholders $ 253,951 $ 304,413 $ 931,564 $ 634,516 Diluted average shares outstanding: Basic shares outstanding 320,096 319,737 320,253 319,444 Dilutive effect of stock options and other 667 291 792 188 320,763 320,028 321,045 319,632 Diluted net earnings per share $ 0.79 $ 0.95 $ 2.90 $ 1.99
Anti-dilutive Stock Options	The following stock options were excluded from the computation of diluted net earnings per share for the third quarter and first nine months of 2017 and 2016 because their effect would have been anti-dilutive (in thousands, except per share amounts): Three Months (13 Weeks) Ended Nine Months (39 Weeks) Ended Sept. 30, 2017 Oct. 1, 2016 Sept. 30, 2017 Oct. 1, 2016 Anti-dilutive stock options: Weighted-average shares 698 — 309 1,254 Weighted-average exercise price $ 59.07 $ — $ 59.07 $ 47.04

Basis of Interim Presentation -

Basis of Interim Presentation - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payment of tax withholdings on certain stock-based compensation	$ 13,960	$ 10,410

Basis of Interim Presentation37

Basis of Interim Presentation - Schedule of Adjustments to Condensed Consolidated Statement of Earnings (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of products sold	$ 4,591,153	$ 3,608,000	$ 13,111,226	$ 10,669,103
Provision for income taxes	104,500	152,807	442,239	318,388
Net earnings	266,105	331,365	985,477	725,231
Earnings attributable to noncontrolling interests	11,255	25,918	50,680	88,599
Net earnings attributable to Nucor stockholders	254,850	305,447	934,797	636,632
Net earnings per share:
Cost of products sold	4,591,153	3,608,000	13,111,226	10,669,103
Provision for income taxes	104,500	152,807	442,239	318,388
Net earnings	266,105	331,365	985,477	725,231
Earnings attributable to noncontrolling interests	11,255	25,918	50,680	88,599
Net earnings attributable to Nucor stockholders	$ 254,850	$ 305,447	$ 934,797	$ 636,632
Basic	$ 0.79	$ 0.95	$ 2.91	$ 1.99
Diluted	$ 0.79	$ 0.95	$ 2.90	$ 1.99
As Originally Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of products sold		$ 3,665,900		$ 10,774,040
Provision for income taxes		131,788		281,401
Net earnings		294,484		657,281
Earnings attributable to noncontrolling interests		24,448		82,719
Net earnings attributable to Nucor stockholders		270,036		574,562
Net earnings per share:
Cost of products sold		3,665,900		10,774,040
Provision for income taxes		131,788		281,401
Net earnings		294,484		657,281
Earnings attributable to noncontrolling interests		24,448		82,719
Net earnings attributable to Nucor stockholders		$ 270,036		$ 574,562
Basic		$ 0.84		$ 1.79
Diluted		$ 0.84		$ 1.79
Effect of Change [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cost of products sold		$ (57,900)		$ (104,937)
Provision for income taxes		21,019		36,987
Net earnings		36,881		67,950
Earnings attributable to noncontrolling interests		1,470		5,880
Net earnings attributable to Nucor stockholders		35,411		62,070
Net earnings per share:
Cost of products sold		(57,900)		(104,937)
Provision for income taxes		21,019		36,987
Net earnings		36,881		67,950
Earnings attributable to noncontrolling interests		1,470		5,880
Net earnings attributable to Nucor stockholders		$ 35,411		$ 62,070
Basic		$ 0.11		$ 0.20
Diluted		$ 0.11		$ 0.20

Basis of Interim Presentation38

Basis of Interim Presentation - Schedule of Adjustments to Condensed Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net earnings	$ 266,105	$ 331,365	$ 985,477	$ 725,231
Changes in inventories			(957,029)	(289,257)
Changes in deferred income taxes			$ (38,335)	86,821
As Originally Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net earnings		294,484		657,281
Changes in inventories				(184,320)
Changes in deferred income taxes				49,834
Effect of Change [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net earnings		$ 36,881		67,950
Changes in inventories				(104,937)
Changes in deferred income taxes				$ 36,987

Acquisitions and Dispositions -

Acquisitions and Dispositions - Additional Information (Detail)	Sep. 01, 2017USD ($)FacilityT	Jan. 20, 2017USD ($)FacilityT	Jan. 09, 2017USD ($)FacilityT	Sep. 30, 2017USD ($)	Oct. 01, 2016USD ($)	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Goodwill				$ 2,208,246,000		$ 2,052,728,000
Republic [Member]
Business Acquisition [Line Items]
Business acquisition approximate purchase price		$ 331,600,000
Approximate annual shipment tons | T		146,000
Number of manufacturing facilities | Facility		2
Goodwill		$ 115,562,000
Other Acquisitions [Member]
Business Acquisition [Line Items]
Business acquisition approximate purchase price				212,700,000	$ 48,100,000
Southland [Member]
Business Acquisition [Line Items]
Business acquisition approximate purchase price			$ 130,000,000
Approximate annual shipment tons | T			240,000
Southland [Member] | Alabama [Member]
Business Acquisition [Line Items]
Number of manufacturing facilities | Facility			1
St. Louis Cold Drawn, Inc. [Member]
Business Acquisition [Line Items]
Business acquisition approximate purchase price	$ 60,000,000
Approximate annual shipment tons | T	200,000
Number of manufacturing facilities | Facility	2
St. Louis Cold Drawn, Inc. [Member] | St Louis Missouri [Member]
Business Acquisition [Line Items]
Number of manufacturing facilities | Facility	1
St. Louis Cold Drawn, Inc. [Member] | Monterrey, Mexico [Member]
Business Acquisition [Line Items]
Number of manufacturing facilities | Facility	1
Steel Mills [Member]
Business Acquisition [Line Items]
Goodwill				$ 745,484,000		$ 620,156,000
Steel Mills [Member] | Republic [Member]
Business Acquisition [Line Items]
Goodwill		115,600,000
Goodwill expected to be deductible for tax purposes		$ 118,600,000

Acquisitions and Dispositions40

Acquisitions and Dispositions - Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Jan. 20, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 2,208,246		$ 2,052,728
Republic [Member]
Business Acquisition [Line Items]
Cash		$ 206
Accounts receivable		39,177
Inventory		33,561
Other current assets		1,101
Property, plant and equipment		67,412
Goodwill		115,562
Other intangible assets		89,200
Other assets		3,118
Total assets acquired		349,337
Current liabilities		17,743
Total liabilities assumed		17,743
Net assets acquired		$ 331,594

Acquisitions and Dispositions41

Acquisitions and Dispositions - Purchase Price Allocation of Identifiable Intangible Assets (Detail) - Republic [Member] $ in Thousands	Jan. 20, 2017USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 89,200
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 80,800
Weighted - Average Life	12 years
Trademarks and Trade Names [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 8,400
Weighted - Average Life	13 years

Inventories - Additional Inform

Inventories - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials and supplies in inventory, percentage	43.00%	37.00%
Finished and semi-finished products in inventory, percentage	57.00%	63.00%
Lower of cost or market adjustments	$ 1.9	$ 2.2

Property, Plant and Equipment -

Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 8,610,000	$ 8,160,000
Property, plant and equipment, net	5,095,880	5,078,650
Group Of Wells Assets With Carrying Value Closest To Its Undiscounted Cash Flows [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	74,000	$ 80,800
Other Groups of Wells Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	$ 183,900

Goodwill and Other Intangible44

Goodwill and Other Intangible Assets - Schedule of Change in Net Carrying Amount of Goodwill by Segment (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)
Goodwill [Line Items]
Balance, beginning of period	$ 2,052,728
Acquisitions	132,485
Translation	23,033
Balance, end of period	2,208,246
Steel Mills [Member]
Goodwill [Line Items]
Balance, beginning of period	620,156
Acquisitions	125,328
Balance, end of period	745,484
Steel Products [Member]
Goodwill [Line Items]
Balance, beginning of period	702,995
Acquisitions	7,157
Translation	23,033
Balance, end of period	733,185
Raw Materials [Member]
Goodwill [Line Items]
Balance, beginning of period	729,577
Balance, end of period	$ 729,577

Goodwill and Other Intangible45

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016
Finite And Indefinite Lived Intangible Assets [Line Items]
Impairment of goodwill		$ 0
Intangible asset amortization expense	$ 23,000,000		$ 18,500,000	$ 68,400,000	$ 54,100,000
Future amortization expense, in 2017	91,200,000			91,200,000
Future amortization expense, in 2018	89,600,000			89,600,000
Future amortization expense, in 2019	86,700,000			86,700,000
Future amortization expense, in 2020	84,400,000			84,400,000
Future amortization expense, in 2021	$ 83,100,000			$ 83,100,000
Minimum [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, useful life				5 years		5 years
Maximum [Member]
Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets, useful life				22 years		22 years

Goodwill and Other Intangible46

Goodwill and Other Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	$ 1,662,326	$ 1,520,461
Intangible assets, Accumulated Amortization	722,021	653,626
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	1,422,569	1,295,803
Intangible assets, Accumulated Amortization	622,440	566,884
Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	176,950	161,851
Intangible assets, Accumulated Amortization	74,551	66,494
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	62,807	62,807
Intangible assets, Accumulated Amortization	$ 25,030	$ 20,248

Equity Investments - Additional

Equity Investments - Additional Information (Detail) $ in Thousands, € in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)	Oct. 01, 2016USD ($)	Sep. 30, 2017USD ($)Sheet	Oct. 01, 2016USD ($)	Sep. 30, 2017EUR (€)	Dec. 31, 2016USD ($)	Dec. 31, 2016EUR (€)
Schedule of Equity Method Investments [Line Items]
Equity method investment	$ 695,200		$ 695,200			$ 663,400
Distributions from affiliates			48,037	$ 38,474
Amortization expense due to fair value step-up			68,394	54,066
NuMit LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment	$ 311,900		$ 311,900			325,100
Equity method investment, ownership percentage	50.00%		50.00%		50.00%
Period used for lag basis, in months			1 month
Distributions from affiliates	$ 100	$ 500	$ 47,000	37,500
Steel Technologies LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	100.00%		100.00%		100.00%
Number of sheet processing facilities operated by Steel Technologies | Sheet			25
Duferdofin Nucor S.r.l. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment	$ 280,800		$ 280,800			256,600
Equity method investment, ownership percentage	50.00%		50.00%		50.00%
Period used for lag basis, in months			1 month
Equity method investments, share of net assets	$ 112,600		$ 112,600
Basis difference due to the step-up to fair value of certain assets and liabilities	168,200		168,200
Step-up to fair value of equity method investment, portion related to identification of goodwill	91,000
Amortization expense due to fair value step-up	2,300	$ 2,200	6,600	$ 6,600
Due from related parties, noncurrent	41,300		$ 41,300		€ 35	36,900	€ 35
Notes receivable, related parties, interest rate			0.83%
Interest rate per year in excess of Euribor as of date of the notes			1.00%
Equity method investments notes payable with parent company, maturity date			Jan. 31, 2019
Facility A [Member] | Duferdofin Nucor S.r.l. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments credit facilities, amount	144,600		$ 144,600		122.5
Total amount outstanding under equity method investments credit facilities	$ 144,600		$ 144,600		€ 122.5	$ 112,700	€ 107
Guarantor obligation percentage of exposure in case of default	50.00%		50.00%		50.00%
Line of credit facility, maturity period			Oct. 12, 2018

Current Liabilities - Additiona

Current Liabilities - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Liabilities, Current [Abstract]
Book overdrafts	$ 125.3	$ 61.3
Dividends payable, current	$ 121	$ 121.3

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	$ 50,000	$ 150,000
Total assets	16,503,834	15,223,518
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	1,143,259	1,609,523
Short-term investments	50,000	150,000
Commodity and foreign exchange contracts, assets	400	2,029
Total assets	1,193,659	1,761,552
Commodity and foreign exchange contracts, liabilities	(2,318)	(605)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	1,143,259	1,609,523
Short-term investments	50,000	150,000
Total assets	1,193,259	1,759,523
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	400	2,029
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Contracts and Foreign Exchange Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity and foreign exchange contracts, assets		2,029
Commodity and foreign exchange contracts, liabilities	(2,318)
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Commodity Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity and foreign exchange contracts, assets	$ 400
Commodity and foreign exchange contracts, liabilities		$ (605)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair value of short-term and long-term debt, including current maturities	$ 4,750	$ 4,700

Contingencies - Additional Info

Contingencies - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Accrual for environmental loss contingencies, gross	$ 18.7	$ 21.9
Accrued environmental loss contingencies, current	6.3	9.5
Accrued environmental loss contingencies, noncurrent	$ 12.4	$ 12.4

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017USD ($)	Oct. 01, 2016USD ($)	Sep. 30, 2017USD ($)AnniversariesInstallment	Oct. 01, 2016USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercise prices as percentage of the market value on the date of the grant			100.00%
Compensation expenses for stock options	$ 0.4	$ 0.3	$ 7.9	$ 7.6
Restricted Stock [Member] | LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Portion of restricted stock award vesting on anniversary			0.333%
Eligible age of officer for restricted stock award			55 years
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock	40.4		$ 40.4
Weighted-average recognition period for unrecognized compensation expense related to stock (years)			2 years 3 months 19 days
Number of anniversaries of grant date upon which restricted stock units vest | Anniversaries			3
Installments in which restricted stock units vest and are converted to common stock | Installment			3
Compensation expense	6.1	5.7	$ 32.2	28.9
Restricted Stock Units [Member] | AIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Eligible age of officer for restricted stock award			55 years
Amount of annual incentive award payment participant can elect to defer			50.00%
Additional common stock units for election of deferred annual incentive award, percentage			25.00%
Restricted Stock And Restricted Stock Units [Member] | AIP and LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to stock	1.3		$ 1.3
Weighted-average recognition period for unrecognized compensation expense related to stock (years)			1 year 10 months 25 days
Compensation expense	3.6	$ 0.7	$ 11.1	$ 7.7
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting period			3 years
Stock options term, years			10 years
Unrecognized compensation expense related to stock	$ 2.5		$ 2.5
Weighted-average recognition period for unrecognized compensation expense related to stock (years)			2 years 2 months 12 days

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Stock Option Plans Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)$ / sharesshares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding at beginning of year, Shares | shares	3,591
Granted, Shares | shares	698
Exercised, Shares | shares	(144)
Canceled, Shares | shares	0
Outstanding at end of year, Shares | shares	4,145
Stock Options exercisable at end of year, Shares | shares	1,848
Outstanding at beginning of year, Weighted - Average Exercise Price | $ / shares	$ 45.32
Granted, Weighted - Average Exercise Price | $ / shares	59.07
Exercised, Weighted - Average Exercise Price | $ / shares	37.54
Canceled, Weighted - Average Exercise Price | $ / shares	0
Outstanding at end of period, Weighted - Average Exercise Price | $ / shares	47.90
Stock options exercisable at end of year, Weighted - Average Exercise Price | $ / shares	$ 43.37
Outstanding at end of period, Weighted - Average Remaining Contractual Life	7 years 4 days
Stock options exercisable at end of period, Weighted - Average Remaining Contractual Life	5 years 2 months 12 days
Exercised, Aggregate Intrinsic Value | $	$ 3,618
Outstanding at end of period, Aggregate Intrinsic Value | $	35,842
Stock options exercisable at end of period, Aggregate Intrinsic Value | $	$ 23,415

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Nucor's RSU Activity (Detail) shares in Thousands	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested at beginning of year, Shares	1,040
Granted, Shares	721
Vested, Shares	(634)
Canceled, Shares	(13)
Unvested at end of year, Shares	1,114
Unvested at beginning of year, Grant Date Fair Value | $ / shares	$ 48.47
Granted, Grant Date Fair Value | $ / shares	59.07
Vested, Grant Date Fair Value | $ / shares	53.21
Canceled, Grant Date Fair Value | $ / shares	50.21
Unvested at end of year, Grant Date Fair Value | $ / shares	$ 52.61
Restricted Stock Units and Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for future grants	7,268

Stock-Based Compensation - Su55

Stock-Based Compensation - Summary of Nucor's Restricted Stock Activity under AIP and LTIP (Detail) - Restricted Stock And Restricted Stock Units [Member] - AIP and LTIP [Member] shares in Thousands	9 Months Ended
	Sep. 30, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested at beginning of year, Shares	67
Granted, Shares	172
Vested, Shares	(144)
Canceled, Shares	0
Unvested at end of year, Shares	95
Shares reserved for future grants	683
Unvested at beginning of year, Grant Date Fair Value | $ / shares	$ 45.77
Granted, Grant Date Fair Value | $ / shares	60.62
Vested, Grant Date Fair Value | $ / shares	51.69
Canceled, Grant Date Fair Value | $ / shares	0
Unvested at end of year, Grant Date Fair Value | $ / shares	$ 54.45

Employee Benefit Plan - Additio

Employee Benefit Plan - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Employee Benefit Plan [Abstract]
Profit Sharing and Retirement Savings Plan, plan expense	$ 35.7	$ 38.5	$ 138.2	$ 86.3

Interest Expense (Income) - Sch

Interest Expense (Income) - Schedule of Components of Net Interest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Interest Revenue (Expense), Net [Abstract]
Interest expense	$ 47,621	$ 46,519	$ 141,486	$ 137,370
Interest income	(4,311)	(3,510)	(9,991)	(8,955)
Interest expense, net	$ 43,310	$ 43,009	$ 131,495	$ 128,415

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate	28.20%	31.60%
Benefit related to return to provision changes in estimate and state tax credits	$ 13,200,000
Non-current deferred tax assets included in other assets	600,000		$ 0
Non-current deferred tax liabilities included in deferred credits and other liabilities	$ 516,000,000		$ 558,600,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	Sep. 30, 2017	Oct. 01, 2016	Sep. 02, 2015
Common Stock [Member]
Stockholders' Equity [Line Items]
Stock repurchase program remaining amount	$ 738,000,000
Common Stock [Member] | Maximum [Member]
Stockholders' Equity [Line Items]
Stock repurchase program authorized amount			$ 900,000,000
Nucor-Yamato Steel Company [Member]
Stockholders' Equity [Line Items]
Noncontrolling interest, ownership percentage by parent	51.00%	51.00%

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Change in Stockholder's Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Stockholders' Equity [Line Items]
Stockholders' equity, beginning of period			$ 8,254,708	$ 7,849,877
Total comprehensive income	$ 341,184	$ 324,159	1,085,464	788,009
Stock options			13,300	13,229
Issuance of stock under award plans, net of forfeitures			30,787	25,929
Amortization of unearned compensation			1,000	600
Treasury stock acquired			(90,305)	(5,173)
Dividends declared			(364,046)	(360,955)
Distributions to noncontrolling interests			(85,094)	(86,808)
Other				(2,378)
Stockholders' equity, end of period	8,845,814	8,222,330	8,845,814	8,222,330
Total Nucor Stockholders' Equity [Member]
Stockholders' Equity [Line Items]
Stockholders' equity, beginning of period			7,879,865	7,477,816
Total comprehensive income			1,034,784	699,410
Stock options			13,300	13,229
Issuance of stock under award plans, net of forfeitures			30,787	25,929
Amortization of unearned compensation			1,000	600
Treasury stock acquired			(90,305)	(5,173)
Dividends declared			(364,046)	(360,955)
Other				(602)
Stockholders' equity, end of period	8,505,385	7,850,254	8,505,385	7,850,254
Noncontrolling Interests [Member]
Stockholders' Equity [Line Items]
Stockholders' equity, beginning of period			374,843	372,061
Total comprehensive income			50,680	88,599
Distributions to noncontrolling interests			(85,094)	(86,808)
Other				(1,776)
Stockholders' equity, end of period	$ 340,429	$ 372,076	$ 340,429	$ 372,076

Accumulated Other Comprehensi61

Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance, Gains and Losses on Hedging Derivatives	$ (300)	$ (3,900)	$ 750	$ (11,700)
Other comprehensive income (loss) before reclassifications, Gains and Losses on Hedging Derivatives	405	(600)	(1,301)	912
Amounts reclassified from accumulated other comprehensive income (loss) into earnings, Gains and Losses on Hedging Derivatives	195	2,000	851	8,288
Net current-period other comprehensive income (loss), Gains and Losses on Hedging Derivatives	600	1,400	(450)	9,200
Ending Balance, Gains and Losses on Hedging Derivatives	300	(2,500)	300	(2,500)
Beginning Balance, Foreign Currency Gain (Loss)	(300,212)	(289,481)	(326,170)	(351,665)
Other comprehensive income (loss) before reclassifications, Foreign Currency Gain (Loss)	74,479	(8,606)	100,437	53,578
Amounts reclassified from accumulated other comprehensive income (loss) into earnings, Foreign Currency Gain (Loss)	0	0	0	0
Net current-period other comprehensive income (loss), Foreign Currency Gain (Loss)	74,479	(8,606)	100,437	53,578
Ending Balance, Foreign Currency Gain (Loss)	(225,733)	(298,087)	(225,733)	(298,087)
Beginning Balance, Adjustment to Early Retiree Medical Plan	7,577	12,003	7,577	12,003
Other comprehensive income (loss) before reclassifications, Adjustment to Early Retiree Medical Plan	0	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss) into earnings, Adjustment to Early Retiree Medical Plan	0	0	0	0
Net current-period other comprehensive income (loss), Adjustment to Early Retiree Medical Plan	0	0	0	0
Ending Balance, Adjustment to Early Retiree Medical Plan	7,577	12,003	7,577	12,003
Beginning Balance, Accumulated Other Comprehensive Loss	(292,935)	(281,378)	(317,843)	(351,362)
Other comprehensive income (loss) before reclassifications	74,884	(9,206)	99,136	54,490
Amounts reclassified from accumulated other comprehensive income (loss) into earnings	195	2,000	851	8,288
Net current-period other comprehensive income (loss)	75,079	(7,206)	99,987	62,778
Ending Balance, Accumulated Other Comprehensive Loss	$ (217,856)	$ (288,584)	$ (217,856)	$ (288,584)

Accumulated Other Comprehensi62

Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss) into earnings, Gains and Losses on Hedging Derivatives	$ 195	$ 2,000	$ 851	$ 8,288
AOCI reclassification impact on tax	0	1,200	300	4,800
Cost of Products Sold [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss) into earnings, Gains and Losses on Hedging Derivatives	195	2,000	851	8,288
AOCI reclassification impact on tax	$ 0	$ 1,200	$ 300	$ 4,800

Segments - Additional Informati

Segments - Additional Information (Detail)	3 Months Ended
	Oct. 01, 2016
Hunter Ridge Energy Services LLC [Member]
Segment Reporting Information [Line Items]
Equity method investment ownership percentage, percentage of investee's ownership interest sold	50.00%

Segments - Segments (Detail)

Segments - Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net sales	$ 5,170,117	$ 4,290,236	$ 15,160,065	$ 12,251,584
Earnings (loss) before income taxes and noncontrolling interests	370,605	484,172	1,427,716	1,043,619
Total assets	16,503,834		16,503,834		$ 15,223,518
Operating Segments [Member] | Steel Mills [Member]
Segment Reporting Information [Line Items]
Net sales	3,639,488	2,960,642	10,982,636	8,611,553
Earnings (loss) before income taxes and noncontrolling interests	432,718	591,799	1,734,245	1,402,898
Total assets	9,272,209		9,272,209		8,084,773
Operating Segments [Member] | Steel Products [Member]
Segment Reporting Information [Line Items]
Net sales	1,089,519	1,011,602	2,919,992	2,763,335
Earnings (loss) before income taxes and noncontrolling interests	59,225	72,578	131,956	197,891
Total assets	2,893,703		2,893,703		2,544,344
Operating Segments [Member] | Raw Materials [Member]
Segment Reporting Information [Line Items]
Net sales	441,110	317,992	1,257,437	876,696
Earnings (loss) before income taxes and noncontrolling interests	9,957	14,313	102,575	(76,240)
Total assets	3,462,340		3,462,340		3,235,237
Intercompany Eliminations [Member] | Steel Mills [Member]
Segment Reporting Information [Line Items]
Net sales	767,268	567,854	2,189,123	1,592,512
Intercompany Eliminations [Member] | Steel Products [Member]
Segment Reporting Information [Line Items]
Net sales	28,537	31,117	80,652	80,277
Intercompany Eliminations [Member] | Raw Materials [Member]
Segment Reporting Information [Line Items]
Net sales	2,333,840	1,774,538	6,971,831	4,717,370
Corporate and Eliminations Items [Member]
Segment Reporting Information [Line Items]
Net sales	(3,129,645)	(2,373,509)	(9,241,606)	(6,390,159)
Earnings (loss) before income taxes and noncontrolling interests	(131,295)	$ (194,518)	(541,060)	$ (480,930)
Total assets	$ 875,582		$ 875,582		$ 1,359,164

Earnings Per Share - Computatio

Earnings Per Share - Computations of Basic and Diluted Net Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Earnings Per Share [Abstract]
Basic net earnings	$ 254,850	$ 305,447	$ 934,797	$ 636,632
Earnings allocated to participating securities, Basic	(900)	(1,034)	(3,239)	(2,115)
Net earnings available to common stockholders, Basic	$ 253,950	$ 304,413	$ 931,558	$ 634,517
Average shares outstanding	320,096	319,737	320,253	319,444
Basic net earnings per share	$ 0.79	$ 0.95	$ 2.91	$ 1.99
Diluted net earnings	$ 254,850	$ 305,447	$ 934,797	$ 636,632
Earnings allocated to participating securities, Diluted	(899)	(1,034)	(3,233)	(2,116)
Net earnings available to common stockholders, Diluted	$ 253,951	$ 304,413	$ 931,564	$ 634,516
Basic shares outstanding	320,096	319,737	320,253	319,444
Dilutive effect of stock options and other	667	291	792	188
Diluted average shares outstanding	320,763	320,028	321,045	319,632
Diluted net earnings per share	$ 0.79	$ 0.95	$ 2.90	$ 1.99

Earnings Per Share - Anti-dilut

Earnings Per Share - Anti-dilutive Stock Options (Detail) - $ / shares shares in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Oct. 01, 2016
Earnings Per Share [Abstract]
Weighted-average shares	698	309	1,254
Weighted-average exercise price	$ 59.07	$ 59.07	$ 47.04

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2017$ / shares
Subsequent Events [Abstract]
Diluted share expense related to subsequent event	$ 0.05