Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228

EARNINGS PER SHARE (Details) - USD ($)	3 Months Ended			9 Months Ended
EARNINGS PER SHARE (Details) - USD ($)	Sep. 29, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ 4,448,000		$ 35,208,000	$ 76,689,000	$ 119,851,000
Shares outstanding basic (in shares)	22,215,000		22,527,000	22,421,000	22,505,000
Per share amount basic (in dollars per share)	$ 0.20		$ 1.56	$ 3.42	$ 5.33
Dilutive Effect of Stock Options
Dilutive Effect of Stock Options	$ 0		$ 0	$ 0	$ 0
Dilutive effect of stock options number of shares (in shares)	137,000		224,000	153,000	212,000
Dilutive effect of stock options (in dollars per share)	$ 0.00		$ (0.01)	$ (0.02)	$ (0.05)
Diluted EPS
Diluted EPS	$ 4,448,000		$ 35,208,000	$ 76,689,000	$ 119,851,000
Shares outstanding dilutive (in shares)	22,352,000		22,751,000	22,574,000	22,717,000
Per share amount diluted (in dollars per share)	$ 0.20		$ 1.55	$ 3.40	$ 5.28
Impact on net income (loss) available for common stockholders	$ (4,448,000)		$ (35,208,000)	$ (76,689,000)	$ (119,851,000)
Impact effect on earnings per share basic (in dollars per share)	$ (0.20)		$ (1.56)	$ (3.42)	$ (5.33)
Impact effect on net income (loss) available to common stockholders, diluted (in dollars per share)	$ (4,448,000)		$ (35,208,000)	$ (76,689,000)	$ (119,851,000)
Impact effect on earnings per share diluted (in dollars per share)	$ (0.20)		$ (1.55)	$ (3.40)	$ (5.28)
Antidilutive Securities
Outstanding stock options with exercise prices exceeding the market price of common stock, excluded from the computation of diluted earnings per share (in shares)				190,021	0
2018 Restructuring Plan
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ (7,858,000)			$ (17,478,000)
Per share amount basic (in dollars per share)	$ (0.35)			$ (0.77)
Diluted EPS
Diluted EPS	$ (7,858,000)			$ (17,478,000)
Per share amount diluted (in dollars per share)	$ (0.35)			$ (0.77)
Impact on net income (loss) available for common stockholders	$ 7,858,000			$ 17,478,000
Impact effect on earnings per share basic (in dollars per share)	$ 0.35			$ 0.77
Impact effect on net income (loss) available to common stockholders, diluted (in dollars per share)	$ 7,858,000			$ 17,478,000
Impact effect on earnings per share diluted (in dollars per share)	$ 0.35			$ 0.77
Donhad \| Disposed by sale
Basic EPS
Net earnings attributable to Valmont Industries, Inc.		$ 5,455,000
Per share amount basic (in dollars per share)		$ 0.24
Diluted EPS
Diluted EPS		$ (5,455,000)
Per share amount diluted (in dollars per share)		$ (0.24)
Impact on net income (loss) available for common stockholders		$ (5,455,000)
Impact effect on earnings per share basic (in dollars per share)		$ (0.24)
Impact effect on net income (loss) available to common stockholders, diluted (in dollars per share)		$ 5,455,000
Impact effect on earnings per share diluted (in dollars per share)		$ 0.24
2018 Acquisitions [Member]
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ (2,349,000)			$ (3,155,000)
Per share amount basic (in dollars per share)	$ (0.11)			$ (0.14)
Diluted EPS
Diluted EPS	$ (2,349,000)			$ (3,155,000)
Per share amount diluted (in dollars per share)	$ (0.11)			$ (0.14)
Impact on net income (loss) available for common stockholders	$ 2,349,000			$ 3,155,000
Impact effect on earnings per share basic (in dollars per share)	$ 0.11			$ 0.14
Impact effect on net income (loss) available to common stockholders, diluted (in dollars per share)	$ 2,349,000			$ 3,155,000
Impact effect on earnings per share diluted (in dollars per share)	$ 0.11			$ 0.14
Senior Unsecured Notes 6.625% Due 2020 \| Senior Unsecured Notes
Basic EPS
Net earnings attributable to Valmont Industries, Inc.	$ (11,115,000)
Per share amount basic (in dollars per share)	$ (0.50)
Diluted EPS
Diluted EPS	$ (11,115,000)
Per share amount diluted (in dollars per share)	$ (0.50)
Impact on net income (loss) available for common stockholders	$ 11,115,000
Impact effect on earnings per share basic (in dollars per share)	$ 0.50
Impact effect on net income (loss) available to common stockholders, diluted (in dollars per share)	$ 11,115,000
Impact effect on earnings per share diluted (in dollars per share)	$ 0.50
Goodwill and trade name
Diluted EPS
Asset impairment charges effect on net income (loss) available for common stockholders	$ 15,479,000
Impairment effect on earnings per share (in dollars per share)	$ 0.69